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Biodegradable membranes loaded with curcumin to be used as engineered independent devices in active packaging
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Biodegradable membranes loaded with curcumin to be used as engineered independent devices in active packaging Lucia Baldino, Stefano Cardea, Ernesto Reverchon∗ Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy
a r t i c l e
i n f o
Article history: Received 28 April 2016 Revised 8 November 2016 Accepted 17 December 2016 Available online xxx Keywords: Curcumin Cellulose acetate Antioxidant membranes Antimicrobial membranes Supercritical phase inversion Active packaging
a b s t r a c t Curcumin is an excellent candidate to be used in the realization of controlled release devices for food packaging. Various techniques have been tested to produce these devices but, among them, SC-CO2 assisted phase inversion has been particularly successful. Biodegradable cellulose acetate + curcumin nanostructured membranes have been developed in this study: we tested different process conditions (12–24% w/w polymer concentration, 10–20% w/w curcumin, 35–55 °C, 150–250 bar), obtaining an uniform distribution at nanometric level of curcumin and producing, in a fast process, practically solvent free membranes (5 ppm acetone residue). Moreover, it has been possible to modulate membrane pore size obtaining a very long continued release of curcumin that maintained more than 90% of native antioxidant activity. © 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
1. Introduction The main cause of the spoilage of a great variety of foods is lipid oxidation and microbial growth inside the packaging. The direct addition of antioxidants and/or antimicrobial agents is frequently used; however, this technique can modify the taste and/or the aspect of the food and, as a rule, the action of the additive is largely not optimized. An alternative to this method, is the use of an active packaging [1,2] that can perform the sustained release of the antioxidant/antimicrobial compound during storage and, thus, can largely increase the shelf-life of the food preparation. Active packaging of different kind has been proposed that can be divided in two categories: independent devices and active packaging materials [3–6]. Curcumin is a polyphenolic compound and is the main phytochemical compound contained in Curcuma longa L. It has been demonstrated that it exerts antioxidant and antimicrobial activities [7]. It was resulted to be safe even at high doses (12 g/day) in clinical trials in human [7]. Therefore, several studies have been performed about its use as antibiotic [8], antiviral [9] and antifungal [10] drug. Moreover, it is a well established food additive and coloring matter [11,12]. Therefore, curcumin is an excellent candidate to be used in the realization of controlled release devices for food packaging and medical applications. Some studies have ∗
Corresponding author. E-mail address: [email protected] (E. Reverchon). URL: http://www.supercriticalfluidgroup.unisa.it (E. Reverchon)
been recently published, proposing these applications. Vimala et al. (2011) produced curcumin encapsulated in chitosan–poly(vinyl alcohol)–silver nanocomposite films as antimicrobial packaging, wound dressing and antibacterial materials. They observed a significant reduction of E. coli growth when these films were tested, compared to the action of curcumin and nanocomposite film alone. However, a maximum curcumin released concentration was obtained after only 10 h and glutaraldehyde, used during the processing, unreacted toxic residues were not determined [13]. Wan et al. (2011) developed a sustained-release of curcumin employing a water-insoluble carrier based on cellulose acetate. Films were obtained by solvent evaporation. The curcumin release was controlled up to 12 h, since the solid dispersion of cellulose acetate and curcumin induced the transformation of curcumin from the crystalline to the amorphous state, increasing drug dissolution rate; whereas, water insolubility of the carrier controlled the drug release [14]. Luo et al. (2012) prepared cellulose/curcumin composite films with different curcumin contents by solution casting using a ionic liquid to dissolve both curcumin and cellulose. Dense films were obtained and they found that the inhibition action of these films was proportional to the curcumin content in the composite film. No release studies were performed [15]. Sonkaew et al. (2012) produced by supercritical CO2 based RESOLV, curcumin and ascorbyl dipalmitate nanoparticles with average sizes of about 50 and 80 nm, respectively. Then, these nanoparticles were incorporated into cellulose films that exhibited a maximum antioxidant activity of about 57%. Also in this case, no release tests were performed [16].
http://dx.doi.org/10.1016/j.jtice.2016.12.020 1876-1070/© 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Please cite this article as: L. Baldino et al., Biodegradable membranes loaded with curcumin to be used as engineered independent devices in active packaging, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.12.020
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from Morlando Group S.R.L. (Sant’Antimo, NA – Italy). All materials were processed as received. 2.2. Preparation of curcumin loaded membranes
Fig. 1. Untreated curcumin powder.
Processes assisted by supercritical CO2 (SC-CO2 ) have been proposed as alternative to traditional ones, for example for micro and nanoparticles production [17–20], extraction [21–25] and membranes and aerogel preparation [26–32]. Among these supercritical processes, the formation of membranes by SC-CO2 assisted phase inversion has been particularly successful [33–37] In this specific process, SC-CO2 acts as the non-solvent for the polymer and as the solvent for the liquid used to dissolve the polymer. The result is a phase inversion process with the formation of a continuous polymer phase and a supercritical (liquid + CO2 ) discontinuous phase, that is released during the process, producing porous interconnected structures [33,38]. The advantages of this technique over the liquid-liquid based process [39] or solvent evaporation [40] are the flexibility of SC-CO2 action with pressure and temperature, that allows to produce, in a very fast one step process, membranes tailored in morphology and pore size, and the complete elimination of the liquid solvent. Therefore, a dry and solvent free membrane is produced without any post-processing step and the other compounds eventually present in the starting solution (e.g., the active principles) are, as a rule, well distributed and does not suffer degradation, decomposition and/or deactivation [27]. Therefore, considering the literature analysis, the scope of this work is to produce completely degradable structures to be used as independent devices to be added in food packaging for the prolonged controlled release of curcumin that can be tailored on different contaminants/microorganisms loading in the starting food material. Membranes of cellulose acetate (CA) containing curcumin (Cm) will be produced by SC-CO2 phase inversion, using this process to control the morphology of the obtained nano-structured membranes [41]. Release studies will be performed on these membranes, to verify the preservation of the antioxidant activity of curcumin, the control and the length of the release of the active principle in an appropriate liquid medium.
2. Materials and methods 2.1. Chemicals Cellulose acetate, CA, (average Mn ca. 50,0 0 0 with acetyl content of 39.7%), Acetone (purity 99.5%), curcumin, Cm, (purity >65%; the raw material is shown in Fig. 1), Ethanol (purity >99.8%) and DPPH• (2,2-diphenyl-1-picryl-hydrazyl) were bought from Sigma–Aldrich (Milan, Italy); CO2 (purity 99%) was purchased
Solutions were prepared by dissolving CA at 12, 18 and 24% w/w in acetone at 40 °C, 100 rpm for 12 h. Then, Cm, at 10 or 20% w/w with respect to CA, was added to the solutions, that were mixed for the other 5 h at 40 °C and 100 rpm. The obtained solutions, were distributed on stainless steel caps, having a diameter of 2 cm and an height of about 1 mm. The caps were rapidly put inside the high pressure vessel (a 316 stainless steel vessel with an internal volume of 200 ml) to minimize evaporation of the solvent. The vessel was closed and filled with SC-CO2 up to the desired pressure, using a high pressure pump (mod. LDB1, Lewa, Germany). Then, they were processed by supercritical CO2 phase inversion at different process conditions: temperatures ranging between 35 and 55 °C, pressures ranging between 150 and 250 bar, for 3 h. Pressure in the vessel was measured by a test gauge (mod. MP1, OMET, Italy) and regulated using a micrometering valve (mod. 1335G4Y, Hoke, USA). Temperature was regulated using PID controllers (mod. 305, Watlow, USA). At the exit of the vessel, a rotameter (mod. D6, ASA, Italy) was used to measure CO2 flow rate, that was maintained constant at 1.5 kg/h. 2.3. Analytical methods 2.3.1. Field emission scanning electron microscopy (FESEM) Membranes were cryo-fractured using liquid nitrogen (SOL, Milan, Italy); then, the samples were sputter coated with gold (Agar Auto Sputter Coater mod. 108 A, Stansted, UK) at 30 mA for 160 s and analyzed by a FESEM (mod. LEO 1525, Carl Zeiss SMT AG, Oberkochen, Germany) to study membrane morphology. 2.3.2. Membrane pore size analysis Sigma Scan Pro 5.0 (Jandel Scientific, San Rafael, Canada) and Origin 8.5 (Microcal, Northampton, USA) were used to determine the average diameter of membrane pores. Images taken at various locations in the membrane were used for each calculation. About 300 pores for each sample were measured. Using Origin software, we first represented a histogram with the percentage of the pores having a given diameter; then, we performed a curve fitting to obtain the pore size distribution curve. 2.3.3. Differential scanning calorimetry (DSC) DSC (DSC 30 Mettler, Toledo, Spain) was carried out to analyze and identify any changes in the thermograms of pure substances compared to polymer/drug formulations. Calorimetric analysis was performed in the temperature range between −60 and 300 °C, with a heating rate of 10 °C/min; the inert gas was Nitrogen, with a flow rate of 50 l/min. 2.3.4. Solvent residue analysis Acetone residue was measured by a headspace (HS) sampler (mod. 7694E, Hewlett Packard, USA) coupled to a gas chromatograph (GC) interfaced with a flame ionization detector (GC-FID, mod. 6890 GC-SYSTEM, Hewlett Packard, USA). Acetone was separated using two fused-silica capillary columns connected in series by press-fit: the first column (mod. Carbomax EASYSEP, Stepbios, Italy) connected to the detector, 30 m length, 0.53 mm i.d., 1 μm film thickness and the second one (mod. Cp Sil 5CB CHROMPACK, Stepbios, Italy) connected to the injector; 25 m length, 0.53 mm i.d., 5 μm film thickness. GC conditions were the one described in the USP 467 Pharmacopea with some minor modifications: oven temperature from 45 to 210 °C for 15 min. The injector was maintained at 135 °C (split mode, ratio 4:1) and helium was used as
Please cite this article as: L. Baldino et al., Biodegradable membranes loaded with curcumin to be used as engineered independent devices in active packaging, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.12.020
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the carrier gas (5 ml/min). Head space conditions were: equilibration time, 30 min at 95 °C; pressurization time, 0.15 min, and loop fill time, 0.15 min. Head space samples were prepared in 20-ml vials filled with internal standard DMI (3 ml) and 500 mg of NaCl and water (0.75 ml) in which samples of CA+Cm membrane were suspended. 2.3.5. Curcumin release test Cm release kinetics were determined by measuring the increase of drug concentration in 100 ml of an aqueous solution at 80% v/v distilled water and 20% v/v ethanol (Simulant C, according to the Regulation (UE) N. 10/2011), at room temperature. Cm loaded membrane was placed in a bottle containing the medium, which simulates the food environment, and stirred at 50 rpm. To determine the Cm release rate from the membrane and its concentration, analysis was carried out in continuous using a Varian (mod. Cary 50, Palo Alto, CA) UV/Vis spectrophotometer and reading the absorbance of the sample at 430 nm, which is the wavelength at which Cm shows maximum absorption. 2.3.6. Antioxidant activity test The radical scavenging capacity of the CA+Cm membranes was determined by DPPH• method. A 0.1 mM solution of DPPH• was prepared in ethanol and 1 ml of this solution was added to 3 ml of the solution Cm+water+ethanol, obtained from the release test previously performed. This final solution was mixed by Vortex for 2 min and incubated in the dark for 30 min at room temperature. The absorbance was measured at 517 nm. The capability to scavenge the DPPH• radical was calculated using the following equation:
I (% ) =
1−
As Ac
× 100
where Ac is the absorbance of the control (1 ml, DPPH• solution without Cm) and As is the absorbance of the solution in the presence of Cm [42]. 3. Results and discussion 3.1. Effect of process parameters on membranes morphology The morphology of the CA membranes obtained by SC-CO2 phase inversion has been studied in a previous work [33]. Cellular membranes were obtained that presented a very regular shape and pore distribution and were characterized by connected pores ranging between 2 and 50 μm for CA concentrations between 40 and 5% w/w in acetone. In this work, we performed a series of membrane formation experiments at 250 bar, 35 °C and 3 h contacting time. Acetone was used as the solvent, since CA and Cm are largely soluble in it. CA membranes at 12, 18 and 24% w/w were produced, containing a percentage of 10% or 20% w/w of Cm with respect the CA content. In Fig. 2, a macroscopic view of these membranes is reported: the starting CA membrane is white; whereas, the CA+Cm membrane shows a uniform yellow color due to Cm presence. This first qualitative evidence demonstrates that curcumin after the supercritical process was homogeneously distributed in the polymer matrix, as a consequence of the fast supercritical fluid assisted process that avoided drug irregular deposition inside the membrane. This qualitative information was, then, verified during microscopic characterizations. FESEM images in Fig. 3 report an example of the morphology shown by CA+Cm membranes at different magnifications. The regularity of the structure was confirmed also at microscopic level; particularly the SEM image on the left shows the whole section of the membrane and the image on the right
a
3
b
Fig. 2. Pictures of (a) CA membrane, (b) CA+Cm membrane produced by supercritical phase inversion. (For interpretation of the references to color in this figure, the reader is referred to the web version of this article.)
confirms the very uniform pores distribution. These membranes retained cellular morphology as those formed by CA alone, demonstrating that the presence of curcumin, at the concentrations used in this work, does not interfere on the formation of the continuous polymeric phase. The only differences are given by pore size distributions, as shown in Fig. 4. The membranes at 10% w/w Cm show a mean pore size that decreases with CA content from about 9.6 μm to 9.3 μm to 6.0 μm for CA % of 12, 18 and 24% w/w, respectively. Similar trend was observed for 20% w/w Cm membranes. Then, we maintained the CA contents at 12, 18 and 24% w/w and Cm loading at 10 or 20% w/w with respect to CA and explored different process conditions operating at 150 bar, 55 °C and 200 bar, 45 °C, thus producing a sensible difference in SC-CO2 density, from 0.66 g/cm3 to 0.81 g/cm3 , respectively. The scope of these experiments was to evaluate the influence of SC-CO2 solvent power, which is related to mainly on its density, on the membrane morphology [33]. In all the cases studied, we produced cellular membranes; the different process conditions only influenced the pore size distribution, as it is summarized in Fig. 5, where pore size distributions are reported, for example, for the experiments performed using 24% w/w CA and 10% w/w Cm in the starting solution. The mean pore size increases and its distribution enlarges (standard deviation values: 1.50, 2.60, 2.70 μm for p/T values 250/35, 200/45, 150/55) when SC-CO2 density is decreased. The data collected for all the produced membranes are shown in Table 1. It is also possible to compare the pore mean diameter of the membranes obtained at different Cm loadings (i.e., 10% w/w and 20% w/w), observing data reported in Table 1. In particular, the mean pore size increases at all process conditions tested, increasing Cm percentage; this result can be explained considering that the increase of Cm content probably obstacles the phase separation, making it slower. As a consequence, the pores grow for a longer time until the phase separation process is completed (i.e., larger pores are generated). Solvent residue analyses were also performed, as described in materials and methods section, and acetone residue presenting in the membranes was found to be lower than 5 ppm, at all process conditions tested. 3.2. Membranes characterization We performed extensive DSC analyses comparing the thermograms of unprocessed CA, Cm, CA+Cm physical mixture and CA membranes containing 10 and 20% w/w Cm. The thermograms are summarized in Fig. 6. CA alone shows a glass transition temperature at about 75 °C and a melting temperature at about 230 °C;
Please cite this article as: L. Baldino et al., Biodegradable membranes loaded with curcumin to be used as engineered independent devices in active packaging, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.12.020
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Fig. 3. FESEM pictures at different magnifications of a 24% w/w CA membrane section loaded at 10% w/w Cm; process conditions 250 bar, 35 °C, 3 h. Table 1 Mean pore diameter ± standard deviation (μm) of the CA membranes loaded at 10% w/w or 20% w/w Cm and at all different process conditions used in this work. Cm 10% w/w CA 12% w/w 150 bar – 55 °C 200 bar – 45 °C 250 bar – 35 °C
12.61 ± 3.85 10.73 ± 2.94 9.58 ± 2.01
Cm 20% w/w CA 18% w/w 10.23 ± 2.86 10.20 ± 2.78 9.30 ± 1.87
CA 24% w/w
CA 12% w/w
8.40 ± 2.72 7.38 ± 2.60 6.07 ± 1.53
16.48 ± 6.66 12.86 ± 6.06 12.42 ± 3.15
CA 18% w/w 15.96 ± 4.20 12.38 ± 3.92 10.67 ± 3.05
CA 24% w/w 14.57 ± 3.53 10.84 ± 3.35 8.55 ± 2.68
Fig. 4. Pore size distribution of 10% w/w Cm loaded CA membranes phase separated at 250 bar, 35 °C for 3 h and at different CA content: 12, 18 and 24% w/w.
Fig. 5. Pore size distribution of membranes at 24% w/w CA loaded with 10% w/w Cm, phase separated at different SC-CO2 solvent power.
curcumin alone is crystalline, showing a sharp peak at 175 °C; the physical mixture shows the presence of CA and Cm peaks, the membrane containing 10% w/w Cm shows only the peak related to CA glass transition temperature, indicating that in this case both the compounds are amorphous after supercritical processing. The membrane containing 20% w/w Cm (Fig. 6(e)), surprisingly, shows a second small sharp peak related to curcumin, that, in this case, should be at least partly crystalline.
This last result induced us to perform other series of FESEM analyses on membranes section and external surfaces. We did not find any indication of curcumin presence in FESEM images of CA membranes at 10% w/w Cm: these evidences confirm a nanometric dispersion of curcumin inside the CA porous matrix. In the case of 20% w/w Cm membranes, instead, we found micrometric curcumin crystals randomly located inside the polymeric structure as
Please cite this article as: L. Baldino et al., Biodegradable membranes loaded with curcumin to be used as engineered independent devices in active packaging, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.12.020
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a
b
c
d
e
Fig. 6. Thermograms of: (a) CA, (b) Cm, (c) CA+Cm physical mixture, (d) CA membrane loaded at 10% w/w Cm and (e) CA membrane loaded at 20% w/w Cm.
Please cite this article as: L. Baldino et al., Biodegradable membranes loaded with curcumin to be used as engineered independent devices in active packaging, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.12.020
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Fig. 7. Pictures at different magnifications of Cm crystals dispersed inside the CA membrane, phase separated at 250 bar, 35 °C.
a
b
Fig. 8. Pictures of the H2 O+EtOH medium before (a) and after (b) a curcumin release from a CA membrane. (For interpretation of the references to color in this figure, the reader is referred to the web version of this article.)
shown in the images reported in Fig. 7. Therefore, at the higher curcumin percentage tested, part of curcumin re-crystallized inside the membrane structure. This result is in agreement with the indications given by DSC analysis, related to the appearance of signals of curcumin crystallinity. However, only the internal content of the pores of the membranes was partly changed; no modification of the external surfaces was observed. The explanation of all these observations is that when 20% w/w Cm loading was used, part of curcumin started to crystallize independently on the polymeric structure: this behavior was induced by supersaturation of curcumin during membrane formation. Moreover, this aspect also influences the phase separation rate, confirming the hypothesis, reported above, about the effect of Cm loading on pores size (i.e., increasing the Cm loading, the phase separation is slower and the pores have more time to growth).
3.3. Cm release tests from CA membranes Extensive series of UV/Vis release tests of curcumin from the produced CA membranes were performed using the technique described in materials and methods. In Fig. 8, a macroscopic evidence related to the color of H2 O+EtOH medium, before (Fig. 8(a)) and after (Fig. 8(b)) a curcumin release test, is reported. It
is clearly visible the yellow color confirming that curcumin was released from the CA membrane. In the case of curcumin loading at 10% w/w CA, the Cm release curves were largely dependent on CA percentage and, correspondingly, on the membranes pore diameter, as indicated, for example, for the case 250 bar, 35 °C, reported in Fig. 9(a). In this diagram, the Cm concentration measured during the time (Ct ), normalized to the maximum Cm concentration detected (Cinf ) versus time, is represented. Only 1.8 h was necessary to obtain the maximum concentration of curcumin in the dissolution medium in the case of the membrane at 12% w/w CA; after 8.4 h curcumin maximum concentration was obtained for 18% w/w CA and the longest time to reach the maximum curcumin concentration was 58 h for 24% w/w CA membranes. In particular, the more compact structure observed for membranes at 24% w/w CA (due to the smaller pores) showed a very relevant influence on the release rate of Cm. Similar results were obtained for the loaded membranes produced during the experiments performed at 150 bar, 55 °C and 200 bar, 45 °C (figures not reported) though the Cm release times were very different: for example, the membranes produced at 150 bar, 55 °C and 24% w/w CA, reached the maximum Cm concentration in the release medium after only about 10 h, confirming the relevance of the pores diameter on the control of curcumin release from these membranes. A different behavior was observed for CA membranes loaded with 20% Cm w/w CA. As shown in Fig. 9(b), which is again referred to 250 bar, 35 °C processing conditions, the Cm release times were relatively similar for the different CA percentage in the membranes. Similar results were also obtained for membranes (not shown) produced at the other two process conditions (150 bar, 55 °C; 200 bar, 45 °C), maintaining the Cm loading at 20% w/w CA. In these cases, very longer times were observed with respect to the analogous membranes produced at 10% w/w Cm loading: this aspect is very interesting. The values measured for CA membranes loaded at 10 and 20% w/w Cm are summarized in Table 2. For all membranes tested, no evidence of polymer swelling during the Cm release test was observed. Summarizing, the dependence of Cm release rate from pores diameter for membranes at 20% Cm is less marked that for the membranes loaded at 10% w/w Cm; moreover, very long release times were observed. An explanation of the different behavior between these membranes is given by the deposition of curcumin crystals inside the membrane pores, as observed in Fig. 7. In the case 10% w/w Cm membranes, the active principle is nanodispersed inside the membrane structure; indeed, no curcumin particles were detected. In the case of 20% w/w Cm membranes,
Please cite this article as: L. Baldino et al., Biodegradable membranes loaded with curcumin to be used as engineered independent devices in active packaging, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.12.020
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Table 2 Time required (h) to reach the maximum Cm concentration in the medium for CA membranes loaded at 10% w/w or 20% w/w Cm and at all different phase inversion conditions used in this work. Cm 10% w/w
150 bar – 55 °C 200 bar – 45 °C 250 bar – 35 °C
Cm 20% w/w
CA 12% w/w
CA 18% w/w
CA 24% w/w
CA 12% w/w
CA 18% w/w
CA 24% w/w
1.0 1.7 1.8
1.7 2.5 8.4
10.0 45.0 58.0
22 27 35
25 45 47
56 57 66
instead, the active principle is partly dispersed in the membrane at nanometric level and partly organized inside the membrane cells as microcrystals. It is reasonable to suppose that curcumin microcrystals were not readily solubilizable by the release medium and, therefore, longer release times were required, that can be relatively similar for the various membranes: microcrystals dissolution partly controlled curcumin release in the liquid medium. Therefore, CA membranes containing 10% w/w Cm are true nanostructured devices and active principle release is only controlled by membrane pore size; CA membranes at 20% w/w Cm contain part of Cm at nanometric level and part of Cm as microcrystals and show a control of Cm release partly due to pores diameter and partly related to Cm microcrystals dissolution. We also compared these results with the Cm release from the physical mixture CA+Cm, containing 24% w/w CA and 20% w/w Cm. In this case, the time necessary to obtain the maximum Cm concentration was about 4 h; i.e., longer than the fastest released measured for membranes (1 h), but very small if compared to the longest release time reported in Table 2 (66 h). This result confirms the control of membrane structure and of internal curcumin organization on the release of this compound. Cm release tests only give an indication about the rate of the active principle release from the membranes; but, they do not give any information about the capacity of membrane to maintain its activity when solicited by the proliferation of contaminants in the release medium. To ascertain this characteristic, the release of curcumin was repeated for up to four times on the same CA membrane; i.e., when the maximum Cm concentration in the release medium was obtained, we rinsed the membrane and put it into a fresh release medium. An example of the obtained results is reported in Fig. 10. Even after four release tests, the membrane continued the release of curcumin with a similar behavior as in the first test: only a relatively small increase in the time to obtain the maximum concentration value was observed. 3.4. Antioxidant and antimicrobial activity of CA+Cm membranes
Fig. 9. Cm release curves from CA membranes at 12, 18 and 24% w/w, obtained at 250 bar, 35 °C: (a) 10% w/w Cm; (b) 20% w/w Cm.
At this point of the work, we have established that the Cm release rate can be controlled in a wide range of times; but, what about the effective antioxidant activity of the released Cm? To answer to this question, we measured the antioxidant activity of Cm released from the membranes. A macroscopic, qualitative indication of curcumin activity is proposed in Fig. 11, where DPPH color changes from purple (left) to yellow (right) when the solution obtained after the first release test was added to the control solution. The same experiment was performed using the solution obtained after the other release tests on the same membrane (2° to 4°) and the antioxidant activity was measured. The results are summarized in Table 3. In all cases, antioxidant activity ranging from around 93 to 86% of native curcumin was observed, demonstrating that Cm substantially maintained its properties. But, even what’s more relevant, is the result that curcumin activity was substantially maintained also after the fourth consecutive release in the fresh medium, with a reduction ranging between about 5 and
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However, we measured the maximum released Cm concentration using a calibration curve and, in all cases, it was larger than MIC (Minimally Inhibitory Concentration) of curcumin, that starts at about 15.7 mg/l [43]. The final concentration measured for Cm was always larger than this minimum value, arriving at values as large as about 44 mg/l. But, even more relevant, the inhibitory value was reached, for the faster release, after only 1 h (see Table 2). 4. Conclusions
Fig. 10. Cm release curves from 24% w/w CA membrane loaded at 20% w/w Cm, obtained at 250 bar, 35 °C, when the direct contact with the liquid medium was replicated.
a
b
Completely biodegradable CA+Cm nanostructured membranes have been successful developed in this study. Thanks to the extreme flexibility of the SC-CO2 phase inversion technique, we obtained a uniform distribution at nanometric level of curcumin, when 10% w/w in CA was used, and we produced practically solvent free membranes (5 ppm acetone residue) with a fast processing. It is possible to modulate membrane pore size obtaining a very long continued release of curcumin that maintained more than 80% of native antioxidant activity, even when repeated release tests on the same sample were performed. On the other hand, when an immediate release of the active principle is required (i.e., to face media that exhibit a large contaminants charge), a faster release can be obtained too. Therefore, these membranes can be modulated to the specific target required in food preservation and shelf life increase, used as small independent devices. Modulation of Cm release times can be set in dependence of the timing required: shorter shelf-life against larger antimicrobial/antioxidant loading or longer shelf-life against smaller loading of biological unwanted materials. References
Fig. 11. DPPH• color change from purple (a) to yellow (b) when the solution Cm+water+ethanol, obtained after the I release test from the membrane at 24% w/w CA, was added to the control solution. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) Table 3 Antioxidant activity of 20% w/w Cm loaded CA membranes after I and IV release test. Sample CA CA CA CA CA CA
(12% (12% (18% (18% (24% (24%
I (%) w/w) + Cm w/w) + Cm w/w) + Cm w/w) + Cm w/w) + Cm w/w) + Cm
(20% (20% (20% (20% (20% (20%
w/w) w/w) w/w) w/w) w/w) w/w)
I test IV test I test IV test I test IV test
86.73 81.51 89.22 85.36 92.92 82.13
10% with respect to the first release. This result means that in a release medium, in which curcumin is progressively consumed by oxidation, these membranes are still extremely active. Considering the measured high antioxidant activity of curcumin, there are not doubts about its stability after supercritical processing. In the case of curcumin, it is not necessary to verify the preservation of the antimicrobial activity, as in the case of antimicrobial devices based on bioactive compounds (e.g., enzymes), since this characteristic is preserved until the compound decomposes.
[1] De Moura MR, Mattoso LH, Zucolotto V. Development of cellulose-based bactericidal nanocomposites containing silver nanoparticles and their use as active food packaging. J Food Eng 2012;109(3):520–4. [2] Ramos M, Jiménez A, Peltzer M, Garrigós MC. Characterization and antimicrobial activity studies of polypropylene films with carvacrol and thymol for active packaging. J Food Eng 2012;109(3):513–19. [3] Gómez-Estaca J, López-de-Dicastillo C, Hernández-Muñoz P, Catalá R, Gavara R. Advances in antioxidant active food packaging. Trends Food Sci Technol 2014;35(1):42–51. [4] Appendini P, Hotchkiss JH. Review of antimicrobial food packaging. Innov Food Sci Emerg Technol 2002;3(2):113–326. [5] Ozdemir M, Floros JD. Active food packaging technologies. Crit Rev Food Sci Nutr 2004;44(3):185–93. [6] Vermeiren L, Devlieghere F, Van Beest M, De Kruijf N, Debevere J. Developments in the active packaging of foods. Trends Food Sci Technol 1999;10(3):77–86. [7] Zorofchian Moghadamtousi S, Abdul Kadir H, Hassandarvish P, Tajik H, Abubakar S, Zandi K. A review on antibacterial, antiviral, and antifungal activity of curcumin. BioMed Res Int 2014, Article ID 186864: 1–12. [8] Wang Y, Lu Z, Wu H, Lv F. Study on the antibiotic activity of microcapsule curcumin against foodborne pathogens. Int J Food Microbiol 2009;136(1):71–4. [9] Chen D-Y, Shien J-H, Tiley L, Chiou S-S, Wang S-Y, Chang T-J, et al. Curcumin inhibits influenza virus infection and haemagglutination activity. Food Chem 2010;119(4):1346–51. [10] Sharma M, Manoharlal R, Shukla S, Puri N, Prasad T, Ambudkar SV, et al. Curcumin modulates efflux mediated by yeast ABC multidrug transporters and is synergistic with antifungals. Antimicrob Agents Chemother 2009;53(8):3256–65. [11] Balakrishnan VV, Abidin Z, Naziron N, Nasir K, Rusli M, Lee S, et al. Influence of curcumin natural dye colorant with PMMA-acrylic polyol blended polymer. Pigment Resin Technol 2013;42(2):95–102. [12] Hashem MM, Atta AH, Arbid MS, Nada SA, Asaad GF. Immunological studies on Amaranth, Sunset Yellow and Curcumin as food colouring agents in albino rats. Food Chem Toxicol 2010;48(6):1581–6. [13] Vimala K, Yallapu MM, Varaprasad K, Reddy NN, Ravindra S, Naidu NS, et al. Fabrication of curcumin encapsulated chitosan-PVA silver nanocomposite films for improved antimicrobial activity. J Biomater Nanobiotechnol 2011;2(01):55. [14] Wan S, Sun Y, Qi X, Tan F. Improved bioavailability of poorly water-soluble drug curcumin in cellulose acetate solid dispersion. Aaps Pharmscitech 2012;13(1):159–66. [15] Luo N, Varaprasad K, Reddy GVS, Rajulu AV, Zhang J. Preparation and characterization of cellulose/curcumin composite films. RSC Adv 2012;2(22):8483–8.
Please cite this article as: L. Baldino et al., Biodegradable membranes loaded with curcumin to be used as engineered independent devices in active packaging, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.12.020
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L. Baldino et al. / Journal of the Taiwan Institute of Chemical Engineers 000 (2016) 1–9 [16] Sonkaew P, Sane A, Suppakul P. Antioxidant activities of curcumin and ascorbyl dipalmitate nanoparticles and their activities after incorporation into cellulose-based packaging films. J Agric Food Chem 2012;60(21):5388–99. [17] Campardelli R, Reverchon E. α -Tocopherol nanosuspensions produced using a supercritical assisted process. J Food Eng 2015;149:131–6. [18] Campardelli R, Adami R, Della Porta G, Reverchon E. Nanoparticle precipitation by supercritical assisted injection in a liquid antisolvent. Chem Eng J 2012;192:246–51. [19] Della Porta G, Falco N, Giordano E, Reverchon E. PLGA microspheres by Supercritical Emulsion Extraction: a study on insulin release in myoblast culture. J Biomater Sci Polym Ed 2013;24(16):1831–47. [20] Prosapio V, De Marco I, Scognamiglio M, Reverchon E. Folic acid–PVP nanostructured composite microparticles by supercritical antisolvent precipitation. Chem Eng J 2015;277:286–94. [21] Meneses MA, Caputo G, Scognamiglio M, Reverchon E, Adami R. Antioxidant phenolic compounds recovery from Mangifera indica L. by-products by supercritical antisolvent extraction. J Food Eng 2015;163:45–53. [22] Chen C-R, Lee Y-N, Lee M-R, Chang C-MJ. Supercritical fluids extraction of cinnamic acid derivatives from Brazilian propolis and the effect on growth inhibition of colon cancer cells. J Taiwan Inst Chem Eng 2009;40(2):130–5. [23] Chen C-H, Yang Y-H, Shen C-T, Lai S-M, Chang C-MJ, Shieh C-J. Recovery of vitamins B from supercritical carbon dioxide-defatted rice bran powder using ultrasound water extraction. J Taiwan Inst Chem Eng 2011;42(1):124–8. [24] Yen H-W, Chiang W-C, Sun C-H. Supercritical fluid extraction of lutein from Scenedesmus cultured in an autotrophical photobioreactor. J Taiwan Inst Chem Eng 2012;43(1):53–7. [25] Maran JP, Priya B. Supercritical fluid extraction of oil from muskmelon (Cucumis melo) seeds. J Taiwan Inst Chem Eng 2015;47:71–8. [26] Baldino L, Sarno M, Cardea S, Irusta S, Ciambelli P, Santamaria J, et al. Formation of cellulose acetate–graphene oxide nanocomposites by supercritical CO2 assisted phase inversion. Ind Eng Chem Res 2015;54(33):8147–56. [27] Baldino L, Cardea S, Reverchon E. Supercritical assisted enzymatic membranes preparation, for active packaging applications. J Membr Sci 2014;453:409–18. [28] Baldino L, Cardea S, Reverchon E. Production of antimicrobial membranes loaded with potassium sorbate using a supercritical phase separation process. Innov Food Sci Emerg Technol 2016;34:77–85. [29] García-González C, Alnaief M, Smirnova I. Polysaccharide-based aerogels—promising biodegradable carriers for drug delivery systems. Carbohydr Polym 2011;86(4):1425–38. [30] García-González CA, Concheiro A, Alvarez-Lorenzo C. Processing of materials for regenerative medicine using supercritical fluid technology. Bioconjug Chem 2015;26(7):1159–71.
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[31] Baldino L, Concilio S, Cardea S, De Marco I, Reverchon E. Complete glutaraldehyde elimination during chitosan hydrogel drying by SC-CO2 processing. J Supercrit Fluids 2015;103:70–6. [32] Duarte ARC, Santo VE, Alves A, Silva SS, Moreira-Silva J, Silva TH, et al. Unleashing the potential of supercritical fluids for polymer processing in tissue engineering and regenerative medicine. J Supercrit Fluids 2013;79:177–85. [33] Reverchon E, Cardea S. Formation of cellulose acetate membranes using a supercritical fluid assisted process. J Membr Sci 2004;240(1–2):187–95. [34] Gugliuzza A, Cardea S, Drioli E, Reverchon E. Supercritical CO2 –EtOH expanded liquid processing to produce tailored PEEK-WC membranes. RSC Adv 2014;4(110):65098–107. [35] Huang S, Wu G, Chen S. Preparation of microporous poly (vinylidene fluoride) membranes via phase inversion in supercritical CO2 . J Membr Sci 20 07;293(1):10 0–10. [36] Zaherzadeh A, Karimi-Sabet J, Mousavian SMA, Ghorbanian S. Optimization of flat sheet hydrophobic membranes synthesis via supercritical CO2 induced phase inversion for direct contact membrane distillation by using response surface methodology (RSM). J Supercrit Fluids 2015;103:105–14. [37] Shi W, He G, Zhao W, Zhang L, Du L, Wang Y, et al. Effects of solvent and nonsolvent diffusion velocities on the morphology of cellular polyetherimide membranes prepared using supercritical CO2 phase inversion. J Supercrit Fluids 2013;83:6–14. [38] Van de Witte P, Dijkstra P, Van den Berg J, Feijen J. Phase separation processes in polymer solutions in relation to membrane formation. J Membr Sci 1996;117(1):1–31. [39] Liu X, Ong SL, Ng HY. Fabrication of mesh-embedded double-skinned substrate membrane and enhancement of its surface hydrophilicity to improve anti-fouling performance of resultant thin-film composite forward osmosis membrane. J Membr Sci 2016;511:40–53. [40] Tang YP, Yuwen S, Chung TS, Weber M, Staudt C, Maletzko C. Synthesis of hyperbranched polymers towards efficient boron reclamation via a hybrid ultrafiltration process. J Membr Sci 2016;510:112–21. [41] Reverchon E, Cardea S. PVDF-HFP membrane formation by supercritical CO2 processing: elucidation of formation mechanisms. Ind Eng Chem Res 2006;45(26):8939–45. [42] Ak T, Gülçin I˙ . Antioxidant and radical scavenging properties of curcumin. Chem Biol Interact 2008;174(1):27–37. [43] Gunes H, Gulen D, Mutlu R, Gumus A, Tas T, Topkaya AE. Antibacterial effects of curcumin: an in vitro minimum inhibitory concentration study. Toxicol Ind Health 2013;32(2):246–50.
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Biodegradable membranes loaded with curcumin to be used as engineered independent devices in active packaging Lucia Baldino, Stefano Cardea, Ernesto Reverchon∗ Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy
a r t i c l e
i n f o
Article history: Received 28 April 2016 Revised 8 November 2016 Accepted 17 December 2016 Available online xxx Keywords: Curcumin Cellulose acetate Antioxidant membranes Antimicrobial membranes Supercritical phase inversion Active packaging
a b s t r a c t Curcumin is an excellent candidate to be used in the realization of controlled release devices for food packaging. Various techniques have been tested to produce these devices but, among them, SC-CO2 assisted phase inversion has been particularly successful. Biodegradable cellulose acetate + curcumin nanostructured membranes have been developed in this study: we tested different process conditions (12–24% w/w polymer concentration, 10–20% w/w curcumin, 35–55 °C, 150–250 bar), obtaining an uniform distribution at nanometric level of curcumin and producing, in a fast process, practically solvent free membranes (5 ppm acetone residue). Moreover, it has been possible to modulate membrane pore size obtaining a very long continued release of curcumin that maintained more than 90% of native antioxidant activity. © 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
1. Introduction The main cause of the spoilage of a great variety of foods is lipid oxidation and microbial growth inside the packaging. The direct addition of antioxidants and/or antimicrobial agents is frequently used; however, this technique can modify the taste and/or the aspect of the food and, as a rule, the action of the additive is largely not optimized. An alternative to this method, is the use of an active packaging [1,2] that can perform the sustained release of the antioxidant/antimicrobial compound during storage and, thus, can largely increase the shelf-life of the food preparation. Active packaging of different kind has been proposed that can be divided in two categories: independent devices and active packaging materials [3–6]. Curcumin is a polyphenolic compound and is the main phytochemical compound contained in Curcuma longa L. It has been demonstrated that it exerts antioxidant and antimicrobial activities [7]. It was resulted to be safe even at high doses (12 g/day) in clinical trials in human [7]. Therefore, several studies have been performed about its use as antibiotic [8], antiviral [9] and antifungal [10] drug. Moreover, it is a well established food additive and coloring matter [11,12]. Therefore, curcumin is an excellent candidate to be used in the realization of controlled release devices for food packaging and medical applications. Some studies have ∗
Corresponding author. E-mail address: [email protected] (E. Reverchon). URL: http://www.supercriticalfluidgroup.unisa.it (E. Reverchon)
been recently published, proposing these applications. Vimala et al. (2011) produced curcumin encapsulated in chitosan–poly(vinyl alcohol)–silver nanocomposite films as antimicrobial packaging, wound dressing and antibacterial materials. They observed a significant reduction of E. coli growth when these films were tested, compared to the action of curcumin and nanocomposite film alone. However, a maximum curcumin released concentration was obtained after only 10 h and glutaraldehyde, used during the processing, unreacted toxic residues were not determined [13]. Wan et al. (2011) developed a sustained-release of curcumin employing a water-insoluble carrier based on cellulose acetate. Films were obtained by solvent evaporation. The curcumin release was controlled up to 12 h, since the solid dispersion of cellulose acetate and curcumin induced the transformation of curcumin from the crystalline to the amorphous state, increasing drug dissolution rate; whereas, water insolubility of the carrier controlled the drug release [14]. Luo et al. (2012) prepared cellulose/curcumin composite films with different curcumin contents by solution casting using a ionic liquid to dissolve both curcumin and cellulose. Dense films were obtained and they found that the inhibition action of these films was proportional to the curcumin content in the composite film. No release studies were performed [15]. Sonkaew et al. (2012) produced by supercritical CO2 based RESOLV, curcumin and ascorbyl dipalmitate nanoparticles with average sizes of about 50 and 80 nm, respectively. Then, these nanoparticles were incorporated into cellulose films that exhibited a maximum antioxidant activity of about 57%. Also in this case, no release tests were performed [16].
http://dx.doi.org/10.1016/j.jtice.2016.12.020 1876-1070/© 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
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from Morlando Group S.R.L. (Sant’Antimo, NA – Italy). All materials were processed as received. 2.2. Preparation of curcumin loaded membranes
Fig. 1. Untreated curcumin powder.
Processes assisted by supercritical CO2 (SC-CO2 ) have been proposed as alternative to traditional ones, for example for micro and nanoparticles production [17–20], extraction [21–25] and membranes and aerogel preparation [26–32]. Among these supercritical processes, the formation of membranes by SC-CO2 assisted phase inversion has been particularly successful [33–37] In this specific process, SC-CO2 acts as the non-solvent for the polymer and as the solvent for the liquid used to dissolve the polymer. The result is a phase inversion process with the formation of a continuous polymer phase and a supercritical (liquid + CO2 ) discontinuous phase, that is released during the process, producing porous interconnected structures [33,38]. The advantages of this technique over the liquid-liquid based process [39] or solvent evaporation [40] are the flexibility of SC-CO2 action with pressure and temperature, that allows to produce, in a very fast one step process, membranes tailored in morphology and pore size, and the complete elimination of the liquid solvent. Therefore, a dry and solvent free membrane is produced without any post-processing step and the other compounds eventually present in the starting solution (e.g., the active principles) are, as a rule, well distributed and does not suffer degradation, decomposition and/or deactivation [27]. Therefore, considering the literature analysis, the scope of this work is to produce completely degradable structures to be used as independent devices to be added in food packaging for the prolonged controlled release of curcumin that can be tailored on different contaminants/microorganisms loading in the starting food material. Membranes of cellulose acetate (CA) containing curcumin (Cm) will be produced by SC-CO2 phase inversion, using this process to control the morphology of the obtained nano-structured membranes [41]. Release studies will be performed on these membranes, to verify the preservation of the antioxidant activity of curcumin, the control and the length of the release of the active principle in an appropriate liquid medium.
2. Materials and methods 2.1. Chemicals Cellulose acetate, CA, (average Mn ca. 50,0 0 0 with acetyl content of 39.7%), Acetone (purity 99.5%), curcumin, Cm, (purity >65%; the raw material is shown in Fig. 1), Ethanol (purity >99.8%) and DPPH• (2,2-diphenyl-1-picryl-hydrazyl) were bought from Sigma–Aldrich (Milan, Italy); CO2 (purity 99%) was purchased
Solutions were prepared by dissolving CA at 12, 18 and 24% w/w in acetone at 40 °C, 100 rpm for 12 h. Then, Cm, at 10 or 20% w/w with respect to CA, was added to the solutions, that were mixed for the other 5 h at 40 °C and 100 rpm. The obtained solutions, were distributed on stainless steel caps, having a diameter of 2 cm and an height of about 1 mm. The caps were rapidly put inside the high pressure vessel (a 316 stainless steel vessel with an internal volume of 200 ml) to minimize evaporation of the solvent. The vessel was closed and filled with SC-CO2 up to the desired pressure, using a high pressure pump (mod. LDB1, Lewa, Germany). Then, they were processed by supercritical CO2 phase inversion at different process conditions: temperatures ranging between 35 and 55 °C, pressures ranging between 150 and 250 bar, for 3 h. Pressure in the vessel was measured by a test gauge (mod. MP1, OMET, Italy) and regulated using a micrometering valve (mod. 1335G4Y, Hoke, USA). Temperature was regulated using PID controllers (mod. 305, Watlow, USA). At the exit of the vessel, a rotameter (mod. D6, ASA, Italy) was used to measure CO2 flow rate, that was maintained constant at 1.5 kg/h. 2.3. Analytical methods 2.3.1. Field emission scanning electron microscopy (FESEM) Membranes were cryo-fractured using liquid nitrogen (SOL, Milan, Italy); then, the samples were sputter coated with gold (Agar Auto Sputter Coater mod. 108 A, Stansted, UK) at 30 mA for 160 s and analyzed by a FESEM (mod. LEO 1525, Carl Zeiss SMT AG, Oberkochen, Germany) to study membrane morphology. 2.3.2. Membrane pore size analysis Sigma Scan Pro 5.0 (Jandel Scientific, San Rafael, Canada) and Origin 8.5 (Microcal, Northampton, USA) were used to determine the average diameter of membrane pores. Images taken at various locations in the membrane were used for each calculation. About 300 pores for each sample were measured. Using Origin software, we first represented a histogram with the percentage of the pores having a given diameter; then, we performed a curve fitting to obtain the pore size distribution curve. 2.3.3. Differential scanning calorimetry (DSC) DSC (DSC 30 Mettler, Toledo, Spain) was carried out to analyze and identify any changes in the thermograms of pure substances compared to polymer/drug formulations. Calorimetric analysis was performed in the temperature range between −60 and 300 °C, with a heating rate of 10 °C/min; the inert gas was Nitrogen, with a flow rate of 50 l/min. 2.3.4. Solvent residue analysis Acetone residue was measured by a headspace (HS) sampler (mod. 7694E, Hewlett Packard, USA) coupled to a gas chromatograph (GC) interfaced with a flame ionization detector (GC-FID, mod. 6890 GC-SYSTEM, Hewlett Packard, USA). Acetone was separated using two fused-silica capillary columns connected in series by press-fit: the first column (mod. Carbomax EASYSEP, Stepbios, Italy) connected to the detector, 30 m length, 0.53 mm i.d., 1 μm film thickness and the second one (mod. Cp Sil 5CB CHROMPACK, Stepbios, Italy) connected to the injector; 25 m length, 0.53 mm i.d., 5 μm film thickness. GC conditions were the one described in the USP 467 Pharmacopea with some minor modifications: oven temperature from 45 to 210 °C for 15 min. The injector was maintained at 135 °C (split mode, ratio 4:1) and helium was used as
Please cite this article as: L. Baldino et al., Biodegradable membranes loaded with curcumin to be used as engineered independent devices in active packaging, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.12.020
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the carrier gas (5 ml/min). Head space conditions were: equilibration time, 30 min at 95 °C; pressurization time, 0.15 min, and loop fill time, 0.15 min. Head space samples were prepared in 20-ml vials filled with internal standard DMI (3 ml) and 500 mg of NaCl and water (0.75 ml) in which samples of CA+Cm membrane were suspended. 2.3.5. Curcumin release test Cm release kinetics were determined by measuring the increase of drug concentration in 100 ml of an aqueous solution at 80% v/v distilled water and 20% v/v ethanol (Simulant C, according to the Regulation (UE) N. 10/2011), at room temperature. Cm loaded membrane was placed in a bottle containing the medium, which simulates the food environment, and stirred at 50 rpm. To determine the Cm release rate from the membrane and its concentration, analysis was carried out in continuous using a Varian (mod. Cary 50, Palo Alto, CA) UV/Vis spectrophotometer and reading the absorbance of the sample at 430 nm, which is the wavelength at which Cm shows maximum absorption. 2.3.6. Antioxidant activity test The radical scavenging capacity of the CA+Cm membranes was determined by DPPH• method. A 0.1 mM solution of DPPH• was prepared in ethanol and 1 ml of this solution was added to 3 ml of the solution Cm+water+ethanol, obtained from the release test previously performed. This final solution was mixed by Vortex for 2 min and incubated in the dark for 30 min at room temperature. The absorbance was measured at 517 nm. The capability to scavenge the DPPH• radical was calculated using the following equation:
I (% ) =
1−
As Ac
× 100
where Ac is the absorbance of the control (1 ml, DPPH• solution without Cm) and As is the absorbance of the solution in the presence of Cm [42]. 3. Results and discussion 3.1. Effect of process parameters on membranes morphology The morphology of the CA membranes obtained by SC-CO2 phase inversion has been studied in a previous work [33]. Cellular membranes were obtained that presented a very regular shape and pore distribution and were characterized by connected pores ranging between 2 and 50 μm for CA concentrations between 40 and 5% w/w in acetone. In this work, we performed a series of membrane formation experiments at 250 bar, 35 °C and 3 h contacting time. Acetone was used as the solvent, since CA and Cm are largely soluble in it. CA membranes at 12, 18 and 24% w/w were produced, containing a percentage of 10% or 20% w/w of Cm with respect the CA content. In Fig. 2, a macroscopic view of these membranes is reported: the starting CA membrane is white; whereas, the CA+Cm membrane shows a uniform yellow color due to Cm presence. This first qualitative evidence demonstrates that curcumin after the supercritical process was homogeneously distributed in the polymer matrix, as a consequence of the fast supercritical fluid assisted process that avoided drug irregular deposition inside the membrane. This qualitative information was, then, verified during microscopic characterizations. FESEM images in Fig. 3 report an example of the morphology shown by CA+Cm membranes at different magnifications. The regularity of the structure was confirmed also at microscopic level; particularly the SEM image on the left shows the whole section of the membrane and the image on the right
a
3
b
Fig. 2. Pictures of (a) CA membrane, (b) CA+Cm membrane produced by supercritical phase inversion. (For interpretation of the references to color in this figure, the reader is referred to the web version of this article.)
confirms the very uniform pores distribution. These membranes retained cellular morphology as those formed by CA alone, demonstrating that the presence of curcumin, at the concentrations used in this work, does not interfere on the formation of the continuous polymeric phase. The only differences are given by pore size distributions, as shown in Fig. 4. The membranes at 10% w/w Cm show a mean pore size that decreases with CA content from about 9.6 μm to 9.3 μm to 6.0 μm for CA % of 12, 18 and 24% w/w, respectively. Similar trend was observed for 20% w/w Cm membranes. Then, we maintained the CA contents at 12, 18 and 24% w/w and Cm loading at 10 or 20% w/w with respect to CA and explored different process conditions operating at 150 bar, 55 °C and 200 bar, 45 °C, thus producing a sensible difference in SC-CO2 density, from 0.66 g/cm3 to 0.81 g/cm3 , respectively. The scope of these experiments was to evaluate the influence of SC-CO2 solvent power, which is related to mainly on its density, on the membrane morphology [33]. In all the cases studied, we produced cellular membranes; the different process conditions only influenced the pore size distribution, as it is summarized in Fig. 5, where pore size distributions are reported, for example, for the experiments performed using 24% w/w CA and 10% w/w Cm in the starting solution. The mean pore size increases and its distribution enlarges (standard deviation values: 1.50, 2.60, 2.70 μm for p/T values 250/35, 200/45, 150/55) when SC-CO2 density is decreased. The data collected for all the produced membranes are shown in Table 1. It is also possible to compare the pore mean diameter of the membranes obtained at different Cm loadings (i.e., 10% w/w and 20% w/w), observing data reported in Table 1. In particular, the mean pore size increases at all process conditions tested, increasing Cm percentage; this result can be explained considering that the increase of Cm content probably obstacles the phase separation, making it slower. As a consequence, the pores grow for a longer time until the phase separation process is completed (i.e., larger pores are generated). Solvent residue analyses were also performed, as described in materials and methods section, and acetone residue presenting in the membranes was found to be lower than 5 ppm, at all process conditions tested. 3.2. Membranes characterization We performed extensive DSC analyses comparing the thermograms of unprocessed CA, Cm, CA+Cm physical mixture and CA membranes containing 10 and 20% w/w Cm. The thermograms are summarized in Fig. 6. CA alone shows a glass transition temperature at about 75 °C and a melting temperature at about 230 °C;
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Fig. 3. FESEM pictures at different magnifications of a 24% w/w CA membrane section loaded at 10% w/w Cm; process conditions 250 bar, 35 °C, 3 h. Table 1 Mean pore diameter ± standard deviation (μm) of the CA membranes loaded at 10% w/w or 20% w/w Cm and at all different process conditions used in this work. Cm 10% w/w CA 12% w/w 150 bar – 55 °C 200 bar – 45 °C 250 bar – 35 °C
12.61 ± 3.85 10.73 ± 2.94 9.58 ± 2.01
Cm 20% w/w CA 18% w/w 10.23 ± 2.86 10.20 ± 2.78 9.30 ± 1.87
CA 24% w/w
CA 12% w/w
8.40 ± 2.72 7.38 ± 2.60 6.07 ± 1.53
16.48 ± 6.66 12.86 ± 6.06 12.42 ± 3.15
CA 18% w/w 15.96 ± 4.20 12.38 ± 3.92 10.67 ± 3.05
CA 24% w/w 14.57 ± 3.53 10.84 ± 3.35 8.55 ± 2.68
Fig. 4. Pore size distribution of 10% w/w Cm loaded CA membranes phase separated at 250 bar, 35 °C for 3 h and at different CA content: 12, 18 and 24% w/w.
Fig. 5. Pore size distribution of membranes at 24% w/w CA loaded with 10% w/w Cm, phase separated at different SC-CO2 solvent power.
curcumin alone is crystalline, showing a sharp peak at 175 °C; the physical mixture shows the presence of CA and Cm peaks, the membrane containing 10% w/w Cm shows only the peak related to CA glass transition temperature, indicating that in this case both the compounds are amorphous after supercritical processing. The membrane containing 20% w/w Cm (Fig. 6(e)), surprisingly, shows a second small sharp peak related to curcumin, that, in this case, should be at least partly crystalline.
This last result induced us to perform other series of FESEM analyses on membranes section and external surfaces. We did not find any indication of curcumin presence in FESEM images of CA membranes at 10% w/w Cm: these evidences confirm a nanometric dispersion of curcumin inside the CA porous matrix. In the case of 20% w/w Cm membranes, instead, we found micrometric curcumin crystals randomly located inside the polymeric structure as
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a
b
c
d
e
Fig. 6. Thermograms of: (a) CA, (b) Cm, (c) CA+Cm physical mixture, (d) CA membrane loaded at 10% w/w Cm and (e) CA membrane loaded at 20% w/w Cm.
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Fig. 7. Pictures at different magnifications of Cm crystals dispersed inside the CA membrane, phase separated at 250 bar, 35 °C.
a
b
Fig. 8. Pictures of the H2 O+EtOH medium before (a) and after (b) a curcumin release from a CA membrane. (For interpretation of the references to color in this figure, the reader is referred to the web version of this article.)
shown in the images reported in Fig. 7. Therefore, at the higher curcumin percentage tested, part of curcumin re-crystallized inside the membrane structure. This result is in agreement with the indications given by DSC analysis, related to the appearance of signals of curcumin crystallinity. However, only the internal content of the pores of the membranes was partly changed; no modification of the external surfaces was observed. The explanation of all these observations is that when 20% w/w Cm loading was used, part of curcumin started to crystallize independently on the polymeric structure: this behavior was induced by supersaturation of curcumin during membrane formation. Moreover, this aspect also influences the phase separation rate, confirming the hypothesis, reported above, about the effect of Cm loading on pores size (i.e., increasing the Cm loading, the phase separation is slower and the pores have more time to growth).
3.3. Cm release tests from CA membranes Extensive series of UV/Vis release tests of curcumin from the produced CA membranes were performed using the technique described in materials and methods. In Fig. 8, a macroscopic evidence related to the color of H2 O+EtOH medium, before (Fig. 8(a)) and after (Fig. 8(b)) a curcumin release test, is reported. It
is clearly visible the yellow color confirming that curcumin was released from the CA membrane. In the case of curcumin loading at 10% w/w CA, the Cm release curves were largely dependent on CA percentage and, correspondingly, on the membranes pore diameter, as indicated, for example, for the case 250 bar, 35 °C, reported in Fig. 9(a). In this diagram, the Cm concentration measured during the time (Ct ), normalized to the maximum Cm concentration detected (Cinf ) versus time, is represented. Only 1.8 h was necessary to obtain the maximum concentration of curcumin in the dissolution medium in the case of the membrane at 12% w/w CA; after 8.4 h curcumin maximum concentration was obtained for 18% w/w CA and the longest time to reach the maximum curcumin concentration was 58 h for 24% w/w CA membranes. In particular, the more compact structure observed for membranes at 24% w/w CA (due to the smaller pores) showed a very relevant influence on the release rate of Cm. Similar results were obtained for the loaded membranes produced during the experiments performed at 150 bar, 55 °C and 200 bar, 45 °C (figures not reported) though the Cm release times were very different: for example, the membranes produced at 150 bar, 55 °C and 24% w/w CA, reached the maximum Cm concentration in the release medium after only about 10 h, confirming the relevance of the pores diameter on the control of curcumin release from these membranes. A different behavior was observed for CA membranes loaded with 20% Cm w/w CA. As shown in Fig. 9(b), which is again referred to 250 bar, 35 °C processing conditions, the Cm release times were relatively similar for the different CA percentage in the membranes. Similar results were also obtained for membranes (not shown) produced at the other two process conditions (150 bar, 55 °C; 200 bar, 45 °C), maintaining the Cm loading at 20% w/w CA. In these cases, very longer times were observed with respect to the analogous membranes produced at 10% w/w Cm loading: this aspect is very interesting. The values measured for CA membranes loaded at 10 and 20% w/w Cm are summarized in Table 2. For all membranes tested, no evidence of polymer swelling during the Cm release test was observed. Summarizing, the dependence of Cm release rate from pores diameter for membranes at 20% Cm is less marked that for the membranes loaded at 10% w/w Cm; moreover, very long release times were observed. An explanation of the different behavior between these membranes is given by the deposition of curcumin crystals inside the membrane pores, as observed in Fig. 7. In the case 10% w/w Cm membranes, the active principle is nanodispersed inside the membrane structure; indeed, no curcumin particles were detected. In the case of 20% w/w Cm membranes,
Please cite this article as: L. Baldino et al., Biodegradable membranes loaded with curcumin to be used as engineered independent devices in active packaging, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.12.020
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Table 2 Time required (h) to reach the maximum Cm concentration in the medium for CA membranes loaded at 10% w/w or 20% w/w Cm and at all different phase inversion conditions used in this work. Cm 10% w/w
150 bar – 55 °C 200 bar – 45 °C 250 bar – 35 °C
Cm 20% w/w
CA 12% w/w
CA 18% w/w
CA 24% w/w
CA 12% w/w
CA 18% w/w
CA 24% w/w
1.0 1.7 1.8
1.7 2.5 8.4
10.0 45.0 58.0
22 27 35
25 45 47
56 57 66
instead, the active principle is partly dispersed in the membrane at nanometric level and partly organized inside the membrane cells as microcrystals. It is reasonable to suppose that curcumin microcrystals were not readily solubilizable by the release medium and, therefore, longer release times were required, that can be relatively similar for the various membranes: microcrystals dissolution partly controlled curcumin release in the liquid medium. Therefore, CA membranes containing 10% w/w Cm are true nanostructured devices and active principle release is only controlled by membrane pore size; CA membranes at 20% w/w Cm contain part of Cm at nanometric level and part of Cm as microcrystals and show a control of Cm release partly due to pores diameter and partly related to Cm microcrystals dissolution. We also compared these results with the Cm release from the physical mixture CA+Cm, containing 24% w/w CA and 20% w/w Cm. In this case, the time necessary to obtain the maximum Cm concentration was about 4 h; i.e., longer than the fastest released measured for membranes (1 h), but very small if compared to the longest release time reported in Table 2 (66 h). This result confirms the control of membrane structure and of internal curcumin organization on the release of this compound. Cm release tests only give an indication about the rate of the active principle release from the membranes; but, they do not give any information about the capacity of membrane to maintain its activity when solicited by the proliferation of contaminants in the release medium. To ascertain this characteristic, the release of curcumin was repeated for up to four times on the same CA membrane; i.e., when the maximum Cm concentration in the release medium was obtained, we rinsed the membrane and put it into a fresh release medium. An example of the obtained results is reported in Fig. 10. Even after four release tests, the membrane continued the release of curcumin with a similar behavior as in the first test: only a relatively small increase in the time to obtain the maximum concentration value was observed. 3.4. Antioxidant and antimicrobial activity of CA+Cm membranes
Fig. 9. Cm release curves from CA membranes at 12, 18 and 24% w/w, obtained at 250 bar, 35 °C: (a) 10% w/w Cm; (b) 20% w/w Cm.
At this point of the work, we have established that the Cm release rate can be controlled in a wide range of times; but, what about the effective antioxidant activity of the released Cm? To answer to this question, we measured the antioxidant activity of Cm released from the membranes. A macroscopic, qualitative indication of curcumin activity is proposed in Fig. 11, where DPPH color changes from purple (left) to yellow (right) when the solution obtained after the first release test was added to the control solution. The same experiment was performed using the solution obtained after the other release tests on the same membrane (2° to 4°) and the antioxidant activity was measured. The results are summarized in Table 3. In all cases, antioxidant activity ranging from around 93 to 86% of native curcumin was observed, demonstrating that Cm substantially maintained its properties. But, even what’s more relevant, is the result that curcumin activity was substantially maintained also after the fourth consecutive release in the fresh medium, with a reduction ranging between about 5 and
Please cite this article as: L. Baldino et al., Biodegradable membranes loaded with curcumin to be used as engineered independent devices in active packaging, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.12.020
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However, we measured the maximum released Cm concentration using a calibration curve and, in all cases, it was larger than MIC (Minimally Inhibitory Concentration) of curcumin, that starts at about 15.7 mg/l [43]. The final concentration measured for Cm was always larger than this minimum value, arriving at values as large as about 44 mg/l. But, even more relevant, the inhibitory value was reached, for the faster release, after only 1 h (see Table 2). 4. Conclusions
Fig. 10. Cm release curves from 24% w/w CA membrane loaded at 20% w/w Cm, obtained at 250 bar, 35 °C, when the direct contact with the liquid medium was replicated.
a
b
Completely biodegradable CA+Cm nanostructured membranes have been successful developed in this study. Thanks to the extreme flexibility of the SC-CO2 phase inversion technique, we obtained a uniform distribution at nanometric level of curcumin, when 10% w/w in CA was used, and we produced practically solvent free membranes (5 ppm acetone residue) with a fast processing. It is possible to modulate membrane pore size obtaining a very long continued release of curcumin that maintained more than 80% of native antioxidant activity, even when repeated release tests on the same sample were performed. On the other hand, when an immediate release of the active principle is required (i.e., to face media that exhibit a large contaminants charge), a faster release can be obtained too. Therefore, these membranes can be modulated to the specific target required in food preservation and shelf life increase, used as small independent devices. Modulation of Cm release times can be set in dependence of the timing required: shorter shelf-life against larger antimicrobial/antioxidant loading or longer shelf-life against smaller loading of biological unwanted materials. References
Fig. 11. DPPH• color change from purple (a) to yellow (b) when the solution Cm+water+ethanol, obtained after the I release test from the membrane at 24% w/w CA, was added to the control solution. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) Table 3 Antioxidant activity of 20% w/w Cm loaded CA membranes after I and IV release test. Sample CA CA CA CA CA CA
(12% (12% (18% (18% (24% (24%
I (%) w/w) + Cm w/w) + Cm w/w) + Cm w/w) + Cm w/w) + Cm w/w) + Cm
(20% (20% (20% (20% (20% (20%
w/w) w/w) w/w) w/w) w/w) w/w)
I test IV test I test IV test I test IV test
86.73 81.51 89.22 85.36 92.92 82.13
10% with respect to the first release. This result means that in a release medium, in which curcumin is progressively consumed by oxidation, these membranes are still extremely active. Considering the measured high antioxidant activity of curcumin, there are not doubts about its stability after supercritical processing. In the case of curcumin, it is not necessary to verify the preservation of the antimicrobial activity, as in the case of antimicrobial devices based on bioactive compounds (e.g., enzymes), since this characteristic is preserved until the compound decomposes.
[1] De Moura MR, Mattoso LH, Zucolotto V. Development of cellulose-based bactericidal nanocomposites containing silver nanoparticles and their use as active food packaging. J Food Eng 2012;109(3):520–4. [2] Ramos M, Jiménez A, Peltzer M, Garrigós MC. Characterization and antimicrobial activity studies of polypropylene films with carvacrol and thymol for active packaging. J Food Eng 2012;109(3):513–19. [3] Gómez-Estaca J, López-de-Dicastillo C, Hernández-Muñoz P, Catalá R, Gavara R. Advances in antioxidant active food packaging. Trends Food Sci Technol 2014;35(1):42–51. [4] Appendini P, Hotchkiss JH. Review of antimicrobial food packaging. Innov Food Sci Emerg Technol 2002;3(2):113–326. [5] Ozdemir M, Floros JD. Active food packaging technologies. Crit Rev Food Sci Nutr 2004;44(3):185–93. [6] Vermeiren L, Devlieghere F, Van Beest M, De Kruijf N, Debevere J. Developments in the active packaging of foods. Trends Food Sci Technol 1999;10(3):77–86. [7] Zorofchian Moghadamtousi S, Abdul Kadir H, Hassandarvish P, Tajik H, Abubakar S, Zandi K. A review on antibacterial, antiviral, and antifungal activity of curcumin. BioMed Res Int 2014, Article ID 186864: 1–12. [8] Wang Y, Lu Z, Wu H, Lv F. Study on the antibiotic activity of microcapsule curcumin against foodborne pathogens. Int J Food Microbiol 2009;136(1):71–4. [9] Chen D-Y, Shien J-H, Tiley L, Chiou S-S, Wang S-Y, Chang T-J, et al. Curcumin inhibits influenza virus infection and haemagglutination activity. Food Chem 2010;119(4):1346–51. [10] Sharma M, Manoharlal R, Shukla S, Puri N, Prasad T, Ambudkar SV, et al. Curcumin modulates efflux mediated by yeast ABC multidrug transporters and is synergistic with antifungals. Antimicrob Agents Chemother 2009;53(8):3256–65. [11] Balakrishnan VV, Abidin Z, Naziron N, Nasir K, Rusli M, Lee S, et al. Influence of curcumin natural dye colorant with PMMA-acrylic polyol blended polymer. Pigment Resin Technol 2013;42(2):95–102. [12] Hashem MM, Atta AH, Arbid MS, Nada SA, Asaad GF. Immunological studies on Amaranth, Sunset Yellow and Curcumin as food colouring agents in albino rats. Food Chem Toxicol 2010;48(6):1581–6. [13] Vimala K, Yallapu MM, Varaprasad K, Reddy NN, Ravindra S, Naidu NS, et al. Fabrication of curcumin encapsulated chitosan-PVA silver nanocomposite films for improved antimicrobial activity. J Biomater Nanobiotechnol 2011;2(01):55. [14] Wan S, Sun Y, Qi X, Tan F. Improved bioavailability of poorly water-soluble drug curcumin in cellulose acetate solid dispersion. Aaps Pharmscitech 2012;13(1):159–66. [15] Luo N, Varaprasad K, Reddy GVS, Rajulu AV, Zhang J. Preparation and characterization of cellulose/curcumin composite films. RSC Adv 2012;2(22):8483–8.
Please cite this article as: L. Baldino et al., Biodegradable membranes loaded with curcumin to be used as engineered independent devices in active packaging, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.12.020
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ARTICLE IN PRESS
[m5G;December 30, 2016;22:3]
L. Baldino et al. / Journal of the Taiwan Institute of Chemical Engineers 000 (2016) 1–9 [16] Sonkaew P, Sane A, Suppakul P. Antioxidant activities of curcumin and ascorbyl dipalmitate nanoparticles and their activities after incorporation into cellulose-based packaging films. J Agric Food Chem 2012;60(21):5388–99. [17] Campardelli R, Reverchon E. α -Tocopherol nanosuspensions produced using a supercritical assisted process. J Food Eng 2015;149:131–6. [18] Campardelli R, Adami R, Della Porta G, Reverchon E. Nanoparticle precipitation by supercritical assisted injection in a liquid antisolvent. Chem Eng J 2012;192:246–51. [19] Della Porta G, Falco N, Giordano E, Reverchon E. PLGA microspheres by Supercritical Emulsion Extraction: a study on insulin release in myoblast culture. J Biomater Sci Polym Ed 2013;24(16):1831–47. [20] Prosapio V, De Marco I, Scognamiglio M, Reverchon E. Folic acid–PVP nanostructured composite microparticles by supercritical antisolvent precipitation. Chem Eng J 2015;277:286–94. [21] Meneses MA, Caputo G, Scognamiglio M, Reverchon E, Adami R. Antioxidant phenolic compounds recovery from Mangifera indica L. by-products by supercritical antisolvent extraction. J Food Eng 2015;163:45–53. [22] Chen C-R, Lee Y-N, Lee M-R, Chang C-MJ. Supercritical fluids extraction of cinnamic acid derivatives from Brazilian propolis and the effect on growth inhibition of colon cancer cells. J Taiwan Inst Chem Eng 2009;40(2):130–5. [23] Chen C-H, Yang Y-H, Shen C-T, Lai S-M, Chang C-MJ, Shieh C-J. Recovery of vitamins B from supercritical carbon dioxide-defatted rice bran powder using ultrasound water extraction. J Taiwan Inst Chem Eng 2011;42(1):124–8. [24] Yen H-W, Chiang W-C, Sun C-H. Supercritical fluid extraction of lutein from Scenedesmus cultured in an autotrophical photobioreactor. J Taiwan Inst Chem Eng 2012;43(1):53–7. [25] Maran JP, Priya B. Supercritical fluid extraction of oil from muskmelon (Cucumis melo) seeds. J Taiwan Inst Chem Eng 2015;47:71–8. [26] Baldino L, Sarno M, Cardea S, Irusta S, Ciambelli P, Santamaria J, et al. Formation of cellulose acetate–graphene oxide nanocomposites by supercritical CO2 assisted phase inversion. Ind Eng Chem Res 2015;54(33):8147–56. [27] Baldino L, Cardea S, Reverchon E. Supercritical assisted enzymatic membranes preparation, for active packaging applications. J Membr Sci 2014;453:409–18. [28] Baldino L, Cardea S, Reverchon E. Production of antimicrobial membranes loaded with potassium sorbate using a supercritical phase separation process. Innov Food Sci Emerg Technol 2016;34:77–85. [29] García-González C, Alnaief M, Smirnova I. Polysaccharide-based aerogels—promising biodegradable carriers for drug delivery systems. Carbohydr Polym 2011;86(4):1425–38. [30] García-González CA, Concheiro A, Alvarez-Lorenzo C. Processing of materials for regenerative medicine using supercritical fluid technology. Bioconjug Chem 2015;26(7):1159–71.
9
[31] Baldino L, Concilio S, Cardea S, De Marco I, Reverchon E. Complete glutaraldehyde elimination during chitosan hydrogel drying by SC-CO2 processing. J Supercrit Fluids 2015;103:70–6. [32] Duarte ARC, Santo VE, Alves A, Silva SS, Moreira-Silva J, Silva TH, et al. Unleashing the potential of supercritical fluids for polymer processing in tissue engineering and regenerative medicine. J Supercrit Fluids 2013;79:177–85. [33] Reverchon E, Cardea S. Formation of cellulose acetate membranes using a supercritical fluid assisted process. J Membr Sci 2004;240(1–2):187–95. [34] Gugliuzza A, Cardea S, Drioli E, Reverchon E. Supercritical CO2 –EtOH expanded liquid processing to produce tailored PEEK-WC membranes. RSC Adv 2014;4(110):65098–107. [35] Huang S, Wu G, Chen S. Preparation of microporous poly (vinylidene fluoride) membranes via phase inversion in supercritical CO2 . J Membr Sci 20 07;293(1):10 0–10. [36] Zaherzadeh A, Karimi-Sabet J, Mousavian SMA, Ghorbanian S. Optimization of flat sheet hydrophobic membranes synthesis via supercritical CO2 induced phase inversion for direct contact membrane distillation by using response surface methodology (RSM). J Supercrit Fluids 2015;103:105–14. [37] Shi W, He G, Zhao W, Zhang L, Du L, Wang Y, et al. Effects of solvent and nonsolvent diffusion velocities on the morphology of cellular polyetherimide membranes prepared using supercritical CO2 phase inversion. J Supercrit Fluids 2013;83:6–14. [38] Van de Witte P, Dijkstra P, Van den Berg J, Feijen J. Phase separation processes in polymer solutions in relation to membrane formation. J Membr Sci 1996;117(1):1–31. [39] Liu X, Ong SL, Ng HY. Fabrication of mesh-embedded double-skinned substrate membrane and enhancement of its surface hydrophilicity to improve anti-fouling performance of resultant thin-film composite forward osmosis membrane. J Membr Sci 2016;511:40–53. [40] Tang YP, Yuwen S, Chung TS, Weber M, Staudt C, Maletzko C. Synthesis of hyperbranched polymers towards efficient boron reclamation via a hybrid ultrafiltration process. J Membr Sci 2016;510:112–21. [41] Reverchon E, Cardea S. PVDF-HFP membrane formation by supercritical CO2 processing: elucidation of formation mechanisms. Ind Eng Chem Res 2006;45(26):8939–45. [42] Ak T, Gülçin I˙ . Antioxidant and radical scavenging properties of curcumin. Chem Biol Interact 2008;174(1):27–37. [43] Gunes H, Gulen D, Mutlu R, Gumus A, Tas T, Topkaya AE. Antibacterial effects of curcumin: an in vitro minimum inhibitory concentration study. Toxicol Ind Health 2013;32(2):246–50.
Please cite this article as: L. Baldino et al., Biodegradable membranes loaded with curcumin to be used as engineered independent devices in active packaging, Journal of the Taiwan Institute of Chemical Engineers (2016), http://dx.doi.org/10.1016/j.jtice.2016.12.020