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Centrifugally spun starch-based fibers from amylopectin rich starches
Accepted Manuscript Title: Centrifugally spun starch-based fibers from amylopectin rich starches Author: Xianglong Li Huanhuan Chen Bin Yang PII: DOI: Reference:
S0144-8617(15)01059-0 http://dx.doi.org/doi:10.1016/j.carbpol.2015.10.079 CARP 10496
To appear in: Received date: Revised date: Accepted date:
18-8-2015 14-10-2015 25-10-2015
Please cite this article as: Li, X., Chen, H., and Yang, B.,Centrifugally spun starchbased fibers from amylopectin rich starches, Carbohydrate Polymers (2015), http://dx.doi.org/10.1016/j.carbpol.2015.10.079 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Centrifugally spun starch-based fibers from amylopectin rich
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starches Xianglong Li, Huanhuan Chen, Bin Yang* National Engineering Lab for Textile Fiber Materials and Processing Technology, College of Materials and Textiles, Zhejiang Sci-Tech University, China, 310018
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Corresponding Author: [email protected]
Abstract
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Centrifugal spinning and electrospinning have proved to be effective techniques for fabricating micro-to-nanofibers. However, starches of amylopectin content above 65% cannot be fabricated to fiber by electrospinning. This paper is focus on the centrifugal spinnability of amylopectin rich starches. We investigated the amylopectin content of starches by Dual-wavelength colorimetry,
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studied the rheological properties of starch dopes to determine entanglement concentration (ce) by rotary rheometer. Results indicated that amylopectin rich native corn and potato starches, which with amylopectin content higher than 65%, were suitable for centrifugal spinning to micro-to-nanofibers. Additionally, starch-based fibers were successfully fabricated from the amylose rich corn starch as spinning.
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well. Rheological studies showed that the entanglement concentration (ce) of starch solution was crucial for successful centrifugal Keywords: starch-based fibers, centrifugal spinning, amylopectin content, entanglement concentration
Chemical compounds studied in this article
NaOH (PubChem CID: 14798); Corn starch (PubChem CID: 24836924); Waxy starch (PubChem CID: 86278134);
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Potato starch (PubChem CID: 49956036); KOH (PubChem CID: 14797); HCl (PubChem CID: 313); KI (PubChem CID: 4875); I2 (PubChem CID: 30165).
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1．Introduction
Micro-to-nanomaterials have enormous applications in food packing (Gonzalez & Igarzabal, 2015; Stijnman, Bodnar & Tromp, 2011), scaffold (Badrossamay et al., 2014; Wang, Shi, Liu, Secret & Chen, 2011), drug delivery (Zamani, Prabhakaran & Ramakrishna, 2013), etc. In these critical fields, bio-based micro-to-nanomaterials have drawn increasingly attention for their advantages of sustainable supply, environmentally-friendly, and biocompatibility. Starch, as one of the most important biopolymer, has been widely used in food, textile, medical, etc. It contains amylose, a linear of lightly branched (1→4)-linked α-glucopyranose and amylopectin constituted by a highly branched molecule of (1→4) -linked α-glucopyranose and α-(1→6) branch linkages (Cheetham & Tao, 1998; Kong & Ziegler, 2014). The relative weight percentages of amylopectin in most native starches are usually between 72% and 82% (Buleon, Colonna, Planchot & Ball, 1998).
In past few decades, starch-based fibers were fabricated mainly by blending native or modified starches with polymers, plasticizers, cross-linkers, or other additives (Curvelo, Carvalho & Agnelli, 2001; Eden, Milltone, Trksak & Manvllle, 1989). Due to a large amount of non-starch components, fibers were prevented from expressing properties of starches (Curvelo, Carvalho & Agnelli, 2001; Gordon, Cabell, Mackey, Michael & Trokhan, 2006). Others were focused on fabricating starch-based fibers from amylose, but was limited by the high cost of purify amylose and great waste of starches. Recently, pure starch-based fibers were successfully fabricated by “electro-wet-spinning” (Kong & Ziegler, 2012, 2014). However, the method was demonstrated to be suitable for starches with amylopectin content below 65% and
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sensitive to amylopectin content of starches, e.g. narrower spinning concentration range and shorter & thicker
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2. Experimental
starch-based fibers with increasing amylopectin content (Kong & Ziegler, 2012). Centrifugal spinning is an emerging technique for fabricating micro-to-nanofibers in recent years. Compared with electrospinning, it is showed advantages of high production rate and insensitive to dielectric constant of materials (Badrossamay, McIlwee, Goss & Parker, 2010; Mary et al., 2013; Padron, Fuentes, Caruntu & Lozano, 2013; Sarkar et al., 2010). This method utilizes centrifugal force to extrude polymer jets out from nozzles. After extensively stretching of jets and accompanying solvent evaporation, micro-to-nanofibers were continuously formed and assembled on collector (Lu et al., 2013; McEachin & Lozano, 2012). At present, many kinds of micron-to-nanofibers have been successfully
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fabricated by centrifugal spinning systems, e.g. polymer materials (Lu et al., 2013; McEachin & Lozano, 2012), composite materials (Badrossamay et al., 2014; Weng et al., 2015), metal oxide (Liu, Chen, Pei, Liu & Liu, 2013), and ceramics (Schabikowski, Tomaszewska, Kata & Graule, 2014).
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In centrifugally spun experiments, we demonstrated that starch-based fibers could be fabricated from amylose rich corn starch, amylopectin rich native corn starch and potato starch. This paper concentrates on investigating the on centrifugal spinnability. Furthermore, fibers are characterized by SEM.
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2.1. Materials
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amylopectin content and rheological properties of starches, and discussing the effect of entanglement concentration (ce)
Amylopectin rich native corn starch was kindly provided by the Zhengzhou honest business Co., Ltd (Henan Province, China). Amylose rich corn starch and waxy maize starch was provided by Fu Yang Biotechnology Co., Ltd. (Shandong Province, China). Amylopectin rich potato starch was produced by our own potatoes. Caustic soda (NaOH),
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potassium hydroxide (KOH), hydrochloric acid solution (HCl), potassium iodide (KI), and iodine (I2) were provided by Aladdin (China). Amylose and amylopectin from maze were provided by Anhui cool seoul bioengineering Co., Ltd Co., Ltd (Jiangsu province, China) 2.2. Amylose contents of starches
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(Anhui province, China). Amylose and amylopectin from potato were provided by Nanjing Aoduofuni Biotechnology
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Amylose contents of starches were studied by Dual-wavelength colorimetry. Samples of 50 mg pure amylose and amylopectin were weighed and transferred into 100 mL meter glass, respectively. KOH solutions (0.5mol/L) of 10 mL were added to the samples with continuously stirring for 30 min in a boiling water bath. Samples were then diluted to 100 mL with distilled water and used as standard solutions (0.5 mg/mL) of pure amylose and amylopectin. The standard solutions (5 mL) of pure amylose and amylopectin were pipetted into 100 mL meter glass and added 40 mL distilled water, respectively. Iodine reagent (2% KI, 0.2% I2) of 1 mL were added into the standard solutions as starch developing agent (Zhu, Jackson, Wehling & Geera, 2008). The pH of solutions was adjusted to about 3.5 with HCL solution (0.1mol/L). These solutions were then diluted to 100 mL with distilled water and allowed to stand 20 min for fully developing color. The samples were subsequently scanned from 400 to 800 nm in a 10 mm quartz cell through a UV spectrophotometer (Lambda 900, Perkin Elmer, United States). Distilled water was used as blank sample. Detection wavelength of amylose (λ1, λ2) was obtained by isosbestic point. Amylose standard solution (0.5 mg/mL) of 1, 2, 3, 4, 5, and 6 mL were pipetted into different 100 mL meter glass and added 40 mL distilled water, respectively. These solutions were then handled in accordance with the previous operation. All samples were scanned at λ1 and λ2 in a 10 mm quartz cell through the UV spectrophotometer. Absorbance difference ΔA (Aλ2 -A λ1) were plotted against amylose content (mg) to determine the standard curve. Test samples were prepared with reference to the standard samples. The samples of 15 mL (v1) were pipetted into 100 mL meter glass and added 30 mL distilled water, respectively. Iodine reagent (2% KI, 0.2% I2) of 1 mL were added into the test samples as starch developing agent. The pH of solutions was adjusted to about 3.5 with HCL solution (0.1mol/L). These solutions were then diluted to 100 mL (v2) with distilled water and allowed to stand 20 min for fully 2
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developing color. Samples were subsequently scanned from λ1 to λ2 in a 10 mm quartz cell through the UV spectrophotometer. Amylose content of starches was calculated by the follow equation:
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where x (mg) is amylose content in test samples that calculated from standard curves, m (50 mg) is sample weight. 2.3. Rheological properties of starch dopes A series of amylose rich corn starch, amylopectin rich native corn starch, amylopectin rich potato starch, and waxy maize starch solutions were prepared by dissolving starch granules in 2% (w/w) caustic soda solution with continuously
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stirring for ten hours at 25 °C. The rheological properties, which were correlated between shear viscosity and shear rates, were then studied by Physica MCR 301rheometer (Anton Paar GmbH, Graz, Austria). The used geometry was that of the coaxial cylinder (26.7 mm diameter; 0.3 mm gap). Viscosity data were collected in the shear rate ranging from 0.1 to
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1000 s-1 at 20 °C. 2.4. Centrifugal spinning
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Spinning solution of amylose rich corn starch, amylopectin rich native corn starch, amylopectin rich potato starch, and waxy maize starch were prepared according to previous operation. Set-up used in this study is made by our own group (Fig.1). The solutions could be pumped into spinneret by a syringe of 1mL. Here, we chose needles of 25 gauge
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(inner-diameter: 0.26 mm) as nozzles. The needles were 13 mm long and have bended angle of 45° at the tip of metal part. Rotational speed and nozzle-to-collector distance were kept constant at 3000 r·min-1 and 60 mm. A hot air (temperature: 50-100 °C, wind velocity: 190-200 L/min) was added to increase the evaporation rate of solvents. pumped into the spinneret each time.
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Centrifugal spinning experiments were operated at 25 °C as humidity below 50%. About 2 mL spinning solution were
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(1)
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Fig.1 Centrifugal spinning set-up used in this study. (a) The overall appearance of the device: (1) High rotational speed supply, (2)
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2.5. Morphological characterization
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3. Results and Discussion
collector, and (3) spinneret. (b) Spinneret structure: (4) Nozzle. (c) Baseplate: (5) apertures can provide for changing the nozzle-to-collector distance.
The morphology of starch-based fibers was characterized through a field emission scanning electron microscopy (EDS/EBSD, Carl Zeiss, Germany). Centrifugally spun starch-based fiber webs were removed from collector with aluminum foil and about 4 mm2 of the aluminum foils were cut into samples. The samples were then mounted on SEM stub and tested at 2 kV. Fiber diameters were analyzed by ImageJ2x software (ImageJ2X 2.1.4.7, National Institutes of Health, Besthesda, MD). SEM images of 1000 times resolution were used for analyzing fiber diameters and about 100 fibers were measured. 3.1. Amylose content of starches 3
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The absorption curves of amylose from maize and potato showed obviously absorption peaks and the amylopectin curves with weak-absorption peaks were observed. We investigated amylose content in starches and calculated amylopectin content by removing the amylose content from starches. For this purpose, the isosbestic point method was applied to determine detection wavelengths. The absorption maximum value of amylopectin from maize and potato were measured at 528 and 525nm, respectively. It was approximate the amylopectin absorption value 530-550 nm (G. Jansen, F. Ordon, E. Knopf & Diekmann, 2012). Therefore, the detection wavelengths of amylose (λ1, λ2) from maize (Fig. 2a) and potato (Fig. 2b) were determined to be (491 nm, 536 nm) and (497 nm, 532 nm), respectively.
Fig. 2 Graphical constructions of detection wavelength for amylose. (a) Starch from maize and (b) starch from potato. Black curve iodine binding with amylopectin. Table 1 Results of amylose determination
Amylose rich corn starch
λ1
λ2
ΔA
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Amylopectin rich
native corn starch
Amylopectin rich potato starch
Waxy maize starch
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reflects profile of visible spectral scan of iodine binding with amylose, and red curve reflects the profile of visible spectral scan of
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Fig. 2 displayed absorption curves of amylose (black curve) and amylopectin (red curve) within ultraviolet spectrum.
Amylose content
Average and standard deviation
(%)
(%)
0.421
0.555
0.134
78.31
0.425
0.560
0.135
79.47
0.422
0.549
0.127
75.20
0.329
0.375
0.046
32.00
0.331
0.365
0.039
28.27
0.297
0.345
0.048
33.7
0.279
0.351
0.072
28.03
0.275
0.344
0.069
27.01
0.269
0.332
0.063
24.91
0.035
0.038
0.003
9.07
0.031
0.037
0.006
10.67
0.033
0.035
0.002
8.53
77.66±1.80
31.11±2.28
26.65±0.76
9.42±0.91
Absorption values, scanned at the detection wavelengths (λ1, λ2), were collected for determining amylose standard curves and results were depicted in Fig. 3. The standard curves of starches from maize (Fig. 3a) and potato (Fig. 3b) had good linearity and with better R2 factors of 0.9935 and 0.9953, respectively. Based on the formula (1), the amylose contents of amylose rich corn starch, amylopectin rich native corn starch, amylopectin rich potato starch, and waxy maize starch were determined to be 77.66±1.80, 31.11±2.28, 26.65±0.76, and 9.42±0.91%, respectively (Table 1). Therefore, we can conclude that the amylopectin contents of these starches were about 23.34, 68.89, 73.35, and 90.58%, respectively. 4
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The results revealed that amylopectin rich native corn starch, amylopectin rich potato starch, and waxy maize starch were not suitable for electrospinning (Kong & Ziegler, 2012).
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Fig. 3 Standard curve for amylose determination. Each sample was used pure amylose with known amylose contents. (a) Amylose
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from maize:
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3.2. Rheological properties of starches
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(n=6).
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(n=6). (b) Amylose from potato:
Fig. 4 plots of apparent viscosity versus shear rate for different concentrations of amylose rich corn starch (a), amylopectin rich native corn starch (b), amylopectin rich potato starch (c), and waxy maize starch (d) in 2% caustic soda solutions.
A series of starch solution of different concentrations were prepared to study the rheological properties, and followed by understanding the correlation between entanglement concentration (ce) and centrifugal spinnability of starches. Flow curves of amylose rich corn starch, amylopectin rich native corn starch, potato starch, and waxy maize starch solution in 2.0 % (w/w) caustic soda solution with varying starch concentration were given in Fig. 4. It was observed that the different concentration of starches in caustic soda solution showed rapid decrease in viscosity as shear rates increased from 0.1 to 1000 s-1 (Fig. 4). According to the previous report, a rapid decrease in viscosity of starch formic acid dispersions is result of amylose leach which decrease entanglement network (Lancuski, Vasilyev, Putaux & Zussman, 2015). To our knowledge, some acid and alkaline media can gelatinize starch at room temperature. Therefore, it was probably for the same reason that the decrease of viscosity in this experiment. Zero shear viscosity (η0) was 5
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obtained from the flow curves, which by using the values for apparent viscosity at 0.1s-1. Specific viscosity (ηsp) was calculated through the following formula (Kong & Ziegler, 2012; Lu et al., 2013):
3 where ηs is solvent viscosity.
Specific viscosity data were plotted against starch concentration to determine the entanglement concentration (ce). By fitting slopes in the semidulte unentangled and the semidilute entangled regimes, the ce value of amylose rich corn starch, amylopectin rich native corn starch and potato starch were determined to be 6.0, 4.0, and 2.0 % (w/w),
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respectively (Fig 5). The exponents indicated that weak entanglement was obtained in amylopectin rich starches, and was weaken as amylopectin content increases. This could be due to amylopectin cannot entangle much for its highly branched structure. In other words, the side chain of amylopectin component is likely to reduce the chances of main chain
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entanglement，so the ce value of waxy maize starch was not obtained in this experiment (Fig. 5d). Therefore, we also conclude that amylose component can be contributed to molecular chain entanglements in starch solution which consistent with previous (Kong & Ziegler, 2012; Lancuski, Vasilyev, Putaux & Zussman, 2015).
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Fig. 5 Plots of specific viscosity versus starch concentrations for entanglement concentration (ce) determination: amylose rich corn
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3.3. The centrifugal spinnability of starch
starch (a), amylopectin rich native corn starch (b), amylopectin rich potato starch (c), and waxy maize starch (d) in 2% caustic soda solutions.
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Amylose rich corn starch, amylopectin rich native corn starch and potato starch in 2% (w/w) caustic soda solution were demonstrated to be suitable for successful centrifugal spinning. To understand the correlation between solution
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intrinsic properties centrifugal spinnability, we considered the concentration of starch-based fibers starts to form easily as the critical concentration (c*) (Kong & Ziegler, 2012; Badrossamay, McIlwee, Goss & Parker, 2010). In the semidilute entangled regime (ce
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amylopectin rich starch solution. Therefore, the good starch-based fibers could be formed only when concentration increased to entangled regime (c*
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entanglement network for the low amylose content of starches. Fiber formation was unsuccessful for waxy maize starch solution with changing concentration from 8 to16 % (w/w) (Table 2). These results implied that spinning solution must first have a ce value for successfully preparing starch-based fibers by centrifugal spinning, followed by the fibers can be formed easily when the spinning solution reached critical concentrations c*. The failure of preparing starch-based fibers
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Fig.6 Optical image of corn starch fibers (a) Fiber web on collector. (b) The fiber web removed from the collector.
from waxy maize starch solution was precisely because of a ce value was not obtained. Fig. 6 showed photographic image of starch-based fibers produced by centrifugal spinning from 14 % (w/w)
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amylopectin rich native corn starch solution at 3000 r•min-1 rotational speed. A large amount of starch-based fibers were deposited on the collector (Fig. 6a) and fiber webs showed loose structures (Fig. 6b). In these experiments, we could fabricate 2 mL starch solution into fibers within 5-6 min.
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spinning: (a, b, c) amylose rich corn starch, (d, e, f,) native corn starch, and (g, h, i) potato starch.
The starch-based fibers, which were fabricated from amylose rich corn starch of 15% (w/w), amylopectin rich native corn starch of 14 % (w/w), and amylopectin rich potato starch solutions of 11 % (w/w), were characterized by SEM. Surface of ultrafine fibers is controlled by phase separation (Bognitzki et al., 2001). The phase separation is a typical
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Fig.7 Scanning Electron Micrograph (SEM) images and fiber diameter distributions of starch-based fibers fabricated by centrifugal
stage of starch gelatinization, and effected by amylose content (Asa Rindlav Westling, Mats Stading & Gatenholm, 2001; Lancuski, Vasilyev, Putaux & Zussman, 2015). In this experiment, the starch-based fibers that obtained from amylose and
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amylopectin rich corn starches were smooth in surface, which showed non-obvious of phase separation (Fig. 7a, 7d). For the amylopectin rich potato starch, the higher amylopectin content caused evident phase separation, and thus resulted rough in surface of obtained fibers (Fig. 7g). Average diameters of amylose rich corn, amylopectin rich native corn and potato starch-based fibers were 1.4±0.2, 1.3±0.4, and 1.5±0.6μm (± std. dev.), respectively (Table 2). Diameters of starch-based fibers were mainly distributed from 0.75 to 2.25 μm (Fig. 7c, 7f, 7i), which indicated a narrow distribution. The starch-based fiber webs contained a lot of cup-like beads (Fig. 7b, 7e, 7h). These beads were another manifestation of the Rayleigh-Taylor instability which was induced by surface tension (Weitz, Harnau, Rauschenbach, Burghard & Kern, 2008). The obtained cup-like beads could be enriched the potential application of the webs in controlled drug release (Ikeuchi, Tane & Ikuta, 2012).
Table 2 Parameter values of all starch solution and obtained fibers α Materials
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Concentration
Fiber diameter parameters (μm)
Average diameter and standard derivation
% (w/w)
Q1
Q2
Q3
(μm)
Amylose rich corn starch
15
1.09
1.26
1.68
1.4±0.2
Amylopectin rich native corn starch
14
1.07
1.23
1.36
1.3±0.4
Amylopectin rich potato starch
11
1.17
1.44
1.68
1.5±0.6
Waxy maize starch
8-16
N/A
N/A
N/A
Only beads
α
Q1, Q2, and Q3 are first, second, and third quartile of fiber diameter distribution which represent 25th, 50th, and 75th percentile,
respectively. These data suggest that all of as-spun fibers are in order of sub-micron and with narrow diameter distributions. 8
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4. Conclusion
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5. Acknowledgment
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6. Reference
In conclusion, amylopectin rich starch-based fibers with an average diameter of sub-microns have been successfully fabricated from amylopectin rich native corn and potato starches by centrifugal spinning. Amylopectin content of the native corn and potato starch were determined to be about 68.89 and 73.35 %, respectively. Certainly amylose rich corn starch was also suitable for centrifugal spinning. In addition, the entanglement concentration (ce) value is demonstrated to be crucial for successful centrifugal spinning, which due to the failed fabricating starch-based fibers from waxy maize starch dopes. Given results of this paper, we believe that centrifugal spinning could be extended to fabricate micro-to-nanofibers from other branched-chain polymer.
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Although the present work has not been focused on properties of the obtained starch-based fibers, we believe that the highlighting of low-cost, environmental-friendly, and sustainability for starch-based fibers give the potential
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application in the food packing, tissue engineering, textile industries, etc.
We acknowledge financial support by Zhejiang Top Priority Discipline of Textile Science and Engineering (grant
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number: 2014KF02) and Zhejiang Leading Team of Science and Technology innovation (grant number: 2011R50004) Badrossamay, M. R., Balachandran, K., Capulli, A. K., Golecki, H. M., Agarwal, A., Goss, J. A., Kim, H., Shin, K., &
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Weng, B., Xu, F., Garza, G., Alcoutlabi, M., Salinas, A., & Lozano, K. (2015). The production of carbon nanotube reinforced poly (vinyl) butyral nanofibers by the forcespinning® method. Polymer Engineering & Science, 55(1),
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81-87. doi:10.1002/pen.23872
Zamani, M., Prabhakaran, M. P., & Ramakrishna, S. (2013). Advances in drug delivery via electrospun and electrosprayed nanomaterials. Int J Nanomedicine, 8, 2997-3017. doi: 10.2147/IJN.S43575 Bognitzki, M., Czado, W., Frese, T., Schaper, A., Hellwig, M., Steinhart, M., Greiner, A., & Wendorf, J. H. (2001). Fibers
via
Electrospinning.
10.1002/1521-4095(200101)13:13.3.CO; 2-8
Advanced
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Nanostructured
Materials,
13(1),
70-72.
DOI:
G. Jansen, F. Ordon, E. Knopf, & Diekmann, K. (2012). Rapid methods for selecting single kernels of waxy barley.
d
Journal of Applied Botany and Food Quality, 84(1), 6-10. Gordon, G. C., Cabell, D. W., Mackey, L. N., Michael, J. G., & Trokhan, P. D. (2006). Electro-spinning process for making starch filaments for flexible structure. U.S. Patent.
Ac ce pt e
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
Lancuski, A., Vasilyev, G., Putaux, J. L., & Zussman, E. (2015). Rheological Properties and Electrospinnability of High-Amylose Starch in Formic Acid. Biomacromolecules, 16(8), 2529-2536. doi: 10.1021/acs.biomac.5b00817 Zhu, T., Jackson, D. S., Wehling, R. L., & Geera, B. (2008). Comparison of Amylose Determination Methods and the Development of a Dual Wavelength Iodine Binding Technique1. Cereal Chemistry, 85(1), 51-58. doi: 10.1094/cchem-85-1-0051
Asa Rindlav Westling, Mats Stading, & Gatenholm, P. (2001). Crystallinity and Morphology in Films of Starch, Amylose and Amylopectin Blends. Biomacromolecules, 3(1), 84-91. DOI: 10.1021/bm010114i
Highlights
37
The centrifugal spinnability of amylopectin rich starches was studied.
38
Entanglement concentration ce was significantly affected by amylopectin content.
39
The ce value of starch solution played a decisive role in centrifugal spinning.
40
Starch-based fibers formed easily when critical concentration c* reaches.
41 10
Page 10 of 11
Table 1 Results of amylose determination
Amylopectin rich native corn starch
Amylopectin rich potato starch
3 4 5 6
0.421
0.555
0.134
78.31
0.425
0.560
0.135
79.47
0.422
0.549
0.127
75.20
0.329
0.375
0.046
32.00
0.331
0.365
0.039
28.27
0.297
0.345
0.048
33.7
0.279
0.351
0.072
28.03
0.275
0.344
0.069
27.01
0.269
0.332
0.063
24.91
0.035
0.038
0.003
0.031
0.037
0.006
0.033
0.035
0.002
Concentration
31.11±2.28
26.65±0.76
9.07
10.67
9.42±0.91
8.53
Q1
Q2
Q3
Average diameter and standard derivation (μm)
Amylose rich corn starch
15
1.09
1.26
1.68
1.4±0.2
Amylopectin rich native corn starch
14
d
% (w/w)
Fiber diameter parameters (μm)
1.07
1.23
1.36
1.3±0.4
Amylopectin rich potato starch
11
1.17
1.44
1.68
1.5±0.6
Waxy maize starch
8-16
N/A
N/A
N/A
Only beads
α
Ac ce pt e
9 10 11 12
77.66±1.80
Table 2 Parameter values of all starch solution and obtained fibers α Materials
7 8
(%)
an
Waxy maize starch
(%)
ΔA
ip t
starch
Average and standard deviation
λ2
cr
Amylose rich corn
Amylose content
λ1
us
Materials
M
1 2
Q1, Q2, and Q3 are first, second, and third quartile of fiber diameter distribution which represent 25th, 50th, and 75th percentile,
respectively. These data suggest that all of as-spun fibers are in order of sub-micron and with narrow diameter distributions.
11
Page 11 of 11
S0144-8617(15)01059-0 http://dx.doi.org/doi:10.1016/j.carbpol.2015.10.079 CARP 10496
To appear in: Received date: Revised date: Accepted date:
18-8-2015 14-10-2015 25-10-2015
Please cite this article as: Li, X., Chen, H., and Yang, B.,Centrifugally spun starchbased fibers from amylopectin rich starches, Carbohydrate Polymers (2015), http://dx.doi.org/10.1016/j.carbpol.2015.10.079 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
1
Centrifugally spun starch-based fibers from amylopectin rich
2
starches Xianglong Li, Huanhuan Chen, Bin Yang* National Engineering Lab for Textile Fiber Materials and Processing Technology, College of Materials and Textiles, Zhejiang Sci-Tech University, China, 310018
8
cr
Corresponding Author: [email protected]
Abstract
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Centrifugal spinning and electrospinning have proved to be effective techniques for fabricating micro-to-nanofibers. However, starches of amylopectin content above 65% cannot be fabricated to fiber by electrospinning. This paper is focus on the centrifugal spinnability of amylopectin rich starches. We investigated the amylopectin content of starches by Dual-wavelength colorimetry,
an
studied the rheological properties of starch dopes to determine entanglement concentration (ce) by rotary rheometer. Results indicated that amylopectin rich native corn and potato starches, which with amylopectin content higher than 65%, were suitable for centrifugal spinning to micro-to-nanofibers. Additionally, starch-based fibers were successfully fabricated from the amylose rich corn starch as spinning.
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well. Rheological studies showed that the entanglement concentration (ce) of starch solution was crucial for successful centrifugal Keywords: starch-based fibers, centrifugal spinning, amylopectin content, entanglement concentration
Chemical compounds studied in this article
NaOH (PubChem CID: 14798); Corn starch (PubChem CID: 24836924); Waxy starch (PubChem CID: 86278134);
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21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41
*
Potato starch (PubChem CID: 49956036); KOH (PubChem CID: 14797); HCl (PubChem CID: 313); KI (PubChem CID: 4875); I2 (PubChem CID: 30165).
Ac ce pt e
9 10 11 12 13 14 15 16 17 18 19 20
ip t
3 4 5 6 7
1．Introduction
Micro-to-nanomaterials have enormous applications in food packing (Gonzalez & Igarzabal, 2015; Stijnman, Bodnar & Tromp, 2011), scaffold (Badrossamay et al., 2014; Wang, Shi, Liu, Secret & Chen, 2011), drug delivery (Zamani, Prabhakaran & Ramakrishna, 2013), etc. In these critical fields, bio-based micro-to-nanomaterials have drawn increasingly attention for their advantages of sustainable supply, environmentally-friendly, and biocompatibility. Starch, as one of the most important biopolymer, has been widely used in food, textile, medical, etc. It contains amylose, a linear of lightly branched (1→4)-linked α-glucopyranose and amylopectin constituted by a highly branched molecule of (1→4) -linked α-glucopyranose and α-(1→6) branch linkages (Cheetham & Tao, 1998; Kong & Ziegler, 2014). The relative weight percentages of amylopectin in most native starches are usually between 72% and 82% (Buleon, Colonna, Planchot & Ball, 1998).
In past few decades, starch-based fibers were fabricated mainly by blending native or modified starches with polymers, plasticizers, cross-linkers, or other additives (Curvelo, Carvalho & Agnelli, 2001; Eden, Milltone, Trksak & Manvllle, 1989). Due to a large amount of non-starch components, fibers were prevented from expressing properties of starches (Curvelo, Carvalho & Agnelli, 2001; Gordon, Cabell, Mackey, Michael & Trokhan, 2006). Others were focused on fabricating starch-based fibers from amylose, but was limited by the high cost of purify amylose and great waste of starches. Recently, pure starch-based fibers were successfully fabricated by “electro-wet-spinning” (Kong & Ziegler, 2012, 2014). However, the method was demonstrated to be suitable for starches with amylopectin content below 65% and
1
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
sensitive to amylopectin content of starches, e.g. narrower spinning concentration range and shorter & thicker
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44
2. Experimental
starch-based fibers with increasing amylopectin content (Kong & Ziegler, 2012). Centrifugal spinning is an emerging technique for fabricating micro-to-nanofibers in recent years. Compared with electrospinning, it is showed advantages of high production rate and insensitive to dielectric constant of materials (Badrossamay, McIlwee, Goss & Parker, 2010; Mary et al., 2013; Padron, Fuentes, Caruntu & Lozano, 2013; Sarkar et al., 2010). This method utilizes centrifugal force to extrude polymer jets out from nozzles. After extensively stretching of jets and accompanying solvent evaporation, micro-to-nanofibers were continuously formed and assembled on collector (Lu et al., 2013; McEachin & Lozano, 2012). At present, many kinds of micron-to-nanofibers have been successfully
ip t
fabricated by centrifugal spinning systems, e.g. polymer materials (Lu et al., 2013; McEachin & Lozano, 2012), composite materials (Badrossamay et al., 2014; Weng et al., 2015), metal oxide (Liu, Chen, Pei, Liu & Liu, 2013), and ceramics (Schabikowski, Tomaszewska, Kata & Graule, 2014).
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In centrifugally spun experiments, we demonstrated that starch-based fibers could be fabricated from amylose rich corn starch, amylopectin rich native corn starch and potato starch. This paper concentrates on investigating the on centrifugal spinnability. Furthermore, fibers are characterized by SEM.
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2.1. Materials
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amylopectin content and rheological properties of starches, and discussing the effect of entanglement concentration (ce)
Amylopectin rich native corn starch was kindly provided by the Zhengzhou honest business Co., Ltd (Henan Province, China). Amylose rich corn starch and waxy maize starch was provided by Fu Yang Biotechnology Co., Ltd. (Shandong Province, China). Amylopectin rich potato starch was produced by our own potatoes. Caustic soda (NaOH),
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potassium hydroxide (KOH), hydrochloric acid solution (HCl), potassium iodide (KI), and iodine (I2) were provided by Aladdin (China). Amylose and amylopectin from maze were provided by Anhui cool seoul bioengineering Co., Ltd Co., Ltd (Jiangsu province, China) 2.2. Amylose contents of starches
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(Anhui province, China). Amylose and amylopectin from potato were provided by Nanjing Aoduofuni Biotechnology
Ac ce pt e
Amylose contents of starches were studied by Dual-wavelength colorimetry. Samples of 50 mg pure amylose and amylopectin were weighed and transferred into 100 mL meter glass, respectively. KOH solutions (0.5mol/L) of 10 mL were added to the samples with continuously stirring for 30 min in a boiling water bath. Samples were then diluted to 100 mL with distilled water and used as standard solutions (0.5 mg/mL) of pure amylose and amylopectin. The standard solutions (5 mL) of pure amylose and amylopectin were pipetted into 100 mL meter glass and added 40 mL distilled water, respectively. Iodine reagent (2% KI, 0.2% I2) of 1 mL were added into the standard solutions as starch developing agent (Zhu, Jackson, Wehling & Geera, 2008). The pH of solutions was adjusted to about 3.5 with HCL solution (0.1mol/L). These solutions were then diluted to 100 mL with distilled water and allowed to stand 20 min for fully developing color. The samples were subsequently scanned from 400 to 800 nm in a 10 mm quartz cell through a UV spectrophotometer (Lambda 900, Perkin Elmer, United States). Distilled water was used as blank sample. Detection wavelength of amylose (λ1, λ2) was obtained by isosbestic point. Amylose standard solution (0.5 mg/mL) of 1, 2, 3, 4, 5, and 6 mL were pipetted into different 100 mL meter glass and added 40 mL distilled water, respectively. These solutions were then handled in accordance with the previous operation. All samples were scanned at λ1 and λ2 in a 10 mm quartz cell through the UV spectrophotometer. Absorbance difference ΔA (Aλ2 -A λ1) were plotted against amylose content (mg) to determine the standard curve. Test samples were prepared with reference to the standard samples. The samples of 15 mL (v1) were pipetted into 100 mL meter glass and added 30 mL distilled water, respectively. Iodine reagent (2% KI, 0.2% I2) of 1 mL were added into the test samples as starch developing agent. The pH of solutions was adjusted to about 3.5 with HCL solution (0.1mol/L). These solutions were then diluted to 100 mL (v2) with distilled water and allowed to stand 20 min for fully 2
Page 2 of 11
1 2
developing color. Samples were subsequently scanned from λ1 to λ2 in a 10 mm quartz cell through the UV spectrophotometer. Amylose content of starches was calculated by the follow equation:
3
where x (mg) is amylose content in test samples that calculated from standard curves, m (50 mg) is sample weight. 2.3. Rheological properties of starch dopes A series of amylose rich corn starch, amylopectin rich native corn starch, amylopectin rich potato starch, and waxy maize starch solutions were prepared by dissolving starch granules in 2% (w/w) caustic soda solution with continuously
ip t
stirring for ten hours at 25 °C. The rheological properties, which were correlated between shear viscosity and shear rates, were then studied by Physica MCR 301rheometer (Anton Paar GmbH, Graz, Austria). The used geometry was that of the coaxial cylinder (26.7 mm diameter; 0.3 mm gap). Viscosity data were collected in the shear rate ranging from 0.1 to
cr
1000 s-1 at 20 °C. 2.4. Centrifugal spinning
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Spinning solution of amylose rich corn starch, amylopectin rich native corn starch, amylopectin rich potato starch, and waxy maize starch were prepared according to previous operation. Set-up used in this study is made by our own group (Fig.1). The solutions could be pumped into spinneret by a syringe of 1mL. Here, we chose needles of 25 gauge
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(inner-diameter: 0.26 mm) as nozzles. The needles were 13 mm long and have bended angle of 45° at the tip of metal part. Rotational speed and nozzle-to-collector distance were kept constant at 3000 r·min-1 and 60 mm. A hot air (temperature: 50-100 °C, wind velocity: 190-200 L/min) was added to increase the evaporation rate of solvents. pumped into the spinneret each time.
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Centrifugal spinning experiments were operated at 25 °C as humidity below 50%. About 2 mL spinning solution were
21
Ac ce pt e
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4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
(1)
22 23 24
Fig.1 Centrifugal spinning set-up used in this study. (a) The overall appearance of the device: (1) High rotational speed supply, (2)
25 26 27 28 29 30 31
2.5. Morphological characterization
32 33
3. Results and Discussion
collector, and (3) spinneret. (b) Spinneret structure: (4) Nozzle. (c) Baseplate: (5) apertures can provide for changing the nozzle-to-collector distance.
The morphology of starch-based fibers was characterized through a field emission scanning electron microscopy (EDS/EBSD, Carl Zeiss, Germany). Centrifugally spun starch-based fiber webs were removed from collector with aluminum foil and about 4 mm2 of the aluminum foils were cut into samples. The samples were then mounted on SEM stub and tested at 2 kV. Fiber diameters were analyzed by ImageJ2x software (ImageJ2X 2.1.4.7, National Institutes of Health, Besthesda, MD). SEM images of 1000 times resolution were used for analyzing fiber diameters and about 100 fibers were measured. 3.1. Amylose content of starches 3
Page 3 of 11
1 2 3 4
The absorption curves of amylose from maize and potato showed obviously absorption peaks and the amylopectin curves with weak-absorption peaks were observed. We investigated amylose content in starches and calculated amylopectin content by removing the amylose content from starches. For this purpose, the isosbestic point method was applied to determine detection wavelengths. The absorption maximum value of amylopectin from maize and potato were measured at 528 and 525nm, respectively. It was approximate the amylopectin absorption value 530-550 nm (G. Jansen, F. Ordon, E. Knopf & Diekmann, 2012). Therefore, the detection wavelengths of amylose (λ1, λ2) from maize (Fig. 2a) and potato (Fig. 2b) were determined to be (491 nm, 536 nm) and (497 nm, 532 nm), respectively.
Fig. 2 Graphical constructions of detection wavelength for amylose. (a) Starch from maize and (b) starch from potato. Black curve iodine binding with amylopectin. Table 1 Results of amylose determination
Amylose rich corn starch
λ1
λ2
ΔA
Ac ce pt e
Materials
Amylopectin rich
native corn starch
Amylopectin rich potato starch
Waxy maize starch
14 15 16 17 18 19
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reflects profile of visible spectral scan of iodine binding with amylose, and red curve reflects the profile of visible spectral scan of
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9 10 11 12 13
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cr
ip t
5 6 7 8
Fig. 2 displayed absorption curves of amylose (black curve) and amylopectin (red curve) within ultraviolet spectrum.
Amylose content
Average and standard deviation
(%)
(%)
0.421
0.555
0.134
78.31
0.425
0.560
0.135
79.47
0.422
0.549
0.127
75.20
0.329
0.375
0.046
32.00
0.331
0.365
0.039
28.27
0.297
0.345
0.048
33.7
0.279
0.351
0.072
28.03
0.275
0.344
0.069
27.01
0.269
0.332
0.063
24.91
0.035
0.038
0.003
9.07
0.031
0.037
0.006
10.67
0.033
0.035
0.002
8.53
77.66±1.80
31.11±2.28
26.65±0.76
9.42±0.91
Absorption values, scanned at the detection wavelengths (λ1, λ2), were collected for determining amylose standard curves and results were depicted in Fig. 3. The standard curves of starches from maize (Fig. 3a) and potato (Fig. 3b) had good linearity and with better R2 factors of 0.9935 and 0.9953, respectively. Based on the formula (1), the amylose contents of amylose rich corn starch, amylopectin rich native corn starch, amylopectin rich potato starch, and waxy maize starch were determined to be 77.66±1.80, 31.11±2.28, 26.65±0.76, and 9.42±0.91%, respectively (Table 1). Therefore, we can conclude that the amylopectin contents of these starches were about 23.34, 68.89, 73.35, and 90.58%, respectively. 4
Page 4 of 11
The results revealed that amylopectin rich native corn starch, amylopectin rich potato starch, and waxy maize starch were not suitable for electrospinning (Kong & Ziegler, 2012).
cr
ip t
1 2
Fig. 3 Standard curve for amylose determination. Each sample was used pure amylose with known amylose contents. (a) Amylose
5
from maize:
6 7
3.2. Rheological properties of starches
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3 4
(n=6).
8 9 10 11 12 13 14 15 16 17 18 19
Ac ce pt e
d
M
an
(n=6). (b) Amylose from potato:
Fig. 4 plots of apparent viscosity versus shear rate for different concentrations of amylose rich corn starch (a), amylopectin rich native corn starch (b), amylopectin rich potato starch (c), and waxy maize starch (d) in 2% caustic soda solutions.
A series of starch solution of different concentrations were prepared to study the rheological properties, and followed by understanding the correlation between entanglement concentration (ce) and centrifugal spinnability of starches. Flow curves of amylose rich corn starch, amylopectin rich native corn starch, potato starch, and waxy maize starch solution in 2.0 % (w/w) caustic soda solution with varying starch concentration were given in Fig. 4. It was observed that the different concentration of starches in caustic soda solution showed rapid decrease in viscosity as shear rates increased from 0.1 to 1000 s-1 (Fig. 4). According to the previous report, a rapid decrease in viscosity of starch formic acid dispersions is result of amylose leach which decrease entanglement network (Lancuski, Vasilyev, Putaux & Zussman, 2015). To our knowledge, some acid and alkaline media can gelatinize starch at room temperature. Therefore, it was probably for the same reason that the decrease of viscosity in this experiment. Zero shear viscosity (η0) was 5
Page 5 of 11
1 2
obtained from the flow curves, which by using the values for apparent viscosity at 0.1s-1. Specific viscosity (ηsp) was calculated through the following formula (Kong & Ziegler, 2012; Lu et al., 2013):
3 where ηs is solvent viscosity.
Specific viscosity data were plotted against starch concentration to determine the entanglement concentration (ce). By fitting slopes in the semidulte unentangled and the semidilute entangled regimes, the ce value of amylose rich corn starch, amylopectin rich native corn starch and potato starch were determined to be 6.0, 4.0, and 2.0 % (w/w),
ip t
respectively (Fig 5). The exponents indicated that weak entanglement was obtained in amylopectin rich starches, and was weaken as amylopectin content increases. This could be due to amylopectin cannot entangle much for its highly branched structure. In other words, the side chain of amylopectin component is likely to reduce the chances of main chain
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entanglement，so the ce value of waxy maize starch was not obtained in this experiment (Fig. 5d). Therefore, we also conclude that amylose component can be contributed to molecular chain entanglements in starch solution which consistent with previous (Kong & Ziegler, 2012; Lancuski, Vasilyev, Putaux & Zussman, 2015).
14
Ac ce pt e
d
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an
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4 5 6 7 8 9 10 11 12 13
(2)
15 16 17
Fig. 5 Plots of specific viscosity versus starch concentrations for entanglement concentration (ce) determination: amylose rich corn
18
3.3. The centrifugal spinnability of starch
starch (a), amylopectin rich native corn starch (b), amylopectin rich potato starch (c), and waxy maize starch (d) in 2% caustic soda solutions.
6
Page 6 of 11
ip t
cr
Amylose rich corn starch, amylopectin rich native corn starch and potato starch in 2% (w/w) caustic soda solution were demonstrated to be suitable for successful centrifugal spinning. To understand the correlation between solution
us
intrinsic properties centrifugal spinnability, we considered the concentration of starch-based fibers starts to form easily as the critical concentration (c*) (Kong & Ziegler, 2012; Badrossamay, McIlwee, Goss & Parker, 2010). In the semidilute entangled regime (ce
an
amylopectin rich starch solution. Therefore, the good starch-based fibers could be formed only when concentration increased to entangled regime (c*
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entanglement network for the low amylose content of starches. Fiber formation was unsuccessful for waxy maize starch solution with changing concentration from 8 to16 % (w/w) (Table 2). These results implied that spinning solution must first have a ce value for successfully preparing starch-based fibers by centrifugal spinning, followed by the fibers can be formed easily when the spinning solution reached critical concentrations c*. The failure of preparing starch-based fibers
d
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Fig.6 Optical image of corn starch fibers (a) Fiber web on collector. (b) The fiber web removed from the collector.
from waxy maize starch solution was precisely because of a ce value was not obtained. Fig. 6 showed photographic image of starch-based fibers produced by centrifugal spinning from 14 % (w/w)
Ac ce pt e
1 2
amylopectin rich native corn starch solution at 3000 r•min-1 rotational speed. A large amount of starch-based fibers were deposited on the collector (Fig. 6a) and fiber webs showed loose structures (Fig. 6b). In these experiments, we could fabricate 2 mL starch solution into fibers within 5-6 min.
7
Page 7 of 11
ip t cr us an
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spinning: (a, b, c) amylose rich corn starch, (d, e, f,) native corn starch, and (g, h, i) potato starch.
The starch-based fibers, which were fabricated from amylose rich corn starch of 15% (w/w), amylopectin rich native corn starch of 14 % (w/w), and amylopectin rich potato starch solutions of 11 % (w/w), were characterized by SEM. Surface of ultrafine fibers is controlled by phase separation (Bognitzki et al., 2001). The phase separation is a typical
d
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Fig.7 Scanning Electron Micrograph (SEM) images and fiber diameter distributions of starch-based fibers fabricated by centrifugal
stage of starch gelatinization, and effected by amylose content (Asa Rindlav Westling, Mats Stading & Gatenholm, 2001; Lancuski, Vasilyev, Putaux & Zussman, 2015). In this experiment, the starch-based fibers that obtained from amylose and
Ac ce pt e
1 2 3
amylopectin rich corn starches were smooth in surface, which showed non-obvious of phase separation (Fig. 7a, 7d). For the amylopectin rich potato starch, the higher amylopectin content caused evident phase separation, and thus resulted rough in surface of obtained fibers (Fig. 7g). Average diameters of amylose rich corn, amylopectin rich native corn and potato starch-based fibers were 1.4±0.2, 1.3±0.4, and 1.5±0.6μm (± std. dev.), respectively (Table 2). Diameters of starch-based fibers were mainly distributed from 0.75 to 2.25 μm (Fig. 7c, 7f, 7i), which indicated a narrow distribution. The starch-based fiber webs contained a lot of cup-like beads (Fig. 7b, 7e, 7h). These beads were another manifestation of the Rayleigh-Taylor instability which was induced by surface tension (Weitz, Harnau, Rauschenbach, Burghard & Kern, 2008). The obtained cup-like beads could be enriched the potential application of the webs in controlled drug release (Ikeuchi, Tane & Ikuta, 2012).
Table 2 Parameter values of all starch solution and obtained fibers α Materials
19 20
Concentration
Fiber diameter parameters (μm)
Average diameter and standard derivation
% (w/w)
Q1
Q2
Q3
(μm)
Amylose rich corn starch
15
1.09
1.26
1.68
1.4±0.2
Amylopectin rich native corn starch
14
1.07
1.23
1.36
1.3±0.4
Amylopectin rich potato starch
11
1.17
1.44
1.68
1.5±0.6
Waxy maize starch
8-16
N/A
N/A
N/A
Only beads
α
Q1, Q2, and Q3 are first, second, and third quartile of fiber diameter distribution which represent 25th, 50th, and 75th percentile,
respectively. These data suggest that all of as-spun fibers are in order of sub-micron and with narrow diameter distributions. 8
Page 8 of 11
1 2 3 4 5 6 7 8 9 10 11
4. Conclusion
12 13 14
5. Acknowledgment
15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44
6. Reference
In conclusion, amylopectin rich starch-based fibers with an average diameter of sub-microns have been successfully fabricated from amylopectin rich native corn and potato starches by centrifugal spinning. Amylopectin content of the native corn and potato starch were determined to be about 68.89 and 73.35 %, respectively. Certainly amylose rich corn starch was also suitable for centrifugal spinning. In addition, the entanglement concentration (ce) value is demonstrated to be crucial for successful centrifugal spinning, which due to the failed fabricating starch-based fibers from waxy maize starch dopes. Given results of this paper, we believe that centrifugal spinning could be extended to fabricate micro-to-nanofibers from other branched-chain polymer.
ip t
Although the present work has not been focused on properties of the obtained starch-based fibers, we believe that the highlighting of low-cost, environmental-friendly, and sustainability for starch-based fibers give the potential
cr
application in the food packing, tissue engineering, textile industries, etc.
We acknowledge financial support by Zhejiang Top Priority Discipline of Textile Science and Engineering (grant
us
number: 2014KF02) and Zhejiang Leading Team of Science and Technology innovation (grant number: 2011R50004) Badrossamay, M. R., Balachandran, K., Capulli, A. K., Golecki, H. M., Agarwal, A., Goss, J. A., Kim, H., Shin, K., &
an
Parker, K. K. (2014). Engineering hybrid polymer-protein super-aligned nanofibers via rotary jet spinning. Biomaterials, 35(10), 3188-3197. doi:10.1016/j.biomaterials.2013.12.072
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
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Highlights
37
The centrifugal spinnability of amylopectin rich starches was studied.
38
Entanglement concentration ce was significantly affected by amylopectin content.
39
The ce value of starch solution played a decisive role in centrifugal spinning.
40
Starch-based fibers formed easily when critical concentration c* reaches.
41 10
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Table 1 Results of amylose determination
Amylopectin rich native corn starch
Amylopectin rich potato starch
3 4 5 6
0.421
0.555
0.134
78.31
0.425
0.560
0.135
79.47
0.422
0.549
0.127
75.20
0.329
0.375
0.046
32.00
0.331
0.365
0.039
28.27
0.297
0.345
0.048
33.7
0.279
0.351
0.072
28.03
0.275
0.344
0.069
27.01
0.269
0.332
0.063
24.91
0.035
0.038
0.003
0.031
0.037
0.006
0.033
0.035
0.002
Concentration
31.11±2.28
26.65±0.76
9.07
10.67
9.42±0.91
8.53
Q1
Q2
Q3
Average diameter and standard derivation (μm)
Amylose rich corn starch
15
1.09
1.26
1.68
1.4±0.2
Amylopectin rich native corn starch
14
d
% (w/w)
Fiber diameter parameters (μm)
1.07
1.23
1.36
1.3±0.4
Amylopectin rich potato starch
11
1.17
1.44
1.68
1.5±0.6
Waxy maize starch
8-16
N/A
N/A
N/A
Only beads
α
Ac ce pt e
9 10 11 12
77.66±1.80
Table 2 Parameter values of all starch solution and obtained fibers α Materials
7 8
(%)
an
Waxy maize starch
(%)
ΔA
ip t
starch
Average and standard deviation
λ2
cr
Amylose rich corn
Amylose content
λ1
us
Materials
M
1 2
Q1, Q2, and Q3 are first, second, and third quartile of fiber diameter distribution which represent 25th, 50th, and 75th percentile,
respectively. These data suggest that all of as-spun fibers are in order of sub-micron and with narrow diameter distributions.
11
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