- Email: [email protected]
blocked isocyanate prepolymers nanofibers with hydrolyzed products of Scutellariae Radix
Materials Letters 65 (2011) 2772–2775
Contents lists available at ScienceDirect
Materials Letters j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / m a t l e t
Preparation of the crosslinked poly(vinyl alcohol)/blocked isocyanate prepolymers nanofibers with hydrolyzed products of Scutellariae Radix R. Nirmala a, Ji-Hui Lee b, c, R. Navamathavan d, Jae Heon Yang c, Hak Yong Kim b, c,⁎ a
Bio-nano System Engineering, Chonbuk National University, Jeonju, 561 756, South Korea Department of Textile Engineering, Chonbuk National University, Jeonju, 561-756, South Korea Center for Healthcare Technology & Development, Chonbuk National University, Jeonju, 561 756, South Korea d School of Advanced Materials Engineering, Chonbuk National University, Jeonju 561 756, South Korea b c
a r t i c l e
i n f o
Article history: Received 25 January 2011 Accepted 26 May 2011 Available online 2 June 2011 Keywords: Polymeric composites Biomaterial Crosslinking Scutellariae Radix Nanofibers Electrospinning
a b s t r a c t We report on the preparation and characterizations of Scutellariae Radix (SR) blended poly(vinyl alcohol) (PVA)/blocked isocyanate prepolymer (BIP) composite nanofibers via electrospinning process. In order to improve the biocompatibility properties, SR biological macromolecules were blended in PVA/BIP composite nanofibers. SEM images revealed that the composite nanofibers were well-oriented and had good incorporation of SR. Ultraviolet (UV) absorbance spectra revealed that the maximum measured absorbance intensities were linearly increased with increasing SR in the composite nanofibers. TEM images revealed a peculiar morphology by the additive SR. This additive SR possesses a lower molecular component which was exhibited at the outside of the nanofibers structure due to strong applied electric field during electrospinning process. These results indicated that the PVA/BIP blended SR composite nanofibers might be utilized for many biomedical applications including control release and wound dressing. © 2011 Elsevier B.V. All rights reserved.
1. Introduction Electrospinning is one of the simplest among all the methods for preparing nanofibers. Poly(vinyl alcohol) (PVA), a hydrophilic and semi-crystalline polymer, has been widely used in industrial plastic objects and pharmaceutical and medical devices because of its high biocompatibility, non-toxicity, and good chemical and thermal stability [1–3]. PVA in the form of nanofiber mats is of great potential importance which can be widely used in various applications due to its biocompatibility and biodegradability. Recently, biodegradable polymer nanofibers can be effectively used as drug delivery in biomedical field due to their therapeutic effect, reduced toxicity, convenience and so on [4–6]. In order to improve the mechanical properties and stability of PVA in water, we successfully fabricated PVA nanofibers crosslinked with blocked isocyanate prepolymer (BIP) by using electrospinning process [7]. These crosslinked PVA/BIP nanofibers, which have excellent stability in water and mechanical robustness together with abundant surface area and porosity, may lead to wound dressing materials. Electrospinning of bio-derived compounds with biologically significant polymers are of interest due to their various biomedical applications. Scutellariae Radix (SR) is known to be the most widely ⁎ Corresponding author at: Center for Healthcare Technology & Development, Chonbuk National University, Jeonju, 561 756, South Korea. Tel.: + 82 63 270 2351; fax: + 82 63 270 4249. E-mail address: [email protected] (H.Y. Kim). 0167-577X/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2011.05.100
used in Chinese herbal medicine with the main ingredients of Baicalein (33.0%) and Baicalin (32.8%) [8,9]. This species possesses variety of biological and pharmacological effects including antiinflammation, anti-viral, anti-tumor, anti-cancer, anti-proliferative and anti-bacterial characteristics [10–14]. Therefore, there is an increasing interest of using this multifunctional SR in various biomedical applications. Though the electrospinning of PVA with many other composite materials, however, there have been no reports based on the blending of SR with PVA/BIP nanofibers. Therefore, we take the advantage from SR, BIP and PVA by blending them into composite nanofibers via electropsinning process. The resultant product would obviously possess many desirable characteristics which can be utilized for the various applications. In this work, we described the preparation and characterizations of PVA/BIP/SR blended composite nanofibers via electrospinning for the first time. The morphology of the resulting nanofibers was analyzed by transmission electron microscopy (TEM). From the TEM analysis, we observed a peculiar morphology of composite nanofibers which was attributed to the lower molecular mass component of SR. The amount of SR release in the PVA/BIP/SR composite nanofibers was observed by using UV absorbance spectroscopy. 2. Materials and methods A 10 wt.% of PVA solution (Number averaged molecular weight (Mw) = 85,000–124,000 g mol − 1, degree of hydrolysis = 87–89%,
R. Nirmala et al. / Materials Letters 65 (2011) 2772–2775
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Fig. 1. SEM images of electrospun PVA/BIP/SR composite nanofibers with different wt.% of SR (a) 0, (b) 1, (c) 3 and (d) 5 wt.%.
7.0mg/250 mL 6.0mg/250 mL 5.0mg/250 mL 4.5mg/250 mL 4.0mg/250 mL 3.5mg/250 mL 3.0mg/250 mL 2.5mg/250 mL 2.0mg/250 mL 1.5mg/250 mL 1.0mg/250 mL 0.5mg/250 mL
(a)
0.4
Absorbance
λ= 274 nm
0.3
0.2
0.1
0.0 200
250
300
350
400
450
500
Wavelength(nm)
(b)
0.30 0.25
Absorbance
Aldrich Co., USA) was prepared by dissolving the PVA in deionized water with vigorous stirring at 80 °C for 12 h. A 50 wt.% of blocked isocyanate prepolymer (BIP, Protex Korea Co., Korea), a type of polyurethane formed by the reaction between polyisocyanate and polyols containing active hydrogens and hydrolyzed products extracted from the roots of Scutellariae Radix (SR, a gift from Healthcare center, Chonbuk National University, Jeonju, South Korea) (Baicalein 33.0%, Baicalin 32.8%) were crosslinked with PVA polymer. Three different PVA/BIP/SR mixed solutions were prepared with different concentrations of SR with 0, 1, 3, and 5 wt.%. These mixtures were stirred vigorously for 10 h to obtain complete mixing. To enhance the crosslinking reaction in the polymers, a catalyst with 9 wt.% of bismuth carboxylates (Protex Korea Co., Korea) dispersed in water was used. A high voltage power supply (CPS-60 K02V1, Chungpa EMT, South Korea) of 15 kV to the syringe micro-tip was supplied to electrospin the nanofibers. The polymer solution was fed to the 5 ml syringe with a plastic micro-tip (with a diameter of 0.3 mm and 10 mm length). The tip-to-collector distance was kept at 15 cm. During electrospinning, the drum was rotated at a constant speed by a DC motor to collect the developing nanofibers. The PVA/BIP/SR blended nanofiber mats were vacuum dried in an oven for 24 h to remove the remaining solvent. The mats were then cured at 170 °C for 2 min to produce crosslinking of PVA with BIP/ SR. The morphology of the as-spun PVA/BIP/SR composite nanofibers was observed by using scanning electron microscopy (SEM, JSM-5900, Hitachi, Japan). The UV absorbance spectra (Lambda 900, Perkin-Elmer, USA) were measured in the wavelength ranging from 200 to 500 nm. Transmission electron microscopy (TEM, JEM-2010, JEOL, Japan) images were obtained at an operated voltage of 200 kV, the TEM grid was placed very close to the syringe micro-tip opening for few seconds to collect the nanofibers.
0.20 0.15 0.10 0.05 0.00 0
1
2
3
4
5
6
7
8
Concentration (mg/250 mL) Fig. 2. (a) UV absorbance intensities of PVA/BIP/SR polymer solutions and (b) the relationship between the absorbance intensity and concentration of the polymer solution at the optimum wavelength.
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R. Nirmala et al. / Materials Letters 65 (2011) 2772–2775
Fig. 3. Plot showing the amount of SR released from the PVA/BIP/SR composite nanofibers at different intervals.
3. Results and discussion Fig. 1(a)–(d) shows the typical SEM images of electrospun PVA/ BIP/SR composite nanofibers for the different concentration of SR with 0, 1, 3 and 5 wt.%, respectively. It can be observed that these randomly oriented as-spun nanofibers exhibited bead-free, smooth surface with almost uniform diameters along their lengths due to the amorphous nature of the PVA/BIP/SR composite nanofibers. When natural SR macromolecule was added to PVA/BIP, independently on their content, no phase separation was observed at the considered magnifications, while the internal structure of the material changes. It was found that the diameters of the PVA/BIP/SR composite nanofibers ranged from 200 to 400 nm.
In order to utilize this blended nanofibers in drug release studies, we performed the preliminary investigations based on the spectrophotometer analysis. The different weight (0.5 to 7 mg) of PVA/BIP/SR nanofibers was put in the 250 ml of water to prepare the solution for the UV measurement. Fig. 2(a) shows the UV absorbance spectra of PVA/BIP/SR blended nanofibers for different concentrations of polymer solutions (starting from 0.5 to 7 mg/250 ml) were measured within the range of 200 to 500 nm. From this Fig. 2(a), the absorbance curves have a maximum value of almost 274 nm. At the same time, the maximum measured absorbance intensities increase linearly with increases in polymer concentration, as shown in Fig. 2(b), which represents the relationship between the polymer concentration and the measured absorbance at 274 nm. As shown in this Fig. 2(b), the absorbance varies linearly with the polymer concentration in a good linear model. Fig. 3 shows the amount of released SR from the PVA/BIP/SR blended nanofibers. The release test was performed for three different intervals (3, 6 and 15 min) for the PVA/BIP/SR nanofibers with various concentrations of SR. It was interestingly observed that the SR was rapidly released from the composite nanofibers with increasing content of SR. In order to study more insightful features, we further carried out TEM analysis. The TEM samples were obtained by placing the TEM grid very close to the syringe micro-tip end for very short time during electrospinning. Fig. 4(a)–(d) shows the TEM images of the nanofiber emerging from the syringe micro-tip for PVA/BIP/SR composite nanofibers with different SR content of 0, 1, 3 and 5 wt.%, respectively. Fig. 4(a) shows the PVA/BIP composite nanofiber demonstrating the clear blending. It is clearly seen from the TEM images (Fig. 4(b)–(c)) that the nanofibers exhibited double layer due to different molecular weight component materials. The outer layer initially formed as the dotted structure for the SR content of 1 wt.%, the dashed structure for the SR content of 3 wt.% followed by the uniformly covered nanofibers (denoted as arrows in Fig. 4(d)) for the SR content of 5 wt.%. This is
Fig. 4. TEM images of electrospun PVA/BIP/SR composite nanofibers with different SR concentration of (a) 0, (b) 1, (c) 3 and (d) 5 wt.%.
R. Nirmala et al. / Materials Letters 65 (2011) 2772–2775
because; the lower molecular mass of SR can be strongly ionized by the applied electric field during electrospinning process and aligned in the outer most layer of the blended nanofibers structure. However, there was no such structure exhibited in the case of PVA/BIP/SR with a SR content of 0 wt.% as shown in Fig. 4(a). Thus the SR concentration strongly influenced the resultant nanofiber structure. This feature can be significantly utilized for the various technological applications. In this study, we performed the drug release study based on these nanofibers. Based on our preliminary experiments results, we believed that the SR blended PVA/BIP composite nanofibers may also be a suitable material for biomedical applications such as the treatment of atopic dermatitis. 4. Conclusions SR blended in PVA/BIP composite nanofibers was successfully prepared by using electrospinning technique. As-electrospun nanofibers were observed to be smooth with uniform diameters along their lengths. PVA/BIP/SR composite nanofibers were with diameters of about 200 to 400 nm. The lower molecular mass of SR was strongly ionized by the applied electric field during the electrospinning process and aligned uniformly in the outer most layers of the blended nanofibers. Such kind of structural arrangement was observed to be the most useful for some specific application like control release of drugs. The amount of released SR from the PVA/BIP/SR blended nanofibers was rapidly increased with increasing content of SR. These results indicated that the PVA/BIP incorporated with SR compounds can be used as a promising candidate for many technological applications.
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Acknowledgements This work was supported by the grant of the Korean Ministry of Education, Science and Technology (The Regional Core Research Program/Center for Healthcare Technology & Development, Chonbuk National University, Jeonju 561-756 Republic of Korea).
References [1] Shao C, Kim HY, Gong J, Ding B, Lee DR, Park SJ. Mater Lett 2003;57:1579–84. [2] Kim CK, Kim BS, Sheikh FA, Lee US, Khil MS, Kim HY. Macromolecules 2007;40: 4823–8. [3] Zheng H, Du YM, Yu JH, Huang RH, Zhang LN. J Appl Polym Sci 2001;80:2558–65. [4] Yang D, Li Y, Nie J. Carbohydr Polym 2007;69:538–43. [5] Vargas EAT, Baracho NCDV, Brito JD, Queriroz AAAD. Acta Biomater 2010;6: 1069–78. [6] Kenawya ER, Abdel-Hay FI, Newehy MHE, Wnek GE. Mater Sci Eng A 2007;459: 390–6. [7] Lee JH, Lee US, Jeong KU, Seo YA, Park SJ, Kim HY. Polym Int 2010;59:1683–9. [8] Chung HL, Yue GGL, To KF, Su YL, Huang Y, Ko WH. World J Gastroenterol 2007;14: 5605–11. [9] Cao YY, Dai BD, Wang Y, Huang S, Xu YG, Cao YB, Gao PH, Zhu ZY, Jiang YY. J Antimicrob Agents 2008;32:73–7. [10] Lin CC, Shieh DE. J Chin Med 1996;24:31–6. [11] Wu JA, Attele AS, Zhang L, Yuan CS. Am J Chin Med 2001;29:69–81. [12] Ikemoto S, Sugimura K, Yoshida N, Yasumoto R, Wada S, Yamamoto K, Kishimoto T. Urology 2000;55:951–5. [13] Huang HC, Wang HR, Hsieh LM. Eur J Pharmacol 1994;251:91–3. [14] Kubo M, Kimura Y, Odani T, Namba K. Planta Med 1981;43:194–201.
Contents lists available at ScienceDirect
Materials Letters j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / m a t l e t
Preparation of the crosslinked poly(vinyl alcohol)/blocked isocyanate prepolymers nanofibers with hydrolyzed products of Scutellariae Radix R. Nirmala a, Ji-Hui Lee b, c, R. Navamathavan d, Jae Heon Yang c, Hak Yong Kim b, c,⁎ a
Bio-nano System Engineering, Chonbuk National University, Jeonju, 561 756, South Korea Department of Textile Engineering, Chonbuk National University, Jeonju, 561-756, South Korea Center for Healthcare Technology & Development, Chonbuk National University, Jeonju, 561 756, South Korea d School of Advanced Materials Engineering, Chonbuk National University, Jeonju 561 756, South Korea b c
a r t i c l e
i n f o
Article history: Received 25 January 2011 Accepted 26 May 2011 Available online 2 June 2011 Keywords: Polymeric composites Biomaterial Crosslinking Scutellariae Radix Nanofibers Electrospinning
a b s t r a c t We report on the preparation and characterizations of Scutellariae Radix (SR) blended poly(vinyl alcohol) (PVA)/blocked isocyanate prepolymer (BIP) composite nanofibers via electrospinning process. In order to improve the biocompatibility properties, SR biological macromolecules were blended in PVA/BIP composite nanofibers. SEM images revealed that the composite nanofibers were well-oriented and had good incorporation of SR. Ultraviolet (UV) absorbance spectra revealed that the maximum measured absorbance intensities were linearly increased with increasing SR in the composite nanofibers. TEM images revealed a peculiar morphology by the additive SR. This additive SR possesses a lower molecular component which was exhibited at the outside of the nanofibers structure due to strong applied electric field during electrospinning process. These results indicated that the PVA/BIP blended SR composite nanofibers might be utilized for many biomedical applications including control release and wound dressing. © 2011 Elsevier B.V. All rights reserved.
1. Introduction Electrospinning is one of the simplest among all the methods for preparing nanofibers. Poly(vinyl alcohol) (PVA), a hydrophilic and semi-crystalline polymer, has been widely used in industrial plastic objects and pharmaceutical and medical devices because of its high biocompatibility, non-toxicity, and good chemical and thermal stability [1–3]. PVA in the form of nanofiber mats is of great potential importance which can be widely used in various applications due to its biocompatibility and biodegradability. Recently, biodegradable polymer nanofibers can be effectively used as drug delivery in biomedical field due to their therapeutic effect, reduced toxicity, convenience and so on [4–6]. In order to improve the mechanical properties and stability of PVA in water, we successfully fabricated PVA nanofibers crosslinked with blocked isocyanate prepolymer (BIP) by using electrospinning process [7]. These crosslinked PVA/BIP nanofibers, which have excellent stability in water and mechanical robustness together with abundant surface area and porosity, may lead to wound dressing materials. Electrospinning of bio-derived compounds with biologically significant polymers are of interest due to their various biomedical applications. Scutellariae Radix (SR) is known to be the most widely ⁎ Corresponding author at: Center for Healthcare Technology & Development, Chonbuk National University, Jeonju, 561 756, South Korea. Tel.: + 82 63 270 2351; fax: + 82 63 270 4249. E-mail address: [email protected] (H.Y. Kim). 0167-577X/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2011.05.100
used in Chinese herbal medicine with the main ingredients of Baicalein (33.0%) and Baicalin (32.8%) [8,9]. This species possesses variety of biological and pharmacological effects including antiinflammation, anti-viral, anti-tumor, anti-cancer, anti-proliferative and anti-bacterial characteristics [10–14]. Therefore, there is an increasing interest of using this multifunctional SR in various biomedical applications. Though the electrospinning of PVA with many other composite materials, however, there have been no reports based on the blending of SR with PVA/BIP nanofibers. Therefore, we take the advantage from SR, BIP and PVA by blending them into composite nanofibers via electropsinning process. The resultant product would obviously possess many desirable characteristics which can be utilized for the various applications. In this work, we described the preparation and characterizations of PVA/BIP/SR blended composite nanofibers via electrospinning for the first time. The morphology of the resulting nanofibers was analyzed by transmission electron microscopy (TEM). From the TEM analysis, we observed a peculiar morphology of composite nanofibers which was attributed to the lower molecular mass component of SR. The amount of SR release in the PVA/BIP/SR composite nanofibers was observed by using UV absorbance spectroscopy. 2. Materials and methods A 10 wt.% of PVA solution (Number averaged molecular weight (Mw) = 85,000–124,000 g mol − 1, degree of hydrolysis = 87–89%,
R. Nirmala et al. / Materials Letters 65 (2011) 2772–2775
2773
Fig. 1. SEM images of electrospun PVA/BIP/SR composite nanofibers with different wt.% of SR (a) 0, (b) 1, (c) 3 and (d) 5 wt.%.
7.0mg/250 mL 6.0mg/250 mL 5.0mg/250 mL 4.5mg/250 mL 4.0mg/250 mL 3.5mg/250 mL 3.0mg/250 mL 2.5mg/250 mL 2.0mg/250 mL 1.5mg/250 mL 1.0mg/250 mL 0.5mg/250 mL
(a)
0.4
Absorbance
λ= 274 nm
0.3
0.2
0.1
0.0 200
250
300
350
400
450
500
Wavelength(nm)
(b)
0.30 0.25
Absorbance
Aldrich Co., USA) was prepared by dissolving the PVA in deionized water with vigorous stirring at 80 °C for 12 h. A 50 wt.% of blocked isocyanate prepolymer (BIP, Protex Korea Co., Korea), a type of polyurethane formed by the reaction between polyisocyanate and polyols containing active hydrogens and hydrolyzed products extracted from the roots of Scutellariae Radix (SR, a gift from Healthcare center, Chonbuk National University, Jeonju, South Korea) (Baicalein 33.0%, Baicalin 32.8%) were crosslinked with PVA polymer. Three different PVA/BIP/SR mixed solutions were prepared with different concentrations of SR with 0, 1, 3, and 5 wt.%. These mixtures were stirred vigorously for 10 h to obtain complete mixing. To enhance the crosslinking reaction in the polymers, a catalyst with 9 wt.% of bismuth carboxylates (Protex Korea Co., Korea) dispersed in water was used. A high voltage power supply (CPS-60 K02V1, Chungpa EMT, South Korea) of 15 kV to the syringe micro-tip was supplied to electrospin the nanofibers. The polymer solution was fed to the 5 ml syringe with a plastic micro-tip (with a diameter of 0.3 mm and 10 mm length). The tip-to-collector distance was kept at 15 cm. During electrospinning, the drum was rotated at a constant speed by a DC motor to collect the developing nanofibers. The PVA/BIP/SR blended nanofiber mats were vacuum dried in an oven for 24 h to remove the remaining solvent. The mats were then cured at 170 °C for 2 min to produce crosslinking of PVA with BIP/ SR. The morphology of the as-spun PVA/BIP/SR composite nanofibers was observed by using scanning electron microscopy (SEM, JSM-5900, Hitachi, Japan). The UV absorbance spectra (Lambda 900, Perkin-Elmer, USA) were measured in the wavelength ranging from 200 to 500 nm. Transmission electron microscopy (TEM, JEM-2010, JEOL, Japan) images were obtained at an operated voltage of 200 kV, the TEM grid was placed very close to the syringe micro-tip opening for few seconds to collect the nanofibers.
0.20 0.15 0.10 0.05 0.00 0
1
2
3
4
5
6
7
8
Concentration (mg/250 mL) Fig. 2. (a) UV absorbance intensities of PVA/BIP/SR polymer solutions and (b) the relationship between the absorbance intensity and concentration of the polymer solution at the optimum wavelength.
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R. Nirmala et al. / Materials Letters 65 (2011) 2772–2775
Fig. 3. Plot showing the amount of SR released from the PVA/BIP/SR composite nanofibers at different intervals.
3. Results and discussion Fig. 1(a)–(d) shows the typical SEM images of electrospun PVA/ BIP/SR composite nanofibers for the different concentration of SR with 0, 1, 3 and 5 wt.%, respectively. It can be observed that these randomly oriented as-spun nanofibers exhibited bead-free, smooth surface with almost uniform diameters along their lengths due to the amorphous nature of the PVA/BIP/SR composite nanofibers. When natural SR macromolecule was added to PVA/BIP, independently on their content, no phase separation was observed at the considered magnifications, while the internal structure of the material changes. It was found that the diameters of the PVA/BIP/SR composite nanofibers ranged from 200 to 400 nm.
In order to utilize this blended nanofibers in drug release studies, we performed the preliminary investigations based on the spectrophotometer analysis. The different weight (0.5 to 7 mg) of PVA/BIP/SR nanofibers was put in the 250 ml of water to prepare the solution for the UV measurement. Fig. 2(a) shows the UV absorbance spectra of PVA/BIP/SR blended nanofibers for different concentrations of polymer solutions (starting from 0.5 to 7 mg/250 ml) were measured within the range of 200 to 500 nm. From this Fig. 2(a), the absorbance curves have a maximum value of almost 274 nm. At the same time, the maximum measured absorbance intensities increase linearly with increases in polymer concentration, as shown in Fig. 2(b), which represents the relationship between the polymer concentration and the measured absorbance at 274 nm. As shown in this Fig. 2(b), the absorbance varies linearly with the polymer concentration in a good linear model. Fig. 3 shows the amount of released SR from the PVA/BIP/SR blended nanofibers. The release test was performed for three different intervals (3, 6 and 15 min) for the PVA/BIP/SR nanofibers with various concentrations of SR. It was interestingly observed that the SR was rapidly released from the composite nanofibers with increasing content of SR. In order to study more insightful features, we further carried out TEM analysis. The TEM samples were obtained by placing the TEM grid very close to the syringe micro-tip end for very short time during electrospinning. Fig. 4(a)–(d) shows the TEM images of the nanofiber emerging from the syringe micro-tip for PVA/BIP/SR composite nanofibers with different SR content of 0, 1, 3 and 5 wt.%, respectively. Fig. 4(a) shows the PVA/BIP composite nanofiber demonstrating the clear blending. It is clearly seen from the TEM images (Fig. 4(b)–(c)) that the nanofibers exhibited double layer due to different molecular weight component materials. The outer layer initially formed as the dotted structure for the SR content of 1 wt.%, the dashed structure for the SR content of 3 wt.% followed by the uniformly covered nanofibers (denoted as arrows in Fig. 4(d)) for the SR content of 5 wt.%. This is
Fig. 4. TEM images of electrospun PVA/BIP/SR composite nanofibers with different SR concentration of (a) 0, (b) 1, (c) 3 and (d) 5 wt.%.
R. Nirmala et al. / Materials Letters 65 (2011) 2772–2775
because; the lower molecular mass of SR can be strongly ionized by the applied electric field during electrospinning process and aligned in the outer most layer of the blended nanofibers structure. However, there was no such structure exhibited in the case of PVA/BIP/SR with a SR content of 0 wt.% as shown in Fig. 4(a). Thus the SR concentration strongly influenced the resultant nanofiber structure. This feature can be significantly utilized for the various technological applications. In this study, we performed the drug release study based on these nanofibers. Based on our preliminary experiments results, we believed that the SR blended PVA/BIP composite nanofibers may also be a suitable material for biomedical applications such as the treatment of atopic dermatitis. 4. Conclusions SR blended in PVA/BIP composite nanofibers was successfully prepared by using electrospinning technique. As-electrospun nanofibers were observed to be smooth with uniform diameters along their lengths. PVA/BIP/SR composite nanofibers were with diameters of about 200 to 400 nm. The lower molecular mass of SR was strongly ionized by the applied electric field during the electrospinning process and aligned uniformly in the outer most layers of the blended nanofibers. Such kind of structural arrangement was observed to be the most useful for some specific application like control release of drugs. The amount of released SR from the PVA/BIP/SR blended nanofibers was rapidly increased with increasing content of SR. These results indicated that the PVA/BIP incorporated with SR compounds can be used as a promising candidate for many technological applications.
2775
Acknowledgements This work was supported by the grant of the Korean Ministry of Education, Science and Technology (The Regional Core Research Program/Center for Healthcare Technology & Development, Chonbuk National University, Jeonju 561-756 Republic of Korea).
References [1] Shao C, Kim HY, Gong J, Ding B, Lee DR, Park SJ. Mater Lett 2003;57:1579–84. [2] Kim CK, Kim BS, Sheikh FA, Lee US, Khil MS, Kim HY. Macromolecules 2007;40: 4823–8. [3] Zheng H, Du YM, Yu JH, Huang RH, Zhang LN. J Appl Polym Sci 2001;80:2558–65. [4] Yang D, Li Y, Nie J. Carbohydr Polym 2007;69:538–43. [5] Vargas EAT, Baracho NCDV, Brito JD, Queriroz AAAD. Acta Biomater 2010;6: 1069–78. [6] Kenawya ER, Abdel-Hay FI, Newehy MHE, Wnek GE. Mater Sci Eng A 2007;459: 390–6. [7] Lee JH, Lee US, Jeong KU, Seo YA, Park SJ, Kim HY. Polym Int 2010;59:1683–9. [8] Chung HL, Yue GGL, To KF, Su YL, Huang Y, Ko WH. World J Gastroenterol 2007;14: 5605–11. [9] Cao YY, Dai BD, Wang Y, Huang S, Xu YG, Cao YB, Gao PH, Zhu ZY, Jiang YY. J Antimicrob Agents 2008;32:73–7. [10] Lin CC, Shieh DE. J Chin Med 1996;24:31–6. [11] Wu JA, Attele AS, Zhang L, Yuan CS. Am J Chin Med 2001;29:69–81. [12] Ikemoto S, Sugimura K, Yoshida N, Yasumoto R, Wada S, Yamamoto K, Kishimoto T. Urology 2000;55:951–5. [13] Huang HC, Wang HR, Hsieh LM. Eur J Pharmacol 1994;251:91–3. [14] Kubo M, Kimura Y, Odani T, Namba K. Planta Med 1981;43:194–201.