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Enhancing effect of glycerol on the tensile properties of Bombyx mori cocoon sericin films.

Zhang H, Deng L, Yang M, Min S, Yang L, Zhu L - Int J Mol Sci (2011)

Bottom Line: An environmental physical method described herein was developed to improve the tensile properties of Bombyx mori cocoon sericin films, by using the plasticizer of glycerol, which has a nontoxic effect compared with other chemical crosslinkers.Scanning Electron Microscopy (SEM) observation revealed that glycerol was homogeneously blended with sericin molecules when its content was 10 wt%, while a small amount of redundant glycerol emerged on the surface of sericin films when its content was increased to 20 wt% or higher.Our results suggest that the introduction of glycerol is a novel nontoxic strategy which can improve the mechanical features of sericin-based materials and subsequently promote the feasibility of its application in tissue engineering.

View Article: PubMed Central - PubMed

Affiliation: Institute of Applied Bioresources, College of Animal Sciences, Zhejiang University, Hangzhou 310029, China; E-Mails: hpzhang@zju.edu.cn (H.Z.); denglianxia2008@163.com (L.D.); yangm@zju.edu.cn (M.Y.); minsj@zju.edu.cn (S.M.); yanglei164@163.com (L.Y.).

ABSTRACT
An environmental physical method described herein was developed to improve the tensile properties of Bombyx mori cocoon sericin films, by using the plasticizer of glycerol, which has a nontoxic effect compared with other chemical crosslinkers. The changes in the tensile characteristics and the structure of glycerolated (0-40 wt% of glycerol) sericin films were investigated. Sericin films, both in dry and wet states, showed enhanced tensile properties, which might be regulated by the addition of different concentrations of glycerol. The introduction of glycerol results in the higher amorphous structure in sericin films as evidenced by analysis of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectra, thermogravimetry (TGA) and differential scanning calorimetry (DSC) curves. Scanning Electron Microscopy (SEM) observation revealed that glycerol was homogeneously blended with sericin molecules when its content was 10 wt%, while a small amount of redundant glycerol emerged on the surface of sericin films when its content was increased to 20 wt% or higher. Our results suggest that the introduction of glycerol is a novel nontoxic strategy which can improve the mechanical features of sericin-based materials and subsequently promote the feasibility of its application in tissue engineering.

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Curve-fitted spectra of various sericin films at amide I band between 1600–1700 cm−1: (A) sericin film; (B) sericin film with 10 wt% glycerol; (C) sericin film with 20 wt% glycerol; (D) sericin film with 30 wt% g 0.39″ lycerol. The broken lines represent the Gaussian fitted curves and the solid lines represent the deconvolution spectra of amide I band.
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f2-ijms-12-03170: Curve-fitted spectra of various sericin films at amide I band between 1600–1700 cm−1: (A) sericin film; (B) sericin film with 10 wt% glycerol; (C) sericin film with 20 wt% glycerol; (D) sericin film with 30 wt% g 0.39″ lycerol. The broken lines represent the Gaussian fitted curves and the solid lines represent the deconvolution spectra of amide I band.

Mentions: To further clarify the effect of glycerol on the secondary structure of sericin film, the quantitative analysis on amide I band of various sericin films was carried out using the Fourier Self Deconvolution (FSD) fitting method. As shown in Figure 2, each sericin film at amide I region were fitted to nine single bands calculated from the second derivative spectra and the area of the fitted single peaks are shown in Table 1. The overlapped nine single bands to the secondary structure were assigned as follows and according to the previous studies [24]: band at 1608 cm−1 as the structure of aggregated strands, 1617 cm−1 and 1627 cm−1 as β-sheet, 1638 cm−1 and 1648 cm−1 as random coil, 1658 cm−1 as α-helices and 1668 cm−1, 1679 cm−1 and 1690cm−1 as turns. The percent content of various secondary structure components in sericin films were calculated as the data in Table 1 and their distribution were shown in Figure 3. It is observed that sericin film, 10 wt% and 20% glycerol blended sericin films predominantly exhibit turns with the content of about 37%, 37% and 36%, respectively. However, the content of turns in sericin film with 30 wt% was about 31% and less than the content of random coil as about 33%. This result indicated that the main secondary structure of sericin film changed to random coil when glycerol content was increased to 30%, which was identical to the estimated structure from the maxima position in the amide I band of the ATR-FTIR original spectra. When glycerol content was 10 wt%, the content of random coil structure decreased from about 30% to 27% and the content of β-sheet increased from about 17% to 20%, due to the physical interaction such as hydrogen bond between sericin and small glycerol molecules. On further increasing the content of glycerol, the content of random coil was greatly increased and the turns decreased, as a result of the plasticizer function of many glycerol molecules by reducing the interaction of sericin molecules.


Enhancing effect of glycerol on the tensile properties of Bombyx mori cocoon sericin films.

Zhang H, Deng L, Yang M, Min S, Yang L, Zhu L - Int J Mol Sci (2011)

Curve-fitted spectra of various sericin films at amide I band between 1600–1700 cm−1: (A) sericin film; (B) sericin film with 10 wt% glycerol; (C) sericin film with 20 wt% glycerol; (D) sericin film with 30 wt% g 0.39″ lycerol. The broken lines represent the Gaussian fitted curves and the solid lines represent the deconvolution spectra of amide I band.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3116183&req=5

f2-ijms-12-03170: Curve-fitted spectra of various sericin films at amide I band between 1600–1700 cm−1: (A) sericin film; (B) sericin film with 10 wt% glycerol; (C) sericin film with 20 wt% glycerol; (D) sericin film with 30 wt% g 0.39″ lycerol. The broken lines represent the Gaussian fitted curves and the solid lines represent the deconvolution spectra of amide I band.
Mentions: To further clarify the effect of glycerol on the secondary structure of sericin film, the quantitative analysis on amide I band of various sericin films was carried out using the Fourier Self Deconvolution (FSD) fitting method. As shown in Figure 2, each sericin film at amide I region were fitted to nine single bands calculated from the second derivative spectra and the area of the fitted single peaks are shown in Table 1. The overlapped nine single bands to the secondary structure were assigned as follows and according to the previous studies [24]: band at 1608 cm−1 as the structure of aggregated strands, 1617 cm−1 and 1627 cm−1 as β-sheet, 1638 cm−1 and 1648 cm−1 as random coil, 1658 cm−1 as α-helices and 1668 cm−1, 1679 cm−1 and 1690cm−1 as turns. The percent content of various secondary structure components in sericin films were calculated as the data in Table 1 and their distribution were shown in Figure 3. It is observed that sericin film, 10 wt% and 20% glycerol blended sericin films predominantly exhibit turns with the content of about 37%, 37% and 36%, respectively. However, the content of turns in sericin film with 30 wt% was about 31% and less than the content of random coil as about 33%. This result indicated that the main secondary structure of sericin film changed to random coil when glycerol content was increased to 30%, which was identical to the estimated structure from the maxima position in the amide I band of the ATR-FTIR original spectra. When glycerol content was 10 wt%, the content of random coil structure decreased from about 30% to 27% and the content of β-sheet increased from about 17% to 20%, due to the physical interaction such as hydrogen bond between sericin and small glycerol molecules. On further increasing the content of glycerol, the content of random coil was greatly increased and the turns decreased, as a result of the plasticizer function of many glycerol molecules by reducing the interaction of sericin molecules.

Bottom Line: An environmental physical method described herein was developed to improve the tensile properties of Bombyx mori cocoon sericin films, by using the plasticizer of glycerol, which has a nontoxic effect compared with other chemical crosslinkers.Scanning Electron Microscopy (SEM) observation revealed that glycerol was homogeneously blended with sericin molecules when its content was 10 wt%, while a small amount of redundant glycerol emerged on the surface of sericin films when its content was increased to 20 wt% or higher.Our results suggest that the introduction of glycerol is a novel nontoxic strategy which can improve the mechanical features of sericin-based materials and subsequently promote the feasibility of its application in tissue engineering.

View Article: PubMed Central - PubMed

Affiliation: Institute of Applied Bioresources, College of Animal Sciences, Zhejiang University, Hangzhou 310029, China; E-Mails: hpzhang@zju.edu.cn (H.Z.); denglianxia2008@163.com (L.D.); yangm@zju.edu.cn (M.Y.); minsj@zju.edu.cn (S.M.); yanglei164@163.com (L.Y.).

ABSTRACT
An environmental physical method described herein was developed to improve the tensile properties of Bombyx mori cocoon sericin films, by using the plasticizer of glycerol, which has a nontoxic effect compared with other chemical crosslinkers. The changes in the tensile characteristics and the structure of glycerolated (0-40 wt% of glycerol) sericin films were investigated. Sericin films, both in dry and wet states, showed enhanced tensile properties, which might be regulated by the addition of different concentrations of glycerol. The introduction of glycerol results in the higher amorphous structure in sericin films as evidenced by analysis of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectra, thermogravimetry (TGA) and differential scanning calorimetry (DSC) curves. Scanning Electron Microscopy (SEM) observation revealed that glycerol was homogeneously blended with sericin molecules when its content was 10 wt%, while a small amount of redundant glycerol emerged on the surface of sericin films when its content was increased to 20 wt% or higher. Our results suggest that the introduction of glycerol is a novel nontoxic strategy which can improve the mechanical features of sericin-based materials and subsequently promote the feasibility of its application in tissue engineering.

Show MeSH