Mechanical Properties of Collagen Biomimetic Films Formed in the Presence of Calcium,Silica and Chitosan

Using eucollagen solutions from ox hide, we cast collagen films to assess the influence of calcium and silica on the reconstitution of the fibrous structure of collagen. The tensile strength and the breaking elongation of the reconstituted collagen films were measured and analysed. Significant differences were observed between reconstituted collagen films with and without calcium and silica. The breaking elongation of the films obtained in the presence of silica was significantly greater, and the degradation was lower than other films of reconstituted collagen. Collagen and chitosan do not exist together as blends in nature, but the specific properties of each may be used to produce in biomimetic way man-made blends with biomedical applications, that confer unique structural, mechanical （detail） and in vivo properties.

Integrated transcriptomic and proteomic study on the different molecular mechanisms of PC12 cell growth on chitosan and collagen/chitosan films

The purpose of this article is to integrate the transcriptomic analysis and the proteomic profiles and to reveal and compare the different molecular mechanisms of PC12 cell growth on the surface of chitosan films and collagen/chitosan films.First,the chitosan films and the collagen/chitosan films were prepared.Subsequently,the cell viability assay was performed;the cell viability of the PC12 cells cultured on the collagen/chitosan films for 24 h was significantly higher than that on the chitosan films.Then,with cDNA microarray,the numbers of differentially expressed genes of PC12 cells on the surface of chitosan and collagen/chitosan films were 13349 and 5165,respectively.Next,the biological pathway analysis indicated that the differentially expressed genes were involved in 40 pathways directly related to cell adhesion and growth.The integrated transcriptomic and our previous proteomic analysis revealed that three biological pathways-extracellular matrix-receptor interaction,focal adhesion and regulation of actin cytoskeleton-were regulated in the processes of protein adsorption,cell adhesion and growth.The adsorbed proteins on the material surfaces further influenced the expression of important downstream genes by regulating the expression of related receptor genes in these three pathways.In comparison,chitosan films had a strong inhibitory effect on PC12 cell adhesion and growth,resulting in the significantly lower cell viability on its surface;on the contrary,collagen/chitosan films were more conducive to promoting PC12 cell adhesion and growth,resulting in higher cell viability.

Fabrication and characterization of microfibrillated cellulose and collagen composite films

Microfibrillated cellulose(MFC)-collagen composite films were prepared with a dispersion of acid swollen collagen fibers and carboxylated MFC at different ratios in an alkaline homogenous system.The surface topographic results obtained from SEM analyses indicated that the MFC entangled uniformly with collagen in the film and formed a closely interwoven network to reinforce the film structure.However,the MFC addition decreased the smoothness and light transparency of the films due to the aggregation of MFC.Compared to the film prepared with pure collagen,the hybrid composite film showed a higher strength and Young’s modulus but lower elongation.The swelling of the composite film in water increased with the increase of the MFC ratio in the film matrix.DSC and TG analyses demonstrated that adding MFC to collagen benefited the thermal stability of the films,due to the conformational and crystal changes in the MFC/collagen structure indicated by the FT-IR and XRD results.The MFC/collagen composite film can potentially be used as an edible material in the food and packaging industry,in particular for meat products.

A proteomics study to explore the role of adsorbed serum proteins for PC12 cell adhesion and growth on chitosan and collagen/chitosan surfaces

The aim of this article is to apply proteomics in the comparison of the molecular mechanisms of PC12 cell adhesion and growth mediated by the adsorbed serum proteins on the surfaces of chitosan and collagen/chitosan films.First,the chitosan and the collagen/chitosan films were prepared by spin coating;and their surface morphologies were characterized by scanning electron microscopy,X-ray energy dispersive spectroscopy,contact angle measurement and Fourier transform infrared spectroscopy.Subsequently,cell proliferation experiments on two materials were performed and the dynamic curves of protein adsorption on their surfaces were measured.Then,proteomics and bioinformatics were used to analyze and compare the adsorbed serum proteins on the surfaces of two biomaterials;and their effects on cell adhesion were discussed.The results showed that the optimum concentration of chitosan film was 2%w/v.When compared with chitosan film,collagen/chitosan film promoted the growth and proliferation of PC12 cells more significantly.Although the dynamic curves showed no significant difference in the total amount of the adsorbed proteins on both surfaces,proteomics and bioinformatics analyses revealed a difference in protein types:the chitosan surface adsorbed more vitronectin whereas collagen/chitosan surface adsorbed more fibronectin 1 and contained more cell surface receptor binding sites and more Leu-Asp-Val sequences in its surface structure;the collagen/chitosan surface were more conducive to promoting cell adhesion and growth.

Regenerating leather waste for flexible pressure sensing applications

Pressure sensor can be applied in a wide range of fields,such as voice recognition,human motions detection and artificial electronic skin,the sensing of which is greatly influenced by the flexibility and stretchability of substrate materials.Here,based on the piezoresistive effect,new kinds of flexible pressure sensors have been realized from a pair of flexible and biocompatible collagen films:one is coated by silver nanowires(Ag NWs)and the other by interdigital electrode,respectively.The collagen films are regenerated from leather waste and could bring economic benefits to society.The prepared pressure sensors are applied for voice recognition and human motion detection.