Novel poss reinforced chitosan composite membranes for guided bone tissue regeneration

In this study, novel composites membranes composed of chitosan matrix and polyhedral oligomeric silsesquioxanes (POSS) were fabricated by solvent casting method. The effect of POSS loading on the mechanical, morphological, chemical, thermal and surface properties, and cytocompatibility of composite membranes were investigated and observed by tensile test, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), protein adsorption assay, air/water contact angle analysis and WST-1 respectively. Swelling studies were also performed by water absorption capacity determination. Results showed that incorporation of Octa-TMA POSS^® nanofiller to the chitosan matrix increased the surface roughness, protein adsorption and swelling capacity of membranes. The addition of POSS enhanced significantly the ultimate tensile strength and strain at break of the composite membranes up to 3 wt% POSS loaded samples. An increase of about 76% in tensile strength and of strain at break 1.28% was achieved for 3 wt% POSS loaded nanocomposite membranes compared with chitosan membranes. The presence of POSS filler into polymer matrix increased the plasma protein adsorption on the surface. Maximum protein capacity and swelling was obtained for 10 wt% loaded samples. High cell viability results were obtained with indirect extraction of chitosan/POSS composites. Besides, cell proliferation and ALP activity results showed that POSS incorporation significantly increased the ALP activity of Saos-2 cells cultured on chitosan membranes. This novel composite membranes with tunable properties could be considered as a potential candidate for guided bone regeneration applications.

Elasticity, thermal stability and bioactivity of polyhedral oligomeric silsesquioxanes reinforced chitosan-based microfibres

A wet-spinning approach was used to extrude ribbon-like micrometer-thick fibres comprising chitosan with 1, 3, 5, 7 and 9% (w/w) polyhedral oligomeric silsesquioxanes (POSS). ANOVA reveals significant variations in the maximum stress (σ), stiffness (E), elastic energy storage (u') and fracture toughness (u) of the microfibres with respect to POSS concentration: σ, u' and u peak at 7% (w/w) but POSS concentration has no effect on E. Scanning electron microscopy of the ruptured microfibres reveals fracture and detachment of POSS precipitates from the chitosan matrix. Bioactivity test using simulated body fluids reveals a net gain in mass (by day 4) and grossly distorted morphology caused by apatite deposition on the microfibre surface. Fourier transform infrared spectroscopy reveals that chitin is partially deacetylated into chitosan and it further shows the presence of POSS in the microfibres. Thermogravimetric analysis shows that the microfibres are thermally stable up to 240°C in a nitrogen atmosphere.