Cellulose phosphates as biomaterials. Mineralization of chemically modified regenerated cellulose hydrogels

Femoral implantation of regenerated cellulose hydrogels revealed their bioc ompatible and osteoconductive properties, but a complete osseointegration c ould not be observed. Phosphorylation was therefore envisaged as the means to enhance cellulose bioactivity. Once implanted, phosphorylated cellulose could promote the formation of calcium phosphates, having therefore closer resemblance to bone functionality and assuring a satisfactory bonding at th e interface between hard tissue and biomaterial. In the present work, regen erated cellulose hydrogels were surface modified via phosphorylation. Phosp horylated materials, having varying degrees of substitution, were soaked in a Simulated Body Fluid (SBF) solution in order to investigate their abilit y to induce the formation of a calcium phosphate layer. Mineralization was assessed by Scanning Electron Microscopy (SEM), Energy Dispersive Spectrosc opy (EDS) and Attenuated Total Reflectance-Fourier Transform Infrared (ATR- FTIR) spectroscopy. It was demonstrated that the calcium salt of cellulose phosphates mineralized at a higher extent than materials only phosphorylate d. The degree of phosphorylation influenced the extent of surface mineraliz ation. Moderate degrees of surface phosphorylation promoted the highest ext ent of mineralization. This was attributed to inadequate functionality of t he surface in terms of density of PO4 groups and overall surface charge, in the case of low and high phosphate contents. (C) 2001 Kluwer Academic Publ ishers.