Investigation into the adequacy of chemically modified chitosan membranes for use as biomaterial: study of in vitre calcification

Author(s)

Cassiano Gomes Aimoli

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Química
• Defense date: 2007-05-18

Examining board members

Ronaldo Nogueira de Moraes Pitombo; Theo Guenter Kieckbusch

• Advisor: Marisa Masumi Beppu

Abstract

The use of biocompatible materials presents increasing interest in the scientific and technological areas. Calcification phenomena are widely associated to the use of biomaterials. It can be desirable for production of resins for adsorption and mechanically resistant materials, but it can be harmful and pathogenic in cardiac valves and contact lenses. In this context, chitosan appears as a material of great importance, since besides being biocompatible, it is derived from the most abundant biomaterial in the nature: chitin. However, its use as substrate for calcification is not extensively studied and its mechanism remains still unknown. Three different experiments involving the deposition of calcium phosphates and carbonates on pristine and acetylated chitosan were conducted in order to understand the mechanism of calcification on this material. Initially, dense membranes underwent calcium compounds deposition through preliminary experiments. Afterwards, deposition in similar conditions to those observed in the living organisms had been conducted and finally, quick tests to induce calcification were done with the intention to observe the influence of the substrate on the deposits. The results indicate that the general mechanism of calcification seems to follow the stages of nucleation and growth in pristine and acetylated chitosan. In initial stages, the acetylated chitosan seems to induce a slower deposition whereas the pristine chitosan seems to provoke an less organized and faster nucleation and in initial stages. However, in the latest stages of growth, pristine chitosan apparently promotes a significant influence on the aglomerates (AU)