Electrically conductive polymeric biomaterials, the process for their preparation and the use thereof in the biomedical and healthcare field

#This application is the national phase under 35 U.S.C. § 371 of PCT International Application No. PCT/EP02/04708 which has an International filing date of April 29, 2002, which designated the United States of America.

#The present invention concerns the preparation of composite biomaterials constituted by hyaluronic acid and the derivatives thereof in combination with polymers that have electrically conductive properties.

#In particular, the methods of preparing biomedical devices formed by a two- or three-dimensional polysaccharide matrix and by an electrically conductive membrane. The matrix is constituted by hyaluronic acid derivatives in the form of membranes, woven fabrics, nonwoven felts, meshes, gauzes, guide channels or sponges, while the electrically conductive membrane is constituted by a film of polypyrrole (polymer conductor) in combination with hyaluronic acid or a derivative thereof (doping agent).

#The present invention describes the preparation of polymer films that are electric conductors based on polypyrrole (PPy), hyaluronic acid (HA) and its sulphated derivatives (HAOSO3) and hypercarboxylates (HTOXX™), either supported or not supported on woven, non-woven fabrics and membranes constituted by benzyl esters of hyaluronic acid (woven and non-woven fabrics based on HYAFF®11p75 and total HYAFF®11 with a higher degree of esterification), to obtain materials for use in the biomedical sector for the regeneration of nerve and bone tissue (for example for the growth and differentiation of nerve cells, the regeneration of bone tissue using supporting materials, the repair of damaged nerves and consequent recovery of lost nervous function).

#A) Electrically Conductive Polymers

#Polypyrrole belongs to the class of polymer materials that are able to vary electric conductibility following a suitable redox reaction, commonly known as doping. It involves the transformation of the neutral-isolating polymer into an ionic complex formed by a polymer cation and a counterion (which is the reduced form of the oxidating agent, doping p) or by a polymer anion and a counterion (which is the oxidised form of the reducing agent, doping n) as indicated in Scheme 1: POLYMER+Electron Attractor (POLYMER)++(EA)−: p type doping POLYMER+Electron Donor (POLYMER)−+(ED)+: n type doping Scheme 1: Typical p and n Type Doping for Semiconductor Polymers