NEW BIODEGRADABLE POLYESTERS AND POLY(ESTER AMIDE)S FOR BIOABSORBIBLE SURGICAL SUTURES. STUDIES OF DRUG DELIVERY, CRYSTALLINE STRUCTURE AND DEGRADATION

This Project deals with the development of materials for applications as bioabsorbable surgical sutures or coatings for multifilament sutures. Copolymers based on trimethylcarbonate units will be the main studied family. The ratio between the different comonomers will be varied, and the influence of the reaction conditions and the transesterification catalysts on properties and polymer microstructure will be studied. Thermal treatment of commercial homopolymers should also induce transesterification reactions that will be evaluated. Poly(ester amide)s derived from copolymerization of morpholinediones with different lactones will also be considered.

A second purpose of the Project consists on the incorporation of substances with a pharmacologic activity into a suture with a monofilament form or into the coating of a braided suture, and also on the study of the liberation kinetics in different media. Drug load will be performed by different methods as diffusion into the suture, direct mixture with the coating, or chemical reaction with functional groups of the coating.

The objective of this group of activities is to obtain new materials that could show some enhanced properties respect to the sutures until now commercialized. In this sense, our collaboration of R&D with B.BRAUN Surgical, one of the most important manufactures of bioabsorbable sutures, has been proved very fruitful.

A second group of activities concerns the study of the crystalline structure of new copolyesters and poly(ester amide)s that have a regular sequence and glycolic acid units. Crystalline morphology will be studied as well as the enzymatic attack on both single crystals and thin spherulitic films. The polymers of this group will be obtained following a synthetic procedure that we have recently patented. Applications of these materials as microspheres for drug delivery and as nanocomposites by mixture with organoclays will be studied.