Chiang Mai Journal of Science

Novel biodegradable polyesters are being developed for use as devices for guided tissue regeneration. Some random co- and terpolymers of L-lactide, e-caprolactone and glycolide have been synthesised, characterised and evaluated for potential use as absorbable nerve guides. The method of synthesis employed was ring-opening bulk polymerisation using stannous octoate as the initiator in conjunction with an alcohol as the coinitiator. The polymer products were characterised in terms of their composition, monomer sequencing, molecular weight, temperature transitions and morphology. Their ¹H-NMR spectra yielded compositions which were consistent with % yields being near-quantitative (>98%), while their ¹³C-NMR spectra confirmed that the co-/terpolymers were mainly random in their monomer sequencing but with some slightly blocky character. All polymers were completely amorphous, as indicated by the absence of any crystalline melting peaks in their DSC thermograms. Processing into the form of small tubes (conduits) by dip-coating from solution was investigated. Transparent, elastic nerve guide tubes were obtained and their mechanical properties evaluated alongside the corresponding surgical requirements. An in  vitro biodegradation study of the polymer tubes was carried out for up to 20 weeks in a phosphate buffer saline solution of pH 7.40 at 37.0 ± 1.0°C. The terpolymer degraded much faster than the copolymer, indicating that the degradation rate was significantly enhanced by the glycolic acid content in the terpolymer. From the results obtained so far, it can be concluded that these products show considerable potential for further development as absorbable nerve guides.