Medical grade thermoplastic collagen – upgrade of a unique biomaterial

Abstract text (incl. figure legends and references)
Introduction

Collagen is a widely used biomaterial in medical applications, mainly in the form of fleeces, sponges, films or threads, produced from soluble collagen or collagen dispersions. A unique collagen powder, which can be processed by thermoplastic techniques, was available until now only in technical or food grade for non-medical applications.

Aim of the work was the reassessment of the production process of thermoplastic collagen resulting in a medical grade, non-cytotoxic material. Up to now, thermoplasts in medical devices are limited to synthetic polymers, like PP, PVC, PEEK or PLA. A biodegradable, collagen based thermoplast provides opportunities for novel products and applications.

The preparation of thermoplastic collagen from the raw material (bovine hide) to the final product (collagen powder) was performed without any chemicals critical for the intended medical use. Special focus was on the denaturation procedure which is a crucial step in thermoplastic collagen production. Biocompatibility of the final powder and resulting products after extrusion was proved by cytotoxicity tests.

Medical grade thermoplastic collagen powder was prepared following a modified procedure which avoids the use of critical chemicals in all relevant process steps. Depending on the denaturation method, collagen powders with different ratios of soluble and insoluble protein fractions were produced. The material can be processed like a thermoplast by extrusion or injection molding and is suitable for additive manufacturing.

Thermoplastic collagen is now available as a medical grade material, which enables the production of collagen based medical devices apart from simple fleeces, sponges or films. Thermoplastic processing, including additive manufacturing techniques, offers a broad range of otherwise inaccessible product forms. Potential applications include customized implants and items for tissue engineering.