Poly (L-lactic acid) coatings on 316 SS substrates for biomedical devices: The impact of surface silanization

Abstract

Metals and their alloys make them critical materials in orthopaedic applications for bone support due to their biocompatibility and mechanical properties. Nevertheless, these materials do not stimulate bone regeneration. A way to overcome this problem, may involve the application of a coating over the alloys using biocompatible and biodegradable materials capable of stimulating bone regeneration. In this work, poly (L-lactic acid) (PLLA) films were used over 316 SS substrates and a silanization reaction was employed to improve the interfacial adhesion between polymer and metal, to achieve physicochemically stable PLLA coatings. PLLA was chosen as a coating due to its biocompatible, biodegradable and piezoelectric properties, stimulating the activity of the host bone tissue. Our results reveal that the functionalization of the metal substrate with silane reagents is effective and efficient in the adhesion of PLLA films to 316 SS. Differences in the degree of adhesion are demonstrated, as well as their dependence on film thickness, concentration of polymer solution, and crystallization degree of the polymeric film. These results have implications on the understanding of how to produce stable PLLA coatings on 316 SS substrates, with suitable adhesion to apply in medical devices, paving the way for the possibility of exploring other advantageous properties of PLLA for bone regeneration such as piezoelectricity.