Surface modification of titanium foams for modulated and targeted release of drug-loaded biocompatible hydrogel. Proof of concept

Abstract

Bone-tissue replacement surgeries usually need medication to mitigate implant rejections or prevent local infections. In this study, a modulated and targeted tetracycline (TC) loaded gelatine type A hydrogel is release from Ti foams as a proof of concept for an innovative and intelligent drug release system. The drugs are released in a localized and controlled manner. The Ti foams fabricated by the space holder technique were surface modified by two different techniques of surface modification, i.e., thermal oxidation and acid etching, to assess their influence on TC release. The characterization carried out after the surface modification indicated that samples modified with acid etching have produced a rougher surface, increasing the diameter of pores (from 500 μm to 700 μm, approximately) due to coalescence of pores. The increase of pore roughness has demonstrated the delaying of the TC release due to the greater adhesion between the surface roughness and the hydrogel. In addition, the increase of pore size improves the possibility to infiltrate high amount of drug-loaded biocompatible hydrogel. Opposite, oxidized surface samples have generated a rutile type TiO₂ layer that, because of its hydrophilic nature facilitate the degradation of the hydrogel, and consequently, the TC release from the Ti foams. Therefore, both methods show opposite behaviour, available to increase (acid etching) or decrease (thermal oxidation) the TC release thanks to the different kinetic degradation of hydrogel, as a potential way for drug-release from metallic implants. Thus, while acid-etched samples showed maximum TC release value of 35 wt%, after 120 min, the oxidized samples surpassed the 40 % of TC release after same 120 min of release time treatment.