The influence of titanium and cooper on physiochemical and antibacterial properties of bioceramic-based composites for orthopaedic applications

Abstract

This study examines the impact of titanium and copper ion modifications on the properties of hybrid hydroxyapatite/chitosan granules, which serve as components of novel injectable bone substitutes - biomicroconcretes. In addition to the hybrid granules, the powdered phase of the composites comprises highly reactive α-tricalcium phosphate (α-TCP) powder. The utilization of a mixture consisting of citrus pectin and disodium phosphate as the liquid phase of bone substitutes facilitated the development of easily mouldable, fully injectable biomicroconcretes based on calcium phosphate, characterized by distinct properties. The resulting biomicroconcretes demonstrated favourable cohesion and setting times falling within acceptable parameters. Furthermore, the incorporation of citrus pectin into the liquid phase significantly augmented the mechanical strength of the materials. The unique attributes of biomicroconcretes containing citrus pectin arise from the presence of both a dual setting system and a double hybrid system. The dual setting mechanism, stemming from the hydrolysis of α-TCP and the crosslinking of citrus pectin in the presence of Ca2⁺ ions, yielded materials distinguished by excellent cohesion and chemical stability. Conversely, the double hybrid system emerged from the coexistence of hybrid granules and interactions between polycationic chitosan within the hybrid granules and polyanionic citrus pectin. All obtained biomicroconcretes exhibited in vitro bioactivity, positioning them as promising candidates for further biological investigations. Notably, the integration of antibacterial copper ions into hybrid hydroxyapatite/chitosan granules significantly enhances their potential utility as bone substitute materials, effectively reducing the risk of S. aureus and E. coli infection during surgical procedures. It has been found that titanium modified composites reduced adhesion of S. aureus but did not reduce the adhesion of E. coli cells. This research validates the advantageous properties of the synthesized ceramic-based biomaterials and sets the stage for subsequent in vitro and in vivo studies.