Wear, fatigue characteristics, and antibacterial performance of UHMWPE reinforced with HAP+TiO2 for biomedical applications

Abstract

Abstract This study aimed to develop and evaluate hybrid composites of ultra-high molecular weight polyethylene (UHMWPE) reinforced with hydroxyapatite (HAP) and titanium dioxide (TiO 2 ) for synthetic cartilage applications in joint prostheses. Three composite formulations were prepared using a solvent dispersing method followed by hot pressing, and their mechanical, tribological, and antibacterial properties were analyzed. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were employed to assess the dispersion quality of the fillers. TiO 2 content was varied (1, 3, 5, and 10 wt%) while HAP content was fixed at 20 wt%. In the UHMWPE matrix, HAP served as a bone osteo-inductive agent and TiO 2 as an anti-wear additive. Wear testing against Ti6Al4V alloy using dry sliding and simulated body fluid (SBF) revealed that 3 wt% TiO 2 enhanced wear resistance due to the formation of a dense lubricant film. The Agar Well Diffusion method confirmed significant antibacterial activity in the composites. Furthermore, fatigue tests conducted at frequencies of 1 Hz and 3 Hz demonstrated improved fatigue life and maximum stress for the P-H-3T composite (3 wt% TiO 2 ). This improvement was attributed to the homogeneous dispersion of the nanoparticles, which facilitated better stress transfer and delayed crack initiation. Excessive TiO 2 led to particle agglomeration, reducing fatigue resistance. The results highlight that 3 wt% TiO 2 provides an optimal balance between strength, wear resistance, and fatigue life for biomedical applications.