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The osseointegration of titanium implants within the host tissue holds crucial importance. The introduction of functional coatings at tissue-implant interface enhances the bioactivity of titanium implants, improves their therapeutic outcomes, and enhances the effectiveness of treatments. In this study, we focused on enhancing the bioactivity of titanium-based implant materials by coating the titanium surfaces with chitosan microspheres, which are loaded with osseointegration-promoting agent dexamethasone (DEX). Initially, chitosan microspheres were successfully produced, followed by DEX loading through diffusion, resulting in a drug loading efficiency of around 50.2 (wt %). The subsequent drug release profile displayed a 24-hour duration, releasing approximately 32.6 (wt %) of the loaded DEX. In cell proliferation assays using human osteosarcoma (SAOS-2) cells, Ti surfaces coated with DEX-loaded chitosan microspheres initially exhibited lower cell numbers compared with DEX-free ones. This observation was attributed to transient osteogenic differentiation effects of DEX, since a notable increase in cell proliferation was observed on the 7th day. Von Kossa staining revealed mineralization beginning on the 14th day, particularly evident in DEX-loaded samples. Moreover, alkaline phosphatase (ALP) activity displayed a pattern of initial increase and subsequent decrease, with DEX release from chitosan microspheres showing a clear influence on the osteogenic differentiation, especially on the 7th day. These findings align with literature, highlighting DEX's potential to enhance osteogenic differentiation and cellular behavior on chitosan microsphere-coated titanium surfaces. This study emphasizes the promising implications for functionalizing surfaces of implant materials with DEX-loaded chitosan microspheres to improve their biocompatibility and bioactivity., (© 2024 The Authors. Journal of Biomedical Materials Research Part A published by Wiley Periodicals LLC.)

Bacterial infections and lack of osseointegration may negatively affect the success of titanium (Ti) implants. In the present study, a functional coating composed of chitosan (CS) microspheres and nano hydroxyapatite (nHA) was prepared to obtain antimicrobial Ti implants with enhanced bioactivity. First, the chitosan microspheres were fixed to Ti surfaces activated by alkali and heat treatment, then nHA coatings were precipitated onto these surfaces. Ciprofloxacin was loaded into the microspheres using two different procedures; encapsulation and diffusion. Scanning electron microscopy micrographs of the modified Ti surfaces showed that the coating was successfully deposited onto the Ti surfaces and stable for 30 days in PBS. The drug was completely released from free microspheres loaded by encapsulation in 21 days whereas only 89% release was observed after immobilization. The burst release also decreased from ca. 55% to ca. 35%. The release was further reduced following the nHA precipitation. The modified Ti surfaces showed antimicrobial activity based on the bacterial time-kill assay using S. aureus , but the efficiency was affected by both nHA precipitation and drug loading strategy. Highest antimicrobial activity was seen in the samples without nHA layer, and when the drug was loaded by diffusion. Fourier transform infrared spectroscopy and X-ray diffraction analyses revealed that nHA on the surface enhanced HA growth in simulated body fluid for 3 weeks, showing increased osseointegration potential. Therefore, the proposed coating may be used to prevent Ti implant failure originated from bacterial infection and/or low bioactivity.