Metal oxides in biomedicine: Advances in imaging, drug delivery, tissue engineering, and biosensing

Metal oxide nanoparticles (MONPs) have garnered significant attention in biomedical applications due to their unique physicochemical properties, including high surface area, tunable band gaps, and reactive oxygen species (ROS) generation. This review aims to comprehensively evaluate the synthesis, functionalization, and biomedical applications of MONPs, focusing on their roles in imaging, targeted drug delivery, tissue engineering, and biosensing. MONPs such as Fe₃O₄, TiO₂, ZnO, CeO₂, and MgO exhibit exceptional optical, magnetic, and catalytic properties, making them highly suitable for multimodal imaging, therapeutic interventions, and regenerative medicine. The objective of this review is to assess the current state of MONP-based technologies, highlighting their advantages, limitations, and translational challenges in clinical applications. A systematic evaluation of recent advancements in MONP synthesis, surface engineering, and in vitro/in vivo studies was conducted to determine their efficacy in biomedical applications. Results indicate that Fe₃O₄ nanoparticles significantly enhance MRI contrast for tumor imaging, while TiO₂ and ZnO improve CT resolution. Functionalized MONPs facilitate site-specific drug delivery through pH- and magnetically responsive mechanisms, reducing systemic toxicity and enhancing therapeutic efficiency. In tissue engineering, MONPs promote osteogenesis, neural regeneration, and wound healing by mitigating oxidative stress and stimulating cellular proliferation. Furthermore, ZnO- and TiO₂-based biosensors exhibit high sensitivity for glucose monitoring, cancer biomarker detection, and infectious disease diagnostics. Despite their promising biomedical potential, challenges such as long-term biocompatibility, nanoparticle aggregation, and large-scale production remain critical hurdles for clinical translation. Addressing these limitations through optimized synthesis strategies, advanced functionalization techniques, and integration into hybrid diagnostic and therapeutic platforms will be essential for realizing the full potential of MONPs in next-generation healthcare solutions.