Structure-optimized and microenvironment-inspired nanocomposite biomaterials in bone tissue engineering

Critical-sized bone defects represent a significant clinical challenge due to their inability to undergo spontaneous regeneration, necessitating graft interventions for effective treatment. The development of tissue-engineered scaffolds and regenerative medicine has made bone tissue engineering a highly viable treatment for bone defects. The physical and biological properties of nanocomposite biomaterials, which have optimized structures and the ability to simulate the regenerative microenvironment of bone, are promising for application in the field of tissue engineering. These biomaterials offer distinct advantages over traditional materials by facilitating cellular adhesion and proliferation, maintaining excellent osteoconductivity and biocompatibility, enabling precise control of degradation rates, and enhancing mechanical properties. Importantly, they can simulate the natural structure of bone tissue, including the specific microenvironment, which is crucial for promoting the repair and regeneration of bone defects. This manuscript provides a comprehensive review of the recent research developments and applications of structure-optimized and microenvironment-inspired nanocomposite biomaterials in bone tissue engineering. This review focuses on the properties and advantages these materials offer for bone repair and tissue regeneration, summarizing the latest progress in the application of nanocomposite biomaterials for bone tissue engineering and highlighting the challenges and future perspectives in the field. Through this analysis, the paper aims to underscore the promising potential of nanocomposite biomaterials in bone tissue engineering, contributing to the informed design and strategic planning of next-generation biomaterials for regenerative medicine.

A surface-engineered multifunctional TiO2 based nano-layer simultaneously elevates the corrosion resistance, osteoconductivity and antimicrobial property of a magnesium alloy

Magnesium biometals exhibit great potentials for orthopeadic applications owing to their biodegradability, bioactive effects and satisfactory mechanical properties. However, rapid corrosion of Mg implants in vivo combined with large amount of hydrogen gas evolution is harmful to bone healing process which seriously confines their clinical applications. Enlightened by the superior biocompatibility and corrosion resistance of passive titanium oxide layer automatically formed on titanium alloy, we employ the Ti and O dual plasma ion immersion implantation (PIII) technique to construct a multifunctional TiO₂ based nano-layer on ZK60 magnesium substrates for enhanced corrosion resistance, osteoconductivity and antimicrobial activity. The constructed nano-layer (TiO₂/MgO) can effectively suppress degradation rate of ZK60 substrates in vitro and still maintain 94% implant volume after post-surgery eight weeks. In animal study, a large amount of bony tissue with increased bone mineral density and trabecular thickness is formed around the PIII treated group in post-operation eight weeks. Moreover, the newly formed bone in the PIII treated group is well mineralized and its mechanical property almost restores to the level of that of surrounding mature bone. Surprisingly, a remarkable killing ratio of 99.31% against S. aureus can be found on the PIII treated sample under ultra-violet (UV) irradiation which mainly attributes to the oxidative stress induced by the reactive oxygen species (ROS). We believe that this multifunctional TiO₂ based nano-layer not only controls the degradation of magnesium implant, but also regulates its implant-to-bone integration effectively. STATEMENT OF SIGNIFICANCE: Rapid corrosion of magnesium implants is the major issue for orthopaedic applications. Inspired by the biocompatibility and corrosion resistance of passive titanium oxide layer automatically formed on titanium alloy, we construct a multifunctional TiO₂/MgO nanolayer on magnesium substrates to simultaneously achieve superior corrosion resistance, satisfactory osteoconductivity in rat intramedullary bone defect model and excellent antimicrobial activity against S. aureus under UV irradiation. The current findings suggest that the specific TiO₂/MgO nano-layer on magnesium surface can achieve the three objectives aforementioned and we believe this study can demonstrate the potential of biodegradable metals for future clinical applications.

Non-Resorbable Nanocomposite Membranes for Guided Bone Regeneration Based On Polysulfone-Quartz Fiber Grafted with Nano-TiO2

The polymer-inorganic nanoparticles composite membranes are the latest solutions for multiple physicochemical resistance and selectivity requirements of membrane processes. This paper presents the production of polysulfone-silica microfiber grafted with titanium dioxide nanoparticles (PSf-SiO₂-TiO₂) composite membranes. Silica microfiber of length 150-200 μm and diameter 12-15 μm were grafted with titanium dioxide nanoparticles, which aggregated as microspheres of 1-3 μm, applying the sol-gel method. The SiO₂ microfibers grafted with nano-TiO₂ were used to prepare 12% polysulfone-based nanocomposite membranes in N-methyl pyrrolidone through the inversion phase method by evaporation. The obtained nanocomposite membranes, PSf-SiO₂-TiO₂, have flux characteristics, retention, mechanical characteristics, and chemical oxidation resistance superior to both the polysulfone integral polymer membranes and the PSf-SiO₂ composite membranes. The antimicrobial tests highlighted the inhibitory effect of the PSf-SiO₂-TiO₂ composite membranes on five Gram (-) microorganisms and did not allow the proliferation of Candida albicans strain, proving that they are suitable for usage in the oral environment. The designed membrane met the required characteristics for application as a functional barrier in guided bone regeneration.