A biodegradable, mechanically tunable micro-arc oxidation AZ91D-based composite implant with calcium phosphate/chitosan coating promotes long-term bone tissue regeneration

The effects of electrodeposition temperature on morphology and corrosion resistance of calcium phosphorus coatings on magnesium alloy: comparative experimental and molecular dynamics simulation studies

In this study, CaP coatings were prepared on the surface of an AZ31B magnesium alloy using electroplating in order to slow down the degradation rate of magnesium alloy in the simulated physiological environment. The effect of plating temperature on the properties of CaP coatings was investigated by combining experimental techniques with molecular dynamics (MD) simulation. The surface morphology of CaP coatings changed from dendritic lamellar to granular structure with the increase of plating temperature, but the main structure of CaP coatings prepared at all temperatures was CaHPO4·2H2O. The CaP coatings prepared at 60 °C have higher corrosion resistance compared to coatings prepared at other temperatures. The MD simulation revealed the DCPD/Mg interfacial binding mechanism, and DCPD/Mg could form a stable interfacial layer at different temperatures because the binding energy was negative. HPO42- and H2O groups in the DCPD structure acted as riveting groups in the interfacial layer and formed Mg-HPO42- and Mg-H2O dipole pairs with Mg respectively through electrostatic interaction and van der Waals forces. The interfacial bonding energy between DCPD/Mg reached its lowest at 60 °C and the relative contents of HPO42- and H2O in the interface layer were the highest at this temperature, which may explain the high corrosion resistance and high bonding force of CaP coatings prepared at this temperature.

Composite Nanocoatings of Biomedical Magnesium Alloy Implants: Advantages, Mechanisms, and Design Strategies

The rapid degradation of magnesium (Mg) alloy implants erodes mechanical performance and interfacial bioactivity, thereby limiting their clinical utility. Surface modification is among the solutions to improve corrosion resistance and bioefficacy of Mg alloys. Novel composite coatings that incorporate nanostructures create new opportunities for their expanded use. Particle size dominance and impermeability may increase corrosion resistance and thereby prolong implant service time. Nanoparticles with specific biological effects may be released into the peri-implant microenvironment during the degradation of coatings to promote healing. Composite nanocoatings provide nanoscale surfaces to promote cell adhesion and proliferation. Nanoparticles may activate cellular signaling pathways, while those with porous or core-shell structures may carry antibacterial or immunomodulatory drugs. Composite nanocoatings may promote vascular reendothelialization and osteogenesis, attenuate inflammation, and inhibit bacterial growth, thus increasing their applicability in complex clinical microenvironments such as those of atherosclerosis and open fractures. This review combines the physicochemical properties and biological efficiency of Mg-based alloy biomedical implants to summarize the advantages of composite nanocoatings, analyzes their mechanisms of action, and proposes design and construction strategies, with the purpose of providing a reference for promoting the clinical application of Mg alloy implants and to further the design of nanocoatings.

Anti-tuberculosis drug delivery for tuberculous bone defects

INTRODUCTION

Traditional therapy methods for treating tuberculous bone defects have several limitations. Furthermore, systemic toxicity and disease recurrence in tuberculosis (TB) have not been effectively addressed.

AREAS COVERED

This review is based on references from September 1998 to September 2021 and summarizes the classification and drug-loading methods of anti-TB drugs. The application of different types of biological scaffolds loaded with anti-TB drugs as a novel drug delivery strategy for tuberculous bone defects has been deeply analyzed. Furthermore, the limitations of the existing studies are summarized.

EXPERT OPINION

Loading anti-TB drugs into the scaffold through various drug-loading techniques can effectively improve the efficiency of anti-TB treatment and provide an effective means of treating tuberculous bone defects. This methodology also has good application prospects and provides directions for future research.