Titanium (Ti) and its alloys are widely recognized as preferred materials for bone implants due to their superior mechanical properties. However, their natural surface bio-inertness can hinder effective tissue integration. To address this challenge, micro-arc oxidation (MAO) has emerged as an innovative electrochemical surface modification technique. Its benefits range from operational simplicity and cost-effectiveness to environmental compatibility and scalability. Furthermore, the distinctive MAO process yields a porous topography that bestows versatile functionalities for biological applications, encompassing osteogenesis, antibacterial, and anti-inflammatory properties. In this review, we undertake an examination of the underlying mechanism governing the MAO process, scrutinize the multifaceted influence of various factors on coating performance, conduct an extensive analysis of the development of diverse biological functionalities conferred by MAO coatings, and discuss the practical application of MAO in implants. Finally, we provide insights into the limitations and potential pathways for further development of this technology in the field of bone implantation.

Degenerative osteoarthritis, a common sequela of articular cartilage defect, significantly impacts the quality of life of millions of individuals worldwide. Three-dimensional (3D) bioprinting has emerged as an advanced tissue engineering strategy, offering precise spatial arrangements of cells, hydrogels, and bioactive cues. Hyaluronic acid (HA) is a crucial component of bioink designed for fabricating cartilage tissue. However, creating a bioink that closely mimics the cartilaginous extracellular matrix (ECM) still remains a challenge. HA hydrogels have limitations in recapitulating tunable mechanical properties, stimuli responsiveness, and flexibility in ligands’ adhesion akin to those of native tissues. In recent years, DNA has emerged as a smart biomaterial that endows hydrogels with tunable properties and allows for precise structural customization of the hydrogels due to its unique programmability. Integrating reversible DNA linkages, reconfigurable DNA architectures, DNA plasmid, and targeted DNA aptamers into HA hydrogels allows them to respond to the extracellular environment and express desired molecules, making them ideal artificial ECMs for 3D bioprinting of cartilage tissue. This review targets this challenge by highlighting the characteristics of DNA moieties designed as reversible crosslinkers, responsive units, and adhesion ligands to functionalize HA hydrogels. Furthermore, we offer perspectives on how DNA-functionalized HA hydrogels can be harnessed to create dynamic and biomimetic bioink capable of recapitulating the more complex functions required for cartilage tissue engineering.