Surface modification technology of titanium alloys promotes "harmonious coexistence"

(1) Surface coating technology
To further enhance the compatibility of titanium alloys with human tissues, researchers have developed various surface coating technologies. Hydroxyapatite (HA) coating is a commonly used one. Hydroxyapatite is the main inorganic component of human bones and teeth, and it has excellent biocompatibility and osteoconductivity. By applying a layer of hydroxyapatite coating on the surface of titanium alloys through methods such as plasma spraying and electrophoretic deposition, it can simulate the composition and structure of human bones, promote the adhesion, proliferation and differentiation of bone cells, and accelerate the process of bone integration. For instance, in spinal fusion surgery, the use of titanium alloy fusion devices coated with hydroxyapatite can integrate with the surrounding bones more quickly, improving the surgical outcome. In addition, there are also bioactive glass coatings, collagen coatings, etc. These coatings enhance the interaction between titanium alloys and human tissues through different mechanisms, achieving better "harmonious coexistence".

(2) Construction of Micro-nano Structures
Constructing micro-nano structures on the surface of titanium alloys is also an important means to enhance their compatibility with human tissues. By using techniques such as photolithography, etching, and laser processing, micro-scale and nano-scale structures can be fabricated on the surface of titanium alloys. Micro-scale grooves, protrusions, and other structures can guide the directional growth and alignment of cells, promoting the ordered repair of tissues. Nano-scale structures can increase the surface roughness and specific surface area, enhance the adsorption capacity of proteins, and provide more adhesion sites for cells. For instance, nano-scale porous structures were fabricated on the surface of titanium alloys by femtosecond laser, and it was found that such structures could significantly promote the adhesion and differentiation of osteoblasts, and improve the bonding strength between titanium alloys and bones.

(3) Chemical modification methods
Chemical modification improves the biocompatibility of titanium alloys by altering their surface chemical composition and properties. Surface grafting is one of the common chemical modification methods, which involves attaching biologically active molecules (such as amino acids, peptides, growth factors, etc.) to the surface of titanium alloys. These biologically active molecules can specifically bind to the receptors on the cell surface, regulate cell behavior, and promote cell growth and differentiation. For instance, grafting bone morphogenetic protein (BMP) onto the surface of titanium alloys can induce mesenchymal stem cells to differentiate into osteoblasts and accelerate bone tissue formation. Additionally, surface oxidation, nitridation, and other methods can be used to change the chemical composition and structure of the titanium alloy surface, thereby enhancing its corrosion resistance and biocompatibility.