The surface properties and performance of biomaterials can be modified using various chemical techniques while retaining their biocompatibility and functionality. These modifications can improve the biomaterial's interaction with the biological environment, enhance cell adhesion, and control the release of drugs or other bioactive molecules. Some of the common chemical techniques used for modifying biomaterial surfaces include:1. Surface functionalization: This involves the introduction of functional groups or molecules onto the surface of the biomaterial. This can be achieved through various methods such as plasma treatment, chemical grafting, or self-assembled monolayers SAMs . These functional groups can improve biocompatibility, promote cell adhesion, or provide sites for further chemical modifications.2. Surface coating: Biomaterial surfaces can be coated with biocompatible polymers, proteins, or other bioactive molecules to improve their performance. Common coating techniques include dip coating, spin coating, and layer-by-layer LbL assembly. These coatings can provide a more favorable surface for cell attachment, reduce protein adsorption, or control the release of drugs or other bioactive molecules.3. Hydrophilic/hydrophobic modification: The surface wettability of biomaterials can be altered by modifying their hydrophilic or hydrophobic properties. This can be achieved through the introduction of hydrophilic or hydrophobic functional groups, or by coating the surface with hydrophilic or hydrophobic materials. Modifying the surface wettability can influence protein adsorption, cell adhesion, and the overall biocompatibility of the material.4. Surface patterning: The surface topography of biomaterials can be modified using techniques such as micro- and nano-patterning, which can influence cell behavior, including adhesion, proliferation, and differentiation. Methods for creating surface patterns include photolithography, soft lithography, and electron beam lithography.5. Immobilization of bioactive molecules: Biomolecules, such as peptides, growth factors, or enzymes, can be immobilized onto the surface of biomaterials to improve their functionality. This can be achieved through covalent bonding, physical adsorption, or entrapment within a polymer matrix. Immobilized bioactive molecules can enhance cell adhesion, promote tissue regeneration, or provide localized drug delivery.6. Crosslinking: Crosslinking can be used to modify the mechanical properties, degradation rate, and swelling behavior of hydrogels and other polymeric biomaterials. Common crosslinking methods include chemical crosslinking using crosslinking agents or photo-initiators and physical crosslinking such as ionic or hydrogen bonding .By carefully selecting and optimizing these chemical techniques, the surface properties and performance of biomaterials can be tailored to meet specific application requirements while maintaining their biocompatibility and functionality.