Surface Modification Strategies for Biomedical Applications: Enhancing Cell–Biomaterial Interfaces and Biochip Performances

Surface modification techniques are crucial in biomedical applications as they determine the direct response to the biological environment against the interfacing materials. Physical and chemical modification techniques have been extensively studied, with the latter being more commonly used due to the need for molecularly thin layers. Achieving uniform and conformal surface coverage on target geometries is critical to optimizing sensor and biomedical applications. However, achieving molecularly thin layers is practically challenging, and thick layers can alter the original properties of the bulk material. Furthermore, delamination of coated layers in humid or aqueous environments is also a concern, which can be prevented by covalent bonding of the functional groups on the substrate or incorporating appropriate functional groups or charges for solid adhesion. In this review, we provide an overview of the consolidated techniques for surface modification of materials for biomedical applications, including protein immobilization, chemical grafting, thin film coating, and plasma treatments. It also discusses the most frequently used surface modification techniques and their applications in the field. Overall, optimizing surface engineering for each case is crucial, even if the method is the same, to achieve a uniform and conformal surface coverage on target geometries for various biomedical devices, sensors, and implants.