Design strategy for surface hydrogel coatings on metal biomedical devices based on interfacial bonding mechanisms

With the rapid development of biomedical engineering, metal biomedical devices have attracted considerable attention for their wide range of applications, including neuromonitoring, cardiovascular therapy, and tissue repair. However, the difference in mechanical modulus between the device's metal substrate and human tissues often causes mechanical mismatch during use, leading to inflammation, tissue damage, and reduced long-term performance. To address this issue, researchers have recently proposed constructing hydrogel coatings on metal surfaces, which enhance the tissue integration of devices by combining the mechanical advantages of metals with the biocompatibility and functionality of hydrogels. In this paper, we systematically review two approaches for constructing hydrogel coatings on metal biomedical devices based on interfacial bonding mechanisms: surface bridging and surface initiation. We discuss the formation mechanisms of these coatings and examine their applications in devices such as implantable electronic devices, vascular stents, and medical guidewires. These studies provide an important theoretical foundation and technical support for the development of high-performance, multifunctional medical devices, thereby driving innovation in biomedical engineering.