Nanoparticle-Assembled Nanobridges for Preferential Surface Modification of Hydrogels

Hydrogels are soft materials with three-dimensional network structures that contain large amounts of water. Their inherent flexibility and excellent biocompatibility have made them attractive for a wide range of applications, including biomaterials, wearable electronics, and robotics. However, the high water content of hydrogels limits interfacial chemical interactions, making stable integration with various materials challenging. As a result, the broader practical application of hydrogels remains restricted.

To overcome these limitations, various surface modification methods, including chemical crosslinking, plasma treatment, and thermal curing, have been investigated. However, many of these approaches require harsh processing conditions that may compromise the intrinsic properties of hydrogels. Therefore, developing strategies that enable selective surface functionalization while preserving the bulk properties of hydrogels remains an important challenge. In this study, we propose a strategy that utilizes interdigitated gold nanoparticle clusters assembled on the hydrogel surface as nanobridges, enabling stable integration not only with polymers, glass, metals, and biological tissues but also with hydrophobic materials. This approach is based on ligand exchange-driven nanoparticle self-assembly, which mediates interfacial interactions between hydrogels and various materials and thereby promotes stable adhesion. Furthermore, we demonstrate that commercial adhesives, which are generally considered incompatible with hydrogels, can be used to achieve strong adhesion to various biological tissues.

These findings highlight the potential of the proposed strategy for bio-integration applications. Overall, this nanoparticle-based surface modification strategy provides an effective route for constructing stable and multifunctional hydrogel interfaces and offers promising opportunities for hydrogel-based systems such as biosensors, soft robotics, and wearable electronics.