Advances in functional hydrogel materials for biosensing.

Functional hydrogels are becoming versatile soft materials for biosensing applications due to their hydrophilic three-dimensional polymeric network, which offers customizable matrices for analyte uptake and molecular recognition. This minireview emphasizes recent developments in functional hydrogel materials, focusing on advances in these materials that impact biosensing applications. These advances include the use of molecularly programmable polymeric networks that respond to the presence of a specific analyte. Hydrogel-based microneedles have been developed to access interstitial fluid in a minimally invasive way. We also discuss the combination of hydrogel and plasmonic materials, such as surface-enhanced Raman scattering (SERS) active metallic nanostructures for accurate molecular detection. Finally, we conclude discussing examples where hydrogel network characteristics, such as crosslinking density, swelling ratio, chemical composition, charge, and antifouling properties, are important factors for sensing/analytical performance. These advances highlight the important role of hydrogel materials in sensing applications and the important role of hydrogel design (both in the polymeric network and biosensing mechanism) for sensing performance. Future advances can potentially combine these advances to bridge high analytical performance with robust biosensing in real-world applications.