pH- and Temperature-Responsive Nanogel Adhesive for Tunable Interfacial Bonding of Hydrogel Materials

The synthesis of high-performance hydrogel adhesives often relies on complex, multi-component systems, complicating their preparation and application. To overcome these limitations, we report a thermosensitive nanogel adhesive (NGA) via a facile one-step precipitation polymerization of N-isopropylacrylamide (NIPAM) and 3-acrylamidophenylboronic acid (AAPBA). This NGA functions as a simple adhesive, forming stable bonds with hydroxyl-rich substrates without requiring additional curing steps. The resulting nanogel exhibits dual sensitivity to temperature and pH, undergoing reversible changes and gelation under specific conditions. Mechanical interfacial bonding tests of hydrogel substrates reveal that a minimal volume of 15 µL of the NGA dispersion achieves a shear strength of 7.0 ± 1.4 kPa and a tensile strength of 15.7 ± 4.2 kPa. Furthermore, the adhesion performance can be precisely tuned by controlling the nanogel particle size, dispersion pH, and concentration. Biocompatibility assessments confirm excellent hemocompatibility and cell viability. This work not only presents a robust and tunable nanogel adhesive platform but also establishes a general model for the design of functional nanogel-based adhesives, significantly expanding their potential applications.