In Situ Self-assembly of Nanoparticles into Waxberry-like Starch Microspheres Enhanced the Mechanical Strength, Fatigue Resistance, and Adhesiveness of Hydrogel

Owing to the diminishing resources and growing awareness of environmental issues, significant scientific attention has been paid to the development of physical gel materials using renewable and low-cost natural resources. Inspired by the strengthened mechanism of double-network and nanocomposite gels, we report a facile and green method to realize a mechanically stiff, fatigue-resistant, and adhesive-debranched waxy corn starch/PVA double-crosslinked nanocomposite gel (W-Gel) skeleton material with dynamic non-covalent bonds. The in situ formation of DBS nanoparticles leads to self-assembly into 3D waxberry-like microspheres, which act as physical crosslinkers by embedding themselves within network skeleton structures. The resulting hydrogel exhibited excellently mechanical behavior, including a good stretchability over 1200% strain, a maximum compressive strength of up to 780.7 ± 27.8 kPa, and the ability to sustain as much weight as 4.6 kg (about 2,000 times its own weight). Notably, the recovery efficiency exceeded 93% after the 60th compressive successive loading-unloading cycle at 50% strain. The hydrogel successfully adhered onto soft and hard substrates, such as skins, plastics, gauzes, glasses, and metals, manifesting in long-term, stable sustained release of epigallocatechin gallate (EGCG). The EGCG-loaded W-Gels exhibited predominant antibacterial activity against both Gram-positive bacteria (S. aureus) and Gram-negative bacteria (E. coli and S. typhus).