Tough, durable and strongly bonded self-healing cartilage-mimicking noncovalently assembled hydrogel nanostructures: the interplay between experiment and theory

High-strength, strongly bonded and self-healing materials are of great interest for several applications; however, the experimental and <i>in silico</i> design of all such properties in a single material is challenging. In the present work, inspired by cartilage tissue, polyacrylamide (PAM)-based tough and durable dimer (PAM-Ag and PAM-BNOH) and trimer (PAM-Ag-BNOH) nanocomposites were synthesized by encapsulating silver (Ag) and hydroxylated hexagonal boron nitride (BNOH). Strong interfacial interaction was achieved by introducing (computational modelling and DFT approaches) noncovalent bonds in the dimer and trimer nanohybrids. The fabricated PAM-Ag-BN nanocomposite showed higher mechanical strength (0.31 MPa compressive strength and 0.29 MPa Young's modulus) than dimer hydrogel composites. The long-term durability of the hydrogel samples was tested by electrochemical testing of hydrogels in a simulated body fluid, and a higher corrosion resistance (<i>i</i>_corr = 2.65 × 10^-5 A cm^-2) was obtained for trimer hydrogels. Moreover, the supramolecular cross-linked assembly of PAM-Ag-BN perfectly exhibited bioactivities, including bone formation ability, self-healing performance, restricted cytotoxicity, and anti-microbial activity. The synergistic effect of nano- and micron-sized particles in PAM-Ag-BN ensued in strong interfacial interlocking through the formation of hydrogen bonding between Ag, BNOH and PAM. Therefore, the fabricated tough hydrogel composite can be a leading biomaterial for soft tissue (articular cartilage) regeneration. The present research opens new directions for developing smart self-healing nanocomposites, which are extensively used in cartilage tissue engineering.