Multi-responsive, room-temperature self-healing salep-based nanocomposite hydrogels with enhanced mechanical performance as smart biomaterial

Self-healing hydrogels are advanced materials that can restore their original functionality and properties after mechanical damage, either through intrinsic mechanisms or via external stimuli. However, their widespread application is often limited by challenges such as insufficient mechanical strength, low thermal stability, and inadequate self-healing efficiency. In this study, we developed a novel self-healing hydrogel based on salep. This natural polysaccharide was modified through free radical polymerization using two distinct polymers: polyacrylamide (PAM) and poly)diallyldimethylammonium( chloride (PDADMAC). Additionally, Fe₃O₄ magnetic nanoparticles (MNPs) were synthesized and incorporated into the hydrogel matrix, imparting magnetic responsiveness. The resulting semi-interpenetrating (semi-IPN) hydrogel network exhibited robust self-healing properties, attributed to dynamic, reversible hydrogen bonds within the polymer chains. The inclusion of Fe₃O₄ MNPs further facilitated the mobility of polymer chains under an external magnetic field, significantly improving the efficiency and rate of self-repair. The PAM-modified nanocomposite hydrogel achieved an equilibrium swelling ratio of ~ 2300%, while the PDADMAC-based composite reached ~ 1875% at pH = 7. Notably, the semi-IPN structure endowed the hydrogel with self-healing, enabling it to recover its original mechanical integrity within 35 min at room temperature. Combining a natural salep matrix with synthetic polymer networks and Fe₃O₄ MNPs produced a self-healing hydrogel with markedly improved strength, stability, and functionality. The dynamic hydrogen-bonded network ensures rapid, autonomous repair, while the magnetic component provides tunable responsiveness under external fields. These features, together with High tensile properties and antimicrobial efficacy, suggest broad applicability in biomedical, agricultural, and environmental technologies.