Photo-responsive chitosan-based supramolecular hybrid hydrogel with reactive oxygen species scavenging capacity for efficient alleviation of plant salt stress

Since soil salinization has emerged as a major abiotic stress constraining agricultural productivity, developing eco-friendly and efficient strategies for salt stress alleviation is critical for sustainable agricultural development. Herein, an environmentally friendly photo-responsive chitosan-based supramolecular hybrid (LPSeAQCs) hydrogel was facilely fabricated via multiple noncovalent interactions between 2-selenium-bridged β-cyclodextrin (SeCD), arylazopyrazole-modified quaternary ammonium chitosan (AAP-QCs), and nanoclay laponite (LP) to alleviate salt stress. This hydrogel possessed crosslinked porous architecture that facilitate plant growth regulator loading. Rheological characterizations confirmed its stable gel network, favorable self-healing capacity, excellent thermal stability and good injectability. Besides, LPSeAQCs hydrogel exhibited superior photo-responsive cargo release performance. Moreover, the hydrogel displayed outstanding reactive oxygen species (ROS)-scavenging activity and excellent biocompatibility. Under 100 mM NaCl salt stress, LPSeAQCs hydrogel achieved the optimal stress-alleviating efficacy, with wheat growth parameters comparable to those of the unstressed blank control. Specifically, this formulation markedly enhanced the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) in salt-stressed wheat, while significantly reducing malondialdehyde (MDA) levels. Additionally, LPSeAQCs hydrogel effectively preserved the morphological structure of wheat root cells against high-salt injury and maintained the structural integrity of root tissues. These findings provide novel insights into the application of supramolecular nanomaterials in sustainable agriculture.