pH- and Salt-triggered Release of dsRNA from Adipic Acid-Crosslinked Chitosan Microgels

The increasing use of synthetic polymers in agrochemical formulations is raising concerns about their environmental impact. Chitosan, a naturally derived biopolymer, is a sustainable alternative due to its biocompatibility and biodegradability. The protonable amine groups generating positive charges along chitosan backbone enable high loadings and efficient release of RNA. However, the design of chitosan microgels with tailored release profiles remains challenging. This study presents adipic acid-crosslinked chitosan microgels (100 - 500 µm) for the release of insecticidal dsRNA via chitosanase-triggered degradation. Mechanical properties, swelling degree and enzymatic degradability of the microgels were tunable via crosslinker content. The diffusive release of dsRNA was triggered by high pH and ionic strength. Finally, microbial degradation of chitosan-based microgels in soil was shown by incubation experiments. The experimental results suggest potential use of the developed chitosan microgels as gut-specific delivery systems in insects.