Biodegradable redox sensitive chitosan based microgels for potential agriculture application

In this work, we report redox sensitive, 2,3-dihydroxybenzoic acid (DH) functionalized chitosan/stearic acid microgels (DH-ChSt MGs) for controlled delivery of insecticide and capturing of heavy metal ions. DH-ChSt MGs (≈146 nm) are prepared by disulfide crosslinking of SH functionalized chitosan and stearic acid rendering them biodegradable. DH-ChSt MGs exhibit high loading (≈8 %) and encapsulation (≈85 %) efficiency for imidacloprid insecticide, and offer its prolonged release (≈75 % after 133 h) under reducing conditions. Functionalization with DH provides enhanced foliar adhesion on pea leaves. DH-ChSt MGs also bind Fe³⁺ very efficiently due to the strong chelation of Fe³⁺ by DH, offering the opportunity of supplying Fe³⁺ nutrient for plant care. MTT assay results using different cells confirm that DH-ChSt MGs are nontoxic up to the experimental concentration of 120 μg/mL. Additionally, reduced DH-ChSt MGs having free thiol groups are also capable of binding heavy metal ions, thus presenting the reported formulation as a promising platform for agriculture application.