pH/temperature dual-responsive carboxymethyl cellulose-based nanogel for enhanced foliar retention and targeted delivery of matrine

A biobased nanogel enables pH/temperature-dual responsive matrine delivery. • Nanogel boosts leaf deposition by 23.3% and rainfastness 3.9‑fold vs. free MT. • pH 8.0 triggers 87.99% drug release, matching alkaline pest gut conditions. • Nanogel shows superior activity against P. xylostella (EC₅₀ = 3.71 mg/L). • Nanogel exhibits low toxicity to zebrafish at effective application doses. The development of intelligent pesticide delivery systems based on nanomaterials offers a promising strategy to enhance targeted utilization and reduce environmental residues. Such systems enable dynamic modulation of drug release through environmental response mechanisms while improving pesticide adhesion to leaf surfaces and resistance to rainwater erosion. In this study, we constructed an environmentally responsive controlled-release pesticide system using carboxymethyl cellulose (CMC) as the backbone. Tea saponin (TS), tannic acid (TA), and polyethyleneimine (PEI) were integrated to form a biocompatible interpenetrating network gel (CPTT). Matrine (MT) was further loaded into this network to generate a stable three-dimensional mesh structure (MT@CPTT@SLS). The resulting nanogel exhibited high drug encapsulation efficiency (88.7%) and loading capacity (34.5%). It achieved 23.3% foliar deposition and significantly improved rainfastness, retaining 71.6% of the pesticide under moderate rain (20 mm/h) and 52.3% under heavy rain (40 mm/h). The nanogel showed pH-sensitive drug release, with cumulative release reaching 87.99% at pH 8.0 (alkaline pest gut condition) compared to only 51.2% at pH 5.7. Insecticidal toxicity tests revealed enhanced efficacy against diamondback moth larvae with an EC₅₀ value of 3.71 mg/L, which is notably lower than that of free matrine. Moreover, zebrafish acute toxicity assays confirmed favorable aquatic biosafety (80% survival at 1 mg/L after 108 h). Collectively, this study provides a promising strategy for the application of intelligent nanogel pesticides in green plant protection, integrating efficient targeted delivery with environmental sustainability. Download: Download high-res image (126KB) Download: Download full-size image A Stimuli-Responsive Nanogel for Intelligent Pesticide Delivery