Mesoporous silica nanoparticles based on a dual environmental response corresponding to temperature and α-amylase for the control of Spodoptera litura

The design and development of stimuli-responsive nanocarriers hold the promise of the smart delivery of pesticides to target organisms. Herein, we successfully prepared mesoporous silica nanoparticles using the self-templating method, which were grafted with both N-isopropylacrylamide (NIPAM) and cyclodextrin (CD) and loaded with indoxacarb (IN) to afford a pesticide release system with a dual-stimulated response of temperature and α-amylase, referred to as IN@MSNs@NIPAM@CD. Physicochemical characterisation revealed the successful preparation of IN@MSNs@NIPAM@CD with 46.30 % indoxacarb loading. The results showed that IN@MSNs@NIPAM@CD was able to release IN rapidly in the environment of high temperature and α-Amylase, with excellent dual-responsive property. The UV resistance evaluation showed that IN@MSNs@NIPAM@CD could effectively improve the photodegradation resistance of indoxacarb. Fluorescent inverted microscope showed that FITC@MSNs@NIPAM@CD has excellent uptake and translocation properties in corn plants. Bioactivity tests showed that at 14 d, IN@MSNs@NIPAM@CD (LC 50 = 9.83 mg L −1 ) exhibited higher insecticidal activity and longer effective duration than IN@EC (LC 50 = 14.64 mg L −1 ). Acute toxicity test revealed that the IN@MSNs@NIPAM@CD nanoparticles were less acutely toxic to earthworms, zebrafish, BEAS-2B cells and MSNs@NIPAM@CD nanocarriers were safe for the growth of corn. Thus, the dual-responsive nano-controlled-release formulation of IN@MSNs@NIPAM@CD can provide an effective way of achieving the precise delivery and reduced use of pesticides.