Size effect of ZIF-8 based nanocarrier pesticide delivery system on targeted release and insecticidal activity

Traditional chemical pesticides are easily lost by surface runoff and only small quantities reach the target, thus causing serious environmental pollution. In this work, dinotefuran@zeolitic imidazolate framework-8@polydopamine@zein (DNF@ZIF-8@PDA@zein), was constructed to deliver DNF with pH and enzyme double response of release, thereby achieving targeted release and efficient long-term pest control.

DNF@ZIF-8@PDA@zein was synthesized with three hydrated diameters (249.73 ± 9.99 nm, 142.94 ± 5.63 nm and 75.16 ± 4.66 nm, respectively). The release of DNF from DNF@ZIF-8@PDA@zein after 28 h was significantly higher at pH 5.0 (89.22 ± 7.18%) compared to that at pH 8 (81.8 ± 6.11%). Protease-assisted release of DNF was notably higher than that without protease (pH 5: 89.22 ± 5.55% versus 27.19 ± 3.22%; pH 8: 81.8 ± 6.11% versus 25.39 ± 3.87%). The stimuli-responsive release of DNF from DNF@ZIF-8@PDA@zein increased with decreased particle size due to increased pore size, reduced binding forces (i.e., weaker π-π stacking, hydrogen bonding, and Zn-N covalent bonding), and the shortening of diffusion path, leading to faster disintegration and drug release. Additionally, the anti-photolysis ability of DNF@ZIF-8@PDA@zein was 3.2 times that of pure DNF. The insecticidal activity improved with smaller nanoparticles due to higher drug release rate and greater inhibition of detoxification enzyme activity by more zinc ion (Zn²⁺) dissolution.

The pH and enzyme dual-responsive release as well as insecticidal activity of DNF@ZIF-8@PDA@zein increase with decreased nanoparticle size, showing effective pest management in long-term and potential application prospects in sustainable agriculture. © 2024 Society of Chemical Industry.