Green liquid marble-based hydrogels as pesticidal pyrethrin slow-release carriers

Pyrethrin are effective agents against mosquito larval but their rapid degradation rate in water reduces the deinsectization efficiency and increases the cost of deinsectization. Based on liquid marble,a biodegradable slow-release hydrogel carrier is prepared using green and low-cost materials for the slow release of natural pyrethrin on water surfaces to kill mosquito larvae. Green carriers with high stability and loading of high concentrations of pyrethrin are synthesized by cross-linking Ca2+ in 5% CaCl2 solution with sodium alginate. The superior stability of liquid marble at the water surface and the electrostatic interaction between alginate and gelatin can effectively reduce the degradation rate of pyrethrin in water. Furthermore, the carrier system displayed long sustained-release time (>144 h) and maintained larvicidal performance after 168 h. Good floating stability is demonstrated for the liquid marble hydrogels. The larvicidal activity of obtained drug carrier reached 100% with different water volume but same dosage. This work provides a strategy to highly efficiently exterminate mosquito larvae by preparing a green hydrogel drug slow-release carrier, which provides a new approach to expanding the application of liquid marbles in green chemistry.