Novel fabrication of a yeast biochar-based photothermal-responsive platform for controlled imidacloprid release

For improving the utilization efficiency of pesticides, we developed a novel pesticide delivery particle (YINCP@EC) with a core-shell structure based on yeast biochar, imidacloprid (IMI), ammonium bicarbonate (NH₄HCO₃), calcium alginate (CA), and ethyl cellulose (EC). Therein, yeast biochar, IMI and NH₄HCO₃ were absorbed in the network-structured of CA to obtain YINCP through hydrogen bonds. The resulting composite was granulated using an ion gelation technique and then coated with EC to form YINCP@EC. In this platform, yeast biochar serving as a photothermal agent can efficiently convert sunlight energy into thermal energy, thereby triggering NH₄HCO₃ decomposition into CO₂ and NH₃ that can break through the EC coating and facilitate IMI release. In addition, the influence of yeast biochar content, pH, and coexisting ions was systematically studied to evaluate the release behavior of IMI from YINCP@EC. Moreover, the hydrophobic EC shell endowed YINCP@EC with high stability in aqueous solution for at least 60 days. Consequently, this novel composite with simple preparation, low cost and remarkable photothermal-responsive properties has a huge application potential in agriculture.