Optimization of extraction technology of poly-mannuronic acid to a green delivery system for the water-insoluble pesticide, λ-Cyhalothrin.

Poly-mannuronic acids (PMs) have been considered as great biodegradable polymers as a green carrier for the potential pesticide deliver. In this work, the response surface design and microwave-assisted degradation were employed to obtain the optimum extraction conditions (i.e., 81 °C, 4.1 h, acid concentration 17.65 g/L). Meanwhile, the Ugi multi-component reaction makes the PM to be amphiphilic, called Ugi-PM, which induces the aggregation in aqueous solution at the concentration of 0.0895 g/L. The corresponding chemical structure and thermal stability of PM and Ugi-PM were determined by the FTIR, 1H NMR and thermogravimetric analysis (TG). Furthermore, the construction of novel emulsion-based delivery system using synthetic Ugi-PM was explored to prepare the pesticide of λ-Cyhalothrin. Interestingly, with the Ugi-PM concentration at 0.5 wt%, the stability of the Ugi-PM emulsion and the sustainable release of λ-Cyhalothrin are better than other concentrations and our previous system without degradation (Ugi-Alg emulsion). It is possible that electrostatic repulsion and steric hindrance derived from the hydrophobic Ugi-PM can promote the stability and flexible structure may be the reason for excellent sustained release of Ugi-PM emulsions in the pesticide deliver. The above-mentioned preparation progress is an efficient way to provide a valuable pesticide formulation.