| Development of pesticide drug carrier material is an important research direction in today’s new pesticide research in the field of drug delivery systems.With people’s increasing awareness of environmental protection, how to develop a highly efficient, low toxicity, environmentally friendly pesticides containing important trend in the development of pesticide drug formulation. In recent years, sodium alginate and layered double hydroxides as a drug carrier material development and research in the field of hot direction. Layered double hydroxide (LDH) due positively charged layered structure, the interlayer anions with exchangeable and interlayer distance which can be effectively regulated. Therefore, the drug can be inserted between the layers to achieve effective controlled release of drugs via electrostatic interactions and hydrogen bonding between the drug and the layer ions. Thus LDH material is considered a highly promising new drug delivery transport materials.A water soluble amphiphilic sodium alginate derivative grafted with hydrophobic cholesteryl groups has been synthesized with DCC as a coupling agent and DMAP as a catalyst at room temperature. Using nonsteady copreipitation method,the Mg-Al LDH with Mg/Al molar ratio2:1was prepared. Then with the resulting has charged the layered structure of the Mg/Al LDH as emulsifier, stabilized oil-in-water Pickering emulsion. The morphology and size of LDH were studied with TEM and light scattering technolog. The TEM images of LDH show that the particles are all hexagonal plate-like with an average particle size150nm. The results of the FT-IR and1H-NMR show that the cholesterol group successfully grafted onto the side chain of sodium alginate. The effect of NaCl on the adsorption behavior of LDH/Alg-Chol at oil/water interface and the emulsions stabilized by LDH/Alg-Chol was investigated here. The contact angle is close to90°, the measure result shows that the sufacant and nano-particles have little influence on the emulsion wettability under different NaCl concentration. With the increase of NaCl concentration, Pickering emulsion gradually formed in the three-dimensional space network structure, which improved the structure strength of dispersion significantly. Modified sodium alginate (Alg-Chol) and nano-particles (LDH) in Pickering emulsion on the surface of the dispersed phase droplet self-assemble into a layer of interfacial layer, and particles will flocculation in oil-water interface, thereby increasing the stability of the emulsion.In order to increase the loading dose of hydrophobic drugs on alginate and control the drug release, dodecanol was covalently coupled to sodium alginate via ester functions using a coupling reagent to provide an amphiphilic dodecanol alginate(DA) for subsequent use in oil-in-water Pickering emulsion loaded cyhalothrin application. The structure of DA was confirmed by FT-IR,1H NMR spectrometry, results proved that dodecanol side chain successfully grafted onto the molecular skeleton of sodium alginate. And the dodecanol alginate and CTAB with LDH nanoparticles for mixture respectively, the Zeta potential was+44.9mV and-33.2mV, at the same time, the particle size increased to93.3nm and659.8nm. The results showed that negatively charged DA adsorption on the surface of LDH particles can block the mutual coalescence effect between particles, in the Pickering emulsions showed good stability. The drug-loaded Pickering emulsion was prepared under high-speed shearing condition. The results indicated that dodecanol alginate(DA) and LDH nanoparticles stabilized Pickering emulsion presented better drug-controlled release effect. |
