介孔二氧化硅纳米肥料的制备及控制释放

Preparation and Controlled Release of Nanofertilizer Mediated by Mesoporous Silica Nanoparticles

以纳米科技为基础的载运体系为提高农化投入品使用效率、减少农业成本提供了新的途径。本研究合成了颗粒直径约为20 nm,孔径为3.0 nm的介孔二氧化硅纳米颗粒(MSNs)。尿素肥料通过水溶液自由扩散,以物理吸附直接装载于纳米颗粒的介孔中。结果表明,当尿素溶液浓度为10 mg/mL时,MSNs的最大包载率为69.15%。通过接枝到MSNs表面的门控分子1-癸硫醇实现了对尿素的封堵,而拉曼光谱和氮吸附分析则证明了门控分子通过双硫键与纳米颗粒相互连接。利用激发因子谷胱甘肽(GSH)与门控分子产生的化学反应,促使双硫键断裂,实现对包载尿素的控制释放。体外释放测试表明,在没有GSH存在的条件下,尿素从1-癸硫醇封堵的MSNs中几乎“零”释放。当GSH存在时,肥料释放的速度由GSH的浓度控制。本研究研制了一种还原响应型介孔二氧化硅纳米肥料,实现了对尿素肥料的有效装载和控制释放,为进一步研究新型纳米肥料奠定了基础。

Nanotechnology-based agrochemical delivery systems will provide novel ways for improving the efficiency of very important agricultural inputs.In the present study,mesoporous silica nano particles(MSNs)with particle diameter of approximate 20 nm and pore size of around 3.0 nm were synthesized and functionalized.The fertilizer of urea was encapsulated inside the mesopores of MSNs by free diffusion loading and physisorption using aqueous urea solution.The highest loading rate of 69.15%was achieved when the urea concentration was 10 mg/mL.The loaded urea was blocked inside the mesopores using a novel decanethiol gatekeeper system grafted onto the surface of MSNs through disulfide linkages,and that was confirmed by Raman and nitrogen sorption isotherm analyses.The controlled release of encapsulated urea was obtained through the reaction between the gatekeeper and trigger factor of glutathione(GSH),which led to the cleavage of disulfide bonds.The in vitro release of urea from decanethiol gated MSNs indicated that almost no premature release was observed in the absence of stimulus GSH,and the release rate was highly determined by the amount of GSH.Herein,a MSN-mediated delivery system with redox-responsive gatekeepers was created.The fertilizer urea was effectively loaded and the controlled release was achieved using the novel system,which would offer the base for developing new type nano-fertilizer in the future.