Construction And Efficacy Of Novel Multifunctional Silicon-based Nano Delivery System

Pesticides play an irreplaceable role in the prevention and control of agricultural crop diseases and the improvement of grain yield.However,due to various factors such as photolysis,biodegradation,volatilization,rainwater erosion and non-target biological ingestion,pesticides have low effective utilization rate in the field and strong pollution to the whole ecological system.With the development of science and technology,nanotechnology gradually gets people’s attention.Nano materials have brought revolutionary changes to the field of pesticides because of their characteristics such as small size and special structure.The research and development of new nano slow/controlled-release pesticides with intelligent response had significant advantages in improving the utilization rate of pesticides and reducing the pollution caused by pesticides and nano carriers,and has a far-reaching impact on green agriculture and ensuring people’s safety.In this thesis,from the perspective of the universality and environmental friendliness of the function of nanoparticles,taking prochloraz as the model drug and based on inorganic mesoporous silicon nanomaterials,intelligent nano delivery system with p H/redox response and degradable metal chelated mesoporous silicon nano slow /controlled release delivery system were successfully prepared,and their characteristics and practicability were tested and evaluated respectively.This study provides a new idea for the development of multifunctional intelligent nano pesticide preparations.The specific contents are as follows:(1)Preparation of double mesoporous silica BMMs as a drug carrier by sol-gel method.By modifying the silane coupling agent MPTES-SS-Py containing-S-S-,loading the fungicide Pro,and sealing the pores with high molecular organic β-CD with hydrophilic and hydrophobic structure,the nano pesticide with dual response of p H/redox was successfully prepared as Pro@BMMs-SS-Py/β-CD.Nanoparticles had regular spherical structure and uniform distribution,with an average particle size of546.4 ± 3.0 nm.The pesticide loading of Pro was 28.1%,which could realize the dual response release of p H and redox.Due to the protective effect of nano carriers,nanoparticles also had excellent photostability and storage stability.Compared with Pro technical control,nano pesticides with the same concentration of Pro had better fungicidal activity against Rhizoctonia solani.In addition,compared with the same concentration of Pro technical,it had better leaf wettability.At the same time,the nanocarrier had good biosafety.(2)A biodegradable Fe-MSNs nano carrier was prepared by doping iron ions into MSN by improved St?ber method.After loading pesticides Pro and coating it with tannic acid,intelligent nano pesticides with corresponding p H were designed and synthesized Pro@Fe-MSNs/TA nanoparticles.Nanoparticles had ellipsoidal structure and good water dispersion.The pesticide loading of Pro was as high as 30.2%.Nanopesticide could degrade slowly and released Pro in weak acid environment owing to the sensitivity to acid.Due to the coating of TA,the nanoparticles had excellent slow-release effect and good leaf wettability,and the retention of pesticides in leaves was improved.Nano carrier could shield ultraviolet light,so it had great photostability.Compared with Pro technical,the nano pesticide had better inhibitory effect on Rhizoctonia solani.Nano carriers had no biological toxicity and could provide trace elements for plants through self-degradation.