Preparation Plication Of Functional Pesticide Carrier Mesoporous Silica Particles

With the development of pesticides,it is not only difficult to develop and create high-efficient and low-toxic pesticides,but also the problem of how to give better play to the efficacy of pesticides also needs to be solved.In order to find a new pesticide formulation that can make the pesticide effective,this paper will use mesoporous silica nanoparticles,pH-responsive carboxymethyl chitosan,and mitochondrial targeting triphenylphosphine cations.Through organically combined,several functional nano-particle pesticide carrier systems have been prepared,and the application of the above-mentioned functionals nano-particle pesticide-carrying particles in agrochemicals have been initially explored.The purpose is to reduce the cost of pesticide use and improve the pesticide utilization rate.In this paper,the experimental conditions were optimized based on the classic solgel method,and relatively uniform mesoporous silica nanoparticles were prepared.Tetraethyl orthosilicate was selected as the silicon source provider,and cetyltrimethylammonium bromide(cationic surfactant)was used as the structure directing agent and template,and the particles size were 80-120 nm.Mesoporous silica nanoparticles with a pore size range of about 3 nm.The synthesis process and posttreatment conditions were explored and optimized,and the reaction conditions were determined:1.0 g of cetyltrimethylammonium bromide was added to 480 mL of clean deionized water to fully dissolve it at 800 rpm The reaction system was stirred at the stirring speed,and then 3.5 mL of 2 M sodium hydroxide solution was added to the above system,and then oil bath heating was started.After the reaction system stabilizes at 80℃ and there is no foam in the system,5 mL of TEOS was added dropwise to the reaction system at a rate of 0.5 mL/min.After the addition of TEOS was completed,the reaction system continues to be heated for 6 hours.After the heating was stopped,the filter cake was repeatedly washed with a certain ratio of mixed solution of water and ethanol after suction filtration,and the filter cake is dried in an oven to remove internal moisture.Then using a muffle furnace for high-temperature calcination,the heating rate was set to 5℃/min,and keeping the temperature at 550℃ for 5 hours to remove the template agent to obtain MSN with relatively uniform particles.After amination of MSN surface with(3-aminopropyl)triethoxy silane,CMCs,TPP and CMCs-TPP were chemically connected to the MSN surface under the action of two carboxyl activating reagents,EDC and NHS.After the functional nano-pesticide carrier was characterized by FT-IR,SEM,TEM,BET,TGA,DLS and other characterization methods,the successful preparation of the functional nano-pesticide carrier was proved.Pyraclostrobin was used as a model pesticide to perform related performance tests on functional mesoporous silica carriers.The pesticide loading rates of MSN-CMCs and MSN-CMCs-TPP both reached 32%,while the loading rate of MSN-TPP can reach 33%.In the pesticide release experiment in vitro,the slow-release effect of the nanoparticles was proved,and the pH responsiveness of MSN modified with CMCs group also verified.In the same time,the model pesticide pyraclostrobin released by functional nanoparticles containing CMCs groups in a low pH release medium is obviously not as much as in a high pH release medium.At 48 h,the pesticide release rates of MSN-CMCs and MSN-CMCs-TPP in the sustained release medium with pH 5.5 were 45%and 47%,respectively.However,the pesticide release rates of the two pesticide delivery systems were more than 65%in the sustained release media with pH of 7.4 and 8.7.The antifungal activities of functional pesticide carriers were studied by determining the bioactivity of fungicide with pyraclostrobin technical and suspension as control.Compared with the control group,the functional pesticide carriers showed long-term antifungal ability.Taking corn northern leaf blight as an example,with a concentration of 10 mg/L,the antifungal effect of the MSN-CMCs-TPP pesticide carrier system reached 79±1.7%on the eighth day,and the antifungal activity of the original pesticide and the suspension was 63 ± 1.1%and 84 ± 1.7%,respectively.On the tenth day,the antifungal activity of the MSN-CMCs-TPP pesticide carrier reached 72 ± 1.4%,and the antifungal activity of the original pesticide and suspension were 57± 1.8%and 68±1.3%,respectively.After the mitochondria were fluorescently labeled with Mito-tracker Red,the targeting properties of functional pesticide carriers containing TPP groups were studied by using a laser confocal microscope.After attaching FITC fluorescent probe to the functional pesticide carrier,observe under CLSM,it was found that the functional pesticide carrier containing TPP group effectively aggregates around the mitochondria,while the nanoparticles without TPP group are not regularly dispersed in the mycelium.This just shows that functional pesticide carriers containing TPP groups have mitochondrial targeting.This paper provides a new idea of mesoporous silica as a fungicide carrier.By introducing functional groups containing mitochondrial targeting and pH responsiveness,a mesoporous silica carrier with good slow-release properties can be prepared.Pyraclostrobin with the cytochrome oxidase in the mitochondria as the target was used as a medicament to preliminarily test the mitochondrial targeted delivery effect of the carrier on the fungicide,which significantly improved the utilization rate of the fungicide.The new strategy of pesticide reduction and efficiency enhancement provides a reference.