title: Synthesis and Characterization of Chlorpyrifos/Copper(II) Schiff Base Mesoporous Silica with pH Sensitivity for Pesticide Sustained Release.
abstract: The salicylaldehyde-modified mesoporous silica (SA-MCM-41) was prepared through a co-condensation method. Through the bridge effect from the copper ion, which also acts as the nutrition of the plant, the model drug chlorpyrifos (CH) was supported on the copper(II) Schiff base mesoporous silica (Cu-MCM-41) to form a highly efficient sustained-release system (CH-Cu-MCM-41) for pesticide delivery. The experimental results showed that the larger the concentration of the copper ion, the more adsorption capacity (AC) of Cu-MCM-41 for chlorpyrifos and the smaller its release rate. The results confirmed the existence of a coordination bond between SA-MCM-41 and copper ions as well as a coordination bond between Cu-MCM-41 and chlorpyrifos. The AC of SA-MCM-41 is 106 mg/g, while that of Cu-MCM-41 is 295 mg/g. The as-synthesized system showed significant pH sensitivity. Under the condition of pH ≤ 7, the release rate of chlorpyrifos decreased with increasing pH, whereas its release rate in weak base conditions was slightly larger than that in weak acid conditions. Meanwhile, the drug release rate of the as-synthesized system was also affected by the temperature. Their sustained-release curves can be described by the Korsmeyer-Peppas equation.
authors.affiliation: College of Chemistry and Chemical Engineering, Zhongkai University of Agriculture and Engineering , Guangzhou, Guangdong 510225, People's Republic of China.
authors.forename: Huayao
authors.initials: H
authors.lastname: Chen
authors.affiliation: College of Chemistry and Chemical Engineering, Zhongkai University of Agriculture and Engineering , Guangzhou, Guangdong 510225, People's Republic of China.
authors.forename: Yueshun
authors.initials: Y
authors.lastname: Lin
authors.affiliation: College of Chemistry and Chemical Engineering, Zhongkai University of Agriculture and Engineering , Guangzhou, Guangdong 510225, People's Republic of China.
authors.forename: Hongjun
authors.initials: H
authors.lastname: Zhou
authors.affiliation: College of Chemistry and Chemical Engineering, Zhongkai University of Agriculture and Engineering , Guangzhou, Guangdong 510225, People's Republic of China.
authors.forename: Xinhua
authors.initials: X
authors.lastname: Zhou
authors.affiliation: College of Chemistry and Chemical Engineering, Zhongkai University of Agriculture and Engineering , Guangzhou, Guangdong 510225, People's Republic of China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Gong
authors.affiliation: College of Chemistry and Chemical Engineering, Zhongkai University of Agriculture and Engineering , Guangzhou, Guangdong 510225, People's Republic of China.
authors.forename: Hua
authors.initials: H
authors.lastname: Xu
mesh_terms: D004390:Chlorpyrifos / Q000737:chemistry* / Q000493:pharmacokinetics*; D003300:Copper / Q000737:chemistry; D065546:Drug Liberation; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D010575:Pesticides / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics; D012545:Schiff Bases; D012822:Silicon Dioxide / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013818:Thermogravimetry; D014961:X-Ray Diffraction
chemical_list: D010575:Pesticides; D012545:Schiff Bases; D012822:Silicon Dioxide; D003300:Copper; D004390:Chlorpyrifos
keywords: MCM-41; copper(II) Schiff base; pH sensitive; sustained release