The shielding protection given by self-prepared porous hollow silica nanoparticles (PHSN) to pesticides from degradation by UV light was investigated using avermectin as a model pesticide. It was demonstrated that PHSN carriers with a shell thickness of approximately 15 nm and a pore diameter of 4-5 nm have an encapsulation capacity of 625 g kg(-1) for avermectin using a supercritical fluid loading method. PHSN carriers exhibited remarkable UV-shielding properties for avermectin. This was affected by the intensity of UV light, the pH and the temperature of the release medium. Rises in UV intensity, pH and/or temperature reduced the UV protection of PHSN for avermectin. In addition, avermectin loaded into the inner core of the PHSN carriers was released slowly into the release medium for about 30 days following a typical sustained-release pattern. It thus appears that PHSN carriers have a promising future in applications requiring sustained pesticide release.
Copyright 2007 Society of Chemical Industry.