Title: Solid lipid particles in lipid films to control diffusive release of 2-heptanone Authors
Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 16, 2012
Publication Date: January 28, 2013
Citation: Bilbao-Sainz, C., Chiou, B., Glenn, G.M., Gregorski, K.S., Williams, T.G., Wood, D.F., Klamczynski, A., Orts, W.J. 2013. Solid lipid particles in lipid films to control diffusive release of 2-heptanone. Pest Management Science. 69(8):975-982. DOI:10.1002/ps.34162. Interpretive Summary: The potential hazards of using conventional agrochemicals to public health and wildlife have increased the commercial interest for safer pesticide controlled-release formulations. These formulations are combinations of the pesticide active agent with inert materials that protect and release the active agent over the required time. 2-Heptanone is a highly volatile pheromone effective in controlling parasitic mites, particularly Varroa mites. In this manuscript, we describe a process for encapsulating 2-heptanone in solid lipid particles (SLPs) that are further incorporated into a lipid film. The SLPs are made from lipids that solidify at room temperature to form a crystalline or amorphous matrix in which the bioactive is incorporated. It was observed an improvement in the release rate of 2-heptanone using SLPs when there was a good chemical compatibility between the SLPs and the lipid films.
Technical Abstract: Controlled-release formulations of bioactive agents are gaining increasing interest for effective pest control. Volatile 2-heptanone is a bioactive agent that has shown potential to be used as a pesticide. The aim of this study was to investigate the kinetics of 2-heptanone release, which had been incorporated into lipid films or composite solid lipid particle (SLP) films. Different film matrices were used based on paraffin wax, Acetem and their blends with stearic acid. Effective 2-heptanone diffusivity was estimated to be between 0.1 and 2.5 mm2/day during the first week and between 0.05 and 0.1 mm2/day during the next 5 weeks. The films that showed better retention of 2-heptanone were the paraffin lipid films. Inclusion of SLP’s into paraffin films increased the release rate of 2-heptanone, mainly due to a decrease in the film firmness as the composite SLP film became less crystalline and more brittle. In contrast, SLP’s decreased the kinetics of 2-heptanone release in Acetem films due to an increase in the firmness of the films. These results presented here indicated that the use of SLP’s as a method for controlled release can improve the delivery of the natural pesticide 2-heptanone if the SLP’s have good compatibility with the matrix, leading to an increase in firmness of the films without increasing their porosity.