Formulation and physicochemical properties of promising avermectin microemulsion with biodegradable surfactant and oil

Abstract

Green microemulsion suitable for oil-soluble pesticide delivery has been prepared using butyl acetate as oil phase, alkyl polyglycoside (APG) and linear alkylbenzene sulfonate (LAS) as mixed surfactant, and short chain alcohol as cosurfactant. Pseudoternary phase diagrams were constructed to investigate the effects of APG and LAS mixing ratio, the chain length of the cosurfactant on the microemulsion phase behavior. A fully dilutable region run through the phase diagram can be observed and the structure of the microemulsion transformed from water-in-oil, bicontinuous to oil-in-water along with the addition of water according to the result of conductivity measurement. Based on the phase diagram, the avermectin microemulsion formulations were chosen from the fully dilutable line with the minimum surfactant to oil ratio. Dilution stability of the microemulsion with hard water was studied by dynamic light scattering (DLS), the microemulsion can maintain the uniform and homogeneous appearance although the droplet size increased after dilution. The diluted microemulsion were also studied by dynamic surface tension and dynamic contact angle, and the excellent wetting and spreading properties on hydrophobic surface was demonstrated. GRAPHICAL ABSTRACTDownloaded by [University of Regina] at 02:08

Microemulsion formulation of a new biopesticide to control the diamondback moth (Lepidoptera: Plutellidae)

“…When σ reaches the maximum value (1.25 S m −1 , φ w ≈ 40%), then a phase inversion from reverse swollen micelles (w/o) to direct micelles (o/w) is suggested 23 , 32 . Thereafter, σ values then drop because of dilutional impacts 33 . The structure of the microemulsion from w/o to a discontinuous phase and then o/w using titration is indicated by the derivative of the conductivity (Fig.…”

“…Once the diluted microemulsion systems reached a new balance again, the droplet size tended to become stable with time. Therefore, a microemulsion possessing macroscopical dilution stability was obtained 7 , 35 .

Figure 3 The variation of droplet size of 5% norcantharidin microemulsion based on time under different dilution times with standard water (342 mg/L).

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“…A microemulsion is a single optically isotropic and thermodynamically stable liquid solution, having an ultramicroscopic droplet size (typically below 100 nm) and being completely water-dilutable 6 , 7 . Generally, microemulsions are optically transparent or translucent dispersions of pesticides in water presenting solubilization of the surfactants and/or co-surfactants 7 , 8 . This small droplet size and lowered surface tension of the whole system may produce higher pesticide efficiency and ease any tendency to coalesce.…”

“…Oil-in-water (O/W) and water in oil (W/O) are two basic types of microemulsions, within which the O/W microemulsion can improve the solubility of poorly water-soluble active ingredients. Some studies have shown that microemulsions are superior to traditional formulations and exhibit superior control efficiency when compared to traditional commercial pesticides 3 , 7 , 9 . Meanwhile, it has been reported that λ-cyhalothrin and triadimefon microemulsions possess better thermodynamic stability, properties and efficacy than their other formulations 10 , 11 .…”

Bio-Based Nanoemulsion Formulations Applicable in Agriculture, Medicine, and Food Industry

“…Consequently, NEs incorporating pesticides settle evenly on the leaves of plants. Some studies have shown that NE improves the solubility of poorly water-soluble pesticides, resulting in the increasing of bioactivity of the pesticides in comparison with conventional pesticides (Leng et al 2014;Wang et al 2017). Using a Quillaja saponin as a natural surfactant Kumari et al (2018) prepared and characterized thymol NE.…”