In Cheon Hwang

Photoprotection for deltamethrin using chitosan-coated beeswax solid lipid nanoparticles

BACKGROUNDnIn the natural environment, photodegradation is one of the most common degradative processes of pesticides. In order to reduce the photodegradation of pesticides, and so increase their killing activity against target pests, chitosan-coated beeswax solid lipid nanoparticles (CH-BSLNs) were prepared by a combination of hot homogenization and sonication, with deltamethrin as an active ingredient.nnnRESULTSnUnder optimal conditions, the highest encapsulation efficiency (95%) and a high payload of deltamethrin (approximately 12.5%) were achieved. In direct photolysis, in the case of CH-BSLNs after UV irradiation for 24 h, 37.3% of deltamethrin remained, as opposed to only 14.6% of the free-form deltamethrin. In addition, in indirect photolysis, in the case of CH-BSLNs after UV irradiation for 2 h in 2% acetone solution, approximately 74.5% of deltamethrin remained, as opposed to only 37.6% of the free-form deltamethrin.nnnCONCLUSIONnCH-BSLNs showed good protection for deltamethrin against photodegradation. This novel nanocarrier may be useful in crop protection as an economical strategy to enhance the effect of pesticides in the field and protect the environment as well.

Enhanced payload and photo-protection for pesticides using nanostructured lipid carriers with corn oil as liquid lipid

With the aim to establish a novel nanocarrier system with higher payload and higher photo-protection for deltamethrin (active ingredient) compared to solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC) were prepared by combining hot homogenization and sonication with different ratios of corn oil (liquid lipid) and beeswax (solid lipid). Compared to SLN, the incorporation of corn oil gave a higher payload, slower release rate and higher photo-protection for deltamethrin. Particularly, compared to beeswax solid lipid nanoparticles (BSLN), NLC gave a higher payload (approximately 1.79 times) with a high encapsulation efficiency (83.6%), higher photo-protection in direct photolysis (1.8 times) after 12u2009h exposure of ultraviolet light (UV) and in indirect photolysis (1.37 times) after 2u2009h exposure of UV in 2% (v/v) acetone solution used as a photosensitizer. This study demonstrated that novel nanocarrier possesses a wide range of applicability in protecting photo-labile compounds for the crop, food and pharmaceutical industries.

Enhanced photoprotection for photo-labile compounds using double-layer coated corn oil-nanoemulsions with chitosan and lignosulfonate

With the aim to establish a novel nanocarrier system with relatively high payload and high photoprotection capacity for photo-labile active compounds, in this work, deltamethrin (photo-labile compound) was encapsulated into corn oil-nanoemulsions (NE) by a hot high pressure homogenization technique followed by coating with chitosan as the first coating layer (CH-NE) and lignosulfonate as the second coating layer to form a double-layer coated NE (L-CH-NE). The optimal conditions for preparation of NE, chitosan coating and lignosulfonate coating were investigated. The results indicate that polymer coating and the number of coating layers significantly affected the release profile and photoprotection capacity of nanocarriers. In particular, after coating, the release rate became slower and photoprotection capacity became higher. Moreover, in the case of L-CH-NE after 24h of UV exposure in direct photolysis and 2.5h of UV exposure in indirect photolysis, the non-degraded amount of deltamethrin was approximately 4.5 times and 2.1 times, respectively, higher than that of the free-from deltamethrin. In the future, this novel nanocarrier system will show great potential and be widely applied to many fields related to protection of photo-labile compounds against photo-degradation.

Changes of Feeding Behaviors of Myzus persicae (Homoptera: Aphididae) Depending on Inflow Concentrations of Imidacloprid

After treatment with imidacloprid, there were clear differences in the time to the first reaction of Myzus persicae among the concentrations treated. The time taken for the proboscis of the aphids to penetrate, during the recording plants increased as the imidacloprid concentration increased. Imidacloprid concentration inflow into a leaf was investigated using high-performance liquid chromatography, and the residues of the imidacloprid varied slightly with the different concentrations treated. However, the inflow rates of this insecticide into a leaf increased as the dipping times increased. Furthermore, it was shown that there was no relationship in inflow concentration between the concentrations and times of treatment. However, the concentration in the leaf differed according to the dipping time. Judging from the fact that the first reaction behavior against imidacloprid displayed at an inflow concentration of 0.32-0.35 ㎎/L, we concluded that inflow concentrations causing the first reaction of the aphids to the insecticide were much lower than the concentration treated. The general feeding characteristics of the aphids indicated that xylem and/or phloem feeding behavior continued after a series of probing behaviors and stylet activity during the first 3 h from the start of EPG recording. After 90 min treatment with imidacloprid, feeding behavior over the next 30 min indicated a significant increase in the withdrawal of the stylet from the plant at all treated concentrations. Xylem and/or phloem feeding patterns were significantly decreased during this time. In particular, the proportion of xylem feeding differed according to the concentration of imidacloprid.

Enhanced payload of lipid nanocarriers using supersaturated solution prepared by solvent-mediated method

With the aim to effectively enhance the payload for nanocarriers, supersaturated deltamethrin (SSD) solution was prepared using the solvent-mediated method to produce lipid nanocarriers by a combination method of homogenization and sonication. In this study, deltamethrin was used as an active ingredient, corn oil was used as a lipid medium, soybean lecithin and Tween-80 were used as surfactants. At 25°C, the solubility of deltamethrin in SSD solution prepared by solvent-mediated method was 3.4 times and 1.5 times higher than that in saturated deltamethrin (SD) solution and that in SSD solution prepared by thermal-mediated method, respectively. Therefore, compared to the use of SD solution for the production of nanocarriers, the use of SSD solution significantly enhanced the payload, while keeping the encapsulation efficiency high. Particularly, nanocarriers produced from SSD solution prepared by solvent-mediated method had the higher payload of 2.1 times and 4.4 times compared with preparations using SSD solution prepared by thermal-mediated method and SD solution, respectively.