Enhancing insecticidal efficacy of Bacillus thuringiensis Cry1Ab through pH-sensitive encapsulation.

Nanotechnology is a promising way to enhance the stability of Bacillus thuringiensis (Bt) insecticidal proteins under environmental conditions. In this work, two emulsions were prepared through the Pickering emulsion technique, stabilized by Cu2+-SQDs/S-CN nanocomposites and by GO nanosheets. In addition, a pH-sensitive polymer was incorporated into these emulsions, allowing the Bt protein, Cry1Ab, to be released in an alkaline pH environment, as it occurs in the lepidopteran pests' gut. The effectiveness of these two nanomaterials in protecting Cry1Ab from degradation, and therefore enhancing its pesticidal activity, was assessed by exposing samples of the purified unprotected protein and encapsulated protein to high-intensity UV light and 40°C temperature treatments. The UV treatment results were evaluated using SDS-PAGE analysis and pointed out that Cry1Ab could be structurally protected by the emulsions. The bioassays with first instar larvae of the lepidopteran pest Ostrinia nubilalis confirm the nanomaterial protection to UV and temperature treatments, i.e., decreasing about half the degradation rate and increasing up to 12-fold the residual activity after UV treatment. Our results indicate that encapsulation could be an effective strategy to improve the effectiveness of Cry1Ab under environmental conditions. KEY POINTS: • Pickering emulsions are effective for solubilized Cry1Ab encapsulation. • Structural and toxicity Cry1Ab properties are enhanced by pH-sensitive encapsulation. • Cu2+-SQDs/S-CN and GO nanomaterials improve the efficacy of Bt insecticides.

Electrospun nanofibers of cellulose acetate/metal organic framework-third generation PAMAM dendrimer for the removal of methylene blue from aqueous media.

In this research, magnetic metal-organic framework nanofibers were produced by the electrospinning method. The nanocomposite was functionalized by third generation hyperbranched poly(amidoamine) dendrimer (PAMAM) to improve its dye adsorption efficiency from aqueous media. The characteristics of the synthesized magnetic nanocomposite was determined by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) along with elemental mapping analysis and scanning electron microscopy (SEM). Central composite design (CCD) based on response surface methodology (RSM) was performed to optimize the adsorption variables and the values of coefficient of determination (R2) and adjusted R2 were 0.9837 and 0.9490, respectively. The results obtained demonstrated remarkable properties of the synthesized nanofiber as adsorbent for methylene blue from aqueous solutions with the removal efficiency of 95.37% and maximum methylene blue (MB) adsorption capacity of 940.76 mg g-1 under optimized conditions. In addition, it was shown that kinetics and adsorption isotherm of the dye removal process followed Langmuir and pseudo-second-order models, respectively. Thermodynamic study of the dye removal indicated that the process was spontaneous and favorable at higher temperatures. Also, the reusability study shows favorable dye removal efficiency of 80.67% even after 4 cycles. To investigate the performance of the adsorbent for the removal of MB in real samples, a sewage sample from a local hospital was used. The result showed good efficiency of the adsorbent.

Ultraviolet protection of Bacillus thuringiensis through microencapsulation with Pickering emulsion method.

An encapsulated formulation of Bacillus thuringiensis (Bt) was produced by the Pickering emulsion technique to improve its activity and stability under UV-A radiation. In this technique latex particles, GO nanosheets, olive oil, ethanol, and water were used to encapsulate Bt in colloidosomes. The protective efficacy of this formulation in protecting Bt subsp. Kurstaki against deactivation by UV-A irradiation was measured, so that spore viability and mortality on Ephestia kuehniella (E. kuehniella) Zeller larvae under UV-A radiation are investigated. According to the results of both tests, encapsulated formulation at a concentration of 0.045% has the highest protection of viability. Hence, colloidosome microcapsule formulations successfully provide good protection against UV radiation.

A novel method for biosynthesis of different polymorphs of TiO2 nanoparticles as a protector for Bacillus thuringiensis from Ultra Violet.

Bacillus thuringiensis (Bt) were used for biosynthesis of amorphous TiO2 converted to distinct polymorphs (anatase, rutile, mix) under different temperature conditions. Characterizations of TiO2 nanoparticles were performed by using X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and, energy-dispersive X-ray spectroscopy (EDX) analysis. Stability of five formulations under ultraviolet (UV) radiation with spore viability and mortality test on Ephestia kuehniella Zeller larvae were investigated. TiO2(mix) showed the highest viabilities of 79.76% after exposure to ultraviolet (UVA385 nm), while viabilities of non-protected spores under these conditions were 41.32%. The mortality of TiO2(mix), TiO2(anatase), TiO2(rutile), TiO2(amorphous) and free spore formulations on second-instar larvae of Ephestia kuehniella were 73.76%, 71.24%, 57.12%, 51.32%, and 50.32%, respectively on the 10th day of the experiment. The obtained results suggest that TiO2(amorphous) does not increase Bt resistance, but both phases of TiO2 nanoparticles synthesized (anatase and rutile) through the Bacillus thuringiensis and phase mixture can increase the persistence of Bt to the UV light. Furthermore, the combination of both crystalline phases of TiO2(mix) has the highest performance in improving the Bt resistance.

Magnetic solid-phase extraction and determination of ultra-trace amounts of antimony in aqueous solutions using maghemite nanoparticles.

A magnetic solid-phase extraction method was developed using maghemite as an efficient sorbent for the separation and preconcentration of antimony prior to its determination by ET-AAS. Maghemite was synthesized through a simple method and characterized by XRD, FT-IR and SEM. Various factors affecting maghemite synthesis, separation and preconcentration of antimony such as desorption solvent type, concentration and volume, desorption temperature and time, sample pH, amount of sorbent, and extraction temperature and time were optimized. The effects of interfering ions were also investigated. Under optimized conditions, the method exhibited good linearity (r2 > 0.9960). The sorption capacity and enrichment factor (EF) of the method were 37.5 mg g-1 and 242, respectively. The limit of detection (LOD) was 0.03 ng mL-1. The intraday, interday, and batch-to-batch relative standard deviations (%RSDs) were quite reasonable. The proposed method was applied to various real samples and the relative recoveries found were between 95.8 and 104.0 %.

A novel sorbent based on carbon nanotube/amino-functionalized sol-gel for the headspace solid-phase microextraction of α-bisabolol from medicinal plant samples using experimental design.

A novel sol-gel coating on a stainless-steel fiber was developed for the first time for the headspace solid-phase microextraction and determination of α-bisabolol with gas chromatography and flame ionization detection. The parameters influencing the efficiency of solid-phase microextraction process, such as extraction time and temperature, pH, and ionic strength, were optimized by the experimental design method. Under optimized conditions, the linear range was between 0.0027 and 100 µg/mL. The relative standard deviations determined at 0.01 and 1.0 µg/mL concentration levels (n = 3), respectively, were as follows: intraday relative standard deviations 3.4 and 3.3%; interday relative standard deviations 5.0 and 4.3%; and fiber-to-fiber relative standard deviations 6.0 and 3.5%. The relative recovery values were 90.3 and 101.4% at 0.01 and 1.0 µg/mL spiking levels, respectively. The proposed method was successfully applied to various real samples containing α-bisabolol.

Frits coated with nano-structured conducting copolymer for solid-phase extraction of polycyclic aromatic hydrocarbons in water samples and liquid chromatographic analysis.

A novel nano-structured conducting copolymer of pyrrole and o-toluidine was electrosynthesized on steel frit as a new sorbent. The applicability of the frit was assessed for the solid-phase extraction (SPE) of Polycyclic aromatic hydrocarbons (PAHs) by coupling with HPLC-UV. The combination of pyrrole and o-toluidine in a copolymer form presents desirable opportunities to produce materials for new applications. The scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and FTIR spectrum for the coated frit were studied. Improved lifetime and satisfactory extraction efficiency were obtained by doping with dodecylbenzenesulfonate (DBS) and oxalate groups into the framework of copolymer. The effects of potential, time and solution concentration (pyrrole, o-toluidine, DBS and oxalic acid) were evaluated in the coating step. The effects of various parameters on the efficiency of the solid-phase extraction process, such as the sample loading rate, elution solvent type, salt effect, volume and flow rate of sample and elution solvent, were investigated. Under optimum conditions, LODs were 0.01-0.08 ng mL(-1). The method showed linearity in the range of 0.1-300 ng mL(-1) with coefficients of determination >0.98. The intra-day (n=7) RSDs obtained at an 8 ng mL(-1) concentration level were <11.4% under optimized conditions respectively. The recoveries (8 and 40 ng mL(-1)) ranged from 64% to 119%.

Preparation and application of carbon nanotubes/poly(o-toluidine) composite fibers for the headspace solid-phase microextraction of benzene, toluene, ethylbenzene, and xylenes.

A novel nanocomposite coating of poly(o-toluidine) and oxidized multiwalled CNTs (MWCNTs, where CNTs is carbon nanotubes) was electrochemically prepared on a stainless-steel wire. The applicability of the fiber was assessed for the headspace solid-phase microextraction of benzene, toluene, ethylbenzene, and xylenes in aqueous samples followed by GC with flame ionization detection. In order to obtain an adherent and stable composite coating, several experimental parameters related to the coating process, such as polymerization potential and time, and the concentration of o-toluidine and oxidized MWCNTs were optimized. The combination of MWCNTs and polymer in a nanocomposite form presents desirable opportunities to produce materials for new applications. The effects of various parameters on the efficiency of the headspace solid-phase microextraction process, such as desorption temperature and time, extraction temperature and time, and ionic strength were also investigated. At the optimum conditions, LODs were 0.03-0.06 µg/L. The method showed linearity in the range of 0.5-300 µg/L with coefficients of determination >0.99. The intraday and interday RSDs obtained at a 5 µg/L concentration level (n = 5) using a single fiber were 1.2-5.2 and 3.2-7.5%, respectively. The fiber-to-fiber RSD (%; n = 3) at 5 µg/L was 6.1-9.2%.

A new second-derivative spectrophotometric method for the determination of permethrin in shampoo.

Permethrin, a highly effective insecticide agent, has been widely used for the pest control in agriculture and the treatment of lice in human. A fast and reliable method for the determination of permethrin was highly desirable to support formulation screening and quality control. A second-derivative UV spectroscopic method was developed for the determination of permethrin in the shampoo dosage form after extraction. The second-derivative spectrum recorded between 250 and 310 nm, and a zero-crossing technique for second-derivative measurement at 279 nm was selected. It is found that the selectivity and sensitivity of the method to be in desirable range. In comparison with the direct UV method, second-derivative UV spectroscopy eliminates the interference from UV absorbing excipients. This method is also fast and economical in comparison with the more time-consuming GC method regularly used for formulation screening and quality control and can be used routinely by any laboratory possessing a spectrophotometer with a derivative accessory. The linear concentration ranges were 0.25-1.5 ppm (D2=0.00042Conc.+0.0018, r=0.9972, n=10). Between day of CV%