Inclusion effect of alpha-cyclodextrin on chemical degradation of malathion water

Recognition of malathion pesticides in agricultural samples by using α-CD functionalized gold nanoparticles as a colorimetric sensor

Herein, a rapid, precise alpha-cyclodextrin (α-CD) based gold nanoparticles (AuNPs) for selective detection of malathion pesticides has been reported. These are organophosphorus pesticides (OPPs), that can cause a neurological disease by inhibiting the activity of acetylcholinesterase (AChE). It is important to exploit a quick and sensitive approach for monitoring OPPs. Hence in the present work, a colorimetric assay for the detection of malathion has been developed as a model of OPPs from the environmental sample matrices. The physical and chemical properties of synthesized alpha-cyclodextrin stabilized gold nanoparticles (AuNPs/α-CD) were studied with various characterization techniques, including UV-visible spectroscopy, TEM, DLS and FTIR. The designed sensing system displayed linearity in the broad range of malathion concentrations, 10-600 ng mL^-1 with a limit of detection and the limit of quantification values 4.03 ng mL^-1 and 12.96 ng mL^-1, respectively. The application of the designed chemical sensor was extended to the malathion pesticide determination in real samples such as vegetables, which resulted in almost 100% recovery rates in all the spiked samples. Thus, due to these advantages, the present study established a selective, facile and sensitive colorimetric platform for the direct detection of malathion within a very short time (5 min) with a low detection limit. The practicality of the constructed platform was further executed by the detection of the pesticide in vegetable samples.

Organophosphorus hydrolase-poly-β-cyclodextrin as a stable self-decontaminating bio-catalytic material for sorption and degradation of organophosphate pesticide

A region suffering from an attack of a nerve agent requires not only a highly sorptive material but also a fast-acting catalyst to decontaminate the lethal chemical present. The product should be capable of high sorptive capacity, selectivity and quick response time to neutralize the long lasting harmful effects of nerve agents. Herein, we have utilized organophosphorus hydrolase (OPH) as a non-toxic bio-catalytic material held in with the supporting matrix of poly-β-cyclodextrin (PCD) as a novel sorptive reinforced self-decontaminating material against organophosphate intoxication. OPH coated PCD (OPH-PCD) will not only be providing support for holding enzyme but also would be adsorbing methyl paraoxon (MPO) used as a simulant, in a host-guest inclusion complex formation. Sorption trend for PCD revealed preference towards the more hydrophobic MPO against para-nitrophenol (pNP). The results show sorption capacity of 1.26 mg/g of 100 μM MPO with PCD which was 1.7 times higher compared to pNP. The reaction rate with immobilized OPH-PCD was found to be 23% less compared to free enzyme. With the help of OPH-PCD, continuous hydrolysis (100%) of MPO into pNP was observed for a period of 24 h through packed bed reactor with good reproducibility and stability of enzyme. The long-term stability also confirmed its stable nature for the investigation period of 4 days where it maintained activity. Combined with its fast and reactive nature, the resulting self-decontaminating regenerating material provides a promising strategy for the neutralization of nerve agents and preserving the environment.

Encapsulation of lemongrass oil with cyclodextrins by spray drying and its controlled release characteristics

Inclusion of the two isomers of citral (E-citral and Z-citral), components of lemongrass oil, was investigated within the confines of various cyclodextrin (α-CD, β-CD and γ-CD) host molecules. Aqueous complex formation constants for E-citral with α-CD, β-CD and γ-CD were determined to be 123, 185, and 204 L/mol, respectively, whereas Z-citral exhibited stronger affinities (157, 206, and 253 L/mol, respectively). The binding trend γ-CD > β-CD > α-CD is a reflection of the more favorable geometrical accommodation of the citral isomers with increasing cavity size. Encapsulation of lemongrass oil within CDs was undertaken through shaking citral:CD (1:1, 1.5:1, and 2:1 molar ratio) mixtures followed by spray drying. Maximum citral retention occurred at a 1:1 molar ratio with β-CD and α-CD demonstrating the highest levels of total E-citral and Z-citral retention, respectively. Furthermore, the β-CD complex demonstrated the slowest release rate of all inclusion complex powders.

Nanogels with high active β-cyclodextrin content as physical coating system with sustained release properties

We present the application of nanogels with high functional β-cyclodextrin (β-CD) content as new and versatile method for the modification and protection of textiles. The complexation potential of covalently embedded β-CD in nanogels is demonstrated for the common insecticide permethrin in aqueous environment. It is shown that permethrin containing β-CD nanogels can be applied easily, homogeneously and safely on keratin fibers like wool fabrics and human hairs. The permethrin concentration on fibers is directly controlled by the permethrin content in nanogels. We tested the permanence of permethrin on treated fibers with regard to washing and UV fastness. Our results show that permethrin complexed in nanogels is removed from the textile during washing, but that the complexation of permethrin by β-CD domains in the nanogels protects the active ingredient from UV degradation. Bioassay tests against the larvae of Tineola bisselliella and Anthrenocerus australis show that the activity of the ingredients does not decrease after complexation in β-CD gels and it results in protection of the wool fibers against degradation by the insect larvae.

Probing the chiral separation mechanism and the absolute configuration of malathion, malaoxon and isomalathion enantiomers by chiral high performance liquid chromatography coupled with chiral detector-binding energy computations

Chiral separation mechanism determination and absolute configuration assignment are fundamental to the development of chiral stationary phases (CSPs) and the evaluation of both the enantioselective bioactivity and fate of chiral compounds. This work investigated the process of chiral separation and the assignment of the absolute configurations of malathion, malaoxon, and isomalathion using chiral high performance liquid chromatography (HPLC) coupled with chiral detector-binding energy computations. Hydrogen bonding was found to be a very important factor in the chiral separation of isomalathion on Chiralpak AD, although it did not exhibit a significant effect on the chiral separation of malathion and malaoxon on Chiralcel OJ. Based on the sign of a chiral detector, the relationships between the cotton effect, optical dispersion and absolute configuration were established for individual enantiomers of malathion, malaoxon, and isomalathion. The elution orders of the enantiomers of malathion and malaoxon on Chiralcel OJ and the stereoisomers of isomalathion on Chiralpak AD predicted by binding energy computations were found to coincide precisely with those observed in the chiral separation experiments. The result suggests that binding energy computations can be used to assign the absolute configuration of the enantiomers of chiral compounds eluted on CSPs.

In vitro detoxification of cyclosarin (GF) by modified cyclodextrins

Developing potent detoxification strategies for prophylaxis and therapy against organophosphate (OP) intoxication still represents a challenging task. Clinical application of numerous investigated substances including enzymes and low molecular scavengers like metal ions or nucleophiles could not yet be realised due to profound disadvantages. Presenting a promising attempt, cyclodextrins (CDs) efficiently enhance the degradation of some organophosphorus compounds. The present study examined the in vitro GF degradation mediated by three CDs and a nucleophilic precursor performed by mass spectrometric detection with ammonia chemical ionisation. All four compounds caused a notable enhancement of GF detoxification that was synergistically accelerated in the case of 2-O-(3-carboxy-4-iodosobenzyl)-β-cyclodextrin (IBA-β-CD) with the alpha-nucleophile 2-iodosobenzoic acid (IBA) grafted on the secondary face of β-cyclodextrin (β-CD). In vitro toxicokinetic investigations of CD derivatives are needed to evaluate the effect of slow terminal elimination phase of the more toxic (-)-GF shown for two CD-derivatives underlining the necessity of detecting the complete kinetic course of inactivation. The observed effect of fast high affinity binding (20-30%) represents an additional therapeutic option of an extremely rapid reduction of GF concentration in vivo. Distinctive differences in the course of reaction are detected depending on β-CD-derivatives, allowing a first inference of possible mechanisms and relevance of attached substituents. However, further profound investigation needs to be done to evaluate the basis of a clinical application of substituted CDs as potential detoxification agents.