A rapid and sensitive fluoroimmunoassay based on quantum dot for the detection of chlorpyrifos residue in drinking water

Insights into the Binding Profile of Anti-chlorpyrifos Recombinant Antibodies: From Computational Simulation to Immunoassay Validation

A novel virtual screening strategy was proposed for the profiling and discovery of active variable regions (VRs) that encode hapten-specific recombinant antibodies (rAbs). Chlorpyrifos, a hazardous organophosphorus pesticide, was selected as the target. First, a VR model-14G4 from anti-chlorpyrifos hybridoma was built via homology modeling. Its binding pattern toward seven organophosphorus analogues was assessed through virtual screening by performing molecular docking. Based on energy scoring, visual examination, and molecular interaction analysis, chlorpyrifos-methyl was also inferred as the high-affinity target for model-14G4 and was then confirmed via a non-competitive surface plasmon resonance (SPR) assay. Subsequently, we attempted to discover hapten-specific VRs by creating a collection of VR models for anonymous testing. Chlorpyrifos and model-14G4 were employed as the known hit and active VRs, respectively. After molecular docking, a novel anti-chlorpyrifos VR (model-1) was identified due to its satisfactory energy scoring and a similar binding pattern to the reference model-14G4. Expressed by HEK293(F) mammalian cells, the newly prepared full-length rAb-model-1 and rAb-14G4 exhibited high sensitivities for detecting chlorpyrifos by the indirect competitive enzyme-linked immunosorbent assay (ic-ELISA), with IC₅₀ of 3.01 ng/mL and 42.82 ng/mL, respectively. They recognized chlorpyrifos-methyl with a cross-reactivity (CR) of 2.5-17.3%. Moreover, the binding properties of rAb-model-1 for recognizing chlorpyrifos and chlorpyrifos-methyl were confirmed via a non-competitive microscale thermophoresis (MST) method. Thus, the experimental results showed good agreement with computational outputs on antibody profiling. Furthermore, the recognition diversity of rAb-model-1 for chlorpyrifos and chlorpyrifos-methyl was studied via molecular dynamics simulation. Overall, the proposed study provides a versatile and economical strategy for antibody characterization and promotes the in vitro production of rAbs for pesticide monitoring.

Charge-transfer complex-based spectrophotometric method for the determination of mesotrione in environmental samples

A simple, accurate, sensitive, and selective spectrophotometric method has been developed for the determination of mesotrione. This method is based on the reaction of mesotrione with Fe(III) to form a charge transfer metal complex having λ_max at 348 nm. Beer's law was obeyed in the concentration range of 0.2-10.0 µg mL^-1 with limit of detection (LOD) and limit of quantification (LOQ) equal to 0.053 and 0.162 µg mL^-1, respectively. The percent recovery of mesotrione from different environmental and agricultural samples was found to be 95.00-106.50% at various levels. Notably, the developed method was successfully employed for the determination of mesotrione in environmental (pond water, canal water, tap water, and soil) and agricultural (maize grains) samples.

Recent Advances on Detection of Insecticides Using Optical Sensors

Insecticides are enormously important to industry requirements and market demands in agriculture. Despite their usefulness, these insecticides can pose a dangerous risk to the safety of food, environment and all living things through various mechanisms of action. Concern about the environmental impact of repeated use of insecticides has prompted many researchers to develop rapid, economical, uncomplicated and user-friendly analytical method for the detection of insecticides. In this regards, optical sensors are considered as favorable methods for insecticides analysis because of their special features including rapid detection time, low cost, easy to use and high selectivity and sensitivity. In this review, current progresses of incorporation between recognition elements and optical sensors for insecticide detection are discussed and evaluated well, by categorizing it based on insecticide chemical classes, including the range of detection and limit of detection. Additionally, this review aims to provide powerful insights to researchers for the future development of optical sensors in the detection of insecticides.

Quantum Dots Applied to Methodology on Detection of Pesticide and Veterinary Drug Residues

The pesticide and veterinary drug residues brought by large-scale agricultural production have become one of the issues in the fields of food safety and environmental ecological security. It is necessary to develop the rapid, sensitive, qualitative and quantitative methodology for the detection of pesticide and veterinary drug residues. As one of the achievements of nanoscience, quantum dots (QDs) have been widely used in the detection of pesticide and veterinary drug residues. In these methodology studies, the used QD-signal styles include fluorescence, chemiluminescence, electrochemical luminescence, photoelectrochemistry, etc. QDs can also be assembled into sensors with different materials, such as QD-enzyme, QD-antibody, QD-aptamer, and QD-molecularly imprinted polymer sensors, etc. Plenty of study achievements in the field of detection of pesticide and veterinary drug residues have been obtained from the different combinations among these signals and sensors. They are summarized in this paper to provide a reference for the QD application in the detection of pesticide and veterinary drug residues.

Using of Quantum Dots in Biology and Medicine

Quantum dots are nanoparticles, which due to their unique physical and chemical (first of all optical) properties, are promising in biology and medicine. There are many ways for quantum dots synthesis, both in the form of nanoislands self-forming on the surfaces, which can be used as single-photon emitters in electronics for storing information, and in the form of colloidal quantum dots for diagnostic and therapeutic purposes in living systems. The paper describes the main methods of quantum dots synthesis and summarizes medical and biological ways of their use. The main emphasis is laid on the ways of quantum dots surface modification. Influence of the size and form of nanoparticles, charge on the surfaces of quantum dots, and cover type on the efficiency of internalization by cells and cell compartments is shown. The main mechanisms of penetration are considered.

Applications of quantum dots as probes in immunosensing of small-sized analytes

Quantum dots (QDs) are semiconductor nanoparticles with very interesting optical properties, like high quantum yield or narrow and size-tuneable fluorescence spectra. Current applications of QDs are widespread, their use as fluorescence labels in bioassays being one of the most promising. These nanoparticles are usually conjugated to highly specific biomolecules like antibodies, oligonucleotides, enzymes or aptamers to improve assay selectivity. In this review, QD surface passivation, conjugation to biomolecules, and purification strategies are discussed with special emphasis to the development of QD-based immunoassays for the detection of low molecular weight compounds given the relevance of this sort of analytes in health, food safety, pharmaceutical, or environmental monitoring areas. The aim of this review is to summarise the main achievements attained so far and to initialise researchers in the field of antibody-based assays employing QDs as labels, such as fluorescence-linked immunosorbent assay (FLISA), fluorescence (or Förster) resonance energy transfer (FRET), immunochromatographic methods, and immunosensors.

A fast and sensitive quantitative lateral flow immunoassay for Cry1Ab based on a novel signal amplification conjugate

A novel lateral flow immunoassay (LFIA) signal amplification strategy for the detection of Cry1Ab based on amplification via a polylysine (PL) chain and biotin-streptavidin system (BSAS) is described. In this system, multiple fluorescence dyes (FL) were directly coated on the surface of PL and conjugated with antibody via the BSAS for construction of novel signal amplification (FLPL-BSAS-mAb1) conjugates, in which FL, PL and BSAS were employed to improve the sensitivity of LFIA. Compared with conventional LFIA, the sensitivity of FLPL-BSAS-mAb1-based LFIA was increased by approximately 100-fold. Quantified linearity was achieved in the value range of 0–1,000 pg/mL. The limit of detection (LOD) was reached 10 pg/mL after optimization of reaction conditions. To our knowledge, this represents one of the most sensitive LFIA for Cry1Ab yet reported. Furthermore, the detection time for this method was about 10 min. Therefore, it should be an attractive alternative compared to conventional immunoassays in routine control for Cry1Ab.

Determination of Bisphenol A by Fluorescence Immunoassay Based on Quantum Dots as Probe

A sensitive and selectivity fluoroimmunoassay was established for the determination of bisphenol A, on the basis of being labeled quantum dots. Anti-rabbit IgG conjugated by quantum dots were regarded as a probe in this system. The presented method produced a widely linear range from 0.0001 to 100.0 ng mL-1, with detection limit of 0.078 pg mL-1. The method was applied to determine bisphenol A in plastic leach liquor, with the recoveries from 99.8% to 102.5%. The results were similar to those obtained from a high performance liquid chromatography method, while this method is simple, rapid, sensitive and accurate.