Recent Advances on Detection of Insecticides Using Optical Sensors

The function of microbial enzymes in breaking down soil contaminated with pesticides: a review

The use of pesticides and the subsequent accumulation of residues in the soil has become a worldwide problem. Organochlorine (OC) pesticides have spread widely in the environment and caused contamination from past agricultural activities. This article reviews the bioremediation of pesticide compounds in soil using microbial enzymes, including the enzymatic degradation pathway and the recent development of enzyme-mediated bioremediation. Enzyme-mediated bioremediation is divided into phase I and phase II, where the former increases the solubility of pesticide compounds through oxidation-reduction and hydrolysis reactions, while the latter transforms toxic pollutants into less toxic or nontoxic products through conjugation reactions. The identified enzymes that can degrade OC insecticides include dehalogenases, phenol hydroxylase, and laccases. Recent developments to improve enzyme-mediated bioremediation include immobilization, encapsulation, and protein engineering, which ensure its stability, recyclability, handling and storage, and better control of the reaction.

Toxic effects of organophosphate pesticide monocrotophos in aquatic organisms: A review of challenges, regulations and future perspectives

In recent times, usage of pesticide, herbicides and synthetic fertilizers in farming lands has made the environment worse. The pesticide residues and toxic byproducts from agricultural lands were found to contaminate the aquatic ecosystem. The misuse of synthetic pesticide not only affects the environment, but also affects the health status of aquatic organisms. The organophosphate pesticide pollutants are emerging contaminants, which threatens the terrestrial and aquatic ecosystem. Monocrotophos (MCP) is an organophosphate insecticide, utilized on crops including rice, maize, sugarcane, cotton, soybeans, groundnuts and vegetables. MCP is hydrophilic in nature and their solubilizing properties reduce the soil sorption which leads to groundwater contamination. The half-life period of MCP is 17-96 and the half-life period of technical grade MCP is 2500 days if held stable at 38 °C in a container. MCP causes mild to severe confusion, anxiety, hyper-salivation, convulsion and respiratory distress in mammals as well as aquatic animals. The MCP induced toxicity including survival rate, behavioural changes, reproductive toxicity and genotoxicity in different aquatic species have been discussed in this review. Furthermore, the ultimate aim of this review is to highlight the international regulations, future perspectives and challenges involved in using the MCP.

Breaking boundaries: Artificial intelligence for pesticide detection and eco-friendly degradation

Pesticides are extensively used agrochemicals across the world to control pest populations. However, irrational application of pesticides leads to contamination of various components of the environment, like air, soil, water, and vegetation, all of which build up significant levels of pesticide residues. Further, these environmental contaminants fuel objectionable human toxicity and impose a greater risk to the ecosystem. Therefore, search of methodologies having potential to detect and degrade pesticides in different environmental media is currently receiving profound global attention. Beyond the conventional approaches, Artificial Intelligence (AI) coupled with machine learning and artificial neural networks are rapidly growing branches of science that enable quick data analysis and precise detection of pesticides in various environmental components. Interestingly, nanoparticle (NP)-mediated detection and degradation of pesticides could be linked to AI algorithms to achieve superior performance. NP-based sensors stand out for their operational simplicity as well as their high sensitivity and low detection limits when compared to conventional, time-consuming spectrophotometric assays. NPs coated with fluorophores or conjugated with antibody or enzyme-anchored sensors can be used through Surface-Enhanced Raman Spectrometry, fluorescence, or chemiluminescence methodologies for selective and more precise detection of pesticides. Moreover, NPs assist in the photocatalytic breakdown of various organic and inorganic pesticides. Here, AI models are ideal means to identify, classify, characterize, and even predict the data of pesticides obtained through NP sensors. The present study aims to discuss the environmental contamination and negative impacts of pesticides on the ecosystem. The article also elaborates the AI and NP-assisted approaches for detecting and degrading a wide range of pesticide residues in various environmental and agrecultural sources including fruits and vegetables. Finally, the prevailing limitations and future goals of AI-NP-assisted techniques have also been dissected.

Smartphone-integrated colorimetric and microfluidic paper-based analytical devices for the trace-level detection of permethrin

Permethrin is a pyrethroid pesticide and insect repellent that prevents mosquito-borne infections like dengue and malaria in tropical areas. This work describes a new colorimetric sensor based on metronidazole-stabilized silver nanoparticles (MTZ-AgNPs) for the first rapid, sensitive, and selective permethrin detection. The MTZ-AgNPs-based colorimetric sensor has a limit of detection (LOD) of 0.0104 µM and a limit of quantification (LOQ) of 0.0348 µM, respectively. The sensor is further integrated with smartphone and microfluidic fabrication of paper-based analytical devices (µPADs) for real-time and on-site detection of permethrin. Under optimal settings, no potential environmental contaminants interfere with permethrin detection, confirming its high selectivity. Finally, the practical applicability of sensors is confirmed in real tomato and apple extract samples. The US environmental protection agency's recommended UPLC method validated the detection efficiency of the proposed colorimetric sensor. The % recoveries from UPLC and MTZ-AgNPs suggest that the present sensor can quantitatively analyze permethrin in real samples.

Progress in optical sensors-based uric acid detection

The escalating number of patients affected by various diseases, such as gout, attributed to abnormal uric acid (UA) concentrations in body fluids, has underscored the need for rapid, efficient, highly sensitive, and stable UA detection methods and sensors. Optical sensors have garnered significant attention due to their simplicity, cost-effectiveness, and resistance to electromagnetic interference. Notably, research efforts have been directed towards UA on-site detection, enabling daily monitoring at home and facilitating rapid disease screening in the community. This review aims to systematically categorize and provide detailed descriptions of the notable achievements and emerging technologies in UA optical sensors over the past five years. The review highlights the advantages of each sensor while also identifying their limitations in on-site applications. Furthermore, recent progress in instrumentation and the application of UA on-site detection in body fluids is discussed, along with the existing challenges and prospects for future development. The review serves as an informative resource, offering technical insights and promising directions for future research in the design and application of on-site optical sensors for UA detection.

Recent Advancements in Liquid Chromatographic Techniques to Estimate Pesticide Residues Found in Medicinal Plants around the Globe

In the present review article, different advanced liquid chromatographic techniques and the advanced techniques other than liquid chromatography that are used to estimate the pesticide residues from different plant-based samples are presented. In the beginning of the article, details of pesticides, their health effects and various cell lines used for the related study has been outlined. Afterward, detailed descriptions regarding pesticides classification are inscribed. In the end, recent advancements in the area of analysis of pesticides for herbal drugs are explained. Solid phase micro extraction (SPME) and solid-phase extraction (SPE) are considered as most common method of sample preparation for pesticides and its residual analysis. The most commonly used analytical separation technique for pesticide analysis is liquid chromatography (LC) integrated with mass spectrometry (MS) and MS/MS as Triple Quadrupole Mass Spectrometer (QqQ) for the samples analysis where high level of sensitivity and accuracy is required in quantification.

Bio-efficacy of aluminum phosphide and cypermethrin against some physiological and biochemical aspects of Chrysomya megacephala maggots

Carrion flies play a significant role in forensic entomotoxicology, where they are employed as alternative samples when traditional samples are unavailable. In situations of poisoned death, these toxins disrupt insect development and affect forensic entomology analyses. So, forensic entomotoxicologists must be aware of this impact. The present study aimed to determine the effects of aluminum phosphide (AlP) and cypermethrin (CP) on the biochemical parameters and antioxidant enzymes of the third instar of Chrysomya megacephala maggots. C. megacephala was reared on normal and poisoned rabbit carcasses with aluminum phosphide and cypermethrin. The third larval instar of C. megacephala was studied using by spectrophotometer for detection of total protein, (TP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), total antioxidant capacity (TAC), superoxide dismutase (SOD), glutathione s-transferase (GST), catalase (CAT) and malondialdehyde (MDA). The results indicated to significantly decrease of TP, TAC, SOD, GST and CAT and increase of AST, ALT and MDA in the maggots reared on the poisoned carcasses with AlP or CP compared with control group. In conclusion, the tested insecticides brought about a decrease antioxidant enzyme activity and increase of MDA could be involved in free radicals in C. megacephala larvae leading to oxidative stress by these insecticidal components.

Pesticides in honey: bibliographic and bibliometric analysis towards matrix quality for consumption

Abstract Honey is a matrix noted for its wide consumption as a sweetener and its anti-inflammatory, antioxidant, and antimicrobial properties; however, its physicochemical quality can be compromised by the presence of toxicants such as pesticides. This review aims to gather recent information on pesticides in honey from the approach to their detection, understanding, and adverse effects on human health. A bibliographic and bibliometric analysis was carried out in academic databases limited to the last five and thirty years, respectively, comprising the keywords “honey”, “pesticides” and their types of pesticides or the agrochemical compound directly. It was found that there are about 30 pesticides detected in honey, in which organochlorine, organophosphate, and neonicotinoid compounds stood out for their concentrations concerning Maximum Residue Levels (MRL). Their physicochemical alteration was not well explored beyond slight variations in brightness and manganese concentration, and its consumption may have repercussions on human reproductive health. It was also determined that there was limited development on the scientific subject seeing that it is important to explore and investigate more on the issue due to the great impact of honey as a product of high consumption at a global level.

Structural and Optical Properties of Graphene Quantum Dots-Polyvinyl Alcohol Composite Thin Film and Its Potential in Plasmonic Sensing of Carbaryl

In this study, graphene quantum dots (GQDs) and polyvinyl alcohol (PVA) composite was prepared and then coated on the surface of gold thin film via the spin coating technique. Subsequently, Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), and ultraviolet-visible spectroscopy (UV-Vis) were adopted to understand the structure, surface morphology, and optical properties of the prepared samples. The FT-IR spectral analysis revealed important bands, such as O-H stretching, C=O stretching, C-H stretching, and O=C=O stretching vibrations. The surface roughness of the GQDs-PVA composite thin film was found to be increased after exposure to carbaryl. On the other hand, the optical absorbance of the GQDs-PVA thin film was obtained and further analysis was conducted, revealing a band gap E_g value of 4.090 eV. The sensing potential of the thin film was analyzed using surface plasmon resonance (SPR) spectroscopy. The findings demonstrated that the developed sensor's lowest detection limit for carbaryl was 0.001 ppb, which was lower than that previously reported, i.e., 0.007 ppb. Moreover, other sensing performance parameters, such as full width at half maximum, detection accuracy, and signal-to-noise ratio, were also investigated to evaluate the sensor's efficiency.

A Review on Carbon Dots: Synthesis, Characterization and Its Application in Optical Sensor for Environmental Monitoring

The development of carbon dots (CDs), either using green or chemical precursors, has inevitably led to their wide range application, from bioimaging to optoelectronic devices. The reported precursors and properties of these CDs have opened new opportunities for the future development of high-quality CDs and applications. Green precursors were classified into fruits, vegetables, flowers, leaves, seeds, stem, crop residues, fungi/bacteria species, and waste products, while the chemical precursors were classified into acid reagents and non-acid reagents. This paper quickly reviews ten years of the synthesis of CDs using green and chemical precursors. The application of CDs as sensing materials in optical sensor techniques for environmental monitoring, including the detection of heavy metal ions, phenol, pesticides, and nitroaromatic explosives, was also discussed in this review. This profound review will offer knowledge for the upcoming community of researchers interested in synthesizing high-quality CDs for various applications.

Femtomolar detection of dopamine using surface plasmon resonance sensor based on chitosan/graphene quantum dots thin film

Due to the crucial role of dopamine (DA) in health and peripheral nervous systems, it is particularly important to develop an efficient and accurate sensor to monitor and determine DA concentrations for diagnostic purposes and diseases prevention. Up to now, using surface plasmon resonance (SPR) sensors in DA determination is very limited and its application still at the primary stage. In this work, a simple and ultra-sensitive SPR sensor was constructed for DA detection by preparation of chitosan- graphene quantum dots (CS-GQDs) thin film as the sensing layer. Other SPR measurements were conducted using different sensing layers; GQDs, CS for comparison. The proposed thin films were prepared by spin coating technique. The developed CS-GQDs thin film-based SPR sensor was successfully tested in DA concentration range from 0 fM to 1 pM. The designed SPR sensor showed outstanding performance in detecting DA sensitively (S = 0.011°/fM, R² = 0.8174) with low detection limit of 1.0 fM has been achieved for the first time. The increased angular shift of SPR dip, narrow full width half maximum of the SPR curves, excellent signal-to-noise ratio and figure of merit, and a binding affinity constant (K_A) of 2.962 PM^-1 demonstrated the potential of this sensor to detect DA with high accuracy. Overall, it was concluded that the proposed sensor would serve as a valuable tool in clinical diagnostic for the serious neurological disorders. This in turns has a significant socio-economic impact.