Current Analytical Chemistry - Volume 20, Issue 6, 2024

In today's era, detection of disease is utmost important for the management of disease. Early detection leads to early management of disease. Paper-based microfluidic devices are promising technologies that are cost-effective, portable and easy to use over conventional methods. In addition, paper-based microfluidics offers low reagent/sample volume, less response time and can be used in resource-limited settings. Researchers are highly fascinated by this technology as it has a lot of potential to convert into commercial monitoring devices. The present article covers the uses of paper-based microfluidic technology for the swift and sensitive detection of pathogens from diverse samples, viz. food, water and blood. In this comprehensive review, paper-based microfluidic devices are introduced, including the basic concepts, current status and applications, along with the discussion of the limitations of microfluidics for the detection of pathogens. Although paper-based microfluidic devices are being developed, their commercialization requires simplification of manufacturing processes, reduction in production costs as well as an increase in production efficiency. Nonetheless, the integration of artificial intelligence (AI) and the Internet of Things (IoT) like smartphones, digital cameras, webcam etc. with paper-associated diagnosis has transformed the point-of-care (POC) diagnostics.

The use of organophosphate pesticides (OPPs) in agricultural practices improves crop yield and controls pests, but their indiscriminate use and persistence in the environment pose significant health risks. Therefore, it has become increasingly important to develop reliable and efficient detection methods for OPPs to ensure food safety and monitor their presence. In recent years, OPP detection methods have undergone significant advancements. Sensors such as colorimetric, fluorescence, electrochemical, and impedometric offer several advantages over traditional methods, such as high sensitivity, selectivity, and portability. The purpose of this review paper is to provide an overview of recent developments in OPP detection methods. The paper discusses the different types of sensors that are available for the detection of OPPs, as well as their advantages and disadvantages. Many electrochemical methods have been employed to investigate OPP detection, including voltammetry, impedance spectroscopy, and amperometry. The integration of nanomaterials, such as carbon nanotubes, graphene, and metal nanoparticles, has significantly enhanced the performance of electrochemical sensors by providing high surface area, enhanced electron transfer, and specific analyte interactions. Furthermore, the review discusses the utilization of biomolecules, such as enzymes and aptamers, as recognition elements in sensor platforms for selective and sensitive OPP detection. The incorporation of these biomolecules offers high specificity and enables real-time monitoring of OPP residues in food samples and environmental matrices. It emphasizes the importance of continued research and development to optimize detection methods, improve sensor performance, and make these technologies more widely accessible for effective monitoring and control of OPP contamination in various domains.

Background: The wastewater released from various industries contains substantial amounts of organic compounds such as dyes and naphthols. However, naphthols are toxic to the environment and human health. So, it is essential to eliminate them, which will contribute to manufacturing and environmental management. Methods: In the work, an eco-friendly method is adapted to synthesize reduced graphene oxide (rGO) using Equisetum arvense plant extract as a strong reducing and stabilizing agent. Then, a hybrid nano adsorbent based on rGO and ordered mesoporous carbon (CMK-3) decorated with iron oxide nanoparticles (Fe3O4@rGO/CMK-3) was prepared as an adsorbent. We investigate the performance of Fe3O4@rGO/CMK-3 to remove 2-naphthol (2-NP). Results: The FE-SEM images exhibited spherical magnetite nanoparticles with sizes ranging from 31 to 47 nm on composite. Efficient removal (90%) of 2-NP from aqueous solution is demonstrated using high surface area Fe3O4@rGO/CMK-3 (initial concentration of 2-NP: 10 mg mL^-1, pH: 5.0, time: 30 min, and amount of adsorbent dosage: 3 mg mL^-1). The high surface area of Fe3O4@rGO/CMK-3, hydrogen binding, π-π stacking interaction between the benzene rings of 2-NP and graphitic skeleton of hybrid adsorbent facilitate the adsorption of 2-NP on the Fe3O4@rGO/CMK-3. The 2NP removal capacity by (Fe3O4@rGO/CMK-3) showed a significant decrease during five successive cycles. Conclusion: These results promise the potential of high surface area (Fe3O4@rGO/CMK-3) for efficient removal of 2-NP for wastewater treatment.

Background: Determination of environmental pollutants is important due to their harmful effects on the health of living organisms. However, direct measurement of many of these pollutants is not possible due to their low concentrations, which necessitates the need for sample preparation methods. One of the rapid and simple sample preparation methods is the Air-Agitated Liquid-Liquid Microextraction (AALLME) method, which requires toxic organic solvents that can lead to environmental pollution. Therefore, finding green solvents like Deep Eutectic Solvents (DESs) to replace them can be investigated. Methods: A novel Deep Eutectic Solvent (DES) was synthesized from a combination of choline chloride and 2-phenylethanol with a molar ratio of 1:4, and it was examined using FT-IR analysis. This solvent was used in an AALLME method for measuring copper and cadmium heavy metal ions in complex real samples with Flame Atomic Absorption Spectroscopy (FAAS). Results: The influential parameters of this method, such as solution pH (5.4), extraction cycles (12), and extraction solvent volume (440 μL), were optimized utilizing central composite design (CCD). Underneath the optimized circumstances, the detection limits for Cu²⁺ and Cd²⁺ were 0.14 and 0.09 ng mL^-1, and the linear dynamic range was 0.47-50.0 and 0.32-22.5 ng mL^-1, respectively. The preconcentration factors for these cations were 139.7 and 133.4, respectively. Conclusion: Combining this novel green solvent and rapid sample preparation method for the preconcentration and determination of the studied heavy metal ions has shown promising results in terms of enrichment factors and detection limit values.

Objective: This paper describes a new, digital image colourimetry-based format for the quantification of analytes in an aqueous solution. Methods: The proposed method is based on analyte pre-concentration by adsorption onto Bentone LT. Bentone LT pellet isolation comes after adsorption, followed by in-situ application of an analyteselective chromogenic reaction. The resulting pellet colouration is captured by the phone’s integrated camera and assessed using the free open-source image processing software, ImageJ. Responses are calibrated and quantified. Results: We tested the applicability of the proposed methodology for the quantification of specific model analytes which are of concern in environmental matrices (methyl red, Co(II), uric acid, topotecan). The smartphone-based assay was proven reliable in quantifying the model analytes (standard recovery of 82-116%), alone or in mixture, from dilute aqueous solutions and was found to depict accurately the adsorption behaviour followed photometrically in solution. Lower limit of linearity was calculated at 0.05, 0.11, 0.85 and 0.20 μg/mL for methyl red, Co(II), uric acid, and topotecan, respectively. The proposed format was found superior when compared to alternative published photometric/ colourimetric assays in terms of the lower limit of linearity. In the presence of possible adsorption interferents, the lower limit of linear response was shifted to slightly higher concentrations for topotecan i.e. from 0.2 μg/mL to 0.5 μg/mL. Conclusion: We here demonstrate the extended applicability of the proposed methodology for the smartphone-based quantification of the specific model analytes. The applicability of this analysis format likely extends to other analytes, where analyte-specific colour formation is feasible.

Background: PYX-106 is a novel monoclonal antibody (mAb), targeting the sialic acidbinding immunoglobulin-like lectin 15 (Siglec-15) in the Tumor Microenvironment (TME). Precise measurement of PYX-106 is essential for the thorough assessment of PYX-106 pharmacokinetics in clinical investigations. Methods: A novel Electrochemiluminescence (ECL) immunoassay for the quantitation of PYX- 106 in human serum was developed and validated. Biotinylated anti-PYX-106 antibody Bio-A1A1 was employed as the capture antibody, and ruthenylated anti-PYX-106 antibody Ru-A3G10 was utilized as the detection antibody in the ECL immunoassay on Meso Scale Discovery (MSD) platform. Results: This assay was fully validated in terms of selectivity, accuracy, precision, hook effect, stability, etc., with a dynamic range from 50.0 to 2,500 ng/mL in human serum under the 2018 U.S. Food and Drug Administration (FDA) guidance and the 2022 U.S. FDA ICH M10 guidance. Conclusion: PYX-106 bioanalytical assay validation was reported for the first time in a biological matrix, and this assay has been successfully applied to support a clinical trial PYX-106-101.