PathoSense: a rapid electroanalytical device platform for screening Salmonella in water samples.

Salmonella contamination is a major global health challenge, causing significant foodborne illness. However, current detection methods face limitations in sensitivity and time, which mostly rely on the culture-based detection techniques. Hence, there is an immediate and critical need to enhance early detection, reduce the incidence and impact of Salmonella contamination resulting in outbreaks. In this work, we demonstrate a portable non-faradaic, electrochemical sensing platform capable of detecting Salmonella in potable water with an assay turnaround time of ~ 9 min. We evaluated the effectiveness of this sensing platform by studying two sensor configurations: one utilizing pure gold (Au) and the other incorporating a semiconductor namely a zinc oxide thin film coated on the surface of the gold (Au/ZnO). The inclusion of zinc oxide was intended to enhance the sensing capabilities of the system. Through comprehensive experimentation and analysis, the LoD (limit of detection) values for the Au sensor and Au/ZnO sensor were 0.9 and 0.6 CFU/mL, respectively. In addition to sensitivity, we examined the sensing platform's precision and reproducibility. Both the Au sensor and Au/ZnO sensor exhibited remarkable consistency, with inter-study percentage coefficient of variation (%CV) and intra-study %CV consistently below 10%. The proposed sensing platform exhibits high sensitivity in detecting low concentrations of Salmonella in potable water. Its successful development demonstrates its potential as a rapid and on-site detection tool, offering portability and ease of use. This research opens new avenues for electrochemical-based sensors in food safety and public health, mitigating Salmonella outbreaks and improving water quality monitoring.

Recent Advances in Gas Detection Methodologies with a Special Focus on Environmental Sensing and Health Monitoring Applications─A Critical Review.

With the expansion of the Internet-of-Things (IoT), the use of gas sensors in the field of wearable technology, smart devices, and smart homes has increased manifold. These gas sensors have two key applications─one is the detection of gases present in the environment and the other is the detection of Volatile Organic Compounds (VOCs) that are found in the breath. In this review, we focus systematically on the advancements in the field of various spectroscopic methods such as mass spectrometry-based analysis and point-of-care approach to detect VOCs and gases for environmental monitoring and disease diagnosis. Additionally, we highlight the development of smart sensors that work on the principle of electrochemical detection and provide examples of the same through an extensive literature review. At the end of this review, we highlight various challenges and future perspectives.

How safe is our food we eat? An electrochemical lab-on-kitchen approach towards combinatorial testing for pesticides and GMOs; A case study with edamame.

In our daily life, as consumers we are constantly made aware of the impact of pesticides and other modifications to food products derived from genetically modified organisms (GMO's) that have an impact on human health. In our connected world, there is an immense interest for on-demand information about food quality prior to consumption. The gold standard method to detect pesticides or GMOs residues in food is complex and is not amenable to rapid consumer use. In this study, we demonstrate the feasibility of an electrochemical portable sensing approach for the simultaneous direct detection of spiked pesticides chlorpyrifos (Chlp) and GMOs protein Cry1Ab in real edamame soy matrix. The immunoassay based two-plex sensing platform was fabricated using respective antibody's Chlp on one side and Cry1Ab on other side. A simple lab-on-kitchen level preparation of matrix has been demonstrated and sensor response was tested using non-faradaic electrochemical impedance spectroscopy (EIS), which showed a linear response in Cry1Ab/Chlp concentrations from 0.3 ng/mL to 243 ng/mL with limit of detection 0.3 ng /mL for both the target antigens (Cry1Ab and Chlp) respectively. The spiked and recovery test results fall within ± 20% error in real sample matrix which demonstrates the performance of the our platform with maximum residue limit (MRL) for the given targets. Such electrochemical portable multi-analyte direct sensing tool with simple matrix processing protocol can be a future commercial field-testing tool for use at everyday consumer level.

Pesticide analytical screening system (PASS): A novel electrochemical system for multiplex screening of glyphosate and chlorpyrifos in high-fat and low-fat food matrices.

On-field detection of pesticide residue in complex-food matrices is a challenge when it comes to analytical detection involving multistep extraction and purification. In this study, we test the feasibility of an electrochemical portable device for detection of spiked pesticides Glyphosate (Glyp) and Chlorpyrifos (Chlp) in low-fat and high-fat food matrix. The immunoassay based two-plex sensing platform was fabricated using respective antibody glyphosate on one side and chlorpyrifos antibody on other side. The sensor response was tested using non-faradaic electrochemical impedance spectroscopy (EIS), which showed a linear response in Glyp/Chlp concentrations from 0.3 ng/mL to 243 ng/mL with limit of detection 1 ng/mL for low fat and 1 ng/mL to 243 ng/mL with LOD 1 ng/mL for high-fat matrix respectively. The laboratory-based benchtop data was then compared with portable device for feasibility of application as portable device. Such electrochemical portable sensing approach can be a future commercial field testing tool.

Portable Pesticide Electrochem-sensor: A Label-Free Detection of Glyphosate in Human Urine.

The toxicity levels of and exposure to glyphosate, a widely used herbicide and desiccant, are significant public health issues. In this study, we aim to design a highly sensitive, label-free, portable sensor for the direct detection of glyphosate in human urine. The sensor platform consists of a portable, printed circuit board circular platform with gold working and reference electrodes to enable nonfaradic electrochemical impedance spectroscopy. The sensing platform was an immunoassay-based, gold electrode surface immobilized with a monolayer of dithiobis(succinimidyl propionate) (DSP), a thiol-based cross-linker, which was then modified with a glyphosate antibody (Glyp-Ab) through the bonding of the ester group of DSP with the amide of the antibody (Glyp-Ab). The sensor was tested electrochemically, first using the laboratory-based benchtop method for the glyphosate-spiked urine samples, resulting in a dynamic response in the concentration range of 0.1-72 ng/mL with a limit of detection of 0.1 ng/mL. The platform showed high selectivity in the presence of major interfering analytes in urine [malathion (Mal), 3-phenoxybenzoic acid (PBA), and chlorpyrifos (Chlp)] and high reproducibility. The sensing platform was then translated into a portable device that showed a performance correlation (r = 0.994) with the benchtop (laboratory method). This developed portable sensing approach can be a highly reliable alternate sensor platform for the direct detection of pesticides in human bodily fluids.

γ-Ray-Assisted Synthesis of a Pt-Sn Bimetallic Composite Loaded on Graphene-Graphitic Carbon Nitride Hybrid: A Cocktail Electrocatalyst for the Methanol Oxidation Reaction.

The composite of Pt with transition metals is viewed as the most promising anode material for direct methanol fuel cell (DMFC) applications. Besides the decrease in the Pt loading, these multimetallic structures help in circumventing CO poisoning issues associated with a Pt catalyst. Herein, we prepared and loaded Pt-Sn bimetallic nanoparticles on an electron-rich and stable substrate consisting of graphitic nitride (GCN) and graphene oxide (GO)/reduced graphene oxide (r-GO) hybrid composites. The γ-radiolysis method was employed for coreduction of metal salts to deposit the binary composite of metal nanoparticles over the substrates. These structures were tested as the anode material for the methanol oxidation reaction (MOR). Among various possible combinations, Pt-Sn-loaded rGO-GCN (Pt-Sn/rGO-GCN) demonstrated the current density of ca. 2.4 A/mgPt. To the best of our knowledge, this value is among the highest ones, reported for similar systems in the acidic pH. Furthermore, these composites demonstrated excellent stability in the repeated cycle test. The improved performance is associated to the plenty of -OH groups provided by the Sn counterpart and a large number of adsorption sites from the electron-reached GCN counterpart.

High sensitive determination of dopamine through catalytic oxidation and preconcentration over gold-multiwall carbon nanotubes composite modified electrode.

Electrochemical properties of dopamine, uric acid and ascorbic acid have been investigated using gold nano particles (AuNPs) decorated functionalized multiwall carbon nanotubes (MWCNTs) nano composite modified electrode. MWCNTs were acid functionalized to introduce -COOH functionalities. The functionalized MWCNTs were used as support materials and were decorated with gold nano particles of 20 nm in size. The nano composite materials thus prepared have been named as f-MWCNTs/AuNPs composite. The composite material was characterized using FTIR, RAMAN, TEM, UV-VIS spectroscopy and atomic force microscopy measurements. Electrochemical investigations on the composite modified glassy carbon electrode for dopamine was investigated in presence of interfering agents like ascorbic acid and uric acid. The modified electrode showed sensitivity of 0.002 µAnM-1 for dopamine with the detection limit of 35 nM. Present electrode showed high selectivity for dopamine as the oxidation peak of dopamine and uric acid were very well resolved. The analytical method was found to be suitable for the simultaneous determination of dopamine and uric acid using the modified electrode. Method was applied in spiked real serum sample for the determination of dopamine.

Electrocatalyst on insulating support?: Hollow silica spheres loaded with Pt nanoparticles for methanol oxidation.

Electrocatalytic oxidation of methanol on silica hollow spheres, loaded with platinum nanoparticles (Pt-SiO2-HS), is reported. The functionalized hollow silica spheres were prepared by the surfactant (lauryl ester of tyrosine) template-assisted synthesis. These spheres were loaded with platinum nanoparticles by γ-radiolysis. Energy-dispersive X-ray analysis (EDAX) and X-ray photoelectron spectroscopy (XPS) analyses confirmed presence of Si and Pt in the composite. High-resolution transmission electron microscopy showed the formation of uniformly deposited Pt nanoparticles over the hollow spheres with a predominant Pt(111) lattice plane on the surface. In spite of the poor conducting nature of the silica support, the oxidation potential and current density per unit mass for methanol oxidation were noted to be ca. 0.72 V vs NHE and 270 mA mg(-1), respectively, which are among the best values reported in its class. The composite did not show any sign of a degradation even after repeated use. In fact, the anodic current was found to increase under constant polarization, which is attributed to a facile reaction between adsorbed CO with a surface hydroxyl group present on the silica support. These results are in favor of Pt-SiO2-HS as a promising electrocatalyst material in the direct methanol fuel cell (DMFC) applications.