Electrochemical Immunoassay for Capturing Capsular Polysaccharide of Burkholderia pseudomallei: Early Onsite Detection of Melioidosis.

This study presented the detection and quantification of capsular polysaccharide (CPS) as a biomarker for the diagnosis of melioidosis. After successfully screening four monoclonal antibodies (mAbs) previously determined to bind CPS molecules, the team developed a portable electrochemical immunosensor based on antibody-antigen interactions. The biosensor was able to detect CPS with a wide detection range from 0.1pg/mL to 1 µg/mL. The developed biosensor achieved high sensitivity for the detection of CPS spiked into both urine and serum. The developed assay platform was successfully programmed into a Windows app, and the sensor performance was evaluated with different spiked concentrations. The rapid electro-analytical device (READ) sensor showed great unprecedented sensitivity for the detection of CPS molecules in both serum and urine, and results were cross-validated with ELISA methods.

Characterization of an In-Situ Soil Organic Carbon (SOC) via a Smart-Electrochemical Sensing Approach.

Soil is a vital component of the ecosystem that drives the holistic homeostasis of the environment. Directly, soil quality and health by means of sufficient levels of soil nutrients are required for sustainable agricultural practices for ideal crop yield. Among these groups of nutrients, soil carbon is a factor which has a dominating effect on greenhouse carbon phenomena and thereby the climate change rate and its influence on the planet. It influences the fertility of soil and other conditions like enriched nutrient cycling and water retention that forms the basis for modern 'regenerative agriculture'. Implementation of soil sensors would be fundamentally beneficial to characterize the soil parameters in a local as well as global environmental impact standpoint, and electrochemistry as a transduction mode is very apt due to its feasibility and ease of applicability. Organic Matter present in soil (SOM) changes the electroanalytical behavior of moieties present that are carbon-derived. Hence, an electrochemical-based 'bottom-up' approach is evaluated in this study to track soil organic carbon (SOC). As part of this setup, soil as a solid-phase electrolyte as in a standard electrochemical cell and electrode probes functionalized with correlated ionic species on top of the metalized electrodes are utilized. The surficial interface is biased using a square pulsed charge, thereby studying the effect of the polar current as a function of the SOC profile. The sensor formulation composite used is such that materials have higher capacity to interact with organic carbon pools in soil. The proposed sensor platform is then compared against the standard combustion method for SOC analysis and its merit is evaluated as a potential in situ, on-demand electrochemical soil analysis platform.

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.

Correction: CannibiSenS: an on-demand rapid screen for THC in human saliva.

Correction for 'CannibiSenS: an on-demand rapid screen for THC in human saliva' by Nathan Kodjo Mintah Churcher et al., Analyst, 2023, 148, 2921-2931, https://doi.org/10.1039/D3AN00522D.

Espial: Electrochemical Soil pH Sensor for In Situ Real-Time Monitoring.

We present a first-of-its-kind electrochemical sensor that demonstrates direct real-time continuous soil pH measurement without any soil pre-treatment. The sensor functionality, performance, and in-soil dynamics have been reported. The sensor coating is a composite matrix of alizarin and Nafion applied by drop casting onto the working electrode. Electrochemical impedance spectroscopy (EIS) and squarewave voltammetry (SWV) studies were conducted to demonstrate the functionality of each method in accurately detecting soil pH. The studies were conducted on three different soil textures (clay, sandy loam, and loamy clay) to cover the range of the soil texture triangle. Squarewave voltammetry showed pH-dependent responses regardless of soil texture (while electrochemical impedance spectroscopy's pH detection range was limited and dependent on soil texture). The linear models showed a sensitivity range from -50 mV/pH up to -66 mV/pH with R2 > 0.97 for the various soil textures in the pH range 3-9. The validation of the sensor showed less than a 10% error rate between the measured pH and reference pH for multiple different soil textures including ones that were not used in the calibration of the sensor. A 7-day in situ soil study showed the capability of the sensor to measure soil pH in a temporally dynamic manner with an error rate of less than 10%. The test was conducted using acidic and alkaline soils with pH values of 5.05 and 8.36, respectively.

E-SCAN: Electrochemical Scanning of Carbonates, an In Situ Approach for Screening and Quantifying Inorganic Carbon in Soil.

A modified three-electrode system was utilized with a correlated ion-capture film that is functional to changes in soil carbonate moieties to determine an understudied pool of soil carbon that is vital toward holistic carbon sequestration─carbonous soil minerals (CSM). This composite sensor was tested on soils with varying carbonate contents using cyclic voltammetry, chromatocoulometry (DC-based), and electrochemical impedance spectroscopy to determine signal output as a function of increasing dose. To determine the in-field capability, a portable potentiostat device was integrated into a probe head setup that could be inserted into soil for testing. The results from these experiments showed a linearity of R2 > 0.97 and a measurable sensing range from 0.01% (100 ppm) to 1% (10 000 ppm). Therefore, a first-of-a-kind in-soil sensor system was developed for determining carbonate content in real soil samples using electrochemistry that can be tested in-field to survey the field-deployable and point-of-use capability of the system.

Activated carbon derived from wood biochar for Amperometric sensing of Ammonia for early screening of chronic kidney disease.

Personalized medicine has emerged as an increasingly efficient and effective approach to addressing disease diagnosis and intervention. Ammonia is a waste product produced by the body during the digestion of protein. The requirement to develop an electrochemical sensing platform for monitoring skin ammonia levels holds great potential as an essential solution to pre-screen chronic kidney disease (CKD). In this research, we have manufactured an innovative electrochemical sensor by employing activated carbon derived from wood biochar as the signal transducer. We conducted a comprehensive analysis of the structural and morphological characteristics of the synthesized materials using various techniques. The hypothesized interaction was investigated using chronoamperometry as a transduction technique. To assess cross-reactivity, we conducted a study using common interferants or chemicals present in the environment. The data presented in this paper represents three replicates and is plotted with a 5 % error bar, demonstrating a 95 % confidence interval in the sensor response. In this study, we have elucidated the functionality and usefulness of a wearable microelectronic research prototype integrated with an HTC-activated carbon @RTIL-based electrochemical sensing platform for detecting ammonia levels released from the skin as a marker for chronic kidney disease screening. By enabling early detection and monitoring, these platforms can facilitate timely interventions, such as lifestyle modifications, medication adjustments, or referral to nephrology specialists. This proactive approach can potentially slow down disease progression, minimize the need for dialysis or transplantation, and ultimately improve the quality of life for CKD patients.

Electrochemical Soil Nitrate Sensor for In Situ Real-Time Monitoring.

Sustainable agriculture is the answer to the rapid rise in food demand which is straining our soil, leading to desertification, food insecurity, and ecosystem imbalance. Sustainable agriculture revolves around having real-time soil health information to allow farmers to make the correct decisions. We present an ion-selective electrode (ISE) electrochemical soil nitrate sensor that utilizes electrochemical impedance spectroscopy (EIS) for direct real-time continuous soil nitrate measurement without any soil pretreatment. The sensor functionality, performance, and in-soil dynamics have been reported. The ion-selective electrode (ISE) is applied by drop casting onto the working electrode. The study was conducted on three different soil textures (clay, sandy loam, and loamy clay) to cover the range of the soil texture triangle. The non-linear regression models showed a nitrate-dependent response with R2 > 0.97 for the various soil textures in the nitrate range of 5-512 ppm. The validation of the sensor showed an error rate of less than 20% between the measured nitrate and reference nitrate for multiple different soil textures, including ones that were not used in the calibration of the sensor. A 7-day-long in situ soil study showed the capability of the sensor to measure soil nitrate in a temporally dynamic manner with an error rate of less than 20%.

CannibiSenS: an on-demand rapid screen for THC in human saliva.

Management of substances that possess high potential for abuse requires a comprehensive understanding of the temporal effects of a corresponding volume of intake. Cannabis is deemed as one of the most widely used drugs in the United States and studies related to the primary psychoactive compound present in it, Δ-9-tetrahydrocannabinol (THC), have revealed that it causes adverse health effects. In this study, we present a field-deployable electrochemical sensing system that can detect THC at the 5 ng mL-1 cut-off level with a dynamic range of 0.1-100 ng mL-1 in human saliva. Considering the complexity of the human saliva matrix, the specificity study demonstrated selectivity towards THC with minimum interactions with ethanol and cannabidiol (CBD). Surface Plasmon Resonance (SPR) has been implemented to visualize and validate the capture probe as a means for THC detection. A robust, compatible binary classifier model has been shown in this work to effectively group samples into THC+ (high) and THC- (low) groups from human saliva with an accuracy greater than 90% considering a limited dataset. Hence, we demonstrate the potential of an innovative end-to-end system to effectively regulate cannabis use and prevent substance abuse in our surroundings.

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.

E.P.A.S.S: Electroanalytical Pillbox Assessment Sensor System, A Case Study Using Metformin Hydrochloride.

Adulteration of medications is an emerging and significant threat to human health and well-being, even though adulterants are still often not considered seriously in clinical or forensic toxicology. Screening of drug adulterations is a major challenge and concern for regulatory authorities worldwide. Metformin hydrochloride, an important drug to treat diabetes, is found to be adulterated worldwide and a major reason to worry about the health and safety procedure. We have demonstrated a first-of-a-kind electrochemical biomedical device utilizing exfoliated graphene oxide (GO)─Nafion-modified customized gold screen-printed electrodes (spiral electrochemical notification-coupled electrode, SENCE), driven by electrochemical adsorptive stripping voltammetry, to identify the trace level adulteration in metformin. The GO-Nafion-SPE interface has been characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and Fourier transform infrared. Custom-made screen-printed SENCEs have been functionalized with GO nanoparticles (transducer) to obtain a fingerprint signal response of metformin using differential pulse voltammetry. A linear calibrated dose response has been obtained with n = 3 repetitions with a low limit of detection of 10 ppm for metformin. We have used the sensing response as a function of adulteration, and it is extensively supported by rigorous statistical analysis along with the help of the machine learning tool. This is a first-of-its-kind IoT-enabled electrochemical sensor and analysis platform that can detect drug adulteration as a low, medium, and high output.

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.

Targeted On-Demand Screening of Pesticide Panel in Soil Runoff.

Using pesticides is a common agricultural and horticultural practice to serve as a control against weeds, fungi, and insects in plant systems. The application of these chemical agents is usually by spraying them on the crop or plant. However, this methodology is not highly directional, and so only a fraction of the pesticide actually adsorbs onto the plant, and the rest seeps through into the soil base contaminating its composition and eventually leaching into groundwater sources. Electrochemical sensors which are more practical for in situ analysis used for pesticide detection in soil runoff systems are still in dearth, while the ones published in the literature are attributed with complex sensor modification/functionalization and preprocessing of samples. Hence, in this work, we present a highly intuitive electroanalytical sensor approach toward rapid (10 min), on-demand screening of commonly used pesticides-glyphosate and atrazine-in soil runoff. The proposed sensor functions based on the affinity biosensing mechanism driven via thiol cross-linker and antibody receptors that holistically behaves as a recognition immunoassay stack that is specific and sensitive to track test pesticide analytes. Then, this developed sensor is integrated further to create a pesticide-sensing ecosystem using a front-end field-deployable smart device. The method put forward in this work is compared and validated against a standard laboratory potentiostat instrument to determine efficacy, feasibility, and robustness for a point-of-use (PoU) setting yielding LoD levels of 0.001 ng/ml for atrazine and 1 ng/ml for glyphosate. Also, the ML model integration resulted in an accurate prediction rate of ≈80% in real soil samples. Therefore, a universal pesticide screening analytical device is designed, fabricated, and tested for pesticide assessment in real soil runoff samples.

ElectrochemSENSE: A platform towards field deployable direct on-produce glyphosate detection.

Glyphosate is an organophosphorus herbicide that is applied to the leaves of plants and crops to kill broadleaf plants and grasses. In this paper, for the first time, a field deployable, user-friendly, portable and rapid electrochemical pesticide sensing system is presented that can screen for glyphosate in produce run-off/extract. ElectrochemSENSE comprises the following parts: A polymer based disposable substrate with metallized electrodes that are surface treated with polyclonal antibodies of glyphosate and a custom electronic reader capable of reporting pesticide contamination. Utilizing the principles of capacitive current changes due to selective binding of glyphosate to its capture probe, reporting was achieved rapidly (in under 5 min). ElectrochemSENSE was tested to screen for glyphosate concentrations on produce samples above or below the globally accepted metric criterion, otherwise known as the Maximum Residue Level (MRL). Experiments were conducted on 4 produce types-apples (MRL: 0.2 ppm), strawberries (MRL: 0.2 ppm), bell peppers (MRL: 0.1 ppm) and carrots (MRL: 5 ppm). To further add functionality and increase prediction accuracy- a machine learning binary classifier was integrated with the device as a proof-of-concept so that sensor's response can be trained and characterized to perform with high accuracy, thereby serving as an analytics medium which minimizes error rate. Utilizing this system-the sensor's limit of detection has been determined to be 0.01 ppm (10 ng/mL) considering the permissible Field Operating Range (FOR) for glyphosate residue in various tested produce.

Design and Electrochemical Characterization of Spiral Electrochemical Notification Coupled Electrode (SENCE) Platform for Biosensing Application.

C-reactive protein (CRP) is considered to be an important biomarker associated with many diseases. During any physiological inflammation, the level of CRP reaches its peak at 48 h, whereas its half-life is around 19 h. Hence, the detection of low-level CRP is an important task for the prognostic management of diseases like cancer, stress, metabolic disorders, cardiovascular diseases, and so on. There are various techniques available in the market to detect low-level CRP like ELISA, Western blot, etc. An electrochemical biosensor is one of the important miniaturized platforms which provides sensitivity along with ease of operation. The most important element of an electrochemical biosensor platform is the electrode which, upon functionalization with a probe, captures the selective antibody-antigen interaction and produces a digital signal in the form of potential/current. Optimization of the electrode design can increase the sensitivity of the sensor by 5-10-fold. Herein, we come up with a new sensor design called the spiral electrochemical notification coupled electrode (SENCE) where the working electrode (WE) is concentric in nature, which shows better response than the market-available standard screen-printed electrode. The sensor is thoroughly characterized using a standard Ferro/Ferri couple. The sensing performance of the fabricated platform is also characterized by the detection of standard H2O2 using a diffusion-driven technique, and a low detection limit of 15 µM was achieved. Furthermore, we utilized the platform to detect a low level (100 ng/mL) of CRP in synthetic sweat. The manuscript provides emphasis on the design of a sensor that can offer good sensitivity in electrochemical biosensing applications.

A Rapid Response Electrochemical Biosensor for Detecting Thc In Saliva.

Marijuana is listed as a Schedule I substance under the American Controlled Substances Act of 1970. As more U.S. states and countries beyond the U.S. seek legalization, demands grow for identifying individuals driving under the influence (DUI) of marijuana. Currently no roadside DUI test exists for determining marijuana impairment, thus the merit lies in detecting the primary and the most sought psychoactive compound tetrahydrocannabinol (THC) in marijuana. Salivary THC levels are correlated to blood THC levels making it a non-invasive medium for rapid THC testing. Affinity biosensing is leveraged for THC biomarker detection through the chemical reaction between target THC and THC specific antibody to a measure signal output related to the concentration of the targeted biomarker. Here, we propose a novel, rapid, electrochemical biosensor for the detection of THC in saliva as a marijuana roadside DUI test with a lower detection limit of 100 pg/ml and a dynamic range of 100 pg/ml - 100 ng/ml in human saliva. The developed biosensor is the first of its kind to utilize affinity-based detection through impedimetric measurements with a rapid detection time of less than a minute. Fourier transform infrared spectroscopy analysis confirmed the successful immobilization of the THC immobilization assay on the biosensing platform. Zeta potential studies provided information regarding the stability and the electrochemical behavior of THC immunoassay in varying salivary pH buffers. We have demonstrated stable, dose dependent biosensing in varying salivary pH's. A binary classification system demonstrating a high general performance (AUC = 0.95) was employed to predict the presence of THC in human saliva. The biosensor on integration with low-power electronics and a portable saliva swab serves as a roadside DUI hand-held platform for rapid identification of THC in saliva samples obtained from human subjects.