Quantitative determination of H2O2 for detection of alanine aminotransferase using thin film electrodes

Current trends in electrochemical approaches for liver biomarker detection: a mini-review

Aspartate aminotransferase (AST), alanine aminotransferase (ALT), bilirubin, gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), and albumin are well-established liver biomarkers with significant physiological functions. Alterations in these liver function tests can be indicative of the presence and progression of acute and chronic liver conditions such as liver cirrhosis, non-alcoholic fatty liver disease, biliary disease, and liver failure. Therefore, accurate and quantitative detection of these biomarkers is crucial for diagnosing and monitoring liver disease. There are several commercially available chemistry analyzers capable of simultaneously detecting all these biomarkers, as well as numerous biosensors designed for individual detection. Various techniques have been employed, including colorimetry, surface-enhanced Raman spectroscopy (SERS), electrochemiluminescence (ECL), fluorescence-based techniques, and electrochemical methods. Among these, electrochemical detection stands out due to its simplicity, cost-effectiveness, low sample volume requirement, label-free detection, high sensitivity, fast response times, miniaturization, and portability. Information on recently developed electrochemical biosensors is summarized through detailed tables and is intended to guide future research and development efforts in this area.

A low-cost miniature immunosensor for haemoglobin as a device for the future detection of gastrointestinal bleeding

Gastrointestinal bleeding (GIB) is a serious medical condition, which requires immediate attention to establish the cause of the bleeding. Here, we present the development of a miniaturised electrochemical impedance spectroscopy (EIS) device for the detection of GIB. The device performs EIS measurements up to 100 kHz. Following the development of an immunosensor for haemoglobin (Hb) on screen printed electrodes, the EIS device was used for detecting Hb as an early indication of bleeding. The sensor was able to detect Hb in a redox solution in a linear range between 5 μg mL-1 and 60 μg mL-1, with a limit of detection of 13.3 μg mL-1. It was also possible to detect Hb in simulated intestinal fluid, without the need for a redox solution, within a range of 10 μg mL-1 to 10 mg mL-1 with a limit of detection of 2.31 mg mL-1. The miniature EIS device developed in this work is inexpensive, with an estimated cost per unit of £30, and has shown a comparable performance to existing commercial tools, demonstrating its potential to be used in the future as an ingestible sensor to detect GIB. All these measurements were carried out in a purpose built flow cell with supporting hardware electronics outside the cell. Integration of the hardware and the sensing electrodes was demonstrated in pill form. This pill after integration sampling fluidics has potential to be used in detecting gastrointestinal bleeding.

Alanine aminotransferase detection using TIT assisted four tapered fiber structure-based LSPR sensor: From healthcare to marine life

Alanine aminotransferase (ALT), a type of inactive enzyme largely present in fish liver cells, is essential for the tricarboxylic acid (TCA) cycle. Monitoring ALT activity in the blood/hepatocellular layer has been demonstrated to be a sensitive sign of liver dysfunction and an essential method for determining the health status of fish. This study details the development of a multi-layer material (hybrids of graphene oxide and multi-walled carbon nanotubes (GO/MWCNTs), gold nanoparticles (AuNPs), and glutamate oxidase (GluOx) enzyme) immobilized localized surface plasmon resonance based unique fiber structure biosensor for the quantitative determination of ALT biomolecules at concentrations ranging from 0 to 1000 U/L. For this kind of detection, a novel taper-in-taper with four tapered (TIT4T) structure based on single-mode fiber has been developed. In addition to AuNPs, GO/MWCNTs were immobilized in the probe's sensing region to increase its LSPR efficiency and sensitivity. Synthesis of AuNPs was carried out utilizing the Turkevich method. The selectivity of the sensor is ensured by the effective immobilization of GluOx on the surface treatment. The linearity of sensor is in the range of 0-1000 U/L, whereas the sensitivity, limit of detection, and detection time are individually found at 7.5 p.m./(U/L), 4.84 U/L and 20 min, respectively. After evaluating the prospective applications of the sensors, the sensors' reusability, reproducibility, stability, pH test, and selectivity have all been found to be satisfactory. Proposed fiber optic biosensors have high sensitivity, robustness, reliability, fast detection, no electromagnetic interference, low cost, real-time monitoring, and biocompatible.

A portable electrochemical sensing platform for serotonin detection based on surface-modified carbon fiber microelectrodes

Serotonin (5-HT) is one of the key neurotransmitters in the human body, regulating numerous physiological functions. A disruption in 5-HT homeostasis could result in serious health problems, including neurodegenerative disorders, depression, and 5-HT syndrome. Detection of 5-HT concentrations in biological fluids, such as urine, is a potential solution for early diagnosis of these diseases. In this study, we developed a novel, simple, and low-cost electrochemical sensing platform consisting of a portable workstation with customized electrodes for 5-HT detection in artificial biological fluids. Nafion/carbon nanotubes (CNTs) and electrochemically modified carbon fiber microelectrodes (Nafion-CNT/EC CFMEs) displayed improved 5-HT sensitivity and selectivity. Together with a customized Ag/AgCl reference electrode and Pt counter electrode, the portable 5-HT sensing platform had a sensitivity of 0.074 μA μM^-1 and a limit of detection (LOD) of 140 nM. This system was also assessed to measure 5-HT spiked in artificial urine samples, showing nearly full recovery rates. These satisfactory results demonstrated that the portable system exhibits outstanding performance and confirmed the feasibility of 5-HT detection, which can be used to provide point-of-care analysis in actual biological samples.

Low-Cost High-Resolution Potentiostat for Electrochemical Detection of Nucleic Acids and Biomolecular Interactions

A handheld USB-powered instrument developed for the electrochemical detection of nucleic acids and biomolecular interactions is presented. The proposed instrument is capable of scanning ± 2.25 V while measuring currents up to ±10 mA, with a minimum current resolution of 6.87 pA. Therefore, it is suitable for nucleic acid sensors, which have high background currents. A low-cost microcontroller with an on-chip 16-bit analog-to-digital converter, 12-bit digital-to-analog converter, and a built-in USB controller were used to miniaturize the system. The offset voltages and gain errors of the analog peripherals were calibrated to obtain a superior performance. Thus, a similar performance to those of the market-leader potentiostats was achieved, but at a fraction of their cost and size. The performance of the application of this proposed architecture was tested successfully and was found to be similar to a leading commercial device through a clinical application in the aspects of the detection of nucleic acids, such as calf thymus ssDNA and dsDNA, and their interactions with a protein (BSA) by using single-use graphite electrodes in combination with the differential pulse voltammetry technique.

Development of an Integrated Optical Sensor for Determination of β-Hydroxybutyrate Within the Microplatform

Ketone bodies (acetoacetate, beta-hydroxybutyrate (βHB), acetone) are generated as a result of fatty acid oxidation in the liver and exist at low concentrations in urine and blood. Elevated concentrations can indicate health problems such as diabetes, childhood hypoglycemia, alcohol, or salicylate poisoning. Development of portable and cost-effective bedside point-of-care (POC) tests to detect such compounds can help to reduce the risk of disease progression. In this study, βHB was chosen as a model molecule for developing an optical sensor-integrated microplatform. Prior to sensor optimization, βHB levels were measured at a concentration range of 0.02 and 0.1 mM spectrophotometrically, which is far below the reported elevated ranges of 1-2 mM and resulting absorbance changes were converted into an Arduino microcontroller code for the correlation. Measurements performed with the designed integrated microplatform were found significant. Integrated microplatform was verified with the benchtop spectrophotometer. Measurements between 0.02 and 0.1 mM substrate concentration were found highly sensitive with "y = 0.7347x + 0.00184" with R² value of 0.9796, and the limit of detection was determined as 0.02 mM. Based on these results, the proposed system will allow on-site and early intervention.

Determination of Uric Acid in Artificial Saliva with Compact AMP3291 Reader and Au Nanoparticles Modified Electrode

Uric acid (UA) is a residual product of purines in the body and has been proposed as a valuable biomarker for Diabetes Mellitus, renal disorder, hypertension and preeclampsia. This work presents a sensing platform for nonenzymatic UA detection using a screen-printed electrode modified with gold nanoparticles (SPE-AuNps) operated with the compact and low-cost amperometric reader AMP3291. This laboratory-made instrument was designed using the analog front end LMP91000 and the microcontroller ESP32; the operational parameters like working potential, acquisition time and dynamic measuring range were configured for UA detection. The whole sensing system (AMP3291+ SPE-AuNps) was evaluated for nonenzymatic sensing of UA, showing a fast response time of 3.5 s, a sensitivity of 0.022 μA·μM−1, a linear range from 20 to 200 μM (R2 = 0.993) and a limit of detection of 11.91 μM. Throughout, a piece of commercial equipment was used for validation and noticeably the measurements with the AMP3291-based platform showed improved performance, indicating the feasibility of the developed instrument for UA monitoring and potentially for in situ decentralized applications. Finally, artificial saliva was used as model medium exhibiting interesting analytical parameters, encouraging to consider the reported system as a potentially valuable tool for monitoring UA for clinical applications in resource-limited settings.