Biosensors and Bioelectronics: X最新文献

Infections cause concern for mankind, and sometimes their diagnosis may take much time. Owing to its high sensitivity, rapidity, and specificity, the immunochromatographic assay (ICA) is used widely to diagnose infections. The use of the ICA for this purpose makes it possible to detect dangerous diseases early, prevent their progress, strongly reduce the treatment cost and mortality, and increase life expectancy. One promising ICA format involves the use of gold nanoparticles. Here we present the principles and history of ICA use for the diagnosis of infections and discuss the prospects for using gold nanoparticles in the ICA. We present data on the methods used to make and conjugate gold nanoparticles and on the effect of particle size and shape on ICA sensitivity. We discuss the prospects for using the ICA to diagnose bacterial and viral infections, and we review instrumental methods for quantifying ICA results. Finally, we discuss the prospects for using the gold nanoparticle–based ICA in the diagnosis of infections.

This study focuses on the first-ever high-sensitivity, low-cost, and quick response electrochemical estimation of metadoxine (MTD) in pharmaceuticals and human blood serum using a non-enzymatic nanocomposite modified glassy carbon electrode (CuO/CH/GCE) loaded with chitosan. The electroactive surface of GCE was produced by drop-casting a suspension of CuO/CH nanocomposite in N,N-dimethylformamide (DMF) onto the non-enzymatic electrode surface. Synthesized nanocomposite was characterised by using XRD, XPS, EDX, TEM, Raman and FESEM techniques. EIS technique was utilized to study the enhanced charge-transfer phenomenon occurring at the surface of modified sensor. The electrooxidation of MTD at CuO/CH/GCE surface is depending at pH of supporting electrolyte, scan rate and concentration of analyte. CV and SWV technique were used to carry out electrochemical study, optimised voltammetric response is observed in the BR buffer at pH 2.5, with irreversible diffusion-controlled process. Within the linear concentration range of MTD from 1.99 μg/L to 29.56 μg/L, this sensor exhibited lowest LOD (0.64 μg/L) and LOQ (2.14 μg/L). The MTD in pharmaceutical formulation and human blood serum can be determined with this highly selective peak potential (Ep ∼ 1.2 V), repeatable (%RSD 0.91), and reproducible (%RSD 2.31) method. The average percentage recovery in human blood serum and pharmaceutical formulation is 99.89% and 99.90%. This paper reports a lowest LOD value for MTD detection in the comparison with other reported methods (Table S1). None of the selected excipients were found to interfere more than 5% with redox potential of MTD without affecting the performance of sensor.

In this work, nickel oxide (NiO) nanostructures deposited by glancing angle deposition (GLAD) are fabricated to achieve highly specific catalytic electrooxidation of lactate, replacing the natural enzyme lactate oxidase for electrochemical detection of lactate in sweat. GLAD NiO electrodes exhibit high sensitivity (412 μA mM⁻¹ cm⁻²), wide linear detection range (1–45 mM), low detection limit (3 μM), and excellent specificity in artificial sweat samples. The unique microporous structure of the GLAD NiO electrodes, combined with their high surface area, high catalytic activity, and excellent conductivity, enhance the performance of the sensor and demonstrate their exceptional effectiveness in the sensitive detection of lactate. In-house fabricated gold counter, and stable solid-state Ag/AgCl reference electrodes, all fabricated on a flexible PET substrate along with the GLAD NiO working electrode, demonstrate performance comparable to commercial Pt auxiliary and Ag/AgCl (1M KCl) reference electrodes in lactate detection, along with outstanding flexibility, tested at various radii of curvature (15 mm, 7.5 mm, and 5 mm). The durable and long-lasting GLAD NiO electrode chips overcome numerous challenges in transport, storage, and operation, paving the way for the development of wearable lactate sensors that can detect lactate levels in sweat.

Synthetic single-stranded oligonucleotides play crucial roles in DNA amplification reactions for various applications, such as serving as primers, enabling magnetic separation, and generating dsDNA for subsequent digestion. Typically, these oligos are added in excess to ensure rapid binding to their intended targets. However, while performing rolling circle amplification (RCA) using phi29 DNA polymerase, we observed a decrease in amplification efficiency when oligos were present in the reaction. This phenomenon was consistently observed in two separate laboratories, prompting this study to delve into the root causes responsible for the decline in RCA efficiency. The lowered efficiency was consistent regardless of the manufacturer or any mutations in the phi29 polymerase. We identified several variables that influenced RCA efficiency, mainly the length of the oligos used and the presence of modifications, particularly those obstructing 3’ end digestion. This strongly suggests that the exonuclease domain of phi29 DNA polymerase is responsible for the competition-based inhibition. Our investigation shows that even picomole quantities of oligos can significantly reduce total DNA production during the phi29 DNA polymerase-mediated amplification process. Conversely, the addition of oligos to the reaction did not impede the efficiency of Bst 3.0 polymerase, likely due to the lack of an exonuclease domain of said polymerase. While increasing the quantity of phi29 DNA polymerase in the reaction partially alleviated the adverse effects of excess oligos, we believe it is crucial to carefully optimize the oligo quantities to achieve maximum amplification of the desired targets.

Vibrio vulnificus (Vv) is a marine pathogen that can cause rapid death by septicemia (vibriosis) in humans and several fish species. This pathogen is considered a biomarker of climate change, as both its presence and vibriosis incidence in coastal environments are increasing because of global warming. Currently, gold-standard methods for Vv detection are all PCR-based, requiring expensive equipment and skilled personnel, which hinders their use on a global scale. The aim of this work was to design and test a more affordable method that could be used worldwide for both vibriosis diagnosis and pathogen monitoring in water. To this end, we functionalized thin film microelectrodes with thiolated single-stranded DNA sequences complementary to the species-specific genetic marker, the gene vvha, and monitored the impedance changes upon hybridization. We tested the biosensor specificity with synthetic and natural DNA samples (from cultures of Vv and V. cholerae, a closely related species) and determined the detectable concentration range. The results obtained showed that this biosensor was specific for Vv, achieving detection down to 1 pM synthetic DNA and DNA extracted from 10² bacteria mL⁻¹, which is equivalent to that obtained by PCR. Consequently, this biosensor could be used on a global scale for vibriosis diagnostics, health risk studies and climate change monitoring, with potential application for in situ detection.

The manuscript describes a technique for fabrication and validation of a standalone handheld optical biosensor designed for non-invasive monitoring of glucose through saliva. In this cost-effective process, a 3D-printed glucose test strip was filled with sieving paste comprising of cellulose, polyethylene glycol (PEG), polyvinyl alcohol (PVA) and glycerol, onto which, glucose oxidase-peroxidase (GOD-POD) enzymes and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) chromogenic dye were co-immobilized. The enzymatic reaction produced H₂O₂ as by-product with which the ABTS reacted, leading to colour change on the detection zone of the strip which was detected by the developed glucometer. The in-house developed meter included an optically isolated section in its structure for inserting the strip to prevent interference from the ambient light conditions. The biosensor exhibited a broad detection range of 28–204 mg/dL of glucose concentration, with a sensitivity of 26.89 count/mg/dL and a limit of detection (LOD) at 28 mg/dL, within a response time of 120 s. The device along with strips was validated with clinical samples, comparing salivary glucose levels (SGL) to blood glucose levels (BGL) using a commercial glucometer i.e., Accu-Chek Active. Student's t-test on clinical data yielded p-values of 0.018, 0.01, 0.008, and 0.003 in fasting and post-prandial samples of non-diabetic and diabetic patients respectively, which represents a significant correlation. The device also passed Clarke's error grid analysis and is hence considered medically acceptable. The low-cost and simple-to-use saliva-based glucometer should be ideally suited for mass screening of diabetes as well as day-to-day health check-ups in a non-invasive and painless manner.

Methylglyoxal (MG) is a prominent biomarker for diabetic syndromes and ageing disorders. In the present study, a non-enzymatic electrochemical detection of MG in human saliva at low levels was achieved via polyaniline/nickel oxide nanohybrid modified graphite sheet (PANI/NiO/GS) electrode. The physical characteristics and structure of the PANI/NiO nanohybrid showed the presence of NiO flakes embedded within the irregular granular like structure of PANI matrices. Chronoamperometric (CA) analysis of the nanohybrid electrode showed excellent electrocatalytic activity towards MG with the linear range from 1 to 10 μM in 0.1 M phosphate buffer (pH 7). The proposed sensor boasts a high sensitivity of 1.136 μA.μM⁻¹ including a lower limit of detection of 2.64 nM. The real-time functionality of the proposed biosensor was also employed to estimate the precise quantification of MG levels in both healthy and diabetic patients' saliva. For the healthy and diabetes samples, the recovery values for MG were 95–103 % and 102–111 %, respectively. This approach is truly noninvasive and circumvents the discomforts associated with the traditional modalities.

The threat posed by microbial infections to human health remains very significant, particularly in considering the increasing mechanisms of antibiotic resistance. Pseudomonas aeruginosa is known for its antibiotic resistance and is linked to serious conditions like ventilator-associated pneumonia and cystic fibrosis. Rapid infection elimination relies on identifying harmful bacteria and preventing colonization. Due to the redox-active nature of P. aeruginosa biomarkers metabolites, several electrochemical sensing approaches are being evaluated as diagnostic platforms for the rapid and precise detection of P. aeruginosa with high sensitivity. These sensors must be developed and modified to achieve optimal selectivity, sensitivity, and biocompatibility, enabling dynamic, real-time metabolite detection. This minireview highlights recent advancements in electrochemical and optical biosensors for detecting P. aeruginosa biomarkers, particularly pyocyanin. It highlighted design, analytical performance, biological recognition elements, and personalized wearable electrochemical sensor devices. It concludes with the future suggestions of sensor concepts for clinical diagnostics, environmental monitoring, and food safety.

Soil Health parameters serve as excellent surrogate measures towards assessing environmental quality and understanding effects of climate change mitigation via carbon sequestration. Soil Organic Matter (SOM) is a parameter that is synonymous to soil health and understanding SOM is a key metric to building and influencing good soil and agronomic practices by impacting soil aggregation and water withholding capacity. It is a vital regulator of soil nutrient cycling and uptake as well as a factor in the global carbon cycle and is hence more advantageous than just carbon monitoring. While it is understood that soil health cannot be analyzed directly, the use of an efficient indicator that can relay information about the soil physico-chemical and biological characteristics is highly desirable since it offers the ability to analyze soil information over time and build patterns in terms of geographical location.

The proposed sensing system offers an in-situ electroanalytical approach to survey various electroactive substances present in the soil matrix. Utilizing this experimental framework- A mechanism of interaction between the RTIL (Room Temperature Ionic-Liquid) modified electrode and the OM functional moieties based on hydrogen bonding and pi-pi interactions captured using electrochemical impedance spectroscopy method is utilized to build a first-of-a-kind electrochemical SOM sensor.

Excessive consumption of antibiotics like gentamicin (GEN) can lead to hostile effects as antibiotic resistance. Therefore, the detection is important for which, reduced graphene oxide-Gadolinium oxide nanocomposite (rGO@Gd₂O₃ NC) was composed through co-precipitation method for the detection of GEN. The structural, morphological and functional group characterizations were done using XRD, FT-IR, SEM and TEM techniques. The cyclic voltammetry (CV) showed excellent electrocatalytic activity and superior performance towards GEN detection. Through the use of GEN monoclonal antibodies (anti-GEN) on a screen-printed electrode (SPE), a very sensitive electrochemical immunosensor was fabricated. Covalent interactions were employed to construct the electrochemical immunosensor, while bovine serum albumin (BSA) was employed as a blocking agent on the anti-GEN/rGO@Gd₂O₃/SPE electrode surface. The analysis of the CV response of the BSA/anti-GEN/rGO@Gd₂O₃/SPE bioelectrode demonstrated linear detection range from 1 pM – 100 μM, along with limit of detection (LOD) of 0.424 pM and sensitivity of 44.87 μA pM^-1 cm^{− 2}. Additionally, rGO@Gd₂O₃ immunosensor, exhibited a good level of linearity with R² value of 0.978. These findings indicate the excellent potential of the rGO@Gd₂O₃ electrochemical immunosensor for accurately detecting GEN in spiked milk samples at different concentrations.