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AimsClostridium perfringens is one of the major anaerobic pathogen causing food poisoning and animal enteritis. With the rise of antibiotic resistance and the restrictions of the use of antibiotic growth promoting agents (AGPs) in farming, Clostridium enteritis and food contamination have become more common. It is time-consuming and labor-intensive to confirm the detection by standard culture methods, and it is necessary to develop on-site rapid detection tools. In this study, a combination of recombinase polymerase amplification (RPA) and lateral flow biosensor (LFB) was used to visually detect C. perfringens in chicken meat and milk.Methods and resultsTwo sets of primers were designed for the plc gene of C. perfringens, and the amplification efficiency and specificity of the primers. Selection of primers produces an amplified fragment on which the probe is designed. The probe was combined with the lateral flow biosensor (LFB). The reaction time and temperature of RPA-LFB assay were optimized, and the sensitivity of the assay was assessed. Several common foodborne pathogens were selected to test the specificity of the established method. Chicken and milk samples were artificially inoculated with different concentrations (1 × 102 CFU/mL to 1 × 106 CFU/mL) of C. perfringens, and the detection efficiency of RPA-LFB method and PCR method was compared. RPA-LFB can be completed in 20 min and the results can be read visually by the LFB test strips. The RPA-LFB has acceptable specificity and the lowest detection limit of 100 pg./μL for nucleic acid samples. It was able to stably detect C. perfringens contamination in chicken and milk at the lowest concentration of 1 × 104 CFU/mL and 1 × 103 CFU/mL, respectively.ConclusionIn conclusion, RPA-LFB is specific and sensitive. It is a rapid, simple and easy-to-visualize method for the detection of C. perfringens in food and is suitable for use in field testing work.

Increased level of CD44, transmembrane glycoprotein, is observed in several cancers such as breast, colorectal, head and neck, gastric, and ovarian cancer. Current methods for analyzing CD44 expressing cells are time-consuming, semi-quantitative, use labeled reagents for analysis or are not suitable for in situ analysis. Therefore exploring novel methods which are label-free and fast with the in situ detection capability for the quantification of these cells is of importance.Using optical fiber as a sensing element in biosensors offers low cost, high sensitivity, chemical inertness, and immunity to electromagnetic interference, and possibility of being used in in situ applications. This study reports the first label-free optical fiber biosensor for detection of CD44-expressing cancer cells. A fiber-optic ball resonator (BR) sensor was fabricated and then functionalized with CD44 antibodies. Different concentrations of the cells were incubated with the biosensor to measure the reflected light using optical backscatter reflectometer. The biosensor was able to detect cancer cells with a limit of detection of 335 cells/mL. The presence of the cells on the sensor surface was demonstrated by fluorescent and scanning electron microscope analysis. The work is the first proof-of-concept biosensor based on optical fibers for CD44 cancer cells and acts as a promising tool for in situ detection of cancer cells.

In this work, a novel electrochemical thyroglobulin (Tg) biosensor was fabricated based on modification of a glassy carbon electrode with chitin-ionic liquid (Ch-IL) and gold nanoparticles (Au NPs). Surface of the Au NPs/Ch-IL/GCE was investigated and optimized by the image processing method. Drop-casting of the Ch-IL was performed onto the surface of Au NPs/Ch-IL/GCE to fabricate Ch-IL/Au NPs/Ch-IL/GCE. Then, sortilin (ST) was immobilized onto its surface by the use of glutaraldehyde. Biosensing of Tg in the range of Tg in the range of 0.1 to 8.5 fM was based on its interaction with the ST and change in hydrodynamic differential pulse voltammetric (DPV) response of the biosensor. The second-order calibration methods by U-PLS/RBL, N-PLS/RBL, MCR-ALS and PARAFAC2 were used to determination of Tg in the presence of thyroxine and triiodothyronine as uncalibrated interference, and our results confirmed the best performance was observed for exploiting second-order advantage by PARAFAC2 (sensitivity: 2.8 μA/fM, selectivity: 0.49, inverse of analytical sensitivity: 0.11 fM−1, limit of detection: 0.01fM) which was used to determination of Tg in human serum samples the presence of triiodothyronine and thyroxine as uncalibrated interference with the aim of detection of thyroid cancer treatment success. The ST/Ch-IL/Au NPs/Ch-IL/GCE assisted by PARAFAC2 was an excellent electronic device for medical diagnostic purposes.

The ongoing global concern of cancer worldwide necessitates the development of advanced diagnostic and therapeutic strategies. The majority of recent detection strategies involve the employment of biomarkers. A critical biomarker for cancer immunotherapy efficacy and patient prognosis is Programmed Death Ligand 1 (PD-L1), which is a key immune checkpoint protein. PD-L1 can be particularly linked to cancer progression and therapy response. Current detection methods, such as enzyme-linked immunosorbent assay (ELISA), face limitations like high cost, time consumption, and complexity. This study introduces a microcantilever-based biosensor designed for the detection of soluble PD-L1 (sPD-L1), which has a specific association with PD-L1. The biosensor utilizes anti-PD-L1 as the sensing layer, capitalizing on the specific binding affinity between anti-PD-L1 and sPD-L1. The presence of the sensing layer was confirmed through Atomic Force Microscopy (AFM) and contact angle measurements. Binding between sPD-L1 and anti-PD-L1 induces a shift in the microcantilever's resonance frequency, which is proportional to the PD-L1 concentration. Notably, the resonance frequency shift demonstrates a robust linear relationship with the increasing biomarker concentration, ranging from 0.05 ng/ml to 500 ng/ml. The detection limit of the biosensor was determined to be approximately 10 pg/ml. The biosensor demonstrates excellent performance in detecting PD-L1 with high specificity even in complex biological matrices. This innovative approach not only provides a promising tool for early cancer diagnosis but also holds potential for monitoring immunotherapy efficacy, paving the way for personalized and effective cancer treatments.

In the dynamic field of electrochemical biosensors, the demand for facile yet highly sensitive electrode materials is paramount. This study presents an innovative electrochemical biosensor material designed for the detection of biologically crucial molecules-Tryptophan (Trp) and Bovine Serum Albumin (BSA) utilizing ZrO2 nanoparticles (NPs). Through a successful hydrothermal synthesis, nanosized ZrO2 was employed to modify a glassy carbon electrode (GCE), constituting a novel electrochemical biosensor material. Characterization techniques, including XRD, FE-SEM, EDS, and FT-IR, elucidated the monoclinic crystalline structure, cauliflower-like surface morphology, elemental composition, and chemical state of the prepared NPs. Optical properties were explored using UV–Visible and photoluminescence spectroscopic methods. The electrochemical sensing ability of ZrO2 NPs modified GCE were evaluated through cyclic voltammetry (CV) techniques with meticulous optimization of measurement parameters, revealing a modified GCE shows superior electrocatlytic property towards detection of Trp and BSA molecules as compared to bare GCE due to the large specific surface area of the ZrO2 NPs. The ZrO2 NPs modified GCE exhibited exceptional electrochemical signals, showcasing a linear response within concentration ranges of 1–16 μM for Trp and 1.50–42 nM for BSA. Impressively low detection limits of 0.49 μM and 0.90 nM for Trp and BSA, respectively, were achieved. The electro-oxidation mechanism of Trp were investigated by varying the scan rates and the relation between peak and scan rate revealed that, oxidation process of Trp at ZrO2 NPs modified GCE is an adsorption-controlled process. Further, the effect of interference substance on detection of Trp and BSA were conducted by linear sweep volatmmetry measurements in the absence and presence of interfering compounds, and results endorse that, ZrO2 modified GCE has good selectivity in detection of Trp and BSA. This novel electrochemical sensor demonstrated significant sensitivity, selectivity and a low detection limit, underscoring the potential for ZrO2 NPs in advancing the development of biosensor devices.

Present study examines the protein concentration detection capabilities of biosensor (AB)5D(AB)5 composed of a one-dimensional annular photonic crystal with defect theoretically. The simulation results of this work have been obtained by MATLAB programming based on the modified transfer matrix method. The entire simulation work has been carried out in the visible region of electromagnetic spectrum. The proposed biosensor (AB)5D(AB)5 is consisted of alternating cylindrical layers A and B of materials titanium oxide (TiO2) and silicon oxide (SiO2) respectively. The cylindrical cavity layer D of air is introduced at the centre of the biosensor so that sample under investigation can be poured into it. The study examines parameters such as defect cavity thickness, period number, and Core radius to optimise the biosensor for maximum protein detection performance. The performance of the proposed biosensor becomes optimum with the defect layer thickness 650 nm, period number 5 and Core radius 103 nm. Under optimum conditions biosensor yield maximum sensitivity of 576.27 nm/nmol/L corresponding to sample of protein concentration of c = 10 nmol/L. The numeric values of figure of merit, quality factor and limit of detection of the proposed biosensor 4432.85 nmol/L, 5630.76 and 1.1 × 10−5 respectively. The proposed design shows the ability to detect minute change in protein concentration of the sample of order 10−5. The structural symmetry and the simple implementation of our structure makes it suitable for clinical diagnostics and environmental monitoring.

Total antioxidant capacity of food is one of the critical parameters to evaluate its efficacy. Establishment of a fast and sensitive analytical method for the detection of total antioxidant capacity of food has great significance. In this paper, a metal-organic framework complex nanozyme (Fe-HHTP@ZIF-8) with peroxidase-like activity was firstly designed and successfully synthesized. Then, the morphology, structure and catalytic activity were characterized in detail. The results showed that Fe-HHTP@ZIF-8 possessed a two-dimensional ultra-thin layer structure while its Km and Vmax values towards H2O2 were 0.67 mmol/L and 3.55×10−8 mol/L·s−1, respectively. Ascorbic acid (AA) as a typical antioxidant, an efficient colorimetric biosensor was constructed based on its inhibitory effect on chromogenic reaction catalyzed by nanozyme. Comprehensive validation showed that the colorimetric biosensor had low limit of detection (1.67 μmol/L), wide linear range (5.0~3000.0 μmol/L) and high accuracy (recovery rate of 98.62%~103.13%). By using this colorimetric method, total antioxidant capacity of different beverages was detected and the obtained results were basically consistent with labeled values. Therefore, this study provided a simple, fast and effective colorimetric method for the evaluation of the total antioxidant capacity of food.

Abstract Melatonin is a multifunctional molecule with diverse biological roles that holds great value as a health-promoting bioactive molecule in any food product and yeast’s ability to produce it has been extensively demonstrated in the last decade. However, its quantification presents costly analytical challenges due to the usual low concentrations found as the result of yeast metabolism. This study addresses these analytical challenges by optimizing a yeast biosensor based on G protein-coupled receptors (GPCR) for melatonin detection and quantitation. Strategic genetic modifications were employed to significantly enhance its sensitivity and fluorescent signal output, making it suitable for detection of yeast-produced melatonin. The optimized biosensor demonstrated significantly improved sensitivity and fluorescence, enabling the screening of 101 yeast strains and the detection of melatonin in various wine samples. This biosensor’s efficacy in quantifying melatonin in yeast growth media underscores its utility in exploring melatonin production dynamics and potential applications in functional food development. This study provides a new analytical approach that allows a rapid and cost-effective melatonin analysis to reach deeper insights into the bioactivity of melatonin in fermented products and its implications for human health. These findings highlight the broader potential of biosensor technology in streamlining analytical processes in fermentation science.

Aim.Thе purpose of the work was to develop a new construction of enzyme biosensor based on creatinine deiminase for highly sensitive creatinine determination. Methods. A new construction of enzyme biosensor based on creatinine deiminase was developed for the creatinine determination. A differential pair of gold interdigitated electrodes deposited onto a ceramic substrate was used as the electrochemical transducer. Creatinine deiminase was immobilized by cross-linking with glutaraldehyde on the surface of electrodes. Results. The biosensor showed high sensitivity towards creatinine, the limit of detection was 5 µM. The biosensor was characterized by wide linear range of creatinine determination, high reproducibility of responses and showed high storage stability – after 50 days storage the biosensor retained 83% of the initial response value. Conclusions. In future the developed biosensor can be used for express evaluation of the creatinine in biological samples.

Polydopamine nanoparticles (PDA NPs) are widely utilized in the field of biomedical science for surface functionalization because of their unique characteristics, such as simple and low-cost preparation methods, good adhesive properties, and ability to incorporate amine and oxygen-rich chemical groups. However, challenges in the application of PDA NPs as surface coatings on electrode surfaces and in conjugation with biomolecules for electrochemical sensors still exist. In this work, we aimed to develop an electrochemical interface based on PDA NPs conjugated with a DNA aptamer for the detection of glycated albumin (GA) and to study DNA aptamers on the surfaces of PDA NPs to understand the aptamer-PDA surface interactions using molecular dynamics (MD) simulation. PDA NPs were synthesized by the oxidation of dopamine in Tris buffer at pH 10.5, conjugated with DNA aptamers specific to GA at different concentrations (0.05, 0.5, and 5 μM), and deposited on screen-printed carbon electrodes (SPCEs). The charge transfer resistance of the PDA NP-coated SPCEs decreased, indicating that the PDA NP composite is a conductive bioorganic material. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) confirmed that the PDA NPs were spherical, and dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy data indicated the successful conjugation of the aptamers on the PDA NPs. The as-prepared electrochemical interface was employed for the detection of GA. The detection limit was 0.17 μg/mL. For MD simulation, anti-GA aptamer through the 5′terminal end in a single-stranded DNA-aptamer structure and NH2 linker showed a stable structure with its axis perpendicular to the PDA surface. These findings provide insights into improved biosensor design and have demonstrated the potential for employing electrochemical PDA NP interfaces in point-of-care applications.

This article introduces a novel two-dimensional photonic crystal biosensor designed for the detection of various cancer cell types and the verification of associated parameters. The proposed structure features a circular resonator nanoring with a sensing region at its center, facilitating the connection with cancer cells. The sensor has been tested with a diverse range of cancer cell types including skin, cervical, blood, adrenal, and two subtypes of breast cancer cells (Sort 1 and Sort 2). All outputs of the structure were studied at two different wavelengths and its parameters were analyzed separately. The best quality factor obtained for normal and abnormal cells of the target structure is 13,353 and 3053, respectively. Due to its high-quality factor and high FOM and low DL, this sensor has an acceptable sensitivity of 214.28(nm/RIU). FOM and DL in this sensor are equal to 172.35(RIU−1) and 5.80 × 10−4(RIU), respectively. The resonant wavelength shift of this structure is a relatively good value due to the coupling distance between the input wave and the resonator nanoring.

The ongoing COVID-19 pandemic continues to have a significant impact on our daily lives, necessitating the rapid development of early diagnostic tools to mitigate the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreaks. In this context, biosensor technology has emerged as a highly promising strategy to address the challenges of low sensitivity, specificity, and high cost associated with clinical diagnosis. In this study, we present a novel and cost-effective approach for the rapid detection of SARS-CoV-2 using miniaturized flexible carbon fiber (FCF) electrodes that are modified with immunoglobulin G (IgG). Our strategy take advantage of on the antigen-antibody interaction (IgG-SARS-CoV-2) and leverages the surface chemistry characteristics of FCF to achieve signal amplification. Under standard conditions, we achieved a remarkable detection limit of 0.16 pg mmL−1 for the SARS-CoV-2 RBD protein. Additionally, when analyzing human saliva samples, our biosensing approach demonstrated good agreement with RT-PCR results, specifically for patients who tested positive for SARS-CoV-2. The sensitivity, selectivity, and accuracy of our approach were approximately 93.3%.

Goserelin is an effective anticancer drug, but naturally causes several side effects. Hence the determination of this drug in biological samples, plays a key role in evaluating its effects and side effects. The current studies have concentrated on monitoring Goserelin using an easy and quick DNA biosensor for the first time. In this study, copper(II) oxide nanoparticles were created upon the surface of multiwalled carbon nanotubes (CuO/MWCNTs) as a conducting mediator. The modified pencil graphite electrode (ds-DNA/PA/CuO/MWCNTs/PGE) has been modified with the help of polyaniline (PA), ds-DNA, and CuO/MWCNTs nanocomposite. Additionally, the issue with the bio-electroanalytical guanine oxidation signal in relation to ds-DNA at the surface of PA/CuO/MWCNTs/PGE has been examined to determination Goserelin for the first time. It also, established a strong conductive condition to determination Goserelin in nanomolar concentration. Thus, Goserelin’s determining, however, has a 0.21 nM detection limit and a 1.0 nM-110.0 µM linear dynamic range according to differential pulse voltammograms (DPV) of ds-DNA/PA/CuO/MWCNTs/PGE. Furthermore, the molecular docking investigation highlighted that Goserelin is able to bind ds-DNA preferentially and supported the findings of the experiments. The determining of Goserelin in real samples has been effectively accomplished in the last phase using ds-DNA/PA/CuO/MWCNTs/PGE.

The ongoing genetic mutation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) possesses the capacity to inadvertently lead to an increase in both the rates of transmission and mortality. In this study, we showcase the use of an Al2O3/ZrO2 Dual-Dielectric Gr/CNT Nanoribbon vertical tunnel field-effect transistor biosensor for the purpose of detecting spike proteins of SARS-CoV-2 in clinical samples. The proteins mentioned above are situated within the protein capsids of the virus. The effectiveness of the suggested detector has been assessed through measurements of the alteration in current drain. The present study utilizes the dielectric coefficient analogue of viral proteins as a substitute for biomolecules that exhibit internal hybridization nanogaps. The high sensitivity of the suggested detector, as evaluated on a scale ranging from 0 to 115, suggests its potential as a high-quality sensing instrument. The purpose of this study is to examine the sensitivity of DNA charge density with the aim of identifying any alterations in the virus that may impact its ability to spread and infect humans. The chromosomal composition of SARS-CoV-2 has been determined. The CMC Research Centre, situated in Vellore, Tamil Nadu, India, conducted an examination of SARS-CoV-2 samples. The scientists possess the capability to do genome sequencing on these specimens, so facilitating the examination of mutation patterns and the dispersion of different clades. A total of 250 different mutations were found out of the 600 sequences that were evaluated. The sequencing data consists of a complete collection of 250 distinct variants, including 150 missense mutations, 80 synonymous mutations, 15 mutations in noncoding regions, and 5 deletions. The comprehension of genetic variety is significantly dependent on these mutations. The proposed detector is connected to a variety of previously documented biosensors based on field-effect transistors (FETs), which are employed for the examination of genetic modifications.