Biosensors and Bioelectronics: X最新文献

MicroRNAs (miRNAs) are small non-coding RNA regulators linked to various human diseases incl. heart disease, a leading cause of death in Western countries. Their alterations signify the need for early detection methods. We devised a diffusion microbead assay, combining it with antibody-based miRNA detection. Diffusion involves co-diffusion of miRNAs and antibodies in a microchamber. Randomly ordered size and dye encoded microbeads loaded with specific capture probes target heart disease-associated miRNAs. MiRNA detection is time- and dose-dependent using an anti-DNA:RNA hybrid antibody. The miRNAs are successively exposed to randomly ordered microbeads, which leads to microbeads that become saturated with the target molecules first in front rows. Unbound miRNAs diffuse further and bind to microbeads with free binding sites. Our assay provides real-time multiplex detection of multiple miRNA within 2 h in an isothermal amplification-free environment, with low detection limits (miR-21-5p: 0.21 nM; miR-30a-3p: 0.03 nM; miR-93-5p: 0.43 nM). This study presents a miRNA detection principle that differs from other microbead assays where all microbeads are simultaneously mixed with the sample solution, so that all target molecules bind to microbeads equally, ultimately resulting in an averaged signal intensity.

Organ-on-a-Chip, or OOC, is a widely discussed topic in science due to its many unique advantages in the biomedical field. Nevertheless, there is still much to learn about OOC's various aspects of conception and its significance for the advancement of medical technology in the future. A platform for organs-on-a-chip must go through the fabrication process. Various manufacturing processes were also used depending on the required disease modelling and drug screening. Organs on a chip technology included the Brain-On-Chip, Kidney-On-Chip, Liver-On-Chip, and Heart-On-Chip. In order to provide new beginnings with a thorough understanding of OOC, we have studied the most recent developments in organ-on-a-chip expertise and critically assessed its relevant features in this research.

We report a highly sensitive electrochemical immunosensor based on a nanohybrid platform for the detection of the breast cancer biomarker human epidermal growth factor receptor 2 (HER 2). NanoDiamond (nanoD) and gold nanoparticles (AuNPs) immobilised by drop coating and electrodeposition methods, respectively, were employed to fabricate an immunosensor for HER 2 detections on a glassy carbon electrode (GCE). Voltammetry and electrochemical impedance spectroscopy (EIS) techniques were used to characterise each step of the modification process of the immunosensor. In addition, transmission electron microscopy (TEM), X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques were used to characterise the materials used to fabricate the modified electrode. Under optimal conditions of temperature, time, and pH (35 °C, 50 min, and pH 7.2), different concentrations were investigated within a wide range of 1 pg mL⁻¹ to 50 ng mL⁻¹ using differential pulse voltammetry (DPV). With a low detection limit of 0.29 pg mL⁻¹ from the DPV analysis, the immunosensor showed very good sensitivity and had a high specificity for HER 2. Additionally, the immunosensor demonstrated good applicability in the analysis of HER 2 in human serum samples, demonstrating a potential for use in the early identification of breast cancer.

A novel non-enzymatic sensor has been developed for continuous glucose measurement in physiological body fluids using a Step-wise; amperometric method. Unlike; traditional nickel-based catalysts, this sensor overcomes challenges in biological and neutral pH environments. It utilizes a carbon fiber microelectrode modified with gold and nickel nanoparticles, reinforced by a biopolymer layer derived from quince seed mucilage (QSM). By applying a negative pretreatment potential step, hydroxide ions are locally generated, creating a partially alkaline environment that activates the nickel nanoparticles. Glucose concentration is determined by measuring the current at the electrocatalytic potential of nickel, which directly oxidizes glucose. To clean and reactivate the sensor, a positive pulse potential step is applied at the end of each cycle. The sensor exhibits high sensitivity (13.8 μA mM⁻¹.mm⁻²) and a low limit of detection (11.3 μM) in neutral pH (7.4). These results demonstrate the promising performance of the sensor for continuous glucose measurement in physiological body fluids. Using eco-friendly and biocompatible QSM as a reinforcing layer enhances its potential for biomedical applications. Additionally, a wearable compact electronic module was designed and fabricated to apply the potential, read the sensor's output currents, and monitor and record the results. The module's performance in measuring glucose in blood plasma is comparable to that of a commercial glucometer.

Viruses are infectious agents that cause various diseases worldwide. The recent COVID-19 pandemic has shown the need for rapid and reliable tests to confirm viral infections, aiming at the rapid isolation, treatment, and identification of high-incidence regions. Rapid antigen tests based on lateral flow immunochromatography have proven to be very useful. However, they are not accurate in patients with low viral loadings. The gold standard test is RT-PCR, which identifies parts of the viral genome by detecting specific DNA or RNA sequences. RT-PCR or similar tests such as RT-LAMP involve several steps for sample preparation and amplification of target sequences, require trained personnel to be performed, and can be time-consuming and expensive, limiting their point-of-care application. Biosensors are promising analytical devices for detecting nucleic acids, mainly RNA from viruses, offering advantages such as rapid results, high sensitivity, and low cost compared with the RT-PCR test since the amplification of target sequences is not necessary. Recently, several biosensors have been developed to detect RNA viruses without sequence amplification. Here, we present a review on the design and technology of amplification-free biosensors for the detection of viral RNA as an alternative for diagnosing infectious diseases. The challenges and advances for the point-of-care electrochemical, electrical, and optical biosensors will be addressed.

In this study, we examined the relationship between the sensitivity of interdigitated electrode (IDE) impedimetric biosensors and the gap between the IDEs. Our aim is to find an optimal design to maximize sensitivity. A three-dimensional COMSOL model was constructed for determining the effects of electrode gap, width, and height on impedance sensitivity, revealing a singular linear correlation with the inner gap. Considering both the simulation results and fabrication processes, we have developed three IDE prototype chips with electrode gaps of 3 μm, 4 μm, and 5 μm, respectively. For empirical validation, human anti-SARS-CoV-2 monoclonal antibody (mAb) was utilized, with immobilization of the SARS-CoV-2 spike protein on the chip's surface for mAb capture. This interaction, further amplified by Protein G conjugation, induced shifts in the impedance spectrum. The sensitivity of each prototype chip was evaluated across mAb concentrations ranging from 50 ng/mL to 500 ng/mL. The 3 μm configuration emerged as the most sensitive, demonstrating the ability to detect mAb concentrations as low as 50 ng/mL, a threshold unattainable by the other designs. This outcome underscores the critical influence of reduced inter-electrode gap on enhancing biosensor detection limits. The findings from this investigation offer a foundational approach for advancing biosensor sensitivity via electrode geometric optimization, with broad potential applications extending beyond COVID-19 diagnostics to a wide spectrum of clinical and research contexts.

Early prostate cancer detection can be improved by detecting more specific markers like PCA3 RNA. This study reports a novel and simple method for detecting PCA3 RNA using a sensor based on reduced graphene oxide (RGO), gold nanoparticles (AuNP), and a single-stranded DNA (ssDNA). The device was characterized at each fabrication step using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). The RGO/AuNP/ssDNA sensor exhibited a significant change in resistance (6.51–15.01%) when exposed to varying concentrations of PCA3 (0.1–100 ng/mL). The developed device showed selective response towards PCA3 (14.5% for 50 ng/mL) when compared with negative controls like phosphate buffer saline solution (0.28%), PCA3-negative control sample (1.03%), RNA extracted from lung cancer (0.88%), and breast cancer (1.17%) cell lines. The RGO/AuNP/ssDNA sensor could also be employed to quantify the PCA3 RNA present in the RNA mixture extracted from a prostate cancer cell line and the observed findings were in excellent agreement with semi-quantitative real-time polymerase chain reaction (RT-PCR) results.

High concentrations of H₂O₂, indicative of increased oxidative stress in the lung, are observed in the exhaled breath of individuals affected by different respiratory diseases. Therefore, measuring H₂O₂ in exhaled breath represents a promising and non-invasive approach for monitoring the onset and progression of these diseases. Herein, we have developed an innovative, inexpensive, and easy-to-use device for the measurement of H₂O₂ in exhaled breath. The device is based on a silver layer covered with an electrodeposited thin film of chitosan, that ensures the wettability of the sensor in a humid atmosphere. The s-ensor was calibrated in the aerosol phase using both phosphate buffer solution and cell culture medium. In the buffer, a sensitivity of 0.110 ± 0.0042 μA μM⁻¹ cm⁻² (RSD: 4%) and a limit of detection of 30 μM were calculated, while in the cell culture medium, a sensitivity of 0.098 ± 0.0022 μA μM⁻¹ cm⁻² (RSD 2%) and a limit of detection of 40 μM were obtained. High selectivity to different interfering species was also verified. The sensor was further tested versus an aerosol phase obtained by nebulizing the culture medium derived from human bronchial epithelial cells that had been exposed to pro-oxidant and antioxidant treatments. The results were comparable with those obtained using the conventional cytofluorimetric method. Finally, sensor was tested in real exhaled breath samples and even after undergoing physical deformations. Data herein presented support that in future applications this device can be integrated into face masks allowing for easy breath monitoring.

The detection of endogenous hormones is of great significance for disease diagnosis, treatment guidance, and the development of personalized healthcare. By using biosensors, real-time monitoring and quantitative analysis of endogenous hormone levels can be achieved, providing scientific basis for clinical decision-making. The continuous innovation in this field will bring new breakthroughs in medical diagnosis and treatment, which are expected to accelerate the early detection of diseases and the implementation of personalized treatment plans. In this review, we mainly review the research progress of endogenous hormone biosensors based on different biological recognition elements, namely enzyme-based biosensors, immunobiosensors, aptamer-based biosensors, and molecularly imprinted polymer (MIP) based biosensors. Meanwhile, this paper also analyzes the detection efficiency and clinical application of these biosensors. Finally, we summarize the current challenges and future development directions of the different types of biosensors involved in the discussion.

The overexpression of folate receptors on cell surfaces is associated with abnormalities linked to epithelial cancers. This study reports on a capacitive biosensor that employs folic acid as a recognition molecule for the biosensing of folate receptors. The biosensor is composed of a thin film of Ti–W oxides conjugated with folic acid that serves as a working electrode in a three-electrode electrochemical cell configuration. The thin film of Ti–W oxides, featuring a mixture of TiO₂ anatase and rutile phases, was fabricated using the pulsed laser deposition method and subsequently functionalized with folic acid. Characterization of the thin film before and after functionalization was conducted using AFM, XPS, and contact angle measurements. The functionalization study confirmed a stable bond between folic acid and the surface of the thin film. The interaction between the functionalized transducer and the folate receptor was investigated by determining the electrochemical capacitance using an electrochemical capacitance spectroscopy setup. Folate receptor recognition assays demonstrated that the biosensor response signal, or chemical hardness (in terms of electrochemical capacitance), is selective and directly proportional to the folate receptor concentration, with a limit of detection of 200 pM (0.2 nM). These findings are promising for the application of this detector in the recognition of folate receptors, particularly for point-of-care analysis.