Sensing and Bio-Sensing Research最新文献

The present work demonstrates the applications of a nanocomposite of the cellulose polymer and ZnO nanoparticles with 1:1 weight ratio, prepared by a green assisted precipitation method for a high-performance resistive type humidity sensor. The morphology and nanostructure of prepared cellulose/ZnO composite were characterization by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and transmission electron microscopy are confirmed the decoration of ZnO nanoparticles on cellulose polymer matrix surface. The humidity sensing martials was coated onto the interdigital electrodes. The sensitivity, response/recover and stability studies performance of fabricated humidity sensors have been monitored in 5 to 98% relative humidity (%RH) at room temperature (37 °C). The response and recovery times of the fabricated sensors are observed as ≈ 26 s and ≈ 53 s respectively, and the sensitivity factor (S_f) is 2656 ± 103 Ω. Possible mechanisms of the humidity sensor based on water-induced conductivity increase are discussed. Also, the energy band of cellulose/ZnO nanocomposite was simulated by density functional theory (DFT) studies. The cellulose/ZnO nanocomposite humidity sensor has great potential for practical field applications.

In this paper, an optical chemical sensor is proposed to detect some toxic gases such as Methane (CH₄), Nitrogen (N₂), Nitrogen dioxide (NO2), and Carbon monoxide (CO). This type of chemical sensor consists of graphene ribbons and Kapton materials as sensing elements. Also, exploits electromagnetic properties such as absorption in terms of signal transducing. These kinds of small-scale, flexible architectures and advanced detection techniques are in demand to identify toxic gases as well. To develop the proposed chemical sensor, this study describes the structure in the aspect of an equivalent circuit model (ECM) mathematically, while the full-wave simulation (FEM) is performed as the reference. Acceptable agreement between the ECM and FEM simulations is shown while an interesting tuning capability against external stimulation is obtained. It should be noted that the ECM approach is performed in just a few seconds while the FEM simulation takes more than 3 h to produce results. In addition, the maximum error is around the second absorption peak and is less than 4%.The main contribution of this work is introducing a simple structure to distinguish several toxic gases in the sub-THz gap (0.1–2 THz). Additionally, ample simulations are performed to verify the sensor's reliability. According to the simulation results, the proposed meta-structure can appropriately show different peak frequencies and even different numbers of absorption peaks against different concentrations of toxic gases. Additionally, due to the ultra-thin nature of the graphene and the flexibility of the Kapton, the proposed sensor can be wearable while it is considered non-invasive testing.

For the first time, a novel electrochemical biosensor was fabricated based on modification of a rotating glassy carbon electrode with multi-walled carbon nanotubes-ionic liquid, and molecularly imprinted polymers (MIPs) in which renin (Rn), and aliskiren (AK) were used as templates. By immersion the biosensor in Rn, AK, and their binary system (AK-Rn) solutions, the species (Rn, AK, and AK-Rn) were entrapped within the pathways of the MIPs. These processes and investigation of the inhibition of the Rn by AK helped us to obtain higher electrochemical signals for a good monitorization of the system. The effects of experimental parameters on response of the biosensor to AK were optimized by a small central composite design to obtain the highest response. Hydrodynamic cyclic voltametric (HCV), hydrodynamic differential pulse voltammetric (HDPV), and hydrodynamic linear sweep voltammetric (HLSV) data obtained and recorded in order to be analyzed by classical methods and multivariate curve resolution-alternating least squares (MCR-ALS) as an advanced chemometric method. The results of molecular dockings, classical and chemometric analyses confirmed that the Rn was strongly inhibited by the AK which was good evidence to develop a novel biosensing system for determination of Rn. A novel biosensor was developed for determination of the Rn which had an acceptable performance in determination of Rn in the range of 0–9 fM. This approach opened a new way for investigation of enzymes' inhibition, and developing a new generation of electrochemical biosensors for medical and biomedical applications.

Detecting ovarian cancer at an early stage is crucial for enhancing patient outcomes, underscoring the demand for an efficient and non-invasive detection method. Cancer antigen 125 (CA125) is a vital biomarker in ovarian cancer detection, and there is a pressing demand to develop a quick, sensitive, and simple detection method. Nanobiosensors are increasingly being used by scientists due to their high selectivity and sensitivity, allowing for the swift and precise detection of a wide range of biomarkers. This study aimed to design and fabricate an electrochemical nanobiosensor that could accurately and selectively detect CA125. The nanobiosensor employed graphitic carbon nitrides, molybdenum disulfide, and polyaniline (g-C₃N₄/MoS₂/PANI) to stabilize aptamer strands on a modified glassy carbon electrode. The aptasensor was used to perform electrochemical detection of labeled CA125, utilizing methylene blue and label-free ferrocyanide methods. Ferrocyanide and methylene blue detection limits were determined to be 0.196 U.mL⁻¹ for ferrocyanide and 0.196 U.mL⁻¹ for methylene blue, with a linear detection range of 2–10 U.mL⁻¹ for linear detection. The study results showed that the modified electrode exhibited high selectivity towards CA125 and superior stability compared to other biomolecules. The electrochemical aptasensor also displayed impressive performance when analyzing the serum of patients and healthy people. These findings hold significant promise for future investigation in ovarian cancer diagnosis. This novel electrochemical nanobiosensor may aid in the early detection and management of ovarian cancer, ultimately leading to better patient outcomes.

A new possibility of indirect determination of free chlorine using a graphite–epoxy composite(GEC) electrode instead of Pt disk electrode was suggested by interpreting the relationship between the peak current of the oxidation peak for hydrogen generated through water electrolysis in CV and the amount of the free chlorine. The linear response range of concentration was 0.06–0.2 mg∙L⁻¹ with correlation coefficient of 0.9951 (n = 5) and the sensitivity of 1225 μA cm⁻² mg⁻¹ L. The limit of detection (LOD) calculated from the 3σ IUPAC criteria was 1.2 × 10⁻² mg L⁻¹. The relative standard deviation (RSD) to 0.06 mg L⁻¹ was 4.65%(n = 10). The results show that the amount of free chlorine in the disinfected seawater can be indirectly determined by using a GEC electrode without influence of interferences unlike a Pt disk electrode. On the other hand, in this paper, a new method is proposed to evaluate the relative hydrogen adsorption capacity by the sensitivity of GEC electrode compared with that of Pt disk electrode. During the investigation of the hydrogen adsorption on the surface of the working electrode, we obtained the result that the hydrogen adsorption capacity of GEC is one-third of that of platinum.

Bladder cancer is the 10th most common cancer and the 9th cause of death by malignancy worldwide. Invasiveness and morbidity of cystoscopy, relatively low sensitivity of urinary cytology, lack of clinically approved point of care devices specificity, and the cost of the existing diagnostic procedures have motivated scientists and technologists to develop new bladder cancer detection platforms. In the context of finding an efficient screening system, biosensors have the advantages of detecting the biomarkers of bladder cancer, high sensitivity, simple operation, and relatively low equipment cost. This review summarizes the pathophysiology, common treatments, and the most prominent bladder cancer biomarkers as well as the clinically approved point of care devices and the most recent biosensors and nanobiosensors for detection of bladder cancer biomarkers.

Assessing the effectiveness of activated carbon is essential for the optimal operation of water treatment systems. Traditional evaluation methods, although precise, are typically labor-intensive and require complex equipment This study introduces a novel application of the B.EL.D™ device, utilizing redox potential measurements to gauge the activation level of carbon filters—an approach not previously employed. We hypothesized that redox potential is a reliable indicator of activated carbon's performance, a hypothesis that was rigorously validated through extensive testing against the standard iodine number test (ASTM D4607). Our analysis included both control and operational samples from ongoing water treatment processes over two years, confirming a definitive correlation between redox potential and carbon's adsorptive capacity. The findings demonstrate the potential of our method as a rapid, accurate, and cost-effective alternative to current testing practices. Currently under patent consideration, this study marks a significant advancement towards improving the assessment of activated carbon filters, providing an efficient pathway for water treatment facilities and establishing the foundation for a predictive maintenance model.

A thorough investigation into the development and performance assessment of biosensors that utilize Tunnel Field Effect Transistors (TFETs), showcasing a departure from conventional bio-sensing approaches is carried out. The unique properties of TFETs leverage quantum tunneling effects to enable precise and efficient detection of biomolecules. This review examines the impact of various device schematic modifications on the sensitivity of TFET biosensors. The analysis focuses on methodologies aimed at improving sensitivity levels, exploring models from scholarly literature, and assessing shifts in simulated parameters. Such as ON current (I_ON), Subthreshold Swing (SS), OFF current (I_OFF), ON-OFF current ratio (I_ON/I_OFF), threshold voltage (V_th), sensitivity, and selectivity. Among different architectures reported in the work, Heterojunction Tunneling Field Effect Transistor (HJ-TFET)-based biosensors offer significant advancements in biosensing technology due to their ability to control tunneling rates through versatile bandgap materials. Vertical TFET (VTFET) biosensors also demonstrate promising potential for label-free and specific biomolecule detection, leveraging vertical architectures for enhanced electrostatic control and scalability. Incorporating negative capacitance effects through ferroelectric materials further improves the VTFET performance, with ultra-low subthreshold swing and high sensitivity. Through the exploration of the latest advancements and applications, we illustrate how these nano-enabled gateways to health are opening up new possibilities for rapid, on-site medical diagnostics, ultimately bringing cutting-edge healthcare solutions. By drawing comparisons with established biosensing methods, TFET-based biosensors show immense promise in transforming medical diagnostics and point-of-care applications, offering high sensitivity which is crucial for precise monitoring in various fields such as medical diagnostics, environmental monitoring, and food safety.

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.