Fluorimetric DNA Biosensors

The widespread use of silver raises concerns about environmental and health risks, necessitating highly sensitive detection methods for trace silver ions (Ag+). Surface plasmon resonance (SPR) sensors offer benefits like label-free detection and rapid response, but their sensitivity for Ag+ detection is limited due to weak ion adsorption. Here, we developed an SPR sensor with MoS42--intercalated NiAl-layered double hydroxide (LDH) as the adsorption layer of Ag+ to enhance detection sensitivity. Our sensor achieves a sensitivity of 254.75 nm/μg/L and detects Ag+ at a low concentration of 2.8 pM, outperforming various existing sensors. It also shows excellent repeatability, long-term stability, and selectivity, proving effective in real-world environmental samples. This work advances high-performance SPR sensors for heavy metal ion detection.

Self-referencing SPR biosensing with an ultralow limit-of-detection using long-wavelength excitation

High Throughput Prediction of the Long-Term Stability of Pharmaceutical Macromolecules from Short-Term Multi-Instrument Spectroscopic Data

A review on designing nanofibers with high porous and rough surface via electrospinning technology for rapid detection of food quality and safety attributes

Under certain conditions, a surface plasmon wave along a metal-dielectric interface can be excited by an optical beam. The reflected optical beam will then undergo changes in both intensity and phase. As the level of intensity or phase change is quite sensitive to the coupling conditions such as the molecule concentration on the metal surface, this phenomenon has been utilized for label-free detection of biological species and characterization of molecular interactions during the last two decades. Currently, most of the commercial surface plasmon resonance (SPR) sensors rely on the detection of absorption dip in angular or wavelength spectrum. However, recent researches have shown that phase detection has the potential to achieve lower limit of detection (LoD) and higher throughput. This paper, thus, intends to review various schemes and configurations for SPR phase detection. The performance advantages and disadvantages of various schemes will be emphasized. It is hoped that this paper will provide some insights to researchers interested in SPR sensing and help them to develop SPR sensors with better sensitivity and higher throughput.

Large‐area, freestanding, two‐dimensionally ordered macroporous (2DOM) Ag thin films with adjustable periodic spacings and good mechanical robustness were fabricated via nanosphere lithography at the solution surface (NSLSS) combined with interfacial reactions. The obtained 2DOM Ag thin films exhibited typical properties of plasmonic crystals with well‐resolved reflectivity dips and vivid colors. The facile NSLSS method enabled the 2DOM Ag thin films to be readily transferred to arbitrary substrates to realize application as thin film sensors. Their application as both a surface plasmon resonance (SPR) sensor and a surface‐enhanced Raman scattering (SERS) sensor in the detection of both small molecules and biological macromolecules were explored. As SERS substrates for the detection of 4‐aminothiophenol (4‐ATP) molecules, the 2DOM Ag thin films showed enhancement factors as high as the 107 order, which made them a promising sensor for the detection of trace amount of analyte adsorbed on the surface. As SPR sensors, the 2DOM Ag thin films modified with a self‐assembled monolayer of recognizing molecules as binding sites showed remarkable shift in the reflectivity dips responsive to the chemical environments. When used for the specific detection of avidin molecules, the 2DOM Ag thin film biosensors exhibited excellent performance with low detection limit (≈100 pM) and broad working range (100 pM–200 nM), indicating that they may be a promising candidate for high‐performance biosensors.

In this work, small molecular hydrogel was first employed as a surrounding matrix to stabilize an enzyme model, Cytochrome c (Cyt c), and more importantly to facilitate electron transfer between redox enzyme and electrode. Direct electron transfer of Cyt c was successfully achieved in the molecular hydrogel with redox formal potential (E(0')) of 100.7 ± 3.2 mV versus Ag|AgCl and heterogeneous electron transfer rate constant (ks) up to 18.6 ± 2.3 s(-1). Experimental data demonstrated that Cyt c was stably immobilized into the molecular hydrogel and retained its inherent bioactive activity toward H2O2. The direct redox reaction of Cyt c, followed by the biochemical reaction between Cyt c and H2O2, established a reliable approach to determine H2O2 at an optimized potential with high selectivity over other reactive oxygen species (ROS), oxygen, metal ions, ascobic acid (AA), and so on. In addition, the present biosensor for H2O2 also exhibited wide linear range and low detection limit, which fulfills the requirements for detection of H2O2 in a biological system. The remarkable analytical performance of the present biosensor, as well as the long-term stability and good reproducibility ascribed to the molecular hydrogel-stabilized enzyme, provided a durable platform for real-time determination of H2O2 from live cells.

A label-free electrochemical immunosensor based on 11-mercaptoundecanoic acid grafted chitosan and poly(N-methylaniline) for the detection of carcinoembryonic antigen

Acetic acid is among the most common and damaging airborne contaminants. Exposure to acetic acid gas can irritate the nose and throat, which may harm human health. In light of the increasing use of acetic acid in industry, there is a critical need for an acetic acid detection device that can operate in real time with excellent performance. This study developed an acetic acid gas sensor using a quartz crystal microbalance (QCM) deposited with polyvinylpyrrolidone (PVP) microfiber by a well-recognized electrospinning method. Scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy were employed to observe the morphology and chemical composition of the fabricated microfibers. The obtained sensor has a high sensitivity of (4.144 ± 0.039) Hz·ppm-1 with a low detection limit and rapid response and recovery times of 75 and 66 s, respectively. In addition, the fabricated sensor also exhibits good performance as well as repeatability and long-term stability. Selectivity tests were also conducted for various analytes and exhibited excellent selectivity toward acetic acid. These advancements demonstrate that the PVP microfiber active layers not only address the challenges of detection by enhancing sensitivity but also provide unique mechanism selectivity for acetic acid molecules. However, advanced future research must still be conducted to improve the sensor reversibility, making the sensor more suitable for applications in a real environment.

Performance of white organic light-emitting diode for portable optical biosensor

Recently, transition-metal phosphides and phosphates have been recognized as candidates for electrochemical energy storage and conversion application. However, the preparation of such materials usually requires high energy consumption and toxic precursors which are considered to be drawbacks for real applications. In this study, we report ambient temperature synthesis of transition-metal phosphates for oxygen evolution reaction (OER) and supercapacitors. The prepared iron-doped porous nickel pyrophosphate (NFPy) nanoparticle is synthesized via simple stirring in ambient temperature using only the precursor for Ni, Fe, and pyrophosphate without any heat treatment. The usage of pyrophosphate promotes facile Ni oxidation and high chemical stability, which overall is beneficial for electrochemical applications and the environment. The OER performance of NFPy shows promising results which required an overpotential of 0.210 V to reach 10 mA·cm–2. Also, with the help of carbon nanotubes, the supercapacitor using NFPy exhibits a good electrochemical performance with a capacity of 517 C·g–1 at 1 A·g–1. The prepared NFPy possesses excellent long-term chemical stability that maintained its chemical valence state and electrochemical performance for over 8 months despite the exposure of air.

The food processing industry and biomedical science research are relying on the low limit of detection (LOD) for hydrogen peroxide (H2O2). Organic electrochemical transistors (OECTs) are excellent for biochemical sensing applications due to their excellent signal amplification capability. The paper describes a way of detecting H2O2 through the use of stacked poly(3,4‐ethylenedioxythiophene): bromothymol blue (PEDOT: BTB)/poly(3,4‐ethylenedioxythiophene): polystyrene sulfonate (PEDOT: PSS) as the semiconducting channel of the OECT. The H2O2 sensor presents an ultra‐low LOD, down to 1.8 × 10−12 M, due to the synergistic effect of the Nernst potential generated by the platinum gate electrode catalyzing H2O2 and the Nernst potential generated by the interaction between BTB molecules and hydrogen ions, the by‐product of H2O2 catalysis. A microsystemwith a signal processing circuit and a mobile app for the sensor has been developed, and they are then tested on commercial milk samples to verify their reliability. Since the majority of enzyme‐catalyzed reactions generate or use H2O2 in biochemical reactions, the methodology is applicable not only to the detection of H2O2 but also to the detection of analytes based on enzyme‐catalyzed reactions. For demonstration, glucose detection with a LOD of down to 8.82 × 10−11 M is also presented.

Introducing Schottky interface as a novel strategy for ultrasensitive nonenzymatic glucose detection

Novel surface plasmon resonance sensor chip functionalized with organic silica compounds for antibody attachment

As strain variation and drug resistance become more pervasive, the prevention and control of infection have been a serious problem in recent years. The detection of pathogen is one of the most important parts of the process of diagnosis. Having a series of advantages, such as rapid response, high sensitivity, ease of use, and low cost, biosensors have received much attention and been studied deeply. Moreover, relying on its characteristics of small size, real time, and multiple analyses, biosensors have developed rapidly and used widely and are expected to be applied for microbiological detection in order to meet higher accuracy required by clinical diagnosis. The main goal of this contribution is not to simply collect and list all papers related to pathogen detection based on biosensors published recently, but to discuss critically the development and application of many kinds of biosensors such as electrochemical (amperometric, impedimetric, potentiometric, and conductometric), optical (fluorescent, fibre optic and surface plasmon resonance), and piezoelectric (quartz crystal microbalances and atomic force microscopy) biosensors in pathogen detection as well as the comparisons with the existing clinical detection methods (traditional culture, enzyme-linked immunosorbent assay, polymerase chain reaction, and mass spectrometry).