Sensors and Actuators Reports最新文献

In this study, we developed a novel electrochemical biosensor for detecting IL-6 that uses a nano-electrode array (NEA) fabricated via standard CMOS processing. Miniaturizing the electrodes to the nanoscale and arranging them in an array to form an NEA facilitated the creation of a higher electric field magnitude, compared to that available via the use of microelectrodes, that could be used to improve biosensor sensitivity. Additionally, the array configuration of the NEA aided in providing sufficient reaction sites. Each nano-electrode in the NEA was cylindrically shaped, with a radius of 0.1 µm, and a top layer formed by TiN physical vapor deposition. Each NEA biosensor was divided into four independent banks, with each bank including a set of WE, CE and RE. These banks were capable of independently inputting and outputting electrical signals. This design allowed the NEA biosensor to undergo selective modification by CV input. In this study, we discuss and address material and contamination issues associated with CMOS-produced NEAs and their uses as biosensors. To ameliorate these issues, we stored materials and products in a nitrogen-controlled cabinet and conducted pretreatment cleaning on the electrodes. Both steps had a noticeable impact on the cleanliness of the electrode surfaces. These optimized conditions resulted in a remarkable 96.6 % reduction in R_ct. The NEA surface was functionalized by electrochemically grafting diazonium salts subsequently immobilized with anti-IL-6 antibodies via EDC/NHS chemistry. The resulting NEA biosensor demonstrated sufficient sensitivity to rapidly distinguish inflammatory conditions and disease severity. This showcases the potential for using NEA devices mass-produced via standard CMOS processing as electrodes for biosensors.

Purpose

As an important reference index for the early diagnosis of non-small cell lung cancer (NSCLC), CYFRA21-1 still lacks the detection of low equipment cost, wide linear range and high sensitivity. Surface-enhanced Raman scattering (SERS) is a vibration spectrum technology based on the surface plasma of precious metal nanoparticles, which has been effectively applied to the detection of tumor markers. The combination of SERS technology and sensors has great potential in the ultrasensitive detection of tumor markers. The purpose of this study was to develop a sensitive method using SERS to quantitatively detect CYFRA21-1 for early diagnosis of NSCLC.

Methods

A double-antibody sandwich immunoassay based on SERS was designed and tested to implement the ultrasensitive detection of CYFRA21-1 in the serum of NSCLC patients.

Results

Gold @Ag nanorods (Au @Ag NRs) with higher Raman signals were prepared and used as probes, while magnetic graphene oxide was used as a magnetic substrate. The immunized probe, immune substrate and CYFRA21-1 standard substance in the buffer system formed a double-antibody sandwich structure. The standard curve displayed a liner range from 1pg mL⁻¹ to 10 ng mL⁻¹, and the detection limit (LOD) is 0.8943pg mL⁻¹. The Raman intensity exhibited a wide linear relationship with the logarithm of CYFRA21-1 concentration.

Conclusion

Our study successfully established a double-antibody sandwich immunoassay based on SERS. This method demonstrated high specificity and sensitivity for detecting CYFRA21-1 protein content in serum. It has the potential to be applied for early detection of lung cancer biomarkers.

Dopamine is an important hormone and neurotransmitter, and its levels in human fluids can indicate stress, depression, and various mental disorders. Food products, as well as medications, affect its level in the human body greatly. Therefore, dopamine monitoring is crucial, and necessary for improving the quality of life. The priority is to search for simple and environmentally friendly sensor systems for the in vitro detection of dopamine, enabling mass utilization.

In this study, we explored the use of o-phthalaldehyde (OPA) as an indicator for the detection of dopamine, with fluorescence in the visible range (λ_ex/λ_em = 390/455 nm), while direct dopamine fluorescence measurement was in the UV range (λ_ex/λ_em = 280/320 nm). The longer excitation/emission wavelengths of dopamine-OPA complex, as well as lower detection limits, are useful for developing a simple detection method using LEDs. Three types of poloxamers were tested as additives to improve the fluorescence signal from the reaction between dopamine and OPA. Pluronic F127 led to a 16-fold increase in the fluorescence. Utilizing 4% Pluronic F127 with OPA at pH 7 resulted in a linear response within concentration ranges of dopamine (0.5–3 µM), achieving a limit of detection of 0.015 µM. In contrast, a direct detection of dopamine within the same range exhibited a detection limit of 0.13 µM.

The distinct presence of a central atom surrounded by eight ligands leads to higher light absorption and charge carrier mobility in perovskite materials. The peculiar nature of the structure inspires all the scientists and researchers to work more in sustainable applications, such as solar cells, light emitting diodes, transistor and biosensors. The capability of perovskite material in detecting smaller molecules such as O₂, NO₂ and CO₂ is higher. Therefore, several biosensors are demonstrated based on the perovskite nanomaterial to various chemical and biological species with both solid and solution states. The immense sources of research articles thrived the author, to review the perovskite nanomaterials in the dimension of biosensor application extensively. This review covers major three areas of perovskite nanomaterial, such as components and characteristics of biosensors, properties and preparation of perovskite materials and application and research trends of perovskite nanostructure biosensor.

The Epithelial Sodium Channel (ENaC) is a protein that plays a role in the cellular intake of salt and is known as one of the biomarkers for hypertension in the human body. Higher concentrations of sodium lead to increased activity of the ENaC protein in sodium absorption. In this study, a self-made immunosensor was developed using a homemade Printed Circuit Board-Screen Printed Carbon Electrode (PCB-SPCE) modified with cerium oxide. Anti-ENaC was immobilized on the surface of PCB-SPCE/ceria at pH 7.4, relying on the interaction between carboxyl groups of anti-ENaC and cerium oxide to detect the ENaC protein. Additionally, a portable in-house potentiostat named “UnpadStat” was developed for integration with the immunosensor. UnpadStat features a 5-in. touch screen display to showcase measurement data. Cyclic voltammetry measurements using the redox system of K₃[Fe(CN)₆] were applied to bare PCB-SPCE, PCB-SPCE/Ceria, PCB-SPCE/Ceria/Anti-ENaC, and PCB-SPCE/Ceria/Anti-ENaC/ENaC. Measurement results indicated an increase in current after modification with cerium, reaching 73.805 µA compared to unmodified (63.256 µA). After anti-ENaC immobilization, there was a decrease in current to 64.456 µA, and upon binding with the ENaC protein, a further decrease in current occurred, corresponding to the concentration of the ENaC protein. The detection limit obtained in this study was 0.133 ng/mL, and the quantification limit was 0.444 ng/mL for the concentration range of ENaC protein from 0.375 ng/mL to 6.0 ng/mL. The integration of the PCB-based immunosensor and UnpadStat can be utilized to determine the levels of ENaC protein in non-hypertensive urine samples and hypertensive patients.

Hydrogen (H₂) sensors with excellent performance play an important role in the safety application of H₂ energy. Among current H₂ detection technologies, surface acoustic wave (SAW) based H₂ sensors attract more attention due to their features of high sensitivity, fast response, mico-nano scale and excellent stability, which was composed of a SAW sensing chip and sensing materials depositing along the acoustic wave propagation path, and utilizing the coupling mechanism of force-acoustic-electric multiple physical fields. Here we review the SAW H₂ sensor, focusing on the H₂ sensing materials, SAW sensing mechanisms, sensing devices, sensing circuits, and development status. And prospects were made for its development trends and challenges.

Fluorescence-activated cell sorting (FACS) holds great promise for the separation of single cells or cell populations according to specific light scattering and fluorescent characteristics. Here, we present a new perspective on microfluidic FACS (μFACS) with predictable geometry, which meets the requirements of high-throughput analysis and sorting. Instead of the widely applied elastic polydimethylsiloxane (PDMS), a rigid epoxy resin chip was rapidly fabricated and irreversibly encapsulated to eliminate channel deformation (tenfold reduction) and enhance performance while meeting high pressure (>600 kPa) and high flow rate application scenarios. Fluorescence discrimination and particle differentiation were additionally validated in a self-contained μFACS system using calibration microspheres and mammalian cells. The μFACS chip and system were integrally optimized to achieve a minimum interval (0.58 ms) with a mean flow rate of 1.5 m/s. Ultimately, event recording and automated sorting were accomplished in real time while achieving a sorting efficiency of 87% at cell throughput of 8,000 events/s. This rigid chip for high-throughput μFACS, which is independent of the physical properties of cells could pave the way for cell screening in plasma samples for personalized medicine.

Efficient and timely detection of cancer biomarkers is pivotal for enhancing treatment outcomes and mitigating patient mortality. This study addresses the pressing need for a swift, accurate, and non-invasive method to identify cancer antigen 125 (CA125), a vital biomarker in ovarian cancer. Leveraging the growing prominence of nano-biosensors for their high selectivity and sensitivity, we present the development and characterization of an innovative electrochemical nano-biosensor. The sensor, featuring aptamer strands immobilized on a glassy carbon electrode modified with graphitic carbon nitrides, molybdenum disulfide, and magnetic nanoparticles (g-C₃N₄/MoS₂/Fe₃O₄), demonstrates superior sensitivity and accuracy in CA125 detection. Utilizing methylene blue for electrochemical detection of labeled CA125 and ferrocyanide for label-free detection, our aptasensor achieves a low limit of detection (LOD) at 0.202 U.mL⁻¹ and 0.215 U.mL⁻¹, respectively, with a broad detection range from 2 to 10 U.mL⁻¹. The modified electrode exhibits a pronounced affinity for CA125, demonstrating enhanced stability compared to other biomolecules. Crucially, the evaluation of both patient and normal serum samples underscores the aptasensor's remarkable performance. These findings not only establish a robust foundation for future research in ovarian cancer diagnosis but also highlight the potential clinical impact of our electrochemical nano-biosensor in advancing early cancer detection methodologies.

The paper describes the development and application of a screen-printed electrode cell with a graphite-ink working electrode modified by a molecularly imprinted electropolymerized polypyrrole for the voltammetric determination of the herbicide 4‑chloro-2-methylphenoxyacetic acid (MCPA). The method exploits the direct measurement of the analyte by applying the differential pulse voltammetry (DPV) technique, taking advantage of the irreversible oxidation peak at about +1.0 V vs. Ag/AgCl pseudo reference electrode. The presence of the molecularly imprinted polypyrrole enhances the sensor's selectivity and sensitivity. A chemometric approach has been crucial for quantitative analysis because of the peak's broad and not well-defined shape. Firstly, a proper pretreatment of the voltammetric signals is identified, proving the most effective is the first-derivative function transformation of the signal. The Partial Least Square regression (PLS) is the tool applied for MCPA quantification. A preliminary PLS model has been developed and validated in dihydrogen phosphate solution at pH 5.5, aiming to optimize the data treatment approach. Then, the same approach is used to develop a PLS model analyzing tap water samples fortified with MCPA and other pesticides as possible interferents to simulate contaminated natural waters. The model correctly predicted the analyte concentration in the range of 2.5–75 μM, assuring the reliability and robustness of the sensor for the possible quantification of MCPA in wastewater samples.

One of the most significant drawbacks of metal oxide (MOS) based chemiresistive gas sensors is the requirement of high operating temperature (250–450 °C), which results in significant power consumption and shorter lifetime. To develop room temperature (21±2 °C) MOS chemiresistive gas sensors, the sensing performance of different MOS nanostructures (i.e., tin (IV) oxide (SnO₂) nanoparticles (NPs), indium (III) oxide (In₂O₃) NPs, zinc oxide (ZnO) NPs, tungsten trioxide (WO₃) NPs, copper oxide (CuO) nanotubes (NTs), and indium tin oxide (In₉₀Sn₁₀O₃ (ITO)) NPs) were systematically investigated toward different toxic industrial chemicals (TICs) (i.e., nitrogen dioxide (NO₂), ammonia (NH₃), hydrogen sulfide (H₂S), carbon monoxide (CO), sulfur dioxide (SO₂) and volatile organic compounds (VOCs) (i.e., acetone (C₃H₆O), toluene (C₆H₅CH₃), ethylbenzene (C₆H₅CH₂CH₃), and p-xylene (C₆H₄(CH₃)₂)) in the presence and absence of 400 nm UV light illumination.

Sensing performance enhancement through photoexcitation is strongly dependent on the target analytes. Under 400 nm UV photoexcitation at 76.0 mW/cm² intensity, room temperature (21±2 °C) NO₂ sensing was readily achieved where SnO₂ NPs exhibited the highest sensor response (S = 474.4 toward 10 ppm_m (parts per million by mass)) with good recovery followed by ZnO NPs > In₂O₃ NPs > ITO NPs. Meanwhile, indirect bandgap n-type WO₃ NPs showed limited NO₂ sensing performance under illumination, whereas p-type CuO NTs showed relatively good sensing response. The most significant improvements in SnO₂ compared to other MOS nanoparticles might be attributed to the highest number of photogeneration electrons, which rapidly reacted with adsorbed $N{O}_2^{-}$ species to enhance the reaction kinetics. WO₃ NPs showed a unique sensing response toward aromatic compounds (e.g., ethylbenzene and p-xylene) under UV illumination, where maximum sensitivity was achieved under 36 mW/cm² irradiation. Changing light intensity from 0.0 to 36.4 mW/cm², WO₃ showed 15.4-fold and 6.3-fold enhancement in sensing response toward 25 ppm_m ethylbenzene and 100 ppm_m p-xylene, respectively. 400 nm optical excitation has a limited effect on the sensing performance toward CO, SO_2, toluene, and acetone.