Sensors and Actuators Reports最新文献

Tungsten trioxide (WO₃) is one of most widely investigated metal oxide semiconductors as gas sensing material because of tunable sensing performance toward different analytes through composition modulation (e.g., dopants) and various morphology and crystallinity. In this work, we synthesized WO₃ nanofibers with different diameter and crystallinity through electrospinning of ammonium metatungstate hydrate (AMH)/polyvinyl pyrrolidone (PVP) nanofibers via design of experiments (DOE) followed by thermal heat treatment with the smaller average diameter being 23.0 nm. Through varying the calcination process, WO₃ nanofibers with different crystallinity were also synthesized, with the smaller average grain size being 23.0 nm. These nanofibers were then exposed to many analytes (i.e., H₂S, acetone, toluene, ethanol, ethyl benzene, NO₂, NO, and methane) under different operating temperatures (i.e., 250 to 450 °C) to investigate their effect toward sensing response. These systematic studies indicated that nanocrystalline WO₃ nanofibers with the smaller diameter (i.e., 20 nm) and/or smaller average grain sizes (i.e.,18.7 nm) exhibited best sensing performance independent of target analytes. The barrier energy was also correlated with the gas sensing performance experimentally.

Moraxella catarrhalis (M. catarrhalis) was an underestimated respiratory infection pathogen that has been largely overlooked. The limited availability of rapid and sensitive detection methodologies has hindered M. catarrhalis diagnostic in clinical settings and contributed to its underestimation. To address this issue, we devised two recombinase polymerase amplification (RPA)-based assays for rapid, sensitive and reliable detection of M. catarrhalis, termed M. catarrhalis-RPA-Flu and M. catarrhalis-RPA-LFB, which utilized fluorescence and nanoparticle-based lateral flow biosensor (LFB) for reporting the detection results, respectively. In both assays, the specific copB gene of M. catarrhalis was amplified at 37°C for only a period of 20 minutes. In M. catarrhalis-RPA-Flu system, the detection results were analyzed by either using a real-time fluorescent detector or by direct observation using the naked eye under blue light, while, in M. catarrhalis-RPA-LFB system, biosensors were used for interpreting the results without any specialized instruments. Both methods were able to finalize the entire detection process within a duration of 40 minutes, detect down to 35 fg genomic DNA per test, and correctly differentiate M. catarrhalis from non-M. catarrhalis strains. The feasibility of both techniques was validated by analyzing 96 BALF (Broncho alveolar lavage fluid) samples in clinical settings. Collectively, the newly developed two RPA-based assays exhibit great potential for rapid and accurate identification of M. catarrhalis in standard microbiology laboratories as well as diagnosis of M. catarrhalis infection in clinical settings.

Homocysteine (Hcy) is a non-protein sulfuric amino acid that is produced as a by-product of methionine transmethylation. Increased levels of Hcy in human serum result in hyperhomocysteinemia, which is an indicator for coagulation problems and cardiovascular diseases (CVDs). Therefore, serum Hcy has been suggested as a biomarker to determine redox dysfunction in humans. However, it is necessary to use a reliable method to determine the amount of Hcy in biological fluids and its significance in health and disease. Several studies have used aptamer-based electrochemical sensors (aptasensors) to detect Hcy. The focus of these studies was on speeding up detection and creating novel detection techniques. Apatasensing technology has the potential to improve the diagnosis and treatment of cardiovascular problems. The goal of this review is to provide a general overview of the various Hcy aptasensors in relation to their linear range, detection abilities, and potential medical uses.

During the last decade, nanomaterials and supramolecular assemblies have received considerable attention in different fields of sensing applications. The interest of supramolecular assemblies arises from the exceptional performances of nanostructured films based on such assemblies, which are related to both their well-controlled structure and their large surface area. These characteristics increase the number of active sites and facilitate the charge transport pathways. In addition, supramolecular assemblies can be used to prepare multicomponent sensing layers formed by materials with complementary activity. Finally, supramolecular films are highly efficient platforms for enzyme immobilization leading to highly sensitive biosensing.

This paper describes the main concepts and approaches related to the development of supramolecular sensing layers in electrochemical sensors and biosensors. Different techniques commonly employed to develop supramolecular sensing layers, such as Self-assembling, Layer-by-layer and Langmuir-Blodgett, are described and their role as electron mediators in biosensors is revised using milk as an example of the target analyte. Using this approach, enzymes are immobilized in a biomimetic environment, giving rise to efficient biosensors able to detect glucose, galactose or lactose in milk with high degree of selectivity and low limits of detection.

We also include a brief discussion of the possibilities of the integration of supramolecular assemblies into sensor arrays as the core of electronic and bioelectronic tongues. The advantages of these systems are related to their fast responses and their capability to detect many components in a single measurement. The expected limitations mainly related to the fouling of the electrodes, are also discussed.

Due to increasing pollution threats, terrorism-sensitive rapid sensing of aromatic nitro explosives (picric acid) has gained predominant significance in environmental safety. Herein, imidazole-derived monofunctional fluorescent sensor 2-(4-aminophenyl)-3-(3-(4,5-diphenyl-1H-imidazol-2-yl)-2-hydroxyphenyl) acrylonitrile (ADHA) was successfully developed for the selective recognition of explosive picric acid. The D-π-A configuration of ADHA facilitates extraordinary photophysical properties with remarkable aggregation-induced emission (AIE). The detection process is induced by the photon-induced electron transfer (PET) and resonance energy transfer (RET) and results in the generation of ADHA+PA complex. The structural relationship and the photophysical properties of ADHA were extensively studied by DFT (Density Functional Theory) methods and spectroscopic analysis. It has been calculated that the detection limit of the formed complex is 6.26 nM. In addition, ¹H NMR titrations DFT calculations, and HRMS analysis were performed to understand the detection mechanism better. Test strip-aided detection and invisible ink applications confirmed that ADHA is a versatile sensor for sensitively detecting picric acid without sophisticated instruments. In addition, ADHA was implemented to detect PA in real water samples with remarkable recovery.

The sensing of oxalate within urine has been recognised as one of the most important determinations in the investigation of patients with hyperoxaluria. However, current approaches have reported expensive, time consuming, occasionally poor selectivity and are subject to large inaccuracies if great care is not exercised in the handling and measurement of samples. One approach is the use of electroanalytical sensors, which present rapid but highly selective and sensitive outputs, are economical and miniature providing portable sensing platforms to support on-site analysis. In this minireview, recent advances in the electroanalytical sensing of oxalate are presented, overviewing recent electrode configurations and real sample analysis; comparisons to other analytical methods are presented. Finally, the conclusions and future perspective of this field are described in brief.

MXenes, is an attractive new class of two-dimensional (2D) materials, discovered in 2011. Since then, owing to their unique combination of properties, such as high specific area, high electrical conductivity, tunable hydrophilicity, tunable chemical composition, and potential cytocompatibility, MXenes have made a deep impact on various fields ranging from electronics to energy and more recently to biotechnology. A typical example for the latter, is their use as electroactive biointerfaces in a number of biosensor setups, exhibiting remarkable analytical performance. In particular, MXene-based nanocomposites can serve as bioreceptors, electrochemical transducers or amplification probes towards translating molecular recognition of biological targets into detectable signals, leading to ultrasensitive biosensors for probing biomarkers, or pathogens. This concise review highlights the recent advances of MXene-based electrochemical biosensors for highly selective and sensitive detection of nucleic acids, proteins and pathogens pertaining to biomarker identification and clinical diagnostics. In particular, the effects of synthetic routes, surface chemistry, nanocomposite design, and fabrication methods of MXenes on the resulting relationship between biointerfacial structure, electrochemical properties and device performance is discussed, providing unique perspectives and design criteria for the next wave of biosensors.

MXene has emerged as a prominent two-dimensional material with vast potential for diverse applications, garnering significant attention within the scientific community. This attention is due to its unique surface structure and its capacity for surface modification through functionalization, as well as its exceptional conductivity and elasticity. Extensive theoretical and experimental studies have been conducted to explore the gas sensing capabilities of various MXenes, and this review aims to present the latest advancements in this field through the lens of density functional theory. The review begins by providing a detailed explanation of the theoretical calculations involved, including the various available computational software options and the parameters considered, taking into account both cost and time complexity. The sensing properties of MXene derivatives are then comprehensively reviewed, categorized by their types (M₂X, M₃X₂, M₄X₃), and are discussed in terms of material properties, sensitivity, selectivity, and response time, amongst others. Furthermore, the prospects for these sensors are examined, focusing on their potential applications. Lastly, the review highlights future opportunities for theoretical research and the application of MXene materials in the development of cutting-edge devices. By presenting an overview of theoretical research and recent advancements, this review aims to provide valuable insights into this burgeoning field and pave the way for new avenues in gas detection research.

The conventional approaches to diagnosing cancer are expensive, often involve exposure to radiation, and struggle to identify early-stage lung cancer. As a result, the five-year survival rate is significantly reduced. Fortunately, promising alternatives using magnetoresistance (MR) and magneto-plasmonic sensors have emerged for swiftly, accurately, and inexpensively detecting cancer in its initial phases. These sensor technologies offer numerous advantages over their counterparts, such as minimal background noise, immunity to environmental influences, compatibility with nanofabrication methods, ability to detect multiple substances simultaneously, straightforward integration, high specificity, distinctive identifying capabilities, real-time monitoring, stability, label-free detection, and remarkable sensitivity for detecting individual molecules. Nevertheless, since the use of these techniques for cancer biomarker detection is relatively new, it is essential to conduct a bibliometric analysis and review recent literature to offer guidance to both early-career and established researchers in this domain. Consequently, this study performs a scientometric evaluation of the literature related to cancer biomarker detection using MR and magneto-plasmonic methods. The objective is to pinpoint current preferred techniques and challenges by examining statistics such as publication numbers, authors, countries, journals, and research interests. Furthermore, the paper also presents the latest advancements in MR and magneto-plasmonic sensors for cancer biomarker detection, with a focus on the last decade. In addition, an overview of the ongoing research in the field of MR and magneto-plasmonic sensors for detecting cancer biomarkers is highlighted. Finally, a summary on the level of current research including the significant accomplishments, challenges, and outlooks of MR and magneto-plasmonic sensors for the detection of cancer biomarkers are highlighted.

Microcarriers (MCs, typically 50–200 µm) are promising growth supports for high-throughput cell expansion, with capability to overcome the limitations of surface area availability and nutrient access encountered by cell culture in 2D well plate configurations. Equipping MCs with in-built capability to sense molecular biomarkers is a key step forward to meet the emerging demands of personalized cell-based therapies. However, integrating sensing functionality into MCs is non-trivial due to fabrication limitations imposed by their large size, curved surfaces, and their suspension in fluid. If achieved, the sensor-integrated MCs should face further concerns of reduced stability and cytocompatibility during cell-culture. Here we demonstrate plasmonic microcarriers (PMCs) that integrate spectroscopic sensing and cell expansion functions through the deposition of gold nanoparticle (AuNP) assemblies on dextran-based MCs. Hydrogel characteristics of the dextran microcarriers was found to profoundly enhance the binding density and kinetics of AuNPs, as seen by attainment of saturated densities in few seconds, and at nanoparticle concentrations only twice that of the surface sites. The approaches to prepare PMCs are distinguished by simple, scalable routes, without need for sophisticated lab infrastructure. The capability of PMCs to act as spectroscopic transducers was demonstrated by surface-enhanced spectroscopic (SERS) detection of a model molecular probe.  The growth, proliferation and migration of human mesenchymal stem cells on the PMCs was found to be comparable to that of the uncoated MCs. The results pave the way to smart, multifunctional cell growth supports to interrogate, control and report cell behavior during culture.