Analysis & sensing最新文献

Point-of-care diagnostics relies on optical and electrochemical sensors to develop devices that are both compact and cost-effective. Therefore, the search for new design principles for chemosensors that enable multiple signal outputs is a particularly interesting concept. In this work, we present an unimolecular chemosensor based on cucurbit[7]uril that combines two signal readouts - namely fluorescent and electrochemical signals - in a single chemosensor design. This is achieved by utilizing the tunable fluorescence and the electrochemical properties of the reporter molecule, which depend on whether or not it is engulfed by the cucurbit[7]uril cavity in the absence or presence of the analyte. By setting up an assay using the dual readout chemosensor, illicit drug formulations containing pancuronium bromide or nicotine can be detected at low micromolar concentrations (0–100 μM). This assay is compatible with standard fluorescence plate readers and electrochemical devices, including commercially available screen-printed electrodes. Overall, the chemosensor presented in this study represents a significant advance in the development of cucurbit[7]uril chemosensors, characterized by multimodal detection capabilities. It uniquely combines traditional optical and electrochemical detection methods in a single molecular design.

pH is one of the key parameters in chemistry and impacts almost all chemical and biological processes. Also, within analytical chemistry and sensing, pH plays a critical role. This review underscores the critical role of pH manipulation in overcoming analytical challenges posed by complex sample matrices and dynamic environmental conditions. It explores the available tools to control pH at a local scale and how those are or can be applied to improve sensor performance. We focus on four key areas where pH modulation has been or could be leveraged to advance chemical sensing capabilities: i) sensing alkalinity and buffer capacity, ii) sample pretreatment, iii) sensing pH dependent analytes and iv) reducing biofouling. We analyze existing strategies, but also try to identify unexplored possibilities which may have potential and can be exploited for sensing.

Electrochemical immunosensors have emerged in the last years as outstanding analytical systems for the detection of analytes of clinical interest. As alternative to the traditional enzymatic labels, the use of nanoparticles and especially bimetallic ones has gained increased attention thanks to their advantages related to the higher simplicity, stability and sensitivity offered. Main routes for the detection of such nanoparticle labels are based on i) dissolution of the nanoparticle into the corresponding metal ions followed by voltammetric detection; ii) taking advantage of the electrocatalytic effect of the metals towards secondary reactions; and iii) taking advantage of their electrochemiluminescence properties.

Plant hormones and their receptors play a crucial role in regulating plant growth and adapting to the stress environment. The exploration of interaction between plant hormones and their receptors is significant to comprehend the molecular mechanisms of plant growth and development, the response mechanisms of adaptation to environmental changes, and to optimize the traits and stress-resistance of crops. Since the biosynthesis, transport, and metabolism of hormones in plants are closely relevant to spatio-temporal changes, and their content and distribution are highly dynamic, there is an urgent need for a qualitative and quantitative tool to accurately, real-time, and in situ monitor the dynamic changes of hormones in plants without injury. Fluorescent probes have been widely used in the sensing and imaging of plant hormones and their receptors, due to their high spatio-temporal resolution, high selectivity, non-invasive, high sensitivity, and tailored molecular structures. Here, this paper provides a systematical overview of the research progress in the sensing and imaging of plant hormones and their receptors using fluorescent probes. In addition, the potential prospects and remaining challenges are also discussed to design fluorescent probes with better performance and promote the development of this field.

Two-dimensional conductive metal-organic frameworks (MOFs) featuring structural diversity and high porosity represent promising platforms for chemiresistive humidity sensing. The precise control of the structure of lanthanide-based MOFs and an exploration of its impact on charge transport and sensing applications have consistently been focal points for researchers. In this study, we present the synthesis and characterization of Lu-HHTP (HHTP=2,3,6,7,10,11-hexahydroxytriphenylene) as highly crystalline and conductive porous materials. The polymeric framework of Lu-HHTP encompasses 1D hexagonal channels and exhibits interlayer π–π stacking, resulting in a material with a high surface area and uniform rod-like microstructure. Benefiting from its elevated electrical conductivity, the Lu-HHTP-based humidity sensor exhibited commendable sensing properties within the relative humidity range of 33 % to 95 % at room temperature (25 °C), achieving a response value as high as 19 at 95 % relative humidity. Furthermore, the sensor displayed superior repeatability, characterized by rapid response and recovery speeds in the presence of moisture. These findings indicate that Lu-HHTP holds substantial promise as a material for humidity sensors.

Inspired by the powerful biological olfaction, scientists extracted numerous materials such as olfactory sensory neuron, olfactory receptor (OR) protein, and odorant binding protein from animal olfactory systems, then combined them with transducers to form multiple odor biosensors. These biosensors, despite well inheriting the sensing ability of creatures, have several drawbacks, such as complex preparation process, unstable sensing material characteristics, and high cost. Unlike the biological materials listed above, cell expressing heterologous OR maintains a stable sensing performance after passaging for multiple generations, also its experimental operation is simple, and cost is low. Therefore, odor biosensors based on cell expressing OR have been well developed in recent years. In this review, we first listed several odor biosensors based on cell expressing OR, mainly focusing on fluorescent and electrophysiological measurement methods. Furthermore, we illustrated the techniques to improve the biosensor performance, e. g., wider detection range, longer lifetime, more OR types, and higher quantification efficiency. In addition, we explained the possible prospects such as big sensor array and predicting odor response.

While exercise offers significant potential to enhance overall well-being, unscientific exercise practices often cause exercise fatigue, posing a threat to human health. Flexible sweat sensors have garnered considerable attention owing to their ability to continuously, non-invasively, and dynamically monitor human health during exercise at the molecular level. Therefore, in this study, we constructed a flexible molecularly imprinted polymer (MIP) sensor for the real-time monitoring of cortisol and lactate levels in sweat using cortisol or lactate as template molecules and pyrrole (Py) as functional monomer. Prussian blue (PB) was embedded into the MIP as a built-in redox probe, eliminating the need for an additional probe and facilitating the simultaneous quantification of cortisol and lactate concentrations. Moreover, the MIP-doped platinum nanoparticles (PtNPs) ehanced the electron transfer capability, further improving the sensitivity of the sensors. The fabricated flexibile cortisol and lactate MIP sensors demonstrated low limits of detection (LOD; 1.07 nM and 1.09 mM, respectively), high sensitivity (0.09 μA lg[nM]⁻¹ and 1.28 μA lg[nM]⁻¹), and exceptional stability and selectivity. The flexible MIP sensors could continuously and dynamically monitor changes in sweat cortisol and lactate concentrations, thus contributing to the advancement of next-generation flexible sweat electrochemical sensors and providing a crucial tool for monitoring exercise fatigue.

MicroRNAs (miRNAs) are promising biomarkers especially for early-stage cancer diagnostics, but the implementation of miRNA-based diagnostic tests is still hindered by the limitations of current analytical methods. The small size, low concentrations in biofluids and high sequence homology of miRNAs are challenges for assay development. Currently, most of the sensitive detection methods rely on enzymatic amplification steps, which complicate the analysis and can lead to biases in quantitation. Therefore, there is an increasing need to develop enzyme-free detection methods that are sensitive, specific and user-friendly. In this study, a simple direct hybridization assay for the DNA analogue of miR-20a was developed. The assay is based on upconverting nanoparticle labels, which enable ultrasensitive detection, and hairpin structured probes, which provide additional hybridization stability due to base stacking. The limit of detection was 0.73 fM with plasma recoveries between 76 % and 111 %, demonstrating that the assay could be used for direct detection of miRNAs from complex sample matrices without isolation of RNA. Due to the simplicity and the excellent sensitivity for an amplification-free method, the assay has a great potential for miRNA-based clinical applications.

In this study, we propose an enhanced nanopore sensing strategy that utilizes a peptide nucleic acid (PNA)-based triplex molecular beacon sensor to achieve the simultaneous detection of multiple biomarkers with a high degree of sensitivity. The sensor is a triplex switch composed of a triplex-forming DNA strand and an oligo-arginine-tagged PNA strand, serving as the target recognition moiety and signal output element, respectively. Upon target binding to the recognition element of the sensor, the PNA signal output strand is released and a hybrid complex of the target-DNA recognition strand is formed simultaneously. Due to the positive charges carried by the PNA-Arg strands, they could be driven through the nanopore under positive electric field, effectively eliminating interferences from co-existing target-DNA complexes. This approach enables label-free, one-step detection of targets without requiring complex treatments and procedures. Leveraging the modular properties of DNA recognition strand, this method can be applied universally, and here, we successfully demonstrate its application using three SARS-CoV-2 related biomarkers.

Endogenous aldehydes are produced via tightly regulated metabolic processes and are rapidly cleared by aldehyde dehydrogenases. However, dysregulation of these processes leads to accumulation of toxic aldehydes in affected tissues, resulting in electrophilic stress forming pathogenic DNA- and protein-adducts. The highly reactive aldehydes contribute to numerous pathologies including traumatic brain injury, cancer, cardiovascular diseases, and fibrosis. Due to their transient nature and electrophilicity, the development of molecular imaging probes with the ability to trap and detect aldehydes in vivo remains a challenge. Herein, two classes of aldehyde-mapping MRI probes are discussed: (1) gadolinium and manganese-containing macrocyclic MRI agents targeting extracellular aldehydes produced during active tissue fibrosis, and (2) metal-free hydrazoCEST-MRI agents for total intracellular aldehyde detection. This comprehensive review outlines the development, mechanisms, and potential applications of diverse MRI probes targeting aldehydes, aiming to advance non-invasive diagnostic tools, disease staging, and therapeutic interventions in multiple pathologies.