Analyst最新文献

Glass nano/micron pipettes, owing to their easy preparation, unique confined space at the tip, and modifiable inner surface of the tip, can capture the ion current signal caused by a single entity, making them widely used in the construction of highly sensitive and highly selective electrochemical sensors for single entity analysis. Compared with other solid-state nanopores, their conical nano-tip causes less damage to cells when inserted into them, thereby becoming a powerful tool for the in situ analysis of important substances in cells. However, glass nanopipettes have some shortcomings, such as poor mechanical properties, difficulty in precise preparation (aperture less than 50 nm), and easy blockage during complex real sample detection, limiting their practicability. Therefore, in recent years, researchers have conducted a series of studies on glass micropipettes. Ionic current rectification technology is a novel electrochemical analysis technique. Compared with traditional electrochemical analysis methods, it does not generate redox products during the detection process; therefore, it can not only be used for the determination of non-electrochemically active substances, but also causes less damage to the cell/living body in situ analysis, becoming a powerful analysis technology for the in situ analysis of cells/in vivo in recent years. In this review, we summarize the preparation and functionalization of glass nano/micron pipettes and introduce the sensing mechanisms of two electrochemical sensing platforms constructed using glass nano/micron pipette-based ion current rectification sensing technology as well as their applications in single cell/in vivo analysis, existing problems, and future prospects.

A highly efficient photoelectrochemical (PEC) strategy was proposed for the determination of ascorbic acid (AA). Cerium-doped tungsten trioxide (Ce-WO₃) microrods were synthesized by a hydrothermal method and further characterized through transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. Thereafter, they were deposited onto a cleaned fluorine-doped tin oxide (FTO) glass forming the working electrode as the photoactive material. Under strong visible light irradiation, the resulting PEC sensing platform generated the corresponding electron–hole pairs, converting light signals into electrical signals. Ascorbic acid served as a good electron donor to trap holes for improvement of photocurrent responses on Ce-WO₃/FTO. Besides, the strength of photocurrent signals versus the logarithm of ascorbic acid concentration showed a good linearity over the ascorbic acid concentration range of 100–4000 nM and the limit of detection (LOD) was estimated to be 28.6 nM. Importantly, this PEC sensor had a fast response, high sensitivity, and distinguished selectivity for detecting ascorbic acid. In addition, it also had the features of being simple to fabricate, low production cost, and portable, which made it a promising means of ascorbic acid determination.

Detecting ammonia at low concentrations is crucial in various fields, including environmental monitoring, industrial processes, and healthcare. This study explores the development and performance of an ultra-sensitive ammonia sensor using carboxylic group-functionalized multi-walled carbon nanotubes (f-MWCNTs) overlaid on polyvinyl acetate nanofibers coated on a quartz crystal microbalance (QCM). The sensor demonstrates high responsiveness, with a frequency shift response of over 120 Hz when exposed to 1.5 ppm ammonia, a sensitivity of 23.3 Hz ppm⁻¹ over a concentration range of 1.5–7.5 ppm, and a detection limit of 50 ppb. Additionally, the sensor exhibits a rapid response time of only 14 s, excellent selectivity against other gases, such as acetic acid, formaldehyde, methanol, ethanol, propanol, benzene, toluene, and xylene, and good stability in daily use. These characteristics make the sensor a promising tool for real-time ammonia detection in diverse applications.

One of the challenges facing biology is to understand metabolic events at a single cellular level. While approaches to examine dynamics of protein distribution or report on spatiotemporal location of signalling molecules are well-established, tools for the dissection of metabolism in single living cells are less common. Advances in Raman spectroscopy, such as stimulated Raman scattering (SRS), are beginning to offer new insights into metabolic events in a range of experimental systems, including model organisms and clinical samples, and across a range of disciplines. Despite the power of Raman imaging, it remains a relatively under-used technique to approach biological problems, in part because of the specialised nature of the analysis. To raise the profile of this method, here we consider some key studies which illustrate how Raman spectroscopy has revealed new insights into fatty acid and lipid metabolism across a range of cellular systems. The powerful and non-invasive nature of this approach offers a new suite of tools for biomolecular scientists to address how metabolic events within cells informs on or underpins biological function. We illustrate potential biological applications, discuss some recent advances, and offer a direction of travel for metabolic research in this area.

Respiratory pathogen infections are seasonally prevalent and are likely to cause co-infections or serial infections during peak periods of infection. Since they often cause similar symptoms, simultaneous and on-site detection of respiratory pathogens is essential for accurate diagnosis and efficient treatment of these infectious diseases. However, molecular diagnostic techniques for multiple pathogens in this field are lacking. Herein, we developed a microfluidic LAMP and real-time fluorescence assay for rapid detection of multiple respiratory pathogens using a ten-channel microfluidic chip with pathogen primers pre-embedded in the chip reaction well. The microfluidic chip provided a closed reaction environment, effectively preventing aerosol contamination and improving the accuracy of the detection results. Its corresponding detection instrument could automatically collect and display the fluorescence curve in real time, which was more conducive to the interpretation of results. The results showed that the developed method could specifically recognize the nucleic acid of influenza A(H1N1), Mycoplasma pneumoniae, respiratory syncytial virus type A, and SARS-CoV-2 with low detection limits of 10⁴ copies per mL or 10³ copies per mL. The test results on clinical samples demonstrated that the developed method has high sensitivity (92.00%) and high specificity (100.00%) and even has the capability to differentiate mixed-infection samples. With simple operation and high detection efficiency, the present portable and simultaneous detection assay could significantly improve the efficiency of on-site detection of respiratory infectious diseases and promote the accurate treatment, efficient prevention and control of the diseases.

Electrochemical detection of pollutants (e.g. heavy metals) in real samples often requires the adjustment of pH to allow optimal sensitivity. Such sample pretreatment can be challenging for on-site applications as it implies the use of valves, pumps and storage of base or acid solutions. We report here the use of an electrochemical approach for the control of water sample pH. It offers the possibility for local pH adjustment while simultaneously detecting Pb²⁺, whose detection sensitivity is pH dependent. An effective electrochemical method through local electrochemical acidification is performed to detect Pb²⁺ within a desired pH range without the need to add chemical reagents. Local acidification is based on water electrolysis. An anodic potential is applied to an acidifier to rapidly electrogenerate protons. This allows the sample pH to be tailored to the optimal detection condition. Reduction of the Pt oxide layer formed on the acidifier is key to obtain repeatable results in Pb²⁺ detection. On-site sample acidification is combined with anodic stripping voltammetry to reach a detection limit of 6 ppb (30 nM), which is lower than the World Health Organization guideline value for Pb²⁺ level in drinking water.

Blood glucose concentration is an important index for the diagnosis of diabetes, its self-monitoring technology is the method for scientific diabetes management. Currently, the typical household blood glucose meters have achieved great success in diabetes management, but they are discrete detection methods, and involve invasive blood sampling procedures. Optical detection technologies, which use the physical properties of light to detect the glucose concentration in body fluids non-invasively, have shown great potential in non-invasive blood glucose detection. This article summarized and analyzed the basic principles, research status, existing problems, and application prospects of different optical glucose detection technologies. In addition, this article also discusses the problems of optical detection technology in wearable sensors and perspectives on the future of non-invasive blood glucose detection technology to improve blood glucose monitoring in diabetic patients.

Fluorescence polarization (FP) assays are widely used to quantify biomolecules, and their combination with microfluidic devices has the potential for application in onsite analysis. However, the hydrophobic surface of polydimethylsiloxane (PDMS)-based microfluidic devices and the amphiphilicity of the blocking agents can cause the nonspecific adsorption of biomolecules, which in turn reduces the sensitivity of the FP assay. To address this, we demonstrated an FP assay with improved sensitivity in microfluidic devices using a polyethylene glycol-based surface modification to avoid the use of blocking agents. We evaluated the effectiveness of the modification in inhibiting nonspecific protein adsorption and demonstrated the improved sensitivity of the FP immunoassay (FPIA). Our study addressed the lack of sensitivity of FP assays in microfluidic devices, particularly for the quantification of low-abundance analytes.

The processes of apoptosis and inflammatory responses, which are defensive strategies used by cells to confront external substances, can give rise to diverse diseases when prolonged or disrupted, such as cancer, Alzheimer's disease, and Parkinson's disease. Here we engineered a live-cell imaging fluorescent probe for nitric oxide (NO) based on naphthalimide and o-phenylenediamine, enabling the sensitive detection of NO in cancer cells and thereby live-monitoring of the doxorubicin-induced apoptosis and lipopolysaccharide-triggered inflammation reactions. Importantly, we found that the level of released NO can sensitively indicate the early stages of both cellular inflammatory responses and apoptotic processes. This suggested that cellular NO in fact behaves as a new class of signaling molecule for inflammatory responses and apoptosis processes, providing a potent tool for live-monitoring cellular physiological reactions.

In this study, a novel electrochemiluminescent (ECL) sensor for highly sensitive detection of trilobatin (Tri) was developed based on silver metal–organic frameworks (AgMOFs) and nitrogen-doped carbon quantum dots (N-CDs). N-CDs exhibited high ECL intensity but poor ECL stability, while AgMOFs had a large specific surface area, high porosity, and good adsorption properties. Compositing both of them not only improved the ECL stability of N-CDs, but also enhanced the ECL strength of materials, so AgMOF@N-CD composites were used as the luminophore of the sensor. Under the optimized conditions, the ECL sensor showed a linear range of 1.0 × 10⁻⁷ M to 1.0 × 10⁻³ M for the detection of Tri, and the detection limit was as low as 5.99 × 10⁻⁸ M (S/N = 3). In addition, the sensor had excellent reproducibility, stability, and anti-interference ability. It could be utilized for the detection of Tri in real samples with recoveries of 95.78–102.26%, indicating that the constructed ECL sensor for detecting Tri possessed better application prospects.