Analysis & sensing最新文献

Three-dimensional paper-based microfluidic devices have shown great potential in various applications, including point-of-care diagnostics, environmental monitoring, and tissue engineering. However, their fabrication is still limited to stacking and origami methods. Inspired by the art of bamboo braiding in China, we developed a novel fabrication technique based on the braiding concept to create three-dimensional paper-based microfluidic devices with PDMS-impregnated paper substrate as the building units. The resulting three-dimensional paper device brings unique advantages, including compactness, facile disassembly, and real-time flow visualization. The multiplexed glucose analysis with a braided device integrated with 16-switchable valves for flow control was further fabricated to demonstrate the device‘s applicability. We envision braiding-based fabrication technology opening new possibilities and bringing broad applications for three-dimensional paper microfluidic devices.

A simple and fast (<15 min), two-step laser scribing of cardboard substrates is described as a method for fabricating carbon electrodes modified with metallic nanoparticles. The first scribing step patterned a cardboard substrate (promoting the formation of porous carbon electrodes). The second step was included to produce metallic nanoparticles via a chemical reduction process of cations from an aqueous solution. For these experiments, the effects of copper, silver, nickel, cobalt, zinc, and gold were evaluated considering their effect on the electrical properties and the composition of the carbon materials produced. These experiments revealed that, despite significant changes in resistance (from 138±7 Ω for plain electrodes to just 53±3 Ω for Au-modified electrodes), only marginal changes were observed in the morphology or composition of the material produced (I_G/I_D ranged from 1.2±0.3 for the plain cardboard to 1.8±0.3 for the cobalt-modified electrodes). To demonstrate the applicability of the proposed strategy, Au-modified electrodes were assembled into electrochemical sensors and applied to measure the metabolic activity of live microorganisms in various commercial samples, requiring only 100 μL of sample and 10 min of incubation time.

The ability to monitor protein biomarkers at clinically relevant concentrations is a powerful approach that provides insights into health status. The synergistic combination of microfluidics and photonics (optofluidic) has emerged as a new means to achieve this capability for detection and manipulation of biological samples. Here in this work, we demonstrate an optofluidic device which integrates the detection and the particle-focusing components to facilitate on-chip measurement of protein levels. With this design, we use a laser-induced fluorescence technique for the direct measurement of protein levels on magnetic bead complexes tagged with fluorescein isothiocyanate (FITC) fluorophore. The developed system was employed for the detection of human immunoglobulin G (IgG) as a model protein within a range of 0–20 μg/mL, showing an ability to resolve the fluorescence signal from different IgG concentrations down to 5.4 nM (0.81 μg/mL). The selectivity in detecting specific IgG target was tested by comparing the fluorescence signal levels from other interfering proteins such as bovine serum albumin (BSA) and human IgM. Although our system was designed for detecting IgG protein, this optofluidic device can be a powerful platform for the rapid detection of a diverse range of biomarkers, including viral pathogens retaining adequate signal sensitivity and selectivity.

Fatty acids (FAs) contain a vast amount of structural diversity, and differences in fatty acid structure have been associated with various disease states. Accurate identification and characterization of fatty acids is critical to fully understand the biochemical roles these compounds play in disease progression. Conventional tandem mass spectrometry (MS/MS) workflows do not provide sufficient structural information, necessitating alternative dissociation methods. Gas-phase charge inversion ion/ion reactions can be used to alter the ion type subjected to activation to provide improved or complementary structural information. Herein, we have used an ion/ion reaction between fatty acid (FA) anions and magnesium tris-phenanthroline [Mg(Phen)₃] dications to promote charge remote fragmentation of carbon-carbon bonds along the fatty acid chain, allowing for localization of carbon-carbon double bond (C=C) positions to successfully differentiate monounsaturated fatty acid isomers. Relative quantification was also performed to obtain the relative abundance of fatty acid isomers in different biological tissues. For example, the relative abundance of FA 18 : 1 (9) was determined to vary across regions of rat brain, rat kidney, and mouse pancreas, and FA 16 : 1 (9) was found to have a higher relative abundance in the dermis layer compared to the sebaceous glands in human skin tissue.

Point-of-care technologies need particularly stringent requirements, including portability, rapidity, affordability, and ease of use, enabling healthcare practitioners to perform reliable analyses in decentralized settings. Such diagnostic tests are usually based on bioassays that allow for the detection of clinically relevant biomarkers, namely proteins, antibodies and nucleic acids. In the context of electrochemical biosensors, the implementation of magnetic beads offers unique advantages stemming from their high surface-to-volume ratio, easy manipulation through magnetic fields and versatility in surface chemistries for bio-conjugation. The present concept article highlights the advantages achieved through the implementation of magnetic beads in electrochemical binding assays, immunosensors and genosensors. These methods mostly exploit magnetic beads for immobilization purposes, allowing for the assembly of bio-complexes in liquid suspensions under precise temperature and shaking control, as well as simplifying the manipulation steps to enable untrained personnel to perform analyses. In addition, magnetic beads can also take part in the detection mechanism, leading to innovative sensing strategies with great potential for point-of-care diagnostic applications.

The cover feature illustrates the application of high-brightness green fluorescent polymer dots (Pdots) to intraoperative neuroimaging to achieve excellent tracing effects. Through direct administration, Pdots can rapidly bind to the epineurium and perineurium, stably characterizing the peripheral nerve. In addition, it was found that Pdots bind to nerve membranes, do not invade nerve cells, and have high biosafety. Our study illustrates that Pdots has the potential as a neurotracer in image-guided surgery and has significant implications for reducing iatrogenic nerve injury and related surgical complications. More information can be found in the Research Article by Liqin Xiong and co-workers.

The front cover image illustrates the selective illumination of lipid droplets by BODIPYs, effectively highlighting the trafficking of lipid droplets between neighbouring cells. Two asymmetric BODIPY derivatives, exhibiting a red-shifted emission spectrum and a substantial Stokes shift compared to reference compounds, were successfully synthesized. These favourable fluorescence characteristics enabled the application of these derivatives in probing the influence of starvation on the intercellular exchange of lipid droplets. More information can be found in the Research Article by Amandeep Kaur, Elizabeth J. New, and co-workers.

Over the past few decades, pretargeted bioimaging has made significant contributions to disease diagnosis and the real-time visualization of biological processes. Notably, the inverse electron demand Diels-Alder (IEDDA) reaction between tetrazine (Tz) and trans-cyclooctene (TCO) has shown enormous potential in pretargeted bioimaging applications by capitalizing on its rapid kinetics, specific reactivity, biorthogonality and biocompatibility. To date, imaging probes based on the Tz−TCO click reaction have been extensively developed and widely used for pretargeted bioimaging applications. In this review, we focus on the Tz−TCO click reaction and summarize its applications in pretargeted bioimaging. Firstly, the fundamental principles for designing imaging probes based on the Tz−TCO click reaction are explained. Then, recent advances in imaging probes based on the Tz−TCO click reaction are discussed in detail. Finally, the current challenges and perspectives of the Tz−TCO click reaction in pretargeted bioimaging applications are presented.

The simultaneous detection of multiple analytes using electrochemical biosensor arrays has demonstrated significant potential in various fields, including medical diagnostics. These platforms are designed to be low-cost, easy to use, and offer fast detection of a range of molecules. This concept article discusses the components necessary to achieve multiplexing with electrochemical biosensor arrays. The various methods used to fabricate electrode arrays of different types are discussed. Furthermore, the methods for the selective immobilization of multiple different bioreceptors onto individual electrodes within the array, a crucial step essential for conferring specificity to the analytical processes, are presented with relevant examples. We have focused on enzymes, antibodies and aptamers as examples of bioreceptors that have been deployed in various multianalyte electrochemical detection platforms. Finally, we discuss the key challenges associated with their application for the analysis of real samples and provide a future outlook on possible strategies that can be used to overcome these challenges.

The skeleton plays a significant role in human health. Comprehensive and non-invasive visualization of the bone is in high demand to detect bone-related diseases. Clinically, conventional imaging techniques continue to face challenges in terms of limited imaging sensitivity, extended acquisition durations, and the inherent presence of ionizing radiation. These factors collectively hinder their capacity to furnish real-time spatial insights into cellular activity. Recently, Numerous innovative imaging methodologies employing diverse types of probes have emerged to enhance the clinical detection of bone. In vivo imaging of bone contribute to continuously detecting bone metabolism and growth, diagnosing bone metastases, visualizing medication delivery to bones. Fluorescent probes in dynamic detection of bone metabolism several inherent advantages. First, Fluorescent probes present lower potential long-term toxicity than radioactive isotope labels. Second, fluorescent dyes used in in vitro imaging are more cost-effective and come in a more compact size. Next, Near-infrared (NIR) dyes have deeper tissue penetration capability and lower tissue autofluorescence. However, bone-imaging fluorescent probes highly depend on phosphonate-related ligands. These ligands have multiple side effects in clinic and long half-live of them also exacerbates clearance concerns. This review aims to conclude and analyse the recently reported fluorescent probes for the precise detection of bone. Firstly, we outline the fundamental design mechanism of bone fluorescent probes and describe diverse bone-targeting moieties, emphasizing the targeting ligands, signal moieties, and functionalities of these probes. Secondly, we discuss the recent promising bone fluorescent probes for the precise and sensitive detection of bone. Finally, we offer our insights on potential future advancements in this field. We anticipate that this review will inspire creative ideas for designing and creating innovative bone-targeting probes, with applications in bone imaging, pharmaceutical screening, and assessing therapeutic outcomes.