Microfluidics based biochemical analysis shows distinctive advantages for fast detection of pathogenic microorganisms. This Feature summarizes the progress in the past decade on microfluidic methods ...for purification and detection of pathogenic bacteria and viruses as well as their applications in food safety control, environmental monitoring, and clinical diagnosis.
A highly active and stable electrocatalyst for hydrogen evolution is developed based on the in situ formation of MoS2 nanoparticles on mesoporous graphene foams (MoS2/MGF). Taking advantage of its ...high specific surface area and its interconnected conductive graphene skeleton, MGF provides a favorable microenvironment for the growth of highly dispersed MoS2 nanoparticles while allowing rapid charge transfer kinetics. The MoS2/MGF nanocomposites exhibit an excellent electrocatalytic activity for the hydrogen evolution reaction with a low overpotential and substantial apparent current densities. Such enhanced catalytic activity stems from the abundance of catalytic edge sites, the increase of electrochemically accessible surface area and the unique synergic effects between the MGF support and active catalyst. The electrode reactions are characterized by electrochemical impedance spectroscopy. A Tafel slope of ≈42 mV per decade is measured for a MoS2/MGF modified electrode, suggesting the Volmer‐Heyrovsky mechanism of hydrogen evolution.
A highly active electrocatalyst of MoS2/MGF, where the MoS2 nanoparticles are formed uniformly on mesoporous graphene foams (MGF) via a facile solvothermal approach, is reported. The MoS2/MGF nanocomposites exhibit the high hydrogen evolution reaction activity with a low overpotential and large cathodic currents arising from MGF's high surface area, abundant mesopores, and highly conductive skeleton of graphene.
Nitric oxide (NO) is a transcellular messenger involved in many physiological and pathological processes, but the real-time detection of NO in biological systems is still challenging due to its rapid ...diffusion, low concentration, and short half-life. A novel electrochemical sensing platform based on iron phthalocyanine (FePc) functionalized nitrogen-doped graphene (N-G) nanocomposites was constructed to achieve in situ monitoring of NO released from living cells on the sensing layer. By taking advantage of the synergetic effect of N-G and FePc nanocomposites, the N-G/FePc sensor displays excellent electrocatalytic activity toward NO with a high sensitivity of 0.21 μA μM–1 cm–2 and a low detection limit of 180 nmol L–1. The following layer-by-layer assembly of poly-l-lysine (PLL) and Nafion further improved the capacity of resisting disturbance as well as the biocompatibility of the sensing interface. The flexible design of the ITO substrate based electrode provides a more controlled cellular biosensing system which could capture molecular signals immediately after NO released from human umbilical vein endothelial cells (HUVECs). The exhibited additional features of high sensitivity, rapid response, and ease of operation implies that the proposed N-G/FePc/Nafion/PLL ITO biosensor is a promising powerful platform in various complex biological systems.
Exosomes are considered promising indicators for early cancer diagnosis. The multiple protein biomarkers carried by exosomes are associated with diverse significant biological processes and are ...important biomarkers of cancer subtypes. However, it is challenging to sensitively and accurately quantify protein biomarkers from a few exosomes. Herein, we propose an ultrasensitive method for quantitatively profiling protein biomarkers on the surface of exosomes by integrating mass spectrometry imaging and gold nanoparticle (AuNP)-based signal amplification. Organic oligomers as mass tags and specific antibodies are modified on AuNPs to form biomarker probes. Exosomes captured by the antibody-coated gold chip are recognized by the AuNPs probes, forming a sandwich immunoassay. By mass spectrometry imaging the mass tags, multiple protein biomarkers can be quantitatively detected from the exosomes, with a limit-of-detection (LOD) down to 50 exosome particles. As a proof of concept, exosomes secreted by different breast-cancer cell subtypes, i.e. MCF-7 and MDA-MB231, were distinguished by the level of surface protein biomarkers of CD9, CD44, and epithelial cell adhesion molecule (EpCAM) acquired by the method, demonstrating that exosomes could be used for the diagnosis of cancer at subtype level. In consideration of the advantages of the ultrasensitivity, accuracy, and simplicity, the strategy has potential prospects in biomarker discovery, cellular phenotype characterization, and cancer diagnosis.
Precise and rapid monitoring of metabolites in biofluids is a desirable but unmet goal for disease diagnosis and management. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) ...exhibits advantages in metabolite analysis. However, the low accuracy in quantification of the technique limits its transformation to clinical usage. We report herein the use of Au nanoparticle arrays self-assembled at liquid–liquid interfaces for mass spectrometry (MS)-based quantitative biofluids metabolic profiling. The two-dimensional arrays feature uniformly and closely packed Au nanoparticles with 3 nm interparticle gaps. The experimental study and theoretical simulation show that the arrays exhibit high photothermal conversion and heat confinement effects, which enhance the laser desorption/ionization efficacy. With the nanoscale roughness, the AuNP arrays as laser desorption/ionization substrates can interrupt the coffee-ring effect during droplet evaporation. Therefore, high reproducibility (RSD <5%) is obtained, enabling accurate quantitative analysis of diverse metabolites from 1 μL of biofluids in seconds. By quantifying glucose in the cerebrospinal fluid (CSF), it allows us to identify patients with brain infection and rapidly evaluate the clinical therapy response. Consequently, the method shows potential in advanced metabolite analysis and biomedical diagnostics.
A smart and multifunctional paper-based SERS sensing card is generated through patterning self-assembled interfacial arrays of gold nanoparticles (AuNPs) on the tip of an arrow-shaped paper strip. It ...is found that the closely packed monolayer of AuNPs is evenly distributed on the paper surface, resulting in a multitude of SERS hot spots over the detection zone. The paper card, with its inherent ability to separate and preconcentrate analytes by the capillary force and polarity difference between sample components, was exploited successfully as an integrated platform, allowing for sub-attomolar (50 × 10–18 M) detection from microliter-volume (10 μL) samples. Furthermore, the simple preparation (lithography-free process), fast detection (<5 min), and low cost (<3 cents) demonstrate that the paper card is a practical and portable sensing interface for wide application in environmental and food analysis.
Protein phosphorylation is an important post-translational modification (PTM) involved in diverse cellular functions. It is the most prevalent PTM in both
and
, but its status in
has not been ...reported. Herein, we performed a comprehensive, quantitative phosphoproteomic profile analysis of four stages of the
life cycle: unsporulated oocysts (USO), partially sporulated (7 h) oocysts (SO7h), sporulated oocysts (SO), and sporozoites (S). A total of 15,247 phosphorylation sites on 9514 phosphopeptides corresponding to 2897 phosphoproteins were identified across the four stages. In addition, 456, 479, and 198 differentially expressed phosphoproteins (DEPPs) were identified in the comparisons SO7h vs. USO, SO vs. SO7h, and S vs. SO, respectively. Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of DEPPs suggested that they were involved in diverse functions. For SO7h vs. USO, DEPPs were mainly involved in cell division, actin cytoskeleton organization, positive regulation of transport, and pyruvate metabolism. For SO vs. SO7h, they were related to the peptide metabolic process, translation, and RNA transport. DEPPs in the S vs. SO comparison were associated with the tricarboxylic acid metabolic process, positive regulation of ATPase activity, and calcium ion binding. Time course sequencing data analysis (TCseq) identified six clusters with similar expression change characteristics related to carbohydrate metabolism, cytoskeleton organization, and calcium ion transport, demonstrating different regulatory profiles across the life cycle of
. The results revealed significant changes in the abundance of phosphoproteins during
development. The findings shed light on the key roles of protein phosphorylation and dephosphorylation in the
life cycle.
Rarely reported low-cost molybdenum boride and carbide microparticles, both of which are available in abundant quantities due to their widespread use in industry, adsorb at aqueous ...acid-1,2-dichloroethane interfaces and efficiently catalyse the hydrogen evolution reaction in the presence of the organic electron donor - decamethylferrocene. Kinetic studies monitoring biphasic reactions by UV/vis spectroscopy, and further evidence provided by gas chromatography, highlight (a) their superior rates of catalysis relative to other industrially significant transition metal carbides and silicides, as well as a main group refractory compound, and (b) their highly comparable rates of catalysis to Pt microparticles of similar dimensions. Insight into the catalytic processes occurring for each adsorbed microparticle was obtained by voltammetry at the liquid-liquid interface.
Exosomes has attracted tremendous research interests as they are emerging as a new paradigm of liquid biopsy. Although the concentration of exosomes in blood is relatively abundant, there still ...exists various vesicle-like nanoparticles, such as microvesicles, apoptotic bodies. It's an urgent need to isolate and enrich exosomes from the complex contaminants in biofluid samples. Moreover, the expressing level of exosomal biomarkers varies a lot, which make the sensitive molecular detection of exosomes in high demand. Unfortunately, the efficient isolation and sensitive molecular quantification of exosomes is still a major obstacle hindering the further development and clinical application of exosome-based liquid biopsy. Nanomaterials, with unique physiochemical properties, have been widely used in biosensing and analysis aspects, thus they are thought as powerful tools for effective purification and molecular analysis of exosomes. In this review, we summarized the most recent progresses in nanomaterials assisted exosome isolation and analysis towards liquid biopsy. On the one hand, nanomaterials can be used as capture substrates to afford large binding area and specific affinity to exosomes. Meanwhile, nanomaterials can also be served as promising signal transducers and amplifiers for molecular detection of exosomes. Furthermore, we also pointed out several potential and promising research directions in nanomaterials assisted exosome analysis. It's envisioned that this review will give the audience a complete outline of nanomaterials in exosome study, and further promote the intersection of nanotechnology and bio-analysis.
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Gastric cancer is a common cancer afflicting people worldwide. Although incremental progress has been achieved in gastric cancer research, the molecular mechanisms underlying remain unclear. In this ...study, we conducted bioinformatics methods to identify prognostic marker genes associated with gastric cancer progression. Three hundred and twenty-seven overlapping DEGs were identified from three GEO microarray datasets. Functional enrichment analysis revealed that these DEGs are involved in extracellular matrix organization, tissue development, extracellular matrix-receptor interaction, ECM-receptor interaction, PI3K-Akt signaling pathway, focal adhesion, and protein digestion and absorption. A protein-protein interaction network (PPI) was constructed for the DEGs in which 25 hub genes were obtained. Furthermore, the turquoise module was identified to be significantly positively coexpressed with macrophage M2 infiltration by weighted gene coexpression network analysis (WGCNA). Hub genes of
, and
were overlapped in both PPI hub gene list and the turquoise module with significant association with the prognosis in gastric cancer. Moreover, functional analysis demonstrated that these hub genes play pivotal roles in cancer cell proliferation and invasion. The investigation of the gene markers can help deepen our understanding of the molecular mechanisms of gastric cancer. In addition, these genes may serve as potential prognostic biomarkers for gastric cancer diagnosis.
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