Activity

.The coexistent pollution of multiple mycotoxins displays a synergistic toxicity effect that significantly threatens human health. Therefore, it is essential to establish a rapid detection method for multi-mycotoxins in food. In this study, red, green, and blue latex microspheres (LMs) were applied as the aflatoxin B1 (AFB1), T-2 toxins (T-2), and zearalenone (ZEN) antibodies labeled tracer, respectively. Based on the principle of spatial resolution, a rainbow “traffic light” pattern latex microspheres lateral flow immunoassay (LMs-LFIA) integrated with a portable and user-friendly smartphone-based device was first developed to detect three kinds of mycotoxins simultaneously. The cut-off values of the method for AFB1/T-2/ZEN in cereals were 1/15/40 μg kg-1, the limits of detection were 0.04/0.40/1.21 μg kg-1, respectively. The recoveries ranged from 82.1% to 107.5%, with the coefficient of variation from 3.0% to 8.1%. A parallel analysis in 26 naturally contaminated cereal samples was confirmed by commercial ELISA kits; the results showed a good correlation (R2＞0.99), indicating the practical reliability of the rainbow LMs-LFIA. This method provided a visually enjoyable, portable, and sensitive detection mode for multi-target detection of mycotoxins or other small molecule hazard factors in food.In the present study, a molecular beacon biosensor was developed to enable efficient detection of the viral RNAs using a previously described HyCaSD platform. The HyCaSD molecular beacon probes were labeled with the Cy5 and BHQ3 at each end of the hairpin probes. The fluorescent signal was detected immediately only when the molecular beacon probes specifically hybridized to the target sequence and unfolded their hairpin structures. This combination greatly improved the sensitivity with LOD of 100 copy equivalents per reaction (around 20-fold greater than the original HyCaSD). In addition, our MB-based HyCaSD demonstrated a single-step, single-tube and actual-time RNA detection procedure, thereby bringing it a major step closer to point-of-care diagnostic applications for viral infectious diseases.Circulating tumor cells (CTCs) as non-invasive biomarkers have great potential in evaluating tumor progression and prognosis. However, effective enrichment of CTCs and minimizing phenotypic bias remain a serious challenge. Herein, a DNA tetrahedron-aptamer complex-mediated rolling circle amplification (TDN-RCA) strategy is developed for cell surface protein signal amplification and CTC enrichment, employing DNA tetrahedron-EpCAM aptamer complex as a scaffold and initiating rolling circle amplification (RCA) reaction on the surface of CTCs in situ. The DNA tetrahedron-aptamer complex enables the cell-specific recognition and enhances cell membrane anchoring ability, generating a large number of magnetic beads binding sites through the RCA reaction in situ. Thus, the signals of cell surface markers with low expression levels are amplified in situ and then efficient CTC enrichment is achieved. This method improves the capture efficiency of CTCs with low expression of EpCAM, which has great potential in clinical application.MicroRNAs (miRNAs) and p53 gene can serve as valuable biomarkers for the diagnosis of a variety of cancers. Nevertheless, although the development of the DNA nanostructure on the detection of cancer-related biomarkers was initially demonstrated several years ago, the challenges of developing simpler, cheaper, and multi-level detection DNA biosensors persist. Herein, based on the rolling circle amplification (RCA) coupled with the target-triggered skill, we have developed a well-designed detecting platform. In this study, the dumbbell-shaped probes (DPP) could be cyclized and initiated through targets, thus beginning the target-catalyst RCA (tc-RCA) reaction, therefore engendering numerous dumbbell probe amplicons (DPA). Thereafter the probe primers (PP) mutually complementary to the loop of DPA was introduced, leading to the branch strand displacement reaction (B-SDA). SYBR Green I can effectively bind to the amplified double-stranded structures as a fluorescent reporter. Altering the target-binding sequence of the DPP, this biosensor can also be applied to detect different biomarkers. As a consequence, target miR-21 and p53 gene can be detected down to 0.65 fM and 2.04 fM respectively with a wide dynamic range. Moreover, we have also achieved the qualitative detection of interesting targets in cell lysates as well as the complex biological substrates and compared the results with reverse transcription quantitative PCR (RT-qPCR), thereby indicating the potential application in clinical diagnosis and biomedical research.Elevated C-reactive protein (CRP) levels are linked with bacterial infection, local inflammation in osteoarthritis and the increased risk of developing cardiovascular disease. Here, a sensitive and label-free CRP assay is developed by combining cyclic enzymatic signal amplification and capillary electrophoresis (CE) with UV detection. This assay is constructed of base pairing and target recognition. Thereinto, nicking endonuclease (NEase) can recognize the specific nucleotide sequences in double-stranded DNA (dsDNA), which is formed by a CRP aptamer and its complementary DNA (cDNA). Sequentially, NEase cleaves only cDNA to produce signal DNAs. Therefore, a large number of signal DNAs are generated through continuous enzyme cleavage. In the presence of CRP, the aptamer recognizes and binds to CRP with high affinity and selectivity, which results in a decrease in signal DNAs, and thus the UV absorption value of CE significantly decreases, too. A wide linear range was obtained between 0.0125 and 15 μg mL-1 (0.11-130.5 nM) in 1% human serum with a detection limit of 4 ng mL-1 (35 pM). Additionally, the proposed method is universal and can be applied to analyze other similar substances by altering the matched aptamer.In this study, a novel fluorescence sensor for tetracyclines (TCs) detection was designed using WS2 quantum dots (WS2 QDs). WS2 QDs could be quenched by TCs through the inner filter effect (IFE). The limit of detection of this proprosed method is 39 nM, 52 nM, and 28 nM for tetracycline (TC), doxycycline (DC), and oxytetracycline (OTC), respectively. The as-proposed strategy was successfully applied to detect TC in milk samples and human serum samples. The WS2 QDs were highly biocompatible and showed lower toxicity. Moreover, the WS2 QDs was successfully applied to imaging TC in HeLa cells owing to its excellent optical performance and great biocompatibility.The persistent lack of adequate matrix-matched reference materials still hinders the quantitative analysis of elements and biomolecules in biological samples by LA-ICP-MS. This fact is especially critical in cell cultures due to their complex matrix. In this work, we propose a novel matrix-matched calibration strategy, which fully mimics the matrix of cultured cells, by using the same cell line of the sample to create laboratory standards. As a model case, the quantitative imaging of two cytosolic proteins (MT2A and APOE) in individual HRPEsv cells was performed by LA-ICP-MS, both in cells subjected to inflammation with cytokine Interleukin-1α (IL-1α) and controls (CT). A single biomarker strategy using Au nanoclusters (AuNCs) as specific antibody labels was employed for the analysis of the selected proteins in individual cells by LA-ICP-MS. HRPEsv cells supplemented with suspensions containing nude AuNCs was employed to generate single-cell laboratory standards (HRPEsv cells@AuNCs). The preparation and characterization of the single-cell laboratory standards by both ICP-MS and LA-ICP-MS were optimized as well as the data treatment protocol required for obtaining the quantitative distribution of the proteins in individual cells. The mass of APOE and MT2A per cell in CT and IL1α-treated HRPEsv cells analysed by LA-ICP-MS using the proposed matrix-matched calibration were successfully corroborated with commercial ELISA kits. In addition, quantitative real time polymerase chain reaction (qPCR) analyses were performed to study the proteins gene expression.Promising electrochemical sensing platforms can be constructed by two-dimensional (2D) inorganic materials, metal nanoparticles and conducting polymers (CPs) via suitable and effective composite-structural fabrication. Herein, a sandwich-structured composite film was fabricated with MXene (Ti3C2Tx), PdAu nanoparticles and poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate) (PEDOTPSS). In the fabrication, PdAu nanoparticles were first loaded on the surface of MXene nanosheets by one-pot method, preventing self-stacking and improving the dispersion of MXene nanosheets. And then, the PEDOTPSS/MXene-PdAu/PEDOTPSS sandwich structure was obtained with PEDOTPSS as the upper and lower layers and MXene-PdAu as the interlayer. Indeed, the upper PEDOTPSS film can permeate between MXene-PdAu particles and contribute to the continuity of MXene nanosheets, forming a complete conducting three-dimensional framework. The formed PEDOTPSS/MXene-PdAu/PEDOTPSS framework exhibits promising electrochemical sensing properties towards shikonin detection with a wide range of 0.001-35 μM, a low detection limit of 0.33 nM and a high sensitivity of 5.685 μA μM-1 cm-2. Furthermore, this sensing platform performs favorable selectivity and stability. In the actual sample testing, the sensing platform was used for shikonin detection in Lithospermum erythrorhizon and performed comparable results with high-performance liquid chromatography (HPLC), indicating the promising application prospect of PEDOTPSS/MXene-PdAu/PEDOTPSS film for the qualitative and quantitative analysis of shikonin.Carboxylesterase 2 (CES2) is a serine-type hydrolase that plays important roles in xenobiotic detoxification and lipid metabolism. Its abnormal expression is highly associated with diseases such as diabetes and carcinoma. To date, intense attention has been attracted to CES2 targeted drug discovery and disease diagnosis. Thus, to further explore the physiological function of CES2 is of great importance. However, until now, most medical research on CES2 function and activity assays is still dependent on conventional methods, which could hardly specify CES2 activity. Therefore, there is an urgent need to develop efficient tools for selective measurement and sensing of endogenous CES2 in complicated biological system. In this study, we report the design and construction of an enzyme-activated fluorescent probe for CES2 activity sensing. Devimistat purchase The acquired probe DXMB was characterized as a highly specific and sensitive fluorescent probe for CES2 and possessed superior binding affinity, overall catalytic efficiency, and reaction velocity when compared with the reported CES2 probes. By application of DXMB into living system, it was capable of sensing endogenous CES2 in living cells, dynamic monitoring CES2 in zebrafish development, and visualizing tissue distribution of CES2 in nude mice. Most importantly, abnormally elevated CES2 activity in the intestine of diabetic model mice was first revealed, while significantly decreased CES2 activity in the liver was validated by DXMB. These results indicated that DXMB could serve as a vital tool for further CES2-related biological and medical research.