Rapid identification of diarrheagenic Escherichia coli based on barcoded magnetic bead hybridization

Ultrasensitive quantification of pathogens in milliliters of beverage by filtration-based digital LAMP

The quantitative detection of pathogens in milliliters of beverage sample requires complex preprocessing. To achieve rapid and ultrasensitive quantification of pathogens in large volume food sample, we developed a filtration-based interfacial digital LAMP (idLAMP) system, which consists of a nanoporous membrane for filtration and nanoporous hydrogel for digital amplification. Digital counting of single bacteria at the membrane surface under nanoconfinement could be achieved. The idLAMP successfully accomplished the quantitative detection of Escherichia coli in 100 mL water samples within 30 min, with wide dynamic range from 0.09 to 900 cells/mL. This technique could also be well applied to the quantification of Escherichia coli and Salmonella typhi in real beverage samples (juice, tea drinks, carbonated drinks and alcoholic drinks) without tedious sample pretreatments. With facile operation, higher specificity and sensitivity and better end-point analysis capabilities, the system has great potential in quantitative counting of single bacteria in large-volume food samples.

Advances in the use of nanomaterials for nucleic acid detection in point-of-care testing devices: A review

The outbreak of the coronavirus (COVID-19) has heightened awareness of the importance of quick and easy testing. The convenience, speed, and timely results from point-of-care testing (POCT) in all vitro diagnostic devices has drawn the strong interest of researchers. However, there are still many challenges in the development of POCT devices, such as the pretreatment of samples, detection sensitivity, specificity, and so on. It is anticipated that the unique properties of nanomaterials, e.g., their magnetic, optical, thermal, and electrically conductive features, will address the deficiencies that currently exist in POCT devices. In this review, we mainly analyze the work processes of POCT devices, especially in nucleic acid detection, and summarize how novel nanomaterials used in various aspects of POCT products can improve performance, with the ultimate aims of offering new ideas for the application of nanomaterials and the overall development of POCT devices.

Liquid Crystal Droplet-Based Biosensors: Promising for Point-of-Care Testing

The development of biosensing platforms has been impressively accelerated by advancements in liquid crystal (LC) technology. High response rate, easy operation, and good stability of the LC droplet-based biosensors are all benefits of the long-range order of LC molecules. Bioprobes emerged when LC droplets were combined with biotechnology, and these bioprobes are used extensively for disease diagnosis, food safety, and environmental monitoring. The LC droplet biosensors have high sensitivity and excellent selectivity, making them an attractive tool for the label-free, economical, and real-time detection of different targets. Portable devices work well as the accessory kits for LC droplet-based biosensors to make them easier to use by anyone for on-site monitoring of targets. Herein, we offer a review of the latest developments in the design of LC droplet-based biosensors for qualitative target monitoring and quantitative target analysis.

Novel aerosol detection platform for SARS‑CoV‑2: Based on specific magnetic nanoparticles adsorption sampling and digital droplet PCR detection

The SARS‑CoV‑2 virus is released from an infectious source (such as a sick person) and adsorbed on aerosols, which can form pathogenic microorganism aerosols, which can affect human health through airborne transmission. Efficient sampling and accurate detection of microorganisms in aerosols are the premise and basis for studying their properties and evaluating their hazard. In this study, we built a set of sub-micron aerosol detection platform, and carried out a simulation experiment on the SARS‑CoV‑2 aerosol in the air by wet-wall cyclone combined with immunomagnetic nanoparticle adsorption sampling and ddPCR. The feasibility of the system in aerosol detection was verified, and the influencing factors in the detection process were experimentally tested. As a result, the sampling efficiency was 29.77%, and extraction efficiency was 98.57%. The minimum detection limit per unit volume of aerosols was 250 copies (10² copies/mL, concentration factor 2.5).

Study on the Expression of β-1,3-N-acetylglucosaminyltransferase 3 in Gastric Cancer and the Mechanism Promoting Gastric Cancer Progression Based on the Extraction Method of Nanomagnetic Beads

The oncogenic role of β-1,3-N-acetylglucosaminyltransferase 3 (B3GNT3) in several cancers is well documented. However, the expression, function, and mechanism of B3GNT3 in gastric cancer (GC) remain to be investigated. Here, we extracted RNA using the nanomagnetic bead method and investigated B3GNT3 expression in GC and its mechanism for promoting malignant progression of GC using bioinformatics, quantitative reverse transcription-polymerase chain reaction (qPCR), and western blot (WB). The results showed that the upregulation of B3GNT3 expression was positively related to original T phase, lymph node metastasis, and TNM stage but negatively related to GC prognosis. Meanwhile, the knockdown of the B3GNT3 gene significantly suppressed the growth and infiltration of GC cells. In addition, B3GNT3 promoted the malignant progression of GC cells by upregulating EphA2 transcription and subsequently activating the PI3K/AKT pathway. This work reveals for the first time the upregulation and protumor role of B3GNT3 in GC and highlights the potential clinical applications of B3GNT3/EphA2/AKT signaling in GC diagnosis, treatment, and prognosis prediction.

Coating Silica Layer on Fe₃O₄ Magnetic Nanoparticles and Application in Extracting High Quality Nucleic Acids from Blood Sample

The given research revealed that the size of Fe₃O₄ magnetic nanoparticles (MNPs) could be controlled by varying the pre-mixing conditions in the solvothermal method. Scanning electron microscopy (SEM) showed that the size of the MNPs gradually increased with increasing the initial temperature at which reaction components were mixed while the reaction component's mixing time was kept constant. The smallest sized MNPs were achieved among the five treatments (25, 50, 75, 100, and 125 °C) when reaction components were mixed at 25 °C, while the larger sized MNPs were synthesized among the five treatments when reaction components were mixed at 125 °C. Then, Stöber method was followed for coating silica layer onto the MNPs. However, ammonium hydroxide was replaced with potassium hydroxide as a catalyst, which significantly increased the speed of silica coating onto MNPs. The Fourier transform infrared (FTIR) spectrometer revealed that the MNPs were successfully covered with silica in five minutes. FTIR spectra exhibited a peak about 1088.8 cm^-1, which belonged to the asymmetry stretching vibration of Si-O-Si. Transmission electronic microscopy (TEM) analysis was conducted to confirm the presence of silica layer onto MNPs. Thus, potassium hydroxide was successfully employed as a catalyst for quick silica layer coating onto MNPs. Furthermore, these silica coated MNPs were used to extract high quality nucleic acids from blood sample.

Icariin Attenuation of Diabetic Kidney Disease Through Inhibition of Endoplasmic Reticulum Stress via G Protein-Coupled Estrogen Receptors

Diabetic kidney disease (DKD) is the most common complication of diabetes mellitus and has become the primary cause of End-Stage Renal Disease (ESRD) globally. Icariin (ICA), an effective component extracted from Epimedium, has antiosteoporosis effect, antitumor effects, anti-ischemia effects, and other effects. In this study, a mouse DKD model was established, and Icariin solid nanoliposomes were administered to determine whether ICA had a protective effect on the renal function of DKD mice by regulating estrogen level and endoplasmic reticulum (ER) stress pathway. The results showed that the microalbumin/creatinine in urine, serum urea nitrogen, and CHOL in ICA cultured DKD mice significantly decreased, and mice nephropathy improved significantly. rat renal tubule epithelial cells were further tested, and the rat renal tubule epithelial cells were modeled by cultured cells with high glucose. The results showed that high glucose could promote the proliferation of renal tubular epithelial cells. Simultaneously, ICA can inhibit the proliferation of renal tubular epithelial cells and induce cell apoptosis. Furthermore, the expression of ER stress-related proteins IRE1 and XBP-1S was further detected. Additionally, to ICA intervention, a GPER antagonist (G-15) was added for intervention, the inhibitory effects of IRE1 and XBP-1S were reversed, and the ER stress pathway was activated. Cell experiments showed that ICA could promote GPER expression, while inhibiting GPER expression promoted the activation of ER stress pathway, and GPER expression was negatively correlated with ER stress protein expression. Therefore, the experiment proved that in DKD tissues, a high concentration of ICA can inhibit the ER stress response by promoting the expression of GPER, reducing the proliferation of diabetic nephropathy, and increasing the rate of tissue apoptosis.

Study on the Collection Efficiency of Bioaerosol Nanoparticles by Andersen-Type Impactors

Airborne transmission is much more common than previously thought. Based on our knowledge about SARS-COV-2 (COVID-19) infection, the aerosol transmission routes for all respiratory infections must be reassessed. Thus far, the COVID-19 outbreak has caused catastrophic public health and economic crises, posing a serious threat to the lives and health of people around the world and directing public attention toward the airborne transmission of pathogens. The novel coronavirus transmission in the form of nanoaerosols in a wider range hinders prevention and early warning efforts. As a classical bioaerosol sampler, the Andersen six-stage sampler is widely used in the collection and research of aerosol particles. In this study, the physical and biological collection efficiency of the six-stage sampler was explored by qPCR and colony counting method. Results showed that the physical collection efficiency reached more than 50% when the particle size was larger than 0.75 μm. However, the overall biological collection efficiency was only 0.25%. In addition, fluorescence microscopy and flow cytometry were used to detect the microbial state after sampling, and the results showed that the proportion of the collected live bacteria was less than 15% of the total. This result is of great significance not only for the application of the Andersen six-stage sampler in collecting nanosized bioaerosols, but also provides reference for the selection of subsequent detection technologies for effective collection.

Research on Orientation of Basic Fibroblast Growth Factor with Magnetic Nanoparticles (MNPs) on Regeneration and Recovery of Rats' Dampened Skeletal Muscle and Expressed Level of Matrix Metalloproteinase

The basic fibroblast growth factor (bFGF) has a special role in improving proliferation and differentiation of fiber cells in growth of muscle. The function of bFGF with magnetic nanoparticles (MNPs) on regeneration and recovery of rats' dampened skeletal muscle and expression of MMPS were studied in our research. The MNPs packed with bFGF were prepared and 95 experimental rats were selected. These 30 rats were equally divided into control group, model group (self-healing without obstruction after model was established), bFGF group (disposed with bFGF packaged with MNP). The contractility and stress relaxation of rats' skeletal muscle were observed at the 48th h, 10th, 17th, 24th and 30th days after damage. The remaining 65 rats were divided randomly into control group (5 rats) and experimental group (60 rats intervened with MNPs packaged with bFGF). The groups were randomly divided into 0.5 h, 1 h, 3 h, 6 h, 12 h, 1 d, 2 d, 3 d, 4 d, 7 d, 10 d and 14 d according to different executed time. The levels of bFGF and MMPS were detected by HE staining method and immunohistochemical staining. There was a significant declining tendency of shrinkage stress of muscle in the model, sham-operation, BSA and bFGF groups compared with control group in the second day. The contractility after contusion wound in the regeneration and recovery of rats' skeletal muscle was effectively alleviated with MNPs packaged with bFGF.

Detection of Chymotrypsin Using Peptide Sensor Based on Graphene Oxide Modified with Sulfhydryl Group and Gold Nanoparticles

In this study, GO modified with sulfhydryl group was prepared by thiolation on the surface of GO, which makes a meaningful material. GO with sulfhydryl group combined with gold nanoparticles,...

Magnetic frequency mixing technological advances for the practical improvement of point-of-care testing

Nanomaterials, especially superparamagnetic nanomaterials, have recently played essential roles in point-of-care testing due to their intrinsic magnetic, electrochemical, and optical properties. The inherent superparamagnetism of magnetic nanoparticles makes them highly sensitive for quantitative detection. Among the various magnetic detection technologies, frequency mixing technology (FMT) technology is an emerging detection technique in the nanomedical field. FMT sensors have high potential for development in the field of biomedical quantitative detection due to their simple structure, and they are not limited to the materials used. In particular, they can be applied for large-scale disease screening, early tumor marker detection, and low-dose drug detection. This review summarizes the principles of FMT and recent advances in the fields of immunoadsorption, lateral flow assay detection, magnetic imaging, and magnetic nanoparticles recognition. The advantages and limitations of FMT sensors for robust, ultrasensitive biosensing are highlighted. Finally, the future requirements and challenges in the development of this technology are described. This review provides further insights for researchers to inspire the future development of FMT by integration into biosensing and devices with a broad field of applications in analytical sensing and clinical usage.

Research on Mechanism of Superparamagnetic Iron Oxide Nanoparticles in Activating Endoplasmic Reticulum and Prompting Apoptosis of Liver Cells Through Mediation of Tumor Necrosis Factor-α/Tumor Necrosis Factor Receptor 1 (TNF-α/TNFR1) Pathway

The aim of this study was to assess mechanism of superparamagnetic iron oxide nanoparticles (SPIO-NPs) in activating endoplasmic reticulum (ER) and prompting apoptosis of liver cells through mediating the TNF-α/TNFR1 pathway. The SPIO-NPs were prepared and identified, and HegG2 cells were cultivated in vitro, and their apoptosis was detected. The specific pathogen-free (SPF)-grade rats were divided into several groups; which included blank group, low concentration group, high concentration group and control group. The enzymatic activity of Caspase-3 in liver tissue was tested, and expressions of Caspase-3, Bax, Bcl-2, TNF-α, p-TNFR1, IRE1α, and eIF2α were tested. The size of prepared SPIO-NPs was 7.5 nm and there was no coagulation. There was good dispersity and electric potential, and appearance was stable. The apoptotic rate in the high concentration group was notably higher than in the other groups. There was notable inflammatory cell infiltration in the high concentration group, where quantity of apoptosis was highest. The quantity of apoptosis and fluorocyte in the high concentration group were notably higher than in the other groups. Moreover, there were over expressions of Caspase-3, Bax, Caspase-3, p-TNFR1, IRE1α, and eIF2α in the high concentration group while the expression of TNF-α was lowest. The apoptosis of HegG2 cells was prompted by SPIO-NPs, and quantity of apoptosis was increased with increased adopted concentration. The active expression of p-TNFR1, IRE1α, and eIF2α could be prompted to reduce the expression of TNF-α and increase the expression of Caspase-3 and Bax for prompting the apoptosis.

Development of a Sandwich Chemiluminescence Immunoassay for the Detection of Intact Procollagen Type I N Propeptide with Magnetic Nanosphere Carrier Technology

The metabolic product of type I collagen synthesis, intact procollagen type I N propeptide (intact PINP), is a potential marker of bone formation and osteoporosis, which is not affected by kidney function. We sought to establish a chemiluminescent immunoassay method for the detection of serum intact PINP with previously prepared paired monoclonal antibodies and to evaluate the diagnostic value of the assay in osteoporosis. Using the capture molecule and monoclonal antibody as detection molecule, a diagnostic reagent was developed to detect intact PINP in serum with magnetic nanosphere carriers by the chemiluminescence method, and its analytical performance in the laboratory was evaluated. Serum intact PINP was measured in 142 healthy people and 115 osteoporosis patients. Results were matched with results of a similar test kit, Roche total PINP Elecsys Chemiluminescent Immunoassay Assay. Compared with the performance of the Roche PINP assay product, our method had higher sensitivity (0.02 ng/mL), wider linear range (0.02-1500 ng/mL), and anti-interference. Serum intact PINP values in osteoporosis patients were significantly higher than in healthy subjects (p < 0.001). Our method had good consistency compared with the Roche PINP assay (r = 0.9794). This chemiluminescence method for detecting serum intact PINP (CLIA-intact PINP) with magnetic nanosphere carrier technology meets the requirements of a clinical testing reagent and is expected to have clinical application after further evaluation and can compete with expensive imported kits on the market.

The Related Study on the Pathogenesis of Gastrointestinal Diseases in Gastrointestinal Flora and the Risk of Gastric Ulcer Carcinogenesis

Gastrointestinal diseases are common diseases of many kinds. The pathogenesis of gastrointestinal disease has not been fully understood. In this study with gastric mucosa specimen, among the three groups of chronic gastritis, gastric ulcer, and duodenal ulcer, there were differences of Helicobacter pylori (H. pylori), Lactobacillus, Prevotella, Clostridium, B. fragilis, and Enterobacteriaceae. There was no significant difference in Lactobacillus among chronic gastritis, gastric ulcers, and duodenal ulcers with fecal specimens, but there was a significant difference between these three groups and the gastric cancer group. Correlation analysis showed that six kinds of flora had a negative correlation with H. pylori, procalcitonin (PCT), tumor necrosis factor α (TNF-α), cluster of differentiation 4 (CD4+), cluster of differentiation 8 (CD8+), immunoglobulin G (IgG), and immunoglobulin M (IgM) were different in different gastrointestinal diseases, and PCT, TNF-α and CD8+ were positively correlated with H. pylori and negatively correlated with CD4+, IgM and IgG. Logistic regression analysis showed that age, recurrent gastric ulcer times, atrophic gastritis, and H. pylori were independent risk factors of gastric ulcer canceration. Therefore, we believe that gastrointestinal flora, especially H. pylori, plays a vital role in the pathogenesis of gastrointestinal diseases, and H. pylori is an essential risk factor for gastric ulcer carcinogenesis.

Ultrasensitive chemiluminescence immunoassay with enhanced precision for the detection of cTnI amplified by acridinium ester-loaded microspheres and internally calibrated by magnetic fluorescent nanoparticles

A novel enhanced chemiluminescent immunoassay (CLIA) for ultrasensitive and excellent precisive determination of cardiac troponin I (cTnI) was reported. The method made full use of poly[(N-isopropyl acrylamide)-co-(methacrylic acid)] (P(NIPAM-co-MAA)) microspheres as new potential signal enhancers and magnetic fluorescent nanoparticles as internal standards for better precision. This protocol involved a sandwich format, in which the antigen in the sample was captured by the immobilized antibodies on the surface of magnetic fluorescent beads and recognized by the other antibodies labeled with acridinium ester (AE)-loaded P(NIPAM-co-MAA) microspheres. The combination of the remarkable sensitivity of the enhanced CLIA method and the use of P(NIPAM-co-MAA) microspheres as anti-cTnI carriers for acridinium ester signal amplification provided an extremely sensitive limit of blank (LoB) at 0.097 pg mL^-1, a limit of detection (LoD) at 0.116 pg mL^-1, and a limit of quantitation (LoQ) at 0.606 pg mL^-1, much greater than those achieved by the classical chemiluminescence immunoassay (CLIA, Getein). Moreover, the intra-day variable coefficient can be improved to 1.21-2.12%, and inter-day variability was 2.01-3.49% under the application of magnetic fluorescent beads as an internal standard. The sensitivity and precision have reached a high level, comparable with the current commercial detection kits. The results showed a good correlation with a commercial chemiluminescence assay (CLIA, Abbott), with a correlation coefficient of 0.9883. This proposed method has been successfully applied to the clinical determination of cTnI in the human serum.