Construction and application of the core competence course training system for infectious disease specialist nurses.

OBJECTIVES: This study aims to construct and apply a training course system which was scientific and comprehensive to foster the core competence of infectious disease specialist nurses. DESIGN: A two-round Delphi consultation survey was carried out to collect feedback from experts on constructing the training course system of core competence for infectious disease specialist nurses. Besides, a non-randomized controlled experimental study was adopted to check the application effect of the courses. METHODS: This study adopted a series of methods including group discussion, theoretical analysis and Delphi consultation to draft the training course content of core competence of infectious disease specialist nurses. Twenty-one Chinese experts were invited to participate in the Delphi consultation from November 2021 to December 2021. From October 2022 to January 2023, a total of 105 infectious disease specialist nurses from two training bases were selected by the convenience sampling method, of which the nurses in one training base were the control group and the nurses in the other training base were the observation group. The observation group was trained by the constructed core competence training course. Questionnaire evaluation was used to compare the core competence of infectious disease specialist nurses and the training effect. RESULTS: The experts, regarded as the authorities on the subject, were highly motivated in this study. Besides, they reached a consensus on the results. The final training course system of core competence for infectious disease specialist nurses focused on 5 competence modules and was composed of 12 categories of courses with 66 classes and corresponding objectives. The core competence scores of the observation group were significantly higher than those in the control group after training (P < 0.05), which proved the training system can effectively enhance the core competence of infectious disease specialist nurses. CONCLUSIONS: The research methods embodied scientific and precise properties. The course system was comprehensive in content and reliable in results. It could serve as a reference for training infectious disease specialist nurses.

3D bio-printing-based vascular-microtissue electrochemical biosensor for fish parvalbumin detection.

A novel 3D bio-printing vascular microtissue biosensor was developed to detect fish parvalbumin quickly. The graphite rod electrode was modified with gold and copper organic framework (Cu-MOF) to improve the sensor properties. Polydopamine-modified multi-wall carbon nanotubes (PDA-MWCNT) were mixed with gelatin methacryloyl (GelMA) to prepare a conductive hydrogel. The conductive hydrogel was mixed with mast cells and endothelial cells to produce a bio-ink for 3D bioprinting. High throughput and standardized preparation of vascular microtissue was performed by stereolithography 3D bioprinting. The vascular microtissue was immobilized on the modified electrode to construct the microtissue sensor. The biosensor's peak current was positively correlated with the fish parvalbumin concentration, and the detection linear concentration range was 0.1 ∼ 2.5 µg/mL. The standard curve equation was IDPV(µA) = 31.30 + 5.46 CPV(µg/mL), the correlation coefficient R2 was 0.990 (n = 5), and the detection limit was 0.065 µg/mL. These indicated a biomimetic microtissue sensor detecting fish parvalbumin has been successfully constructed.

A novel 3D bio-printing "liver lobule" microtissue biosensor for the detection of AFB1.

In this paper, a novel "liver lobule" microtissue biosensor based on 3D bio-printing is developed to rapidly determine aflatoxin B1 (AFB1). Methylacylated Hyaluronic acid (HAMA) hydrogel, HepG2 cells, and carbon nanotubes are used to construct "liver lobule" models. In addition, 3D bio-printing is used to perform high-throughput and standardized preparation in order to simulate the organ morphology and induce functional formation. Afterwards, based on the electrochemical rapid detection technology, a 3D bio-printed "liver lobule" microtissue is immobilized on the screen-printed electrode, and the mycotoxin is detected by differential pulse voltammetry (DPV). The DPV response increases with the concentration of AFB1 in the range of 0.1-3.5 µg/mL. The linear detection range is 0.1-1.5 µg/mL and the calculated lowest detection limit is 0.039 µg/mL. Thus, this study develops a new mycotoxin detection method based on the 3D printing technology, which has high stability and reproducibility. It has wide application prospects in the field of detection and evaluation of food hazards.

Diagnostic accuracy and prognostic significance of Glypican-3 in hepatocellular carcinoma: A systematic review and meta-analysis.

Purpose: Glypican-3 (GPC-3) expression is abnormal in the occurrence and development of hepatocellular carcinoma (HCC). To explore whether GPC-3 has diagnostic accuracy and prognostic significance of HCC, we did a systematic review and meta-analysis. Method: PubMed, Embase, Cochrane Library, and China National Knowledge Infrastructure were searched with keywords "GPC-3" and "HCC" and their MeSH terms from inception to July 2022. We applied the hierarchical summary receiver operating characteristic model and evaluated the diagnostic value of GPC-3 alone and combination, and the correlation between high and low GPC-3 expression on clinicopathological features and survival data in prognosis. Results: Forty-one original publications with 6,305 participants were included, with 25 of them providing data for diagnostic value and 18 records were eligible for providing prognostic value of GPC-3. GPC-3 alone got good diagnostic value in patients with HCC when compared with healthy control and moderate diagnostic value when compared with patients with cirrhosis. In addition, combination of GPC-3 + AFP and GPC-3 + GP73 got great diagnostic value in HCC versus cirrhosis groups; the combination of GPC-3 can also improve the diagnostic accuracy of biomarkers. Moreover, we discovered that overexpression of GPC-3 was more likely found in HBV infection, late tumor stage, and microvascular invasion groups and causes shorter overall survival and disease free survival, which means poor prognosis. Conclusion: GCP-3 could be used as a biomarker in HCC diagnosis and prognosis, especially in evaluated diagnostic value in combination with AFP or GP73, and in forecasting worse survival data of overexpression GPC-3. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/, identifier [CRD42022351566].

A biomimetic "intestinal microvillus" cell sensor based on 3D bioprinting for the detection of wheat allergen gliadin.

A biomimetic "intestinal microvillus" electrochemical cell sensor based on three-dimensional (3D) bioprinting was developed, which can specifically and accurately detect wheat gliadin. Self-assembled flower-like copper oxide nanoparticles (FCONp) and hydrazide-functionalized multiwalled carbon nanotubes (MWCNT-CDH) were innovatively synthesized to improve the sensor performance. A conductive biocomposite hydrogel (bioink) was prepared by mixing FCONp and MWCNT-CDH based on GelMA gel. The cluster-shaped microvillus structure of small intestine was accurately printed on the screen printing electrode with the prepared bioink using stereolithography 3D-bioprinting technology, and then the Rat Basophilic Leukemia cells were immobilized on the gel skeleton. Next, the developed cell sensor was used to effectively detect wheat allergen gliadin. The experimental results show that the bioprinted cell sensor sensitively detects wheat gliadin when the optimized cell numbers and immobilized time are 1 × 106 cells/mL and 10 min, respectively. The linear detection range is 0.1-0.8 ng/mL, and the detection limit is 0.036 ng/mL. The electrochemical cell sensor based on 3D printing technology has excellent stability and reproducibility. Thus, a simple and novel electrochemical detection approach for food allergens was established in this study with potential application in food safety detection and evaluation.

Antioxidant activity of Lactobacillus plantarum NJAU-01 in an animal model of aging.

BACKGROUND: Excessive reactive oxygen species (ROS) can cause serious damage to the human body and may cause various chronic diseases. Studies have found that lactic acid bacteria (LAB) have antioxidant and anti-aging effects, and are important resources for the development of microbial antioxidants. This paper was to explore the potential role of an antioxidant strain, Lactobacillus plantarum NJAU-01 screened from traditional dry-cured meat product Jinhua Ham in regulating D-galactose-induced subacute senescence of mice. A total of 48 specific pathogen free Kun Ming mice (SPF KM mice) were randomly allocated into 6 groups: control group with sterile saline injection, aging group with subcutaneously injection of D-galactose, treatments groups with injection of D-galactose and intragastric administration of 107, 108, and 109 CFU/mL L. plantarum NJAU-01, and positive control group with injection of D-galactose and intragastric administration of 1 mg/mL Vitamin C. RESULTS: The results showed that the treatment group of L. plantarum NJAU-01 at 109 CFU/mL showed higher total antioxidant capacity (T-AOC) and the antioxidant enzymatic activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) than those of the other groups in serum, heart and liver. In contrast, the content of the oxidative stress marker malondialdehyde (MDA) showed lower levels than the other groups (P < 0.05). The antioxidant capacity was improved with the supplement of the increasing concentration of L. plantarum NJAU-01. CONCLUSIONS: Thus, this study demonstrates that L. plantarum NJAU-01 can alleviate oxidative stress by increasing the activities of enzymes involved in oxidation resistance and decreasing level of lipid oxidation in mice.

A novel smartphone-based electrochemical cell sensor for evaluating the toxicity of heavy metal ions Cd2+, Hg2+, and Pb2+ in rice.

A novel smartphone-based electrochemical cell sensor was developed to evaluate the toxicity of heavy metal ions, such as cadmium (Cd2+), lead (Pb2+), and mercury (Hg2+) ions on Hep G2 cells. The cell sensor was fabricated with reduced graphene oxide (RGO)/molybdenum sulfide (MoS2) composites to greatly improve the biological adaptability and amplify the electrochemical signals. Differential pulse voltammetry (DPV) was employed to measure the electrical signals induced by the toxicity of heavy metal ions. The results showed that Cd2+, Hg2+, and Pb2+ significantly reduced the viability of Hep G2 cells in a dose-dependent manner. The IC50 values obtained by this method were 49.83, 36.94, and 733.90 µM, respectively. A synergistic effect was observed between Cd2+ and Pb2+ and between Hg2+ and Pb2+, and an antagonistic effect was observed between Cd2+ and Hg2+, and an antagonistic effect at low doses and an additive effect at high doses were found in the ternary mixtures of Cd2+, Hg2+, and Pb2+. These electrochemical results were confirmed via MTT assay, SEM and TEM observation, and flow cytometry. Therefore, this new electrochemical cell sensor provided a more convenient, sensitive, and flexible toxicity assessment strategy than traditional cytotoxicity assessment methods.

Miniaturized Paper-Supported 3D Cell-Based Electrochemical Sensor for Bacterial Lipopolysaccharide Detection.

Sensitive detection of lipopolysaccharides (LPSs), which are present on the outer wall of Gram-negative bacteria, is important to reflect the degree of bacterial contamination in food. For indirect assessment of the LPS content, a miniaturized electrochemical cell sensor consisting of a screen-printed paper electrode, a three-dimensional cells-in-gels-in-paper culture system, and a conductive jacket device was developed for in situ detection of nitric oxide released from LPS-treated mouse macrophage cells (Raw264.7). Nafion/polypyrrole/graphene oxide with excellent selectivity, high conductivity, and good biocompatibility functionalized on the working electrode via electrochemical polymerization could enhance sensing. Raw264.7 cells encapsulated in the alginate hydrogel were immobilized on a Nafion/polypyrrole/graphene oxide/screen-printed carbon electrode in paper fibers as a biorecognition element. Differential impulse voltammetry was employed to record the current signal as-influenced by LPS. Results indicated that LPS from Salmonella enterica serotype Enteritidis caused a significant increase in peak current, varying from 1 × 10-2 to 1 × 104 ng/mL, dose-dependently. This assay had a detection limit of 3.5 × 10-3 ng/mL with a linear detection range of 1 × 10-2 to 3 ng/mL. These results were confirmed by analysis of nitric oxide released from Raw264.7 via the Griess method. The miniaturized sensor was ultimately applied to detect LPSs in fruit juice samples. The results indicated that the method exhibited high recovery and relative standard deviation lower than 2.65% and LPSs in samples contaminated with 102-105 CFU/mL bacteria could be detected, which proved the practical value of the sensor. Thus, a novel, low-cost, and highly sensitive approach for LPS detection was developed, providing a method to assess Gram-negative bacteria contamination in food.

An FcεRI-IgE-based genetically encoded microfluidic cell sensor for fast Gram-negative bacterial screening in food samples.

An FcεRI-IgE-based genetically encoded microfluidic cell sensor was constructed for fast Gram-negative bacterial screening in food samples. CD14-Fcε IgE, produced by the gene engineered antibodies (GEAs) technology, was used for the recognition of the target bacteria or lipopolysaccharide (LPS). Stable cell lines expressing GCaMP6s, a genetically encoded indicator of calcium flux, were first established for monitoring mast cell activation and improving detection sensitivity. The microfluidic system was designed to improve automation and control the reaction time. Once Gram-negative bacteria bound to the CD14-Fcε IgE on the RBL-2H3 cell surface, RBL-2H3 cell receptor (FcεRI)-induced Ca2+ signaling pathway was immediately activated to release Ca2+. The elevated intracellular Ca2+ triggers GCaMP6s for reporting the presence of Gram-negative bacteria. The developed biosensor was able to detect 80 CFU mL-1 Gram-negative bacteria within 2.5 min in pure culture samples. The biosensor was used to detect Gram-negative bacteria in pork samples. With its short screening time and easy operation, the proposed biosensor shows promise in future applications of foodborne pathogen testing in 1 h to 1 day.

An electricalchemical method to detect the branch-chain aminotransferases activity in lactic acid bacteria.

In this study, an electrochemical system was established to detect the branched-chain amino acid aminotransferase (BCAT) activity in lactic acid bacteria (LAB). A nanocomposite of chitosan (CS) with multi-walled carbon nanotubes (MWCNTs) was synthesized, and the composite solution were uniformly spread over the glassy carbon electrode (GCE) surface by drop-casting to fabricate an electrochemical biosensor. The composite was characterized by scanning electron microscopy (SEM) and cyclic voltammetry (TEM). Results indicated that the MWCNTs-CS/GCE electrode exhibited higher stability and sensitivity, compared with the GCE electrode. The linear response for nicotinamide adenine dinucleotide (NADH) was 1.0-9.0 µM and the response limit was 0.12 µM. The system effectively and sensitively detected the BCAT activity by NADH concentration in the LAB culture, comparing with the optical method. The culture condition of LAB was optimized by using this system, evidencing that established method was available to detect the BCAT activity of LAB.

Identification and Quantification of DPP-IV-Inhibitory Peptides from Hydrolyzed-Rapeseed-Protein-Derived Napin with Analysis of the Interactions between Key Residues and Protein Domains.

Previously reported peptides derived from napin of rapeseed ( Brassica napus) have been shown to inhibit DPP-IV in silico. In the present study, napin extracted from rapeseed was hydrolyzed by commercial enzymes and filtered by an ultrafiltration membrane. The napin hydrolysate was then purified by a Sephadex G-15 gel-filtration column and preparative RP-HPLC. A two-enzyme-combination approach with alcalase and trypsin was the most favorable in terms of the DPP-IV-inhibitory activity (IC50 = 0.68 mg/mL) of the napin hydrolysate. Three peptides and one modified peptide (pyroglutamate mutation at the N-terminus) were identified using HPLC-triple-TOF-MS/MS. DPP-IV-inhibitory activity and the types of enzyme inhibition were also determined. Meanwhile, key residues associated with the interactions between the selected peptides and DPP-IV were investigated by molecular docking. IPQVS has key amino acid residues (Tyr547, Glu205, and Glu206) that are consistent with Diprotin A. ELHQEEPL could form a better covalent bond with Arg358 in the S3 pocket of DPP-IV.

A novel electrochemical mast cell-based paper biosensor for the rapid detection of milk allergen casein.

Developing low-cost, portable and simple analysis tools is of vital importance for food safety point-of-care testing. Therefore, herein, a new low-cost, simple to fabricate, disposable, electrochemical mast cell-based paper sensor is proposed and developed to sensitively determine the major milk allergen casein. Then, a graphene (GN)/carbon nanofiber (CN)/ Gelatin methacryloyl (GelMA) composite material with high conductivity and good biocompatibility was modified on the cell-based paper sensor to improve the electrical conductivity and provide a sensing recognition interface for the immobilization of rat basophilic leukemia (RBL-2H3) mast cells. The cyclic voltammetry and differential pulse voltammetry measurement of the mast cells in the paper sensor revealed an irreversible anodic peak, whose peak current is proportional to the number of cells in the range from 1 × 102 to 1 × 108 cells/mL. For the milk allergen detection tests, mast cells exposed to the casein caused a significant reduction in the current signal, displaying an inverse dose-dependent relationship. The developed cell sensor exhibited a range of linearity between 1 × 10-7 and 1 × 10-6 g/mL of casein with a detection limit of 3.2 × 10-8 g/mL and a great reproducibility and selectivity. The electrochemical responses obtained using the cell-based paper sensor were well consistent with the conventional detection assay, with good stability and reproducibility. Therefore, a simple and novel electrochemical method for food allergens detection was developed, demonstrating its potential application in the food safety determination and evaluation.

Caco-2 cell-based electrochemical biosensor for evaluating the antioxidant capacity of Asp-Leu-Glu-Glu isolated from dry-cured Xuanwei ham.

A cell-based electrochemical biosensor was developed to determine the antioxidant activity of Asp-Leu-Glu-Glu (DLEE) isolated from dry-cured Chinese Xuanwei ham. A platinized gold electrode (Pt NPs/GE) covered with silver nanowires (Ag NWs) was fabricated to detect H2O2 using redox signaling via cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Under optimal condition, the detection limit of the modified electrode was 0.12µM with a linear relationship from 0.2 to 2µM, which showed relatively outstanding catalytic effects towards the reduction of H2O2. Furthermore, the generation of reactive oxygen species (ROS) in the cell can be used to indirectly assess changes in intercellular oxidative stress by detecting variations in electrochemical signals. A 3D cell culture of alginate/graphene oxide (NaAlg/GO) was used to encapsulate and immobilize Caco-2 cells. Based on ROS generation and electrochemical results, we found that DLEE could effectively reduce oxidative stress level in Caco-2 cells under external stimulation. DLEE showed high antioxidant activity with a relative antioxidant capacity (RAC) rate of 88.17% at 1.5mg/mL. Finally, an efficient electrochemical biosensor was established using the active 3D Caco-2 cell platform. This system is sensitive and simple to operate with the property to evaluate the antioxidant activity of peptides by the detection of H2O2 in cell membrane. In summary, this work describes a new method for assessing antioxidant capacity of peptide DLEE using cell-based electrochemical signaling with a rapid screening pattern.

A novel and simple cell-based electrochemical biosensor for evaluating the antioxidant capacity of Lactobacillus plantarum strains isolated from Chinese dry-cured ham.

The analysis of antioxidants in foodstuffs has become an active area of research, leading to the recent development of numerous methods for assessing antioxidant capacity. Here we described the fabrication and validation of a novel and simple cell-based electrochemical biosensor for this purpose. The biosensor is used to assess the antioxidant capacity of cell-free extracts from Lactobacillus plantarum strains isolated from Chinese dry-cured ham. The biosensor relies on the determination of cellular reactive oxygen species (ROS) (the flux of H2O2 released from RAW 264.7 macrophage cells) to indirectly assess changes in intracellular oxidative stress level as influenced by L. plantarum strains. A one-step acidified manganese dioxide (a-MnO2) modified gold electrode (GE) was used to immobilize RAW 264.7 macrophage cells, which were then encapsulated in a 3D cell culture system consisting of alginate/ graphene oxide (NaAlg/GO). The biosensor exhibited a rapid and sensitive response for the detection of H2O2 released from RAW264.7 cells. The detection limit was 0.02µM with a linear response from 0.05µM to 0.85µM and the biosensor was shown to have good stability and outstanding repeatability. This technique was then used for evaluating the antioxidant ability of extracts from L. plantarum NJAU-01. According to the electrochemical investigations and assays of SEM, TEM, and ROS, these cell-free extracts effectively reduced the oxidative stress levels in RAW264.7 cells under external stimulation. Extracts from L. plantarum strains at a dose of 1010CFU/mL showed the highest antioxidant activities with a relative antioxidant capacity (RAC) rate of 88.94%. Hence, this work provides a simple and efficient electrochemical biosensing platform based on RAW264.7 cells for fast, sensitive and quantitative assessment of antioxidant capacity of L. plantarum strains. The method demonstrates its potential for rapid screening for evaluating antioxidant properties of samples.

A novel screen-printed mast cell-based electrochemical sensor for detecting spoilage bacterial quorum signaling molecules (N-acyl-homoserine-lactones) in freshwater fish.

A novel screen-printed cell-based electrochemical sensor was developed to assess bacterial quorum signaling molecules, N-acylhomoserine lactones (AHLs). Screen-printed carbon electrode (SPCE), which possesses excellent properties such as low-cost, disposable and energy-efficient, was modified with multi-walled carbon nanotubes (MWNTs) to improve electrochemical signals and enhance the sensitivity. Rat basophilic leukemia (RBL-2H3) mast cells encapsulated in alginate/graphene oxide (NaAgl/GO) hydrogel were immobilized on the MWNTs/SPCE to serve as recognition element. Electrochemical impedance spectroscopy (EIS) was employed to record the cell impedance signal as-influenced by Pseudomonas aeruginosa quorum-sensing molecule, N-3-oxododecanoyl homoserine lactone (3OC12-HSL). Experimental results show that 3OC12-HSL caused a significant decrease in cell viability in a dose dependent manner. The EIS value decreased with concentrations of 3OC12-HSL in the range of 0.1-1µM, and the detection limit for 3OC12-HSL was calculated to be 0.094µM. These results were confirmed via cell viability, SEM, TEM analysis. Next, the sensor was successfully applied to monitoring the production of AHLs by spoilage bacteria in three different freshwater fish juice samples which efficiently proved the practicability of this cell based method. Therefore, the proposed cell sensor may serve as an innovative and effective approach to the measurement of quorum signaling molecule and thus provides a new avenue for real-time monitoring the spoilage bacteria in freshwater fish production.

Preliminary study on an innovative, simple mast cell-based electrochemical method for detecting foodborne pathogenic bacterial quorum signaling molecules (N-acyl-homoserine-lactones).

This paper reports the a novel and simple mast cell-based electrochemical method for detecting of bacterial quorum signaling molecules, N-acylhomoserine lactones (AHLs), which can be utilized to preliminarily evaluate the toxicity of food-borne pathogenic bacteria. Rat basophilic leukemia (RBL-2H3) mast cells encapsulated in alginate/graphene oxide hydrogel were immobilized on a gold electrode, while mast cells as recognition elements were cultured in a 3D cell culture system. Electrochemical impedance spectroscopy (EIS) was utilized to record the cell impedance signal as-influenced by Pseudomonas aeruginosa quorum-sensing molecule, N-3-oxododecanoyl homoserine lactone (3OC12-HSL). The results indicated that cellular activities such as cell viability, apoptosis, intracellular calcium, and degranulation were markedly influenced by the AHLs. Importantly, the exposure of 3OC12-HSL to mast cells induced a marked decrease in the electrochemical impedance signal in a dose-dependent manner. The detection limit for 3OC12-HSL was 0.034µM with a linear range of 0.1-1µM. These results were confirmed via conventional cell assay and transmission electron microscope (TEM) analysis. Altogether, the proposed method appears to be an innovative and effective approach to the quantitative measurement of Gram-negative bacterial quorum signaling molecules; to this effect, it also may serve as a primary evaluation of the cytotoxicity of food-borne pathogens.

High-throughput living cell-based optical biosensor for detection of bacterial lipopolysaccharide (LPS) using a red fluorescent protein reporter system.

Due to the high toxicity of bacterial lipopolysaccharide (LPS), resulting in sepsis and septic shock, two major causes of death worldwide, significant effort is directed toward the development of specific trace-level LPS detection systems. Here, we report sensitive, user-friendly, high-throughput LPS detection in a 96-well microplate using a transcriptional biosensor system, based on 293/hTLR4A-MD2-CD14 cells that are transformed by a red fluorescent protein (mCherry) gene under the transcriptional control of an NF-κB response element. The recognition of LPS activates the biosensor cell, TLR4, and the co-receptor-induced NF-κB signaling pathway, which results in the expression of mCherry fluorescent protein. The novel cell-based biosensor detects LPS with specificity at low concentration. The cell-based biosensor was evaluated by testing LPS isolated from 14 bacteria. Of the tested bacteria, 13 isolated Enterobacteraceous LPSs with hexa-acylated structures were found to increase red fluorescence and one penta-acylated LPS from Pseudomonadaceae appeared less potent. The proposed biosensor has potential for use in the LPS detection in foodstuff and biological products, as well as bacteria identification, assisting the control of foodborne diseases.

A novel mast cell co-culture microfluidic chip for the electrochemical evaluation of food allergen.

In this study a novel cell-to-cell electrochemical microfluidic chip was developed for qualitative and quantitative analysis of food allergen. Microfluidic cell culture, food allergen-induced cell morphological changes, and cell metabolism measurements were performed simultaneously using the aforementioned device. RBL-2H3 mast cells and ANA-1 macrophages have been used within a cell co-culture model to observe their allergic response when they are introduced to the antigen stimulus. Two cell cultivation microfluidic channels are located in the microfluidic chip, which is fabricated with four groups of gold electrodes, with an additional "capillary". In order to detect the allergic response, the cells were stimulated with dinitrophenylated bovine serum albumin (DNP-BSA) without anti-DNP IgE incubation. When exocytosis occurs, the cell-secreted inflammatory cytokines were measured by enzyme-linked immuno sorbent assay (ELISA) and cell impedance changes were detected using cell-based electrochemical assay. Results indicate that the real-time cell allergic response are accurately monitored by this electrochemical microfluidic chip, which provides a general example of rapidly prototyped low-cost biosensor technology for applications in both food allergen detection and investigation.

Magnetic molecularly imprinted polymer nanoparticles based electrochemical sensor for the measurement of Gram-negative bacterial quorum signaling molecules (N-acyl-homoserine-lactones).

We have developed a novel and economical electrochemical sensor to measure Gram-negative bacterial quorum signaling molecules (AHLs) using magnetic nanoparticles and molecularly imprinted polymer (MIP) technology. Magnetic molecularly imprinted polymers (MMIPs) capable of selectively absorbing AHLs were successfully synthesized by surface polymerization. The particles were deposited onto a magnetic carbon paste electrode (MGCE) surface, and characterized by electrochemical measurements. Differential Pulse Voltammetry (DPV) was utilized to record the oxidative current signal that is characteristic of AHL. The detection limit of this assay was determined to be 8×10(-10)molL(-1) with a linear detection range of 2.5×10(-9)molL(-1) to 1.0×10(-7)molL(-1). This Fe3O4@SiO2-MIP-based electrochemical sensor is a valuable new tool that allows quantitative measurement of Gram-negative bacterial quorum signaling molecules. It has potential applications in the fields of clinical diagnosis or food analysis with real-time detection capability, high specificity, excellent reproducibility, and good stability.

Fluorescent magnetic bead-based mast cell biosensor for electrochemical detection of allergens in foodstuffs.

In this study, a novel electrochemical rat basophilic leukemia cell (RBL-2H3) cell sensor, based on fluorescent magnetic beads, has been developed for the detection and evaluation of different allergens in foodstuffs. Fluorescein isothiocyanate (FITC) was successfully fused inside the SiO2 layer of SiO2 shell-coated Fe3O4 nanoparticles, which was superior to the traditional Fe3O4@SiO2@FITC modification process. The as-synthesized fluorescent magnetic beads were then encapsulated with lipidosome to form cationic magnetic fluorescent nanoparticles (CMFNPs) for mast cell magnetofection. The CMFNPs were then characterized by SEM, TEM, VSM, FTIR, and XRD analyses, and transfected into RBL-2H3 cells through a highly efficient, lipid-mediated magnetofection procedure. Magnetic glassy carbon electrode (MGCE), which possesses excellent reproducibility and regeneration qualities, was then employed to adsorb the CMFNP-transfected RBL-2H3 cells activated by an allergen antigen for electrochemical assay. Results show that the exposure of model antigen-dinitrophenol-bovine serum albumin (DNP-BSA) to anti-DNP IgE-sensitized mast cells induced a robust and long-lasting electrochemical impedance signal in a dose-dependent manner. The detection limit was identified at 3.3×10(-4) ng/mL. To demonstrate the utility of this mast cell-based biosensor for detection of real allergens in foodstuffs, Anti-Pen a1 IgE and Anti-PV IgE-activated cells were employed to quantify both shrimp allergen tropomyosin (Pen a 1) and fish allergen parvalbumin (PV). Results show high detection accuracy for these targets, with a limit of 0.03 µg/mL (shrimp Pen a 1) and 0.16 ng/mL (fish PV), respectively. To this effect, we conclude the proposed method is a facile, highly sensitive, innovative electrochemical method for the evaluation of food allergens.