A microfluidic biosensor for multiplex immunoassay of foodborne pathogens agitated by programmed audio signals

Foods are often contaminated by multiple foodborne pathogens,which threatens human health.In this work,we developed a microfluidic biosensor for multiplex immunoassay of foodborne bacteria with agitation driven by programmed audio signals.This agitation,powered by the vibration of a speaker cone during music playing,accelerated the mass transport in the incubation process to form bacterial complexes within 10 min.Immunoassay reagents of the two target bacteria(Escherichia coli O157:H7 and Salmonella typhimurium)were preloaded into the corresponding fore-vacuum storage chamber on the chip,and released to participate in the subsequent immune analysis process by piercing the chambers.All the detection processes were integrated into a single microfluidic chip and controlled by a smartphone through Bluetooth.Under selected conditions,wide linear ranges and low limits of detection(LODs<2CFU/m L)were obtained,and real food samples were successfully determined within 30 min.This biosensing method can be extended to wide-ranging applications by loading different recognizing reagents.

Methodical and pre-analytical characteristics of a multiplex cancer biomarker immunoassay

AIM: To test the methodical and pre-analytical performance of a new multiplex cancer biomarker panel using magnetic beads. METHODS: The MILLIPLEX? MAP Human Circulating Cancer Biomarker Magnetic Bead Panel 1 comprises the tumor markers carcinoembryonic antigen, alpha-fetoprotein, total prostate-specific antigen, cancer antigen 15-3, cancer antigen 19-9, cancer antigen 125, cytokeratine 19-fragment, β-human chorionic gonadotropin, human epididymis protein 4, osteopontin, prolactin, the cell death and angiogenesis markers soluble Fas, soluble Fas-ligand, tumor necrosis factor related apoptosisinducing ligand, vascular endothelial growth factor andthe immunological markers interleukin-6(IL-6), IL-8, tumor necrosis factor-α, transforming growth factor α, fibroblast growth factor-2, macrophage migration inhibitory factor, leptin, hepatocyte growth factor, and stem cell factor. We determined intra- and inter-assay imprecision as well as dilution linearity using quality controls and serum pools. Furthermore, the stability of the 24 biomarkers examined in this panel was ascertained by testing the influence of different storage temperatures and time span before centrifugation.RESULTS: For all markers measured in the synthetic internal quality controls, the intra-assay imprecision ranged between 2.26% and 9.41%, while for 20 of 24 measured markers in the physiological serum pools, it ranged between 1.68% and 12.87%. The inter-assay imprecision ranged between 1.48%-17.12% for 23 biomarkers in synthetic, and between 4.59%-23.88% for 18 biomarkers in physiological quality controls. Here, single markers with very low concentration levels had increased imprecision rates. Dilution linearity was acceptable(70%-130% recovery) for 20 biomarkers. Regarding pre-analytical influencing factors, most markers were stable if blood centrifugation was delayed or if serum was stored for up to 24 h at 4 ℃ and 25 ℃ after centrifugation. Comparable results were obtained in serum and plasma for most markers. However, great changes were observed for single markers.CONCLUSION: MILLIPLEX? MAP Human Circulating Cancer Biomarker Magnetic Bead Panel 1 assay is a stable and precise method for detection of most biomarkers included in the kit. However, single markers have to be interpreted with care.

Cytokines are early diagnostic biomarkers of graft-versus-host disease in liver recipients

BACKGROUND： Graft-versus-host disease （GVHD） is associated with high mortality. Early diagnosis is essential to start treatment and to improve outcomes. Because of the inflammatory nature, we hypothesis that cytokine profile of patients with GVHD may serve as diagnostic markers. The present study was to evaluate the role of cytokine profile in the diagnosis of GVHD. METHODS： An immunoassay was used to detect 29 cytokines simultaneously in the serum; the measuring sensitivity of all cytokines was pg/mL. Healthy subjects undergoing annual routine physical examinations served as negative controls; 23 patients with hepatocellular carcinoma （HCC） who had undergone liver transplantation （the LT group） comprised the test subjects. A total of 22 kidney recipients with biopsyconfirmed GVHD （the RT group） were included for comparison. HCC patients with radical surgery （the HCC group, n=22） served as positive control. The liver contents of the three cytokines, IL-2, IL-18, and IFN-γ, were detected with immunohistochemistry. Serum granzyme B and perforin were measured by flow cytometry.RESULTS： Of the 29 cytokines, the levels of IL-2 and IL-18 were increased significantly in liver recipients with GVHD compared with healthy controls （P〈0.05）. The serum levels of these three cytokines in the healthy, HCC, LT, and RT groups were IL-2： 0.90±0.02, 4.14±0.61, 5.10±0.89, and 1.48±0.09 pg/mL; IL-18： 80.61±9.35, 109.51±10.93, 230.11±12.92, and 61.98±7.88 pg/mL; IFN-γ： 24.06±3.88, 24.84±3.21, 40.37±5.88, and 15.33±4.72 pg/mL, respectively. Immunohistochemistry showed that these 3 cytokines expressions in the liver were parallel to the serum cytokine. After standard anti-GVHD treatment, the expressions of IL-2, IL-18, and IFN-y were de- creased in the liver （P〈0.05）. Serum granzyme B and perforin were significantly increased in GVHD patients （P〈0.05）. CONCLUSIONS： IL-2, IL-18 and IFN-γ were from liver and might serve as biomarkers for monitoring GVHD develop- ment and the effects of anti-GVHD treatment. Granzyme B and perforin may play a role in increasing IL-2, IL-18, and IFN-y levels in GVHD patients.

Changes in Biomarkers after Initial Periodontal Treatment in Gingival Crevicular Fluid from Patients with Chronic Periodontitis Presenting with Drug-Induced Gingival Overgrowth

Calcium channel blocker-induced gingival overgrowth (CCB-GO) is increasing in elderly patients who have been prescribed medication for hypertension for years. The purpose of the present study was to analyze the comprehensive protein expression levels of candidate biomarkers in gingival crevicular fluid (GCF) from CCB-GO patients. Eleven GO patients (10 males and one female, mean ± SD: age: 64.4 ± 14.0 years) who had been systemically prescribed CCBs, either amlodipine or nifedipine, for hypertension for at least 12 months were recruited. Before (baseline) and 4 weeks after initial periodontal treatments, subgingival plaque and GCF samples were taken from two sites per patient: sites affected by CCB-GO and chronic periodontitis. Measurement of clinical parameters and quantitative analysis of periodontopathic bacteria using real-time PCR were performed. Biomarkers/cytokines in GCF were examined using multiplex bead immunoassays. The Mann-Whitney U test was used to compare the collected data between groups. The correlations between pairs of biomarkers were assessed using the Spearman correlation relationship. Levels of two of the 14 biomarkers, interleukin (IL)-1β and transforming growth factor (TGF)- β, were significantly decreased in CCB-GO sites after initial periodontal therapy. The intragroup comparison at baseline showed that counts of Treponema denticola in the GO group were significantly higher than those in the chronic periodontitis group (P β and TGF-β in CCB-GO patients. These factors are involved in initiation and progression of GO as well as periodontitis.