Rapid Determination of Blood Coagulation Factor XIII Activity Using Protein Arrays for Serodiagnosis of Human Plasma

A Portable Microfluidic System for Point-of-Care Detection of Multiple Protein Biomarkers

Protein biomarkers are indicators of many diseases and are commonly used for disease diagnosis and prognosis prediction in the clinic. The urgent need for point-of-care (POC) detection of protein biomarkers has promoted the development of automated and fully sealed immunoassay platforms. In this study, a portable microfluidic system was established for the POC detection of multiple protein biomarkers by combining a protein microarray for a multiplex immunoassay and a microfluidic cassette for reagent storage and liquid manipulation. The entire procedure for the immunoassay was automatically conducted, which included the antibody–antigen reaction, washing and detection. Alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA) and carcinoma antigen 125 (CA125) were simultaneously detected in this system within 40 min with limits of detection of 0.303 ng/mL, 1.870 ng/mL, and 18.617 U/mL, respectively. Five clinical samples were collected and tested, and the results show good correlations compared to those measured by the commercial instrument in the hospital. The immunoassay cassette system can function as a versatile platform for the rapid and sensitive multiplexed detection of biomarkers; therefore, it has great potential for POC diagnostics.

Noble-metal nanoparticle labelling multiplex miRNAs by ICP-MS readout with internal standard isotopes of 115In and 209Bi

Inductively coupled plasma-mass spectrometry (ICP-MS) is one of the most powerful techniques for multiplex nucleotide assay owing to the virtue of the high resolution of multiple-elements' mass to charge ratio, in a mass spectrum. Here, a small sized (less than 20 nm) noble-metal nanoparticle labelled ICP-MS (NP-ICP-MS) is proposed for high-throughput microRNA (miRNA) determination. Three miRNA targets - miR-486-5p, miR-221, and miR-21 - in serum, were distinguished by single-stranded DNA (ssDNA) probes labelled with a small sized noble-metal nanoparticle - silver nanoparticles (AgNPs), platinum nanoparticles (PtNPs), and gold nanoparticles (AuNPs). The counting isotopes ion intensity per second (CPS) of the noble-metal label versus internal standard isotope intensity of ¹¹⁵In and ²⁰⁹Bi, exhibited good linearity in the range 0.25 pM to 100 pM with correlation coefficients (R²) of 0.9680, 0.9305, and 0.9418. The specific sandwich-type miRNA assay using the sensitive NP-ICP-MS readout pushed the detection limits down to 0.18 pM for miR-221, 0.23 pM for miR-486-5p, and 0.22 pM for miR-21. And the relative standard deviations (RSDs) for 10 pM target miRNA were less than 3.7%. This work promises a potential ultrasensitive ICP-MS bioassay of multiplex miRNA biomarkers for clinical serum diagnosis.

A nanozyme tag enabled chemiluminescence imaging immunoassay for multiplexed cytokine monitoring

We report a new concept of a chemiluminescence imaging nanozyme immunoassay (CINIA), in which nanozymes are exploited as catalytic tags for simultaneous multiplex detection of cytokines. The CINIA provides a novel and universal nanozyme-labeled multiplex immunoassay strategy for high-throughput detection of relevant biomarkers and further disease diagnosis.

Real-time monitoring of glucose-6-phosphate dehydrogenase activity using liquid droplet arrays and its application to human plasma samples

Glucose-6-phosphate dehydrogenase (G6PD) regulates nicotinamide adenine dinucleotide phosphate (NADPH) levels and is related to the pathogenesis of various diseases, including G6PD deficiency, type 2 diabetes, aldosterone-induced endothelial dysfunction, and cancer. Therefore, a highly sensitive array-based assay for determining quantitative G6PD activity is required. Here, we developed an on-chip G6PD activity assay using liquid droplet fluorescence arrays. Quantitative G6PD activity was determined by calculating reduced resorufin concentrations in liquid droplets. The limit of detection (LOD) of this assay was 0.162 mU/ml (2.89 pM), which is much more sensitive than previous assays. We used our activity assay to determine kinetic parameters, including Michaelis-Menten constants (Km) and maximum rates of enzymatic reaction (Vmax) for NADP(+) and G6P, and half-maximal inhibitory concentrations (IC50). We successfully applied this new assay to determine G6PD activity in human plasma from normal healthy individuals (n=30) and patients with inflammation (n=30). The inflammatory group showed much higher G6PD activities than did the normal group (p<0.001), with a high area under the curve value of 0.939. Therefore, this new activity assay has the potential to be used for diagnosis of G6PD-associated diseases and utilizing kinetic studies.

Novel chemiluminescent imaging microtiter plates for high-throughput detection of multiple serum biomarkers related to Down's syndrome via soybean peroxidase as label enzyme

Novel chemiluminescent (CL) imaging microtiter plates with high-throughput, low-cost, and simple operation for detection of four biomarkers related to Down's syndrome screening were developed and evaluated. To enhance the sensitivity of CL immunosensing, soybean peroxidase (SBP) was used instead of horseradish peroxide (HRP) as a label enzyme. The microtiter plates were fabricated by simultaneously immobilizing four capture monoclonal antibodies, anti-inhibin-A, anti-unconjugated oestriol (anti-uE3), anti-alpha-fetoprotein (anti-AFP), and beta anti-HCG (anti-β-HCG), on nitrocellulose (NC) membrane to form immunosensing microtiter wells. Under a sandwiched immunoassay, the CL signals on each sensing site of the microtiter plates were collected by a charge-coupled device (CCD), presenting an array-based chemiluminescence imaging method for detection of four target antigens in a well at the same time. The linear response to the analyte concentration ranged from 0.1 to 40 ng/mL for inhibin-A, 0.075 to 40 ng/mL for uE3, 0.2 to 400 ng/mL for AFP, and 0.4 to 220 ng/mL for β-HCG. The proposed microtiter plates possessed high-throughput, good stability, and acceptable accuracy for detection of four antigens in clinical serum samples and demonstrated potential for practical applicability of the proposed method to Down's syndrome screening. Graphical Abstract Schematic evaluation of the microtiter plater for simultaneous detection of the four biomarkers.

Relationships of coagulation factor XIII activity with cell-type and stage of non-small cell lung cancer

PURPOSE

Factor XIII (FXIII), a thrombin-activated plasma transglutaminase zymogen, is involved in cancer development and progression through a triggered coagulation pathway. The aim of this study was to examine whether FXIII activity levels differed in non-small cell lung cancer (NSCLC) patients according to histological types and TNM stage when compared with healthy subjects.

MATERIALS AND METHODS

Twenty-eight NSCLC patients and 28 normal controls who had been individually age-, gender-, body mass index-, smoking status-, and smoking amount-matched were enrolled: 13 adenocarcinomas, 11 squamous cell carcinomas, and four undifferentiated NSCLCs; four stage I, two stage II, 12 stage III, and 10 stage IV NSCLCs. FXIII activity was measured using fluorescence- based protein arrays.

RESULTS

The median FXIII activity level of the NSCLC group [24.2 Loewy U/mL, interquartile range (IQR) 14.9-40.4 Loewy U/mL] was significantly higher than that of the healthy group (17.5 Loewy U/mL, IQR 12.6-26.4 Loewy U/mL) (p=0.01). There were no differences in FXIII activity between adenocarcinoma (median 18.6 Loewy U/mL) and squamous cell carcinoma (median 28.7 Loewy U/mL). NSCLC stage significantly influenced FXIII activity (p=0.02). The FXIII activity of patients with stage III NSCLC (median 27.3 Loewy U/mL, IQR 19.3-40.5 Loewy U/mL) was significantly higher than those of patients with stage I or II (median 14.0 Loewy U/mL, IQR 13.1-23.1 Loewy U/mL, p=0.04). FXIII activity was negatively correlated with aPTT in NSCLC patients (r=-0.38, p=0.04).

CONCLUSION

Patients with advanced-stage NSCLC exhibited higher coagulation FXIII activity than healthy controls and early-stage NSCLC patients.

Integrative proteomic profiling of protein activity and interactions using protein arrays

Proteomic studies based on abundance, activity, or interactions have been used to investigate protein functions in normal and pathological processes, but their combinatory approach has not been attempted. We present an integrative proteomic profiling method to measure protein activity and interaction using fluorescence-based protein arrays. We used an on-chip assay to simultaneously monitor the transamidating activity and binding affinity of transglutaminase 2 (TG2) for 16 TG2-related proteins. The results of this assay were compared with confidential scores provided by the STRING database to analyze the functional interactions of TG2 with these proteins. We further created a quantitative activity-interaction map of TG2 with these 16 proteins, categorizing them into seven groups based upon TG2 activity and interaction. This integrative proteomic profiling method can be applied to quantitative validation of previously known protein interactions, and in understanding the functions and regulation of target proteins in biological processes of interest.