Junhai Kai

A novel microfluidic microplate as the next generation assay platform for enzyme linked immunoassays (ELISA)

In this work we introduce a novel microfluidic enzyme linked immunoassays (ELISA) microplate as the next generation assay platform for unparalleled assay performances. A combination of microfluidic technology with standard SBS-configured 96-well microplate architecture, in the form of microfluidic microplate technology, allows for the improvement of ELISA workflows, conservation of samples and reagents, improved reaction kinetics, and the ability to improve the sensitivity of the assay by multiple analyte loading. This paper presents the design and characterization of the microfluidic microplate, and its application in ELISA.

Highly sensitive rapid, reliable, and automatic cardiovascular disease diagnosis with nanoparticle fluorescence enhancer and mems.

Cardiovascular diseases (CVDs) have been the leading threat to human life. An effective way for sensitive and accurate CVD diagnosis is to measure the biochemical markers released from the damaged myocardial cells in the bloodstream. Here, a multi-analyte, fluorophore mediated, fiber-optic immuno-biosensing system is being developed to simultaneously and rapidly quantify four clinically important cardiac markers, myoglobin, C-reactive protein, cardiac troponin I, and B-type natriuretic peptide. To quantify these markers at a pico-molar level, novel nanoparticle reagents enhancing fluorescence were used and signal enhancement was obtained as high as approximately 230%. Micro-electro-mechanical system (MEMS) was integrated to this system to ensure a reliable and fully-automated sensing performance. A point-of-care, automatic microfluidic sensing system for four cardiac marker quantification was developed with the properties of 3 cm sensor size, 300 microL sample volume, 9-minute assay time, and an average signal-to-noise ratio of 35.

Electrical characterization of suspended gold nanowire bridges with functionalized self-assembled monolayers using a top-down fabrication method

In this paper, a very simple top-down fabrication method, which is compatible with standard silicon (Si) fabrication processes, is proposed to fabricate new suspended gold nanowire bridges with flexible designs. The electrical characteristics of the nanowire bridges which include the V–I curve, thermoresistive and impedance spectra change before and after nanowire bridges release and resistivity change with different design parameters are measured. The suspended nanowire bridge structures show the reduction of interference from the substrate and a large design flexibility to fit varying application desires. Furthermore, the nanowire bridge has shown a high potential for biomolecular detection by the mechanical, electrical or optical sensing mechanism through the formation of functionalized self-assembled monolayers (SAMs) on the bridge structure.

Study on Protein (IgG) Adsorption in Terms of Surface Modification of Cyclic Olefin Copolymer (COC) for Protein Biochip

This paper presents the study of protein, immunoglobulin G (IgG), adsorption on the COC surfaces. The absorption of IgG on plasma-modified surfaces having different contact angle was shown to be distinctive, which may be advantageous in protein patterning. The comparison of normalized intensities of the adsorbed protein from front side with those from rear side is described to check functionality of COC as protein chip substrate in optical detection.

An ultra-high sensitive protein lab-on-a-chip on polymer for prostate cancer diagnostics

In this paper, we report a disposable, fast and high sensitive protein lab-on-a-chip on cyclic olefin copolymer (COC) substrate, which can be used for the detection of prostate specific antigen (PSA), a biomarker of prostate cancer. In this protein lab-on-a-chip, chemiluminescence-based sandwich immunoassay was developed for detecting PSA with the detection limit of 1 ng/mL. With the developed immunoassay, the protein lab-on-a-chips on polymer have successfully detected PSA in the range of 4-200 ng/mL. The protein lab-on-a-chip developed in this work can also be used for the detection of other biomarkers and proteins.

Novel Biomarkers Detection and Identification by Microfluidic- Based MicroELISA

Miniaturized, high throughput detection technologies including microfluidics systems represent powerful tools for biomarker discovery and analysis. Optimiser™ microplate technology combines microfluidics technology with standard SBS-configured 96-well microplate architecture and allows for the improvement of ELISA workflows. In this review, we present the “standard” and “high sensitivity” capabilities of the Optimiser™ ELISA in detecting human cytokine biomarker; IL-4, resulting in improving sensitivity by 1000-fold higher than the typical conventional ELISA. The Optimiser™ ELISA microplate employs standard ELISA equipment and protocols, selectively reduces sample volume 10-20 fold (Static Mode) and has the capability to amplify assay sensitivity by 1,000 fold (Repetitive Loading Flow-Through Mode) relative to conventional high sensitivity ELISA approaches. Optimiser™ allows sensitive and quantitative detection of biomarkers with demonstrated reproducibility, speed and linearity. In this study we demonstrate the utilization of OptmiserTM in the amplification of low-concentration markers. Optimiser™ microfluidic-based technology represents a revolutionary advancement in ELISA technology, and holds great promise for accurate, sensitive detection of novel biomarkers and its potential applications in clinical diagnosis.

Automated Fluidic System with a Chaotic Microfluidic Reaction Chamber for Rapid, Multi-Analyte Immunosensing

In this paper, a fully automated fluidic system with a chaotic reaction chamber for rapid and accurate fiber-optic immuno-sensing has been developed and applied for the measurement of cardiac biomarkers. A new microchannel with serpentine bump structures has improved the sensor performance by generating local turbulence near the sensor surface. A full immunoassay with the automated fluidic system has been successfully performed, and the total assay time spent for detecting four cardiac markers was less than 10 minutes.

An innovative sample-to-answer polymer lab-on-a-chip with on-chip reservoirs for the POCT of thyroid stimulating hormone (TSH)

A new sample-to-answer polymer lab-on-a-chip, which can perform immunoassay with minimum user intervention through on-chip reservoirs for reagents and single microchannel assay, has been designed, developed and successfully characterized as a point-of-care testing (POCT) cartridge for the detection of thyroid stimulating hormone (TSH). Users only need to drop a sample to the POCT cartridge to obtain test results within 30 minutes. The analyzed results of TSH showed a linear range up to 55 μIU/mL with the limit of detection (LOD) of 1.9 μIU/mL at the signal to noise ratio (SNR) of 3. The reagents stored in the on-chip reservoirs maintained their volume more than 97 % of initial volume for 100 days of storage time while the detection antibody retained its activity above 97 %.