Cord-Based Microfluidic Chips as A Platform for ELISA and Glucose Assays

Abstract

This paper describes the development and application of microfluidic cord-based analytical devices (µCADs) in two enzyme-linked immunosorbent assays (ELISAs) and glucose assay. In this study, biotinylated goat anti-mouse immunoglobulin (IgG) antibody, rabbit IgG antibody, and glucose are quantitatively detected. In the ELISA systems, the antibody is spotted on the cord at the detection site and a series of washes, followed by streptavidin-alkaline phosphatase (Strep-ALP) or alkaline phosphatase (ALP)-conjugated secondary antibody and colorimetric substrate, completing the experiment. The devices are subsequently scanned and analyzed yielding a correlation between inverse yellow or inverse blue intensity and antibody concentration. For the first ELISA, a linear range of detection was observed at lower concentrations (2.50 × 10−4–1.75 × 10−3 mg/mL) of Strep-ALP with saturation of the enzyme achieved at higher concentrations (>2.50 × 10−4). For the second ELISA, the L50 was demonstrated to be 167.6 fmol/zone. The glucose assay consisted of spotting increasing concentrations of glucose on the analysis sites and transporting, via capillary action, a solution containing glucose oxidase (GOx), horseradish peroxidase (HRP), and potassium iodide (KI) to the detection sites realizing a yellow-brown color indicating oxidation of iodide to iodine. The device was then dried, scanned, and analyzed to show the correlation between yellow inverse intensity and glucose. Glucose in artificial urine showed good correlation using the devices.

Reusable, Non-Invasive, and Ultrafast Radio Frequency Biosensor Based on Optimized Integrated Passive Device Fabrication Process for Quantitative Detection of Glucose Levels

“…A biosensor can convert different concentrations of glucose into corresponding electrical signals for output, which has advantages of high accuracy, fast analysis, low cost, good repeatability, simple operation and high specificity by comparing with traditional detection methods [10][11][12][13][14][15][16]. With the aid of chips, microfluidics systems and labs-on-a-chip, biosensor technology have developed rapidly and can be divided into electrochemical biosensors and optical biosensors based on the type of signal conversion [17][18][19][20][21][22][23][24][25][26]. Electrochemical biosensors enable the detection of biomarkers by adding specific enzymes on the electrodes, which has many advantages, such as high sensitivity, simple operation and cost-effective [27][28][29].…”