Entrapment and measurement of a biologically functionalized microbead with a microwell electrode.
A chip with integrated electrophoretic and electrochemical systems was developed to manipulate either an individual microbead or a cell inside a microwell electrode (MWE) for electrochemical measurement. The optimal MWE geometry (30 microm diameter and 25 microm depth) was designed to accommodate the micro particles according to the simulated results. A chip device was sequentially built from a slide patterned with Pt electrodes, an adhesive tape defined with a flow channel (200 microm in width and 25 microm in height), and an indium tin oxide (ITO) cover. The MWE not only generated an active electrophoretic force to trap the particle but also provided a low flow velocity area (LFVA) to stabilize the trapped bead or cell in a continuous flow. Scanning electrochemical microscopy (SECM) theory was employed to explain the electrochemical behaviors of the MWE. An enhanced current was confirmed as the redox recycling effect on the conductive ITO cover. The catalytic reaction of an individual alkaline phosphatase coated microbead (ALP-bead) was electrochemically detected with the MWE after being trapped. The ALP on the trapped ALP-bead catalyzed the hydrolysis of p-aminophenylphosphate (PAPP) to p-aminophenol (PAP), and then a decaying amperogram (+0.3 V vs. Ag/AgCl) due to a tiny PAP quantity around the MWE was observed.
Institute of Biomedical Engineering, National Cheng Kung University, Tainan, 701, Taiwan, ROC.
Ching-Yu
CY
Chang
Yasufumi
Y
Takahashi
Tatsuya
T
Murata
Hitoshi
H
Shiku
Hsien-Chang
HC
Chang
Tomokazu
T
Matsue
D001704:Biopolymers / Q000302:isolation & purification*; D002469:Cell Separation / Q000295:instrumentation*; D017076:Computer-Aided Design; D004586:Electrophoresis / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005434:Flow Cytometry / Q000295:instrumentation*; D008839:Microelectrodes; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D008863:Microspheres; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D001704:Biopolymers