Development of Novel Ultrasensitive Electrical Chip-Based Sensing Biomolecule System Using Nanogap Electrodes and Nanoparticles
Date Issued
2006
Date
2006
Author(s)
Chang, Tien-Li
DOI
en-US
Abstract
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The main purpose of this research is to develop a biochip that employs a novel approach for electrical detection of DNA or protein using nanogap electrodes and nanoparticles. Besides, the fluid flow characteristics of microfluidic chip are discussed from the experimental results.
This study presents fabrication of nanogap electrodes, preparation of nanoparticles, electrical detection principle of DNA and protein using self-assembled multilayer gold nanoparticles, and bio-bar-code amplification (BCA) technique for improving detection sensitivity of sensing biochip. The nanogap electrodes of biochip are fabricated by using electron-beam lithography technique. The nanogap distance between the electrodes is around 300 nm and the height of electrodes is 65 nm. Gold nanoparticles (AuNPs) and magnetic nanoparticles (MNPs) are synthesized by using chemical reduction method and co-precipitation method, respectively. The average diameter of AuNPs and MNPs is 12 ± 2.1 nm and 27 ± 3.6 nm, respectively. In addition to these, the microfluidic devices are fabricated utilizing the micromolding of SU-8 photoresist and based on the replica molding technique of polydimethylsiloxane (PDMS).
In this work, the study of electrical detection of DNA and protein is based on nanogap electrodes and self-assembled multilayer AuNPs to amplify the electrical signal. Unfortunately, the current-voltage (I-V) behavior of target DNA and target antigen at some low concentration still can not obey Ohm’s law. Furthermore, a novel ultrasensitive detection based on BCA technique is adopted to integrate above mentioned. In this way, MNPs and bio-bar-code DNA are used to amplify obtainable current through nanogap electrodes from extremely low concentration of target DNA and antigen. The detected concentration of target DNA and antigen with electrical DNA and protein biosensor is lower than 1 fM and 1 pg/µL, respectively. From these results we could find effectively improved electrical signals. Albeit, the results of flow behavior in microfluidic chips including microjet, micromixer and microseparator are discussed. Finally we say that the study of an ultrasensitive electrical detection for nanogap sensing on-chip system and microfluidic chip system will be helpful to improve commercially potential novel biochip platform and development of an integrated Lab-on-a-Chip application.
Subjects
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Nanogap Electrodes
Microfluidic Chip
Magnetic Nanoparticles
Gold Nanoparticles
Self-Assembly
Electrical Detection
Type
thesis
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