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Trace analysis of DNA: preconcentration, separation, and electrochemical detection in microchip electrophoresis using Au nanoparticles.

Authors :
Shiddiky MJ
Shim YB
Source :
Analytical chemistry [Anal Chem] 2007 May 15; Vol. 79 (10), pp. 3724-33. Date of Electronic Publication: 2007 Apr 12.
Publication Year :
2007

Abstract

We have developed a simple and sensitive on-chip preconcentration, separation, and electrochemical detection (ED) method for trace analysis of DNA. The microchip comprised of three parallel channels: the first two are for the field-amplified sample stacking and subsequent field-amplified sampled injection steps, while the third one is for the microchip gel electrophoresis (MGE) with ED (MGE-ED). To improve preconcentration and separation performances of the method, the stacking and separation buffers containing the hydroxypropyl cellulose (HPC) matrix were modified with gold nanoparticles (AuNPs). The formation of AuNPs and HPC/AuNP-modified buffers were characterized by UV-visible spectroscopy and TEM experiments. The conducting polymer-modified electrode was also modified with AuNPs to enhance detection performances of the electrode. The conducting polymer/AuNP layers act as electrocatalysts for the direct detection of DNA based on their oxidation in a solution phase. The total sensitivity was improved by approximately 25 000-fold when compared with a conventional MGE-ED analysis. The calibration plots were linear (r2 = 0.9993) within the range of 0.003-1.0 pg/microL for a 20-bp DNA sample. The sensitivity was 0.20 nA/(fg/microL), with a detection limit of 5.7 amol in a 50-microL sample, based on S/N = 3. The applicability of the method for the analysis of 13 fragments present in a 100-bp DNA ladder was successfully demonstrated.

Details

Language :
English
ISSN :
0003-2700
Volume :
79
Issue :
10
Database :
MEDLINE
Journal :
Analytical chemistry
Publication Type :
Academic Journal
Accession number :
17428034
Full Text :
https://doi.org/10.1021/ac0701177