Miniaturized Multiplex Label-Free Electronic Chip for Rapid Nucleic Acid Analysis Based on Carbon Nanotube Nanoelectrode Arrays

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 50; no. 10; pp. 1886 - 1893
• Main Authors: Koehne, Jessica E, Chen, Hua, Cassell, Alan M, Ye, Qi, Han, Jie, Meyyappan, Meyya, Li, Jun
• Format: Journal Article
• Language: English
• Published: Legacy CDMS Am Assoc Clin Chem 01.10.2004; American Association for Clinical Chemistry; Oxford University Press
• Subjects: Acids; Algorithms; Analytical, structural and metabolic biochemistry; Automation; Biological and medical sciences; Biosensors; Carbon; Chemical vapor deposition; DNA - analysis; Electrochemistry; Electrodes; Fundamental and applied biological sciences. Psychology; Gene amplification; Investigative techniques, diagnostic techniques (general aspects); Lasers; Life Sciences (General); Medical laboratories; Medical sciences; Microelectromechanical systems; Molecular biophysics; Nanotechnology; Nickel; Nucleic Acids - analysis; Oligonucleotide Array Sequence Analysis - instrumentation; Oligonucleotide Array Sequence Analysis - methods; Oxidation; Semiconductors; Silicon wafers; Rapid technique; Biochemical analysis; Free form; Clinical biology; Microequipment; DNA chip; Electronics; Biochemistry; Molecular biology; Chip; Carbon; Nucleic acid
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1373/clinchem.2004.036285

BACKGROUND: Reducing cost and time is the major concern in clinical diagnostics, particularly in molecular diagnostics. Miniaturization technologies have been recognized as promising solutions to provide low-cost microchips for diagnostics. With the recent advancement in nanotechnologies, it is possible to further improve detection sensitivity and simplify sample preparation by incorporating nanoscale elements in diagnostics devices. A fusion of micro- and nanotechnologies with biology has great potential for the development of low-cost disposable chips for rapid molecular analysis that can be carried out with simple handheld devices. APPROACH: Vertically aligned multiwalled carbon nanotubes (MWNTs) are fabricated on predeposited microelectrode pads and encapsulated in SiO2 dielectrics with only the very end exposed at the surface to form an inlaid nanoelectrode array (NEA). The NEA is used to collect the electrochemical signal associated with the target molecules binding to the probe molecules, which are covalently attached to the end of the MWNTs. CONTENT: A 3 x 3 microelectrode array is presented to demonstrate the miniaturization and multiplexing capability. A randomly distributed MWNT NEA is fabricated on each microelectrode pad. Selective functionalization of the MWNT end with a specific oligonucleotide probe and passivation of the SiO2 surface with ethylene glycol moieties are discussed. Ru(bpy)2+ -mediator-amplified guanine oxidation is used to directly measure the electrochemical signal associated with target molecules. SUMMARY: The discussed MWNT NEAs have ultrahigh sensitivity in direct electrochemical detection of guanine bases in the nucleic acid target. Fewer than approximately 1000 target nucleic acid molecules can be measured with a single microelectrode pad of approximately 20 x 20 microm2, which approaches the detection limit of laser scanners in fluorescence-based DNA microarray techniques. MWNT NEAs can be easily integrated with microelectronic circuitry and microfluidics for development of a fully automated system for rapid molecular analysis with minimum cost.