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• Cao, C
• Birtwell, SW.
• Høgberg, J
• Morgan, H
• Wolff, A
• Bang, DDuong
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• Cao, C
• Birtwell, SW.
• Høgberg, J
• Morgan, H
• Wolff, A
• Bang, DDuong
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• Cao, C
• Birtwell, SW.
• Høgberg, J
• Morgan, H
• Wolff, A
• Bang, DDuong

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Diagnostics 2012, 2(4), 72-82; doi:10.3390/diagnostics2040072

Article

Gold Nanoparticles-Coated SU-8 for Sensitive Fluorescence-Based Detections of DNA

Cuong Cao ¹ , Sam W. Birtwell ² , Jonas Høgberg ³ , Hywel Morgan ² , Anders Wolff ¹  and Dang Duong Bang ^4,*

¹ DTU-NANOTECH, Department of Micro and Nanotechnology, Technical University of Denmark, DTU Building 423, DK-2800 Kongens Lyngby, Denmark ² School of Electronics and Computer Science, University of Southampton, Southampton SO17 1BJ, UK ³ DTU-VET, Diagnostic Laboratory, National Veterinary Institute, Technical University of Denmark, Bülowsvej 27, DK-1870 Frederiksberg C, Denmark ⁴ DTU-FOOD, Laboratory of Applied Micro-Nanotechnology (LAMINATE), Diagnostic Engineering, Division of Food Microbiology, National Food Institute, Technical University of Denmark, Mørkhøj Bygade 19, DK-2860 Søborg, Denmark

* Author to whom correspondence should be addressed.

Received: 26 September 2012; in revised form: 24 October 2012 / Accepted: 26 November 2012 / Published: 29 November 2012

(This article belongs to the Special Issue Microfluidic Lab-on-a-Chip Platforms for High-Performance Diagnostics)

Download PDF Full-Text [716 KB, uploaded 29 November 2012 11:39 CET]

Abstract: SU-8 epoxy-based negative photoresist has been extensively employed as a structural material for fabrication of numerous biological microelectro-mechanical systems (Bio-MEMS) or lab-on-a-chip (LOC) devices. However, SU-8 has a high autofluorescence level that limits sensitivity of microdevices that use fluorescence as the predominant detection workhorse. Here, we show that deposition of a thin gold nanoparticles layer onto the SU-8 surface significantly reduces the autofluorescence of the coated SU-8 surface by as much as 81% compared to bare SU-8. Furthermore, DNA probes can easily be immobilized on the Au surface with high thermal stability. These improvements enabled sensitive DNA detection by simple DNA hybridization down to 1 nM (a two orders of magnitude improvement) or by solid-phase PCR with sub-picomolar sensitivity. The approach is simple and easy to perform, making it suitable for various Bio-MEMs and LOC devices that use SU-8 as a structural material.

Keywords: gold nanoparticles; SU-8; autofluorescence; solid-phase PCR amplification; DNA hybridization

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