Label-less fluorescence-based method to detect hybridization with applications to DNA micro-array

Sanjun Niu, Gaurav Singh, Ravi F Saraf

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

By coupling scattered light from DNA to excite fluorescence in a polymer, we describe a quantitative, label-free assay for DNA hybridization detection. Since light scattering is intrinsically proportional to number of molecules, the change in (scattering coupled) fluorescence is highly linear with respect to percent binding of single stranded DNA (ssDNA) target with the immobilized ssDNA probes. The coupling is achieved by immobilizing ssDNA on a fluorescent polymer film at optimum thickness in nanoscale. The fluorescence from the underlining polymer increases due to proportionate increase in scattering from double stranded DNA (dsDNA) (i.e., probe-target binding) compared to ssDNA (i.e., probe). Because the scattering is proportional to fourth power of refractive index, the detection of binding is an order of magnitude more sensitive compared to other label-free optical methods, such as, reflectivity, interference, ellipsometry and surface-plasmon resonance. Remarkably, polystyrene film of optimum thickness 30 nm is the best fluorescent agent since its excitation wavelength matches (within 5 nm) with wavelength for the maximum refractive index difference between ssDNA and dsDNA. A quantitative model (with no fitting parameters) explains the observations. Potential dynamic range is 1 in 104 at signal-to-noise ratio of 3:1.

Original languageEnglish (US)
Pages (from-to)714-720
Number of pages7
JournalBiosensors and Bioelectronics
Volume23
Issue number5
DOIs
StatePublished - Dec 15 2007

Fingerprint

Single-Stranded DNA
Labels
DNA
Fluorescence
Refractometry
Polymers
DNA Probes
Scattering
Refractive index
Light
Wavelength
Surface Plasmon Resonance
Polystyrenes
Ellipsometry
Surface plasmon resonance
Signal-To-Noise Ratio
Fluorescent Dyes
Polymer films
Light scattering
Assays

Keywords

  • Biosensors
  • DNA chip
  • DNA scattering
  • Label-free
  • Label-less
  • Micro-array

ASJC Scopus subject areas

  • Biotechnology
  • Biophysics
  • Biomedical Engineering
  • Electrochemistry

Cite this

Label-less fluorescence-based method to detect hybridization with applications to DNA micro-array. / Niu, Sanjun; Singh, Gaurav; Saraf, Ravi F.

In: Biosensors and Bioelectronics, Vol. 23, No. 5, 15.12.2007, p. 714-720.

Research output: Contribution to journalArticle

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