Gold nanoparticle assays: towards single molecule unamplified DNA detection

R. Verdoold; F. Ungureanu; D. Wasserberg; R. P. H. Kooyman

doi:10.1117/12.818120

30 April 2009 Gold nanoparticle assays: towards single molecule unamplified DNA detection

R. Verdoold, F. Ungureanu, D. Wasserberg, R. P. H. Kooyman

Proceedings Volume 7312, Advanced Environmental, Chemical, and Biological Sensing Technologies VI; 73120N (2009) https://doi.org/10.1117/12.818120
Event: SPIE Defense, Security, and Sensing, 2009, Orlando, Florida, United States

Abstract

The light scattering and absorption properties of gold nanoparticles (GNPs) can be utilised for the detection of DNA. Binding of molecules to the GNP influences the local refractive index. The increase in refractive index can be measured as proportional red-shift of the GNPs extinction maximum; therefore GNPs are suitable for use as nanoparticle chemical sensors. Utilizing this method it is possible to detect DNA in naturally occurring quantities. In bulk measurements we have shown a red-shift of 7 nm of the absorption maximum (λ_max) upon binding of thiolated ssDNA. Subsequently, we were able to follow the interaction between two sets of GNPs functionalised with complementary strands. Randomly immobilised GNPs were visualised with an inverted darkfield microscope. The use of a colour camera enables us to analyse the colour change of each individual particle in the field of view. A change of λ_max of 1 nm can be detected by the colour camera, which corresponds to ~100 20mer ssDNA molecules. For the detection of a single DNA binding events we are developing an assay for DNA detection, utilizing a second set of GNPs. The interaction of two GNPs within a range of 2.5 times the radius of each other results in a shift of ~7 nm in λ_max for the presence of one DNA strand. This increased shift makes the method not only more accurate but also easier to detect.

Citation Download Citation

R. Verdoold, F. Ungureanu, D. Wasserberg, and R. P. H. Kooyman "Gold nanoparticle assays: towards single molecule unamplified DNA detection", Proc. SPIE 7312, Advanced Environmental, Chemical, and Biological Sensing Technologies VI, 73120N (30 April 2009); https://doi.org/10.1117/12.818120

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