Simple colorimetric or fluorescent analysis of small molecules based-on the interaction between DNA aptamers and unmodified gold nanoparticles
- Simple colorimetric or fluorescent analysis of small molecules based-on the interaction between DNA aptamers and unmodified gold nanoparticles
- 김연석; S. Chin; 정종수
- sensor; aptamer; gold nanoparticle
- Issue Date
- The Second Nano Today Conference, 2011
- We developed simple aptamer-based colorimetric or fluorescent detection methods for lowweight
molecules using unmodified gold nanoparticles (umAuNPs). This method was relied on
the different electrostatic interactions of DNA aptamers on the surface of umAuNPs in the
absence or presence of target molecules. In colorimetric assay, the aggregation of umAuNPs
was prevented due to a stabilizing effect of aptamers adsorbed on umAuNPs at high salt
concentration. However, addition of targets into the AuNPs solution triggered the aggregation of
AuNPs because the competitive interaction of target to its aptamer induced the displacement of
DNA aptamer from umAuNPs, subsequently the color change of the mixture from red to purple
was happened. As a result, the red-to-purple color change was proportional to the concentration
of targets and it was easily observed to micro-molar level by naked eye. It was also verified that
the color change of AuNPs solution was not occurred in the addition of other structurally similar
compounds. In fluorescent analysis, DNA aptamers were immobilized on quantum dots (QDs),
and QDs conjugated ssDNA was adsorbed on the surface of umAuNPs. Subsequently the
fluorescence of QDs was effectively quenched by AuNPs due to fluorescence resonance
energy transfer (FRET) of QDs to AuNPs. In the presence of targets, the QDs conjugated
aptamers was detached from AuNPs by target induced conformational change of aptamers
consequently the fluorescence of QDs was recovered proportional to the target concentration.
These homogeneous detection manners were very simple and fast, therefore, they are useful
for the on-site detection of small molecules.
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