Quantitative Colorimetric Detection of DNA Using Oligonucleotide-Functionalized Gold Nanoparticles

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Dr. Jeunghoon Lee


The goal of my current research project is to develop a colorimetric detection scheme to analyze the concentration of a specific DNA strand in solution. By analyzing the color change induced by oligonucleotide-functionalized gold nanoparticle aggregation, the presence of the target DNA in a solution can be determined. Gold nanoparticles synthesized by the reduction of gold (III) salt are functionalized with a thiolated DNA with 20 bases. Using a range of excess target DNA concentrations and observing the plasmon peak shift, the approximate concentration level of the target DNA can be measured. Aggregation is expressed as the color change from deep red to blue-purple, and a shift in absorption peak from 520 nm to 550 nm. Our result shows that there exists an optimum target DNA concentration that maximizes the color change. The degree of shift in absorption is also dependent on the overall concentration of the gold colloids. The colorimetric analysis of DNA nanoparticles could lead to efficient, affordable, and extremely sensitive detection of missing or faulty sequences in DNA strands. In the future, more detailed studies will be carried out to measure the DNA concentration more precisely.

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