As I continue to search for novel and interesting applications for the interaction between biotin and streptavidin, I love seeing the variety of applications that scientists from around the world dream up and develop! Most recently, I came across a paper describing a new method for DNA detection and fluorophore quenching using streptavidin-coated gold nanoparticles.

Chuan-Liang Feng et al. developed a system which utilized colloidal gold nanoparticles (AuNPs) to act as a DNA biosensors, or DNA probe, in order to detect DNA hybridization. Colloidal gold has been used for over a thousand years in various industries, starting with the glass blowers of ancient Rome and Greece who produced some truly amazing and beautiful, colored glass using gold particles dispersed throughout the glass to create light diffraction effects. One of the best known examples of this level of technology is the Lycurgus Cup (click here for another interesting article concerning this magnificent work of art). In our modern era, however, colloidal gold has become popular in the medical field, being investigated extensively as a drug carrier or in this case, gene therapy.

Feng’s novel approach in labeling the AuNPs with streptavidin and using its natural interaction with biotin to create a specific probe. Even more interesting, Feng used the association of biotin/avidin to build small, single-strand, complementary (or near complementary) DNA probes with either a biotin or Cy5 tail. Amazingly, the association, first between the biotin-ssDNA and the StAuNP, and the between the StAuNP/biotin-ssDNA and Cy5-ssDNA created a quenching effect on the fluorescence of the Cy5 molecule! Further, Feng’s group was able to add fully complementary, non-biotin ssDNA probes to the solution and slowly recover Cy5 fluorescence, outcompeting the near-complementary biotin-ssDNA and thus reversing the quenching effect!

This method is a simple and effective means to detect DNA hybridization, and as Feng reports, could be used as a high throughput method of biodiagnostics. Further tests will tell. One thing is for certain, scientists will continue to dream, create and develop new and ever-more fascinating systems to increase our understanding of the world we live in. And I, for one, cannot wait to see what we discover next.

Feng, C. L., Dou, X. Q., Liu, Q. L., Zhang, W., Gu, J. J., Zhu, S. M., Jenkins, A., & Zhang, D. (2013). Dual-Specific Interaction to Detect DNA on Gold Nanoparticles. Sensors, 13(5), 5749-5756.

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