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Biosens Bioelectron. 2016 May 15;79:266-72. doi: 10.1016/j.bios.2015.12.027. Epub 2015 Dec 15.

Single plasmonic nanoparticles for ultrasensitive DNA sensing: From invisible to visible.

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School of Chemical and Biomedical Engineering, Nanyang Technological University, 637457 Singapore, Singapore; Institute of Nanomedicine and Nanobiosensing, Ministry of Education Key Laboratory of Analysis and Detection Technology for Food Safety, College of Chemistry, Fuzhou University, Fuzhou 350116, China.
School of Chemical and Biomedical Engineering, Nanyang Technological University, 637457 Singapore, Singapore.
Division of Integrated Science and Engineering and Department of Integrated OMICS for Biomedical Science, Yonsei University, Seoul 120-749, Republic of Korea; Departments of Biopharmaceutical Sciences, University of Illinois, Chicago, IL 60612, USA. Electronic address:
School of Chemical Engineering, Sungkyunkwan University, 16419, Republic of Korea. Electronic address:


The background signal is a major factor that restricts the limit of detection of biosensors. Herein, we present a zero-background DNA-sensing approach that utilizes enzyme-guided gold nanoparticle (AuNP) enlargement. This sensing strategy is based on the finding that small nanoparticles are invisible under a darkfield optical microscope, thus completely eliminating the background signal. In the event of target binding, Ag deposition is triggered and enlarges the AuNP beyond its optical diffraction limit, thereby making the invisible AuNP visible. Because the plasmon scattering of Ag is stronger than that of Au, only a thin layer of Ag is required to greatly enhance the scattering intensity of the AuNPs. Our investigation revealed that a target DNA concentration as low as 5.0×10(-21)M can transform the darkfield image of the nanoparticle from completely dark (invisible) to a blue dot (visible).


BRCA1; DNA; Darkfield microscopy; Nanoparticle; Plasmonic

[Indexed for MEDLINE]

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