title: Single plasmonic nanoparticles for ultrasensitive DNA sensing: From invisible to visible.
abstract: 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).
authors.affiliation: 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.
authors.forename: Longhua
authors.initials: L
authors.lastname: Guo
authors.affiliation: School of Chemical and Biomedical Engineering, Nanyang Technological University, 637457 Singapore, Singapore.
authors.forename: Lichan
authors.initials: L
authors.lastname: Chen
authors.affiliation: 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: seungpyoh@yonsei.ac.kr.
authors.forename: Seungpyo
authors.initials: S
authors.lastname: Hong
authors.affiliation: School of Chemical Engineering, Sungkyunkwan University, 16419, Republic of Korea. Electronic address: dhkim1@skku.edu.
authors.forename: Dong-Hwan
authors.initials: DH
authors.lastname: Kim
mesh_terms: D015374:Biosensing Techniques; D004247:DNA / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D020349:Surface Plasmon Resonance
chemical_list: D006046:Gold; D004247:DNA
keywords: BRCA1; DNA; Darkfield microscopy; Nanoparticle; Plasmonic