Antibody-conjugated near-infrared luminescent silicon quantum dots for biosensing
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Research Letter
Antibody-conjugated near-infrared luminescent silicon quantum dots for biosensing Hiroto Yanagawa, Technology Innovation Division, Panasonic Corporation, Yagumo-naka-machi, Moriguchi, Osaka 570-8501, Japan; Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501, Japan Asuka Inoue and Hiroshi Sugimoto , Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501, Japan Masahiko Shioi , Life Solutions Company, Panasonic Corporation, Kadoma, Osaka 571-8686, Japan Minoru Fujii , Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501, Japan Address all correspondence to Minoru Fujii at [email protected] (Received 16 May 2019; accepted 15 July 2019)
Abstract A process for bioconjugation of an IgG antibody and silicon quantum dots (Si-QDs) having the luminescence in the near-infrared (NIR) range was developed. For the bioconjugation, the surface of water-soluble all-inorganic Si-QDs was functionalized by using silane-coupling agents. In amino-functionalized Si-QDs, successful conjugation was achieved without strongly affecting the luminescence property. Detailed analyses revealed that Si-QDs are bound covalently to both the light and heavy chains of an IgG antibody. It was also confirmed that the binding property of an IgG antibody with antigen nucleoprotein was not ruined by the process. The successful conjugation of an IgG antibody and NIR luminescent Si-QDs paves the way for designing environmentally friendly bio-sensing and -imaging processes.
Introduction Organic dyes are the most commonly used fluorescent probes for bio-sensing. Due to the small size, they are not likely to interfere biologic interactions monitored.[1] In order to avoid auto-fluorescence of biologic molecules and cells and to achieve high sensitivity, near-infrared (NIR) wavelength is preferentially used for fluorescence bio-sensing.[1] However, NIR luminescent organic dyes often suffer from fast degradation and are not suitable for long-term observations.[2] In addition, the small Stokes shift and resultant difficulty in the complete removal of excitation light degrade the sensitivity.[3] Semiconductor quantum dots (QDs) are considered to be a promising candidate to replace NIR organic fluorescent dyes due to several superior physical and optical properties such as the size controllability of the luminescence wavelength, the narrow luminescence band, the high luminescence quantum yield, and the high photostability.[2–10] However, in the usage of commercially available cadmium (Cd) chalcogenide, e.g., CdS, CdTe, CdSe, and ZnS-capped CdSe, QDs in biomedical fields and the release of free Cd ions, which are a known carcinogen and cause primary liver cell death, are always a concern.[11–13] A silicon (Si)-QD is one of the heavy metal-free QDs potentially suitable for bio-sensing applications due to biocompatibil
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