Silicon Quantum Dot Nanoparticles with Antifouling Coatings for Immunostaining on Live Cancer Cells

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• 作者：Chang-Ching Tu ; Kuang-Po Chen ; Tsu-An Yang ; Min-Yuan Chou ; Lih Y. Lin ; Yaw-Kuen Li
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：June 8, 2016
• 年：2016
• 卷：8
• 期：22
• 页码：13714-13723
• 全文大小：553K
• 年卷期：0
• ISSN：1944-8252

文摘

Fluorescent silicon quantum dots (SiQDs) have shown a great potential as antiphotobleaching, nontoxic and biodegradable labels for various in vitro and in vivo applications. However, fabricating SiQDs with high water-solubility and high photoluminescence quantum yield (PLQY) remains a challenge. Furthermore, for targeted imaging, their surface chemistry has to be capable of conjugating to antibodies, as well as sufficiently antifouling. Herein, antibody-conjugated SiQD nanoparticles (SiQD-NPs) with antifouling coatings composed of bovine serum albumin (BSA) and polyethylene glycol (PEG) are demonstrated for immunostaining on live cancer cells. The monodisperse SiQD-NPs of diameter about 130 nm are synthesized by a novel top-down method, including electrochemical etching, photochemical hydrosilylation, high energy ball milling, and “selective-etching” in HNO₃ and HF. Subsequently, the BSA and PEG are covalently grafted on to the SiQD-NP surface through presynthesized chemical linkers, resulting in a stable, hydrophilic, and antifouling organic capping layer with isothiocyanates as the terminal functional groups for facile conjugation to the antibodies. The in vitro cell viability assay reveals that the BSA-coated SiQD-NPs had exceptional biocompatibility, with minimal cytotoxicity at concentration up to 1600 μg mL^–1. Under 365 nm excitation, the SiQD-NP colloid emits bright reddish photoluminescence with PLQY = 45–55% in organic solvent and 5–10% in aqueous buffer. Finally, through confocal fluorescent imaging and flow cytometry analysis, the anti-HER2 conjugated SiQD-NPs show obvious specific binding to the HER2-overexpressing SKOV3 cells and negligible nonspecific binding to the HER2-nonexpressing CHO cells. Under similar experimental conditions, the immunofluorescence results obtained with the SiQD-NPs are comparable to those using conventional fluorescein isothiocyanate (FITC).