title: Silicon Quantum Dot Nanoparticles with Antifouling Coatings for Immunostaining on Live Cancer Cells.
abstract: 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).
authors.affiliation: Department of Applied Chemistry, National Chiao Tung University , Hsinchu, Taiwan 300, ROC.|LumiSands Inc. , Seattle, Washington 98105, United States.
authors.forename: Chang-Ching
authors.initials: CC
authors.lastname: Tu
authors.affiliation: Department of Applied Chemistry, National Chiao Tung University , Hsinchu, Taiwan 300, ROC.
authors.forename: Kuang-Po
authors.initials: KP
authors.lastname: Chen
authors.affiliation: Department of Applied Chemistry, National Chiao Tung University , Hsinchu, Taiwan 300, ROC.
authors.forename: Tsu-An
authors.initials: TA
authors.lastname: Yang
authors.affiliation: Biomedical Technology and Device Research Laboratories, Industrial Technology Research Institute , Hsinchu, Taiwan 310, ROC.
authors.forename: Min-Yuan
authors.initials: MY
authors.lastname: Chou
authors.affiliation: Department of Electrical Engineering, University of Washington , Seattle, Washington 98195, United States.
authors.forename: Lih Y
authors.initials: LY
authors.lastname: Lin
authors.affiliation: Department of Applied Chemistry, National Chiao Tung University , Hsinchu, Taiwan 300, ROC.
authors.forename: Yaw-Kuen
authors.initials: YK
authors.lastname: Li
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D006224:Cricetinae; D003412:Cricetulus; D053758:Nanoparticles / Q000633:toxicity; D011092:Polyethylene Glycols / Q000737:chemistry; D045663:Quantum Dots; D012710:Serum Albumin, Bovine / Q000737:chemistry; D012825:Silicon; D013194:Staining and Labeling / Q000379:methods*
chemical_list: D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols; D012825:Silicon
keywords: antifouling coatings; bioconjugation; biological labels; immunofluorescence; photoluminescence; silicon quantum dots