Silica-coated CdTe quantum dots functionalized with thiols for bioconjugation to IgG proteins.
Quantum dots (QDs) have been increasingly used in biolabeling recently as their advantages over molecular fluorophores have become clear. For bioapplications QDs must be water-soluble and buffer stable, making their synthesis challenging and time-consuming. A simple aqueous synthesis of silica-capped, highly fluorescent CdTe quantum dots has been developed. CdTe QDs are advantageous as the emission can be tuned to the near-infrared where tissue absorption is at a minimum, while the silica shell can prevent the leakage of toxic Cd(2+) and provide a surface for easy conjugation to biomolecules such as proteins. The presence of a silica shell of 2-5 nm in thickness has been confirmed by transmission electron microscopy and atomic force microscopy measurements. Photoluminescence studies show that the silica shell results in greatly increased photostability in Tris-borate-ethylenediaminetetraacetate and phosphate-buffered saline buffers. To further improve their biocompatibility, the silica-capped QDs have been functionalized with poly(ethylene glycol) and thiol-terminated biolinkers. Through the use of these linkers, antibody proteins were successfully conjugated as confirmed by agarose gel electrophoresis. Streptavidin-maleimide and biotinylated polystyrene microbeads confirmed the bioactivity and conjugation specificity of the thiolated QDs. These functionalized, silica-capped QDs are ideal labels, easily synthesized, robust, safe, and readily conjugated to biomolecules while maintaining bioactivity. They are potentially useful for a number of applications in biolabeling and imaging.
Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California 95064, USA.
Abraham
A
Wolcott
Daniele
D
Gerion
Micah
M
Visconte
Jia
J
Sun
Adam
A
Schwartzberg
Shaowei
S
Chen
Jin Z
JZ
Zhang
D019921:Biotinylation; D001888:Boric Acids / Q000737:chemistry; D019187:Cadmium Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D004492:Edetic Acid / Q000737:chemistry; D004587:Electrophoresis, Agar Gel; D007074:Immunoglobulin G / Q000737:chemistry* / Q000378:metabolism; D008301:Maleimides / Q000737:chemistry; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D036103:Nanotechnology / Q000379:methods*; D011092:Polyethylene Glycols / Q000737:chemistry; D011137:Polystyrenes / Q000737:chemistry; D045663:Quantum Dots; D012822:Silicon Dioxide / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D012995:Solubility; D019809:Streptavidin / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013499:Surface Properties; D013691:Tellurium / Q000737:chemistry*; D014325:Tromethamine / Q000737:chemistry; D014867:Water / Q000737:chemistry
D001888:Boric Acids; D019187:Cadmium Compounds; D007074:Immunoglobulin G; D008301:Maleimides; D011137:Polystyrenes; D013438:Sulfhydryl Compounds; C069591:Tris-borate-EDTA buffer; D014325:Tromethamine; D014867:Water; C043592:maleimide; D011092:Polyethylene Glycols; D012965:Sodium Chloride; D012822:Silicon Dioxide; D019809:Streptavidin; D004492:Edetic Acid; D013691:Tellurium; C028337:cadmium telluride