Fabrication and characterization of silk-fibroin-coated quantum dots

We report a novel technique of directly coating colloidal CdSe/ZnS core/shell quantum dots (QDs) with silk fibroin (SF), a protein derived from the Bombyx mori silk worm. The approach results in protein-modified QDs with little or no particle aggregation, and mitigates the issue of biocompatibility. QDs have desirable optical properties, such as narrow-band emission, broadband absorption, high quantum yield, and high resistance to photobleaching. SF is a fibrous protein polymer with a biomimetic peptide sequence, water and oxygen permeability, low inflammatory response, no thrombogenecity, and cellular biocompatibility, which are desirable properties for in vivo delivery. Combining the unique properties of QDs with the biocompatibility profile of SF, the approach produces particles representing a powerful tool for numerous in vivo and in vitro applications. The design and preparation of these protein-modified QDs conjugates is reported along with functional characterization using luminescence, transmission electron microscope (TEM), and atomic force microscope (AFM). Additionally, we report results obtained using the QDs conjugates as a fluorescent label for bioimaging HEYA8 ovarian cancer cells.