Glucose dithiocarbamate derivatives as capping ligands of water-soluble CdSeS/ZnS quantum dots

In the framework of presented study selected glucose analogues: 1-thio-beta-D-glucose (beta DG-SH), D-glucosamine dithiocarbamate (DG-DTC) and N-methyl-D-glucamine dithiocarbamate (NMDG-DTC) were used to modify CdSexS1-x/ZnS quantum dots via ligand exchange. The special emphasis was put on the careful optimization of DTC synthesis in an aqueous media. Properties of primary and secondary dithiocarbamates, such as stability in solutions of various pH and capability to form complexes with the divalent ions, which are crucial for their applications as surface ligands of QDs, were thoroughly compared. Due to the facility of DTCs preparation as well as colloidal stability and good optical properties of obtained hydrophilic QDs, DTC-derivatives turn out to be an alternative to most commonly used thiolated ligands. Examination of biological activity of DTC-modified QDs on A549 cell line revealed that DTC-ligands exhibit negligible intrinsic cytotoxicity. Biomimetic character of anchored ligands (similar to glucose) combined with satisfactory physicochemical properties of obtained QDs, such as high hydrophilicity and uncharged surface, indicate the potential of so modified QDs for cellular imaging and biosensing. (C) 2016 Elsevier B.V. All rights reserved.