Hydrogels with controlled fluorescent properties based on quantum dots and diamine derivatives of polyethylene glycol

Hydrogels are three-dimensional hydrophilic polymer structures obtained by chemical cross-linking or physical binding. Fluorescent hydrogels based on semiconductor nanocrystals or quantum dots (QDs) are of great interest due to their potential for bioanalytical, biosensor, and microfluidic applications. In the present study an approach to obtaining fluorescent gels with the use of a heterobifunctional cross-linker from water-soluble CdSe/ZnS (core/shell) QDs with the surface functionalized with cysteine and diamine derivatives of polyethylene glycol (PEG) of different lengths has been developed. The structure of the obtained gels was characterized using light, fluorescence, and scanning electron microscopi in comparison with gels obtained by addition of divalent cations. Comparative analysis of the spectral characteristics and fluorescence quantum yield of the obtained gel samples of different structures and morphologies was carried out. It was found that the porosity and optical properties of the obtained gels can be controlled by selecting PEG linkers of different lengths used for chemical gelation.