Fabrication and properties of a supramolecular hybrid hydrogel doped with CdTe quantum dots

Abstract

Fluorescent hydrogels incorporated with photoluminescent nanomaterials have achieved promising progress in bio-sensing or bio-labeling, yet the current techniques mostly rely on chemically cross-linking the hydrogel which involves undesirable chemical reactions that may easily disturb the incorporated nanomaterials. In this work, the fabrication of a fluorescent supramolecular hydrogel doped with semiconductor CdTe quantum dots (QDs) is demonstrated. The colloidal QDs were stabilized with synthetic amphiphilic block copolymer, mercaptan-ended poly(ethylene glycol)–poly(ε-caprolactone). The stability and fluorescent properties of the resultant colloidal QDs were evaluated. A fluorescent supramolecular hydrogel was fabricated based on the host–guest self-assembly between the amphiphilic block copolymer on the QD surface and added cyclic oligosaccharide host molecule, α-cyclodextrin (α-CD). The resultant photoluminescent hydrogel was characterized with rheology and X-ray diffraction, as well as photoluminescence spectra measurements. The gelation kinetics and mechanical strength of the supramolecular hydrogel can be modulated by changing the amount of the amphiphilic block copolymer, α-CD, used or the incorporated QDs. These results suggest new opportunities for developing biocompatible optical materials with tunable fluorescent properties and mechanical properties.