Strongly fluorescent hydrogels with quantum dots embedded in cellulose matrices

Hydrogels having strong fluorescence were fabricated successfully, for the first time, from cellulose and quantum dots (QDs) in a NaOH/urea aqueous system via a mild chemical cross-linking process. The CdSe/ZnS nanoparticles were embedded firmly in the cellulose matrices, as a result of strong interactions between the CdSe/ZnS nanoparticles and cellulose after hydrolysis of the QDs ligands. The results from FTIR spectra, transmission electron microscopy, scanning electron microscopy and photoluminescence (PL) spectra revealed that the cellulose networks in the hydrogels played an important role in the protection of the CdSe/ZnS structure and preservation of the quantum dots characteristics. The cellulose–QDs hydrogels exhibited strong PL emission and nearly pure color from green to red, depending on the size of the QDs. Moreover, the hybrid hydrogels possessed a good transparence and compressive strength. This work provides a new pathway for the construction of safe and biocompatible biopolymer–QDs hydrogels with a high efficiency of PL emission.