Hybrid MPA-CdSe quantum dots-based luminescent hydrogel: White light emission regulation and Cu2+ recognition

In this study, a novel CdSe@PEI-PVP luminescent hydrogel was constructed by using MPA-CdSe quantum dots (QDs) as a single emitter and hydrogen bond cross-linking network between highly branched polyethyleneimine (PEI) and polyvinylpyrrolidone (PVP) as a hydrogel skeleton, in which PEI also works as a passivation ligand for MPA-CdSe quantum dots. Utilizing the dual emission of MPA-CdSe quantum dots and adjusting the surface state of MPA-CdSe with PEI and Cd2+, CdSe@PEI-PVP hydrogel can emit bright white light as a whole. Furthermore, CdSe@PEI-PVP shows specific recognition for Cu2+, luminescent color changes from bright white to orange when Cu2+ is added, which enables CdSe@PEI-PVP hydrogel to serve as a fluorescent probe for ion detection. The luminescent hydrogel has great self-healing ability and reversible morphological thermal responsiveness, existing as a white luminescent hydrogel at room temperatures and transforming into a pale green luminescent solution at high temperatures.