Construction of β-cyclodextrin derived CDs-coupled block copolymer micelles loaded with CdSe/ZnS QDs via host-guest interaction for ratiometric fluorescence sensing of metal ions

The nanostructured hybrid assembly has gained growing interest due to their unique electronic, optical and catalytic properties . Herein, a novel ratiometric fluorescent sensor was constructed by coupling blue-green emission carbon dots (CDs) to a block copolymer micelle-encapsulated red-emission CdSe/ZnS QDs through host-guest interaction. The carbon dots (CDs) were prepared by carbonization of β-cyclodextrin (β-CD) via a simple hydrothermal process. The amphiphilic diblock copolymer AZO-PNIPAM-b-P(St-co-MQ) containing azobenzene (AZO)-terminated hydrophilic poly( N -isopropylacrylamide) (PNIPAM) block and hydrophobic polystyrene (PS) block was synthesized by a typical RAFT polymerization . The 5-(2-methacryloylethyloxymethyl)-8- quinolinol (MQ) units were introduced into PS block, which could make CdSe/ZnS QDs to be embedded into the core of the block polymer micelles via coordination interaction in the self-assembling process. The as-fabricated β-cyclodextrin derived CDs-coupled block copolymer hybrid micelles loaded with CdSe/ZnS QDs as a fluorescence sensor exhibited dual emission peaks of CDs centered at 450 nm and CdSe/ZnS QDs at 620 nm with a large peak separation of 170 nm upon excitation at 360 nm. And the as-prepared hybrid micelles as a ratiometric fluorescence sensor can be applied to detect Hg 2+ and Cu 2+ with the detection limits down to 1.6 and 2.74 μM, respectively.