Poly(4-vinylpyridine) Coated CdTe Core/Shell Quantum Dots

A kind of novel quantum dots (QDs) with poly(4-vinylpyridine) (PVPy) as shell and CdTe QDs as core was presented in this work. This core/shell ODs can conjugate DNA easily because the surface pyridyl exist on QDs, and which has potential application in DNA biosensors field. CdTe QDs were prepared in aqueous solution with 3-mercaptopropionic acid (MPA) as stabilizer. It was found that the fluorescent intensity of QDs was depended the reflux time. Following the increase of reflux time, the fluorescent intensity of QDs reached the maximum at 10 h with about 10 nm in diameters. And the fluorescent intensity of QDs was also increased. When the reflux time was 10 h, the diameter of QDs would increase to about 10 nm. After adjusted the pH of QDs solution system to 7.0, the MPA stabled QDs were purified by ultracentrifugation and freeze-drying respectively. The polymerization was performed in water when 4-vinylpyridine (VPy) used as monomer, N,N’-methylene-bisacrylamide (MBAAm) as crosslinker, potassium persulphate (PPS) as initiator and MPA stabled QDs as seeds. The surface carboxyl of MPA on QDs could promote the form of PVPy coated CdTe QDs. It was shown that the fluorescent intension of core/shell QDs was decreased following the polymerization and the diameter of QDs could increase to 20-30 nm.