Photophysical properties of CdSe/ZnS quantum dot–porphyrin surface complexes in aqueous media

We have studied complexes between CdSe/ZnS quantum dots and metal-free porphyrin molecule in aqueous solution and in human blood plasma. We have established that in aqueous solution, transition of the porphyrin to a stable form occurs 2-5 h after formation of the complexes. We have observed that the porphyrin molecules react with the components of the blood plasma, which hinders direct formation of complexes between them and quantum dots in this medium. When previously prepared complexes between quantum dots and porphyrin molecules are added to the blood plasma, they partially dissociate. In aqueous solutions and in human blood plasma, we observe efficient intracomplex transfer of the photoexcitation energy from the quantum dots to the porphyrin molecules.