Quantum Dots Coupled Body Diagnosis And Treatment Of Tumor Cells

The bovine serum albumin (BSA) coated CdSe/ZnS quantum dots (BSA-QDs) were selected to conjugate with folic acid (FA) forming FA-BSA-QDs. This study aims to develop these small size FA-BSA-QDs (< 10 nm) for the diagnosis of cancers in which the FA receptor (FR) is overexpressed. The enhancement of cellular uptake in FR positive human nasopharyngeal carcinoma cells (KB cells) for FA-BSA-QDs was found by means of confocal fluorescence microscopy with single-photon and two-photon excitations. The enhancement for FA-BSA-QDs was further evaluated as about 3 times higher averagely as compared to BSA-QDs, measured by flow cytometric analysis in 104 KB cells. Such uptake enhancement for FA-BSA-QDs was suppressed when KB cells had been pretreated with excess FA, reflecting that the enhancement was mediated by the association of FR in cell membranes with FA-BSA-QDs. When human embryonic kidney cells (293T) (FR negative cells) and KB cells were incubated with FA-BSA-QDs (1μM) for 40 minutes, respectively, the FA-BSA-QD uptake of 293T cells was much weak as compared with that of KB cells, demonstrating that FA-BSA-QDs can take a preferential binding on FR positive cancer cells. These characteristics suggest that FA-BSA-QDs are potential candidates for cancer diagnosis, and worth investigating further.Dopamine(DA) is an electron donor which can generate single oxygen('02) when oxidated by quantum dots(QDs) that are capable of destructing cancer cells. This mechanism has been proposed as a method for photodynamical therapy of cancer. This research aims to develop new phototoxic drugs CdTe-DA for the destruction of cancer cells.DA conjugation quenched the the fluorescence of the QDs and the new oxidized-dopamine peak on QDs indicates the electron transfer. The new peak became significantly stronger when exposed to ultraviolet or blue irradiation, which proves that the ilumination could make the oxidation more efficiently. The cytotoxicity of QDs measured by MTT assay showed that the damaging effect of irradiated CdTe-DA was much stronger, demonstrating that the creation of single oxygen during the oxidation of DA in the presence of irradiation. These characteristics suggest that CdTe-DA potential candidates for cancer therapy, and worth investigating further.