Effects of green-, yellow- and red-emitting CdTe QDs on the interaction between 7-hydroxyflavone/quercetin with human serum albumin in vitro

Abstract

In this study, 7-hydroxyflavone and quercetin were studied for their affinities for human serum albumin (HSA) in the presence and absence of quantum dots (QDs). Three typical CdTe QDs with maximum emissions of 535 nm (green-emitting, G-QDs), 598 nm (yellow-emitting, Y-QDs) and 654 nm (red-emitting, R-QDs) were tested. The fluorescence intensities of HSA decreased remarkably with addition of QDs. Quercetin resulted in obvious blue-shifts of the maximum λ em of HSA from 340.8 to 332.6 nm and 7-hydroxyflavone hardly changed the maximum λ em of HSA in the absence of QDs. The extents of shifts of the maximum λ em of HSA induced by 7-hydroxyflavone or quercetin in the presence of QDs were larger than that in the absence of QDs. When 8.00 µmol/L of 7-hydroxyflavone was added, the fluorescence decreased by 68.1%, 65.7% and 71.8% in the presence of G-QDs, R-QDs and Y-GDs, respectively, from the original G-QDs, R-QDs and Y-GDs that resulted in 42%, 43% and 55%, respectively. When 8.00 µmol/L of quercetin was tested, the fluorescence decreased by 72.4%, 69.5% and 75.6% in the presence of G-QDs, R-QDs and Y-GDs, respectively. G- and R-QDs hardly affected the affinities of 7-hydroxyflavone and quercetin for HSA. However, Y-QDs decreased the affinities of 7-hydroxyflavone and quercetin for HSA by about 13.61% and 6.8%, respectively.