Biophysical study of CdTe quantum dots interactions with albumin and antibody as the base of photodynamic therapy.

Abstract

Photodynamic therapy is a relatively new type of cancer treatment, or eventually it is used at the elimination of undesirable pathogenic microorganisms. Quantum dots (QDs) are semiconducting nanocrystals with a size of 2-20 nm and can be used in photodynamic therapy. Two types of CdTe QDs were prepared by microwave synthesis (500 W), typical absorption spectra had maxima 'green = 554 nm, - yellow = 580 nm. The determined size of the generated nanoparticles ranged between 5 - 10 nm. CdTe QDs were further studied by fluorescence analysis at excitation wavelength - = 250 nm to obtain emission maxima (?em552) for green and (?em582) for yellow nanoparticles. Interaction study of CdTe QDs with bovine serum albumin (BSA) and with polyclonal chicken antibodies against sarcosine (AntiSar) was performed. BSA (100, 50, 25, 12.5, 6.3, 3.1, 1.6 and 0 'M) and AntiSar (20, 10, 5, 2.5, 1.3, 0.7, 0.3, and 0 g/L) were monitored with 1:1 addition of 50 'M QDsgreen or QDsyellow. The decrease in intensity of the normalized fluorescence signal in the presence of BSA or AntiSar was observed by 70-90%. The observed dependencies showed a linear trend (R2 = 0.9) with relative error of 9-12% calculated from 5 independent repetitions. In addition, it was possible to monitor the signal shift to shorter wavelengths at the highest applied BSA concentration by 4-16 nm. The obtained data suggest that the size of individual QDs will affect intensity of an interaction with biomolecule. Nanoconstructs should therefore be targeted according to these experimental data for their intended use. In further experiments, CdTe QDs modified with AntiSar will be used for targeted prostate cancer therapy using photodynamic effect