Estudo químico-quântico de corantes catiônico e aniônicos para aplicação em terapia fotodinâmica / Quantum-chemical study of cationic and anionic dyes applied in photodynamic therapy / Estudo químico-quântico de corantes catiônico e aniônicos para aplicação em terapia fotodinâmica / Quantum-chemical study of cationic and anionic dyes applied in photodynamic therapy

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

06/04/2011

RESUMO

The present work studies the dyes Methylene Blue, Toluidine Blue, Eosin Y, Erytrosin B, Fluorescein and Rose Bengal using quantum-chemical calculations, aiming to propose an appropriate Density Functional Theory-based methodology and to understand the mechanisms of action of those dyes in photodynamic therapy. Structures in singlet and triplet states were optimized with B3LYP and mPW1PW91 (PW91) functionals and DGTZVP basis set. Solvation (etanol and aqueous solution) was simulated by IEFPCM model. Absorption spectra were calculated with TD-DFT (B3LYP and PW91) and ZINDO methods and emission spectra were simulated with TD-DFT (B3LYP) and MP2 methods. To study the formation of dimers, we have used the BLYP functional corrected to provide the dispersion energy with DCACP. There is no significant difference in geometry, total energy and dipole moment calculated with B3LYP or PW91 functionals. The semi-empirical method ZINDO, parametrized to reproduce absorption spectra, presented erros of 11% in dyes wavelength if compared to experimental data, while TD-DFT presented errors of 18%. The introduction of solvent effect improved TD-DFT absorption spectra in 4%. It was also found that electron transfer should occur easily than hydrogen atom transfer if mechanism type l of photodynamic therapy. Type ll mechanism was not verified because the calculation scheme does not apply to the studied molecules. The formation of dimers was confirmed in the presence of ethanol and aqueous solution.

ASSUNTO(S)

fotossensibilizador corantes dft dcacps terapia fotodinânica dyes photosensitizer dft dcacps photodynamic therapy quimica corantes fotossensibilizador dft dcacps terapia fotodinânica dyes photosensitizer dft dcacps photodynamic therapy

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