Resveratrone: caracterização óptica e aplicação como marcador fluorescente em biomateriais

Abstract

Resveratrone is a new fluorescent compound formed by the UV irradiation of trans- Resveratrol. Its large absorption cross-section has already been determined, making it suitable for fluorescent labeling in bioimaging. In this work, we studied the nonlinear optical properties of Resveratrone and demonstrated its application in labeling cellulose acetate nanofibers. These fibers are used as scaffolds in tissue engineering, where two-photon microscopy visualization is advantageous due to better three-dimensional resolution and less photodamage to the sample. The aim of the work is to determine the optical properties of the compound, visualize the arrangement of the fibers and measure the penetration depth of cells cultured in the scaffold. The optical characterization was performed by absorption measurements of Resveratrone and Resveratrol in three different solvents (methanol, isopropanol, and ethanol) at different concentrations. From these results, the molecular absorption coefficient for both compounds was calculated; the value found for Resveratrol was close to the ones in the literature, and that of Resveratrone showed discrepancies due to the possibility of generating other photoproducts during UV irradiation. Fluorescence emission spectra by two-photon excitation were also obtained using a pulsed Ti-Sapphire laser, with excitation wavelengths in the range of 720-920 nm, for each of the three Resveratrone solutions. The obtained photoluminescence excitation curve showed a wide efficient excitation range. A Stokes shift of about 1 eV was also determined for the compound. Finally, we demonstrated the labeling process where Resveratrone is produced directly in the nanofibers, followed by cell culture. Two-photon excitation fluorescence images showed detailed arrangements of cells and nanofibers in samples stained with Resveratrol in methanol; in samples stained with other solvents, cell culture showed inconsistencies.