Optical properties of nanostructured antiviral and anticancer drugs

Abstract

We present a computational study on the optical absorption properties of some systems of interest in the field of drug delivery. In particular we considered as drug molecules favipiravir (T705, an antiviral molecule) and 5-fluorouracil (5FU, an anticancer molecule) and, on the other hand, pure fullerenes (C₂₄, B₁₂N₁₂, Ga₁₂N₁₂) and doped fullerenes (C₂₃B, CB₁₁N₁₂) are considered as nanocarriers. Some combined configurations between the drug molecules and the carrier nanostructures have been then studied. The optical absorption properties of the above mentioned drug molecules and their carrier nanostructures in the free and bound states are obtained by a TD-DFT method, in gas phase and in aqueous solution. We perform a detailed analysis of the modifications arising in the absorption spectra that take place in some linked configurations between the drug molecules and the carrier nanostructures. These changes could be of importance as an optical fingerprint of the realized drug/carrier link.

Fig. 1. Optimized geometry of the drug molecules (a) T705, (b) 5FU and of the carrier nanostructures (c) C₂₄, (d) B₁₂N₁₂, (e) C₂₃B, (f) CB₁₁N₁₂, (g) Ga₁₂N₁₂. Below we have reported the colors table (please consider that Boron and Gallium are of similar color).

Fig. 2. Optimized geometries of combined systems: (a–d) T705 with pure and doped C/BN carrier after ref. (e and f) 5FU with Ga₁₂N₁₂ as carrier after ref. , (g–j) 5FU with pure and doped C/BN carrier.

Fig. 3. Absorption spectra of the combined systems (a) C₂₄-T705, (b) B₁₂N₁₂-T705, (c) C₂₃B-T705, (d) CB₁₁N₁₂-T705 after ref. , compared to those of the free molecules (C/BN-carrier and T705). The spectra reported in solid line are calculated in gas phase while in dotted red line is shown the one of combined clusters in aqueous solution. The color bars in the (b–d) figures represent the visible region.

Fig. 4. Absorption spectra of the combined systems Ga₁₂N₁₂-5FU (a) with adsorption interaction and (b) with covalent bond after ref. , compared to those of the free molecules (Ga₁₂N₁₂ carrier and 5FU). The spectra reported in solid line are calculated in gas phase while in dotted red line is shown the one of combined clusters in aqueous solution. The color bars in the figures represent the visible region.

Fig. 5. Absorption spectra of the combined systems (a) C₂₄-5FU, (b) B₁₂N₁₂-5FU, (c) C₂₃B-5FU, (d) CB₁₁N₁₂-5FU after this work, compared to those of the free molecules (C/BN-carrier and 5FU). The spectra reported in solid line are calculated in gas phase while in dotted red line is shown the one of combined clusters in aqueous solution. The color bars in the (a–c) figures represent the visible region.

Fig. 6. Absorption spectra calculated with different exchange–correlation functional; comparison for (a) B₁₂N₁₂-5FU and (b) C₂₃B-5FU.