Nitrogen-doped thin titanium dioxide films formed by the reactive magnetron sputtering method on the surface of PLLA electrospun microfibers scaffold were investigated. It was shown that the chemical composition of the films is shifting from titanium dioxide (TiO₂) composites saturated with C–NH, C=N, N–C=N and HN–C=O compounds to solid solutions of titanium oxides (Ti_xO_y) and titanium oxynitrides (TiO_xN_y) with the increased time of the treatment. An empirical model describing changes in the chemical composition of the surface due to the treatment was proposed. It was shown that the modification of the PLLA microfibers scaffolds surface improves cell-scaffold and cell–cell interactions with the highest number of viable adherent cells observed on the scaffold treated for 4 min.