Deliberately inorganic nanoparticles (NP)s in polymer matrices significantly affect their characteristics and therefore their applications, but key factor to achieve the expected efficiency is well dispersion of the NPs in polymer matrix. The work presented here deals with the polymerization of amino acid-based monomer to synthesize optically active poly(ester-imide) (PEI) with hydroxyl terminated groups, using tosyl chloride/pyridine/N,N-dimethylformamide system as a condensing agent. The synthesized polymer was used for the preparation of bionanocomposite (BNC) containing modified titanium dioxide (TiO2) NPs using ultrasonic irradiation. With the aim of γ-amidopropyl-triethoxylsilicane as a coupling agent, the surface of nanoscale TiO2 was modified to decrease aggregation of the NPs in polymer matrix. The obtained PEI/TiO2 BNCs were characterized with fourier transfer infrared (FT–IR), thermogravimetric analysis, field emission scanning electron microscopy (FE–SEM), X-ray diffraction and transmission electron microscopy (TEM) techniques. Morphology study of resulting PEI/TiO2 BNCs by FE–SEM and TEM analyses demonstrated that the hydroxyl-terminated polymer chains reduced aggregation of the NPs and thus lead to better dispersion of the NPs in the polymer matrix.