The surface of titanium dioxide (TiO₂) nanoparticles was treated with a silane coupling agent of γ-aminopropyl-triethoxy silane. An optically active poly(amide-imide) (PAI) was synthesized by the indirect polycondensation reaction of the L-phenylalanine based diacid chloride and 4,4′-diaminodiphenylether in the presence of triethylamine in N-methyl-2-pyrrolidone. Then PAI and surface modified TiO₂ nanoparticles were used to produce a polymer based bionanocomposites (BNCs) via ultrasonic irradiation process. The obtained BNCs were characterized by means of X-ray diffraction, electron microscopy and thermogravimetric analysis techniques. The results showed that the nanoparticles are homogeneously dispersed in PAI matrix with particle size ranging from 30 to 50 nm.