This study aimed to develop and characterize bio-nanocomposite coatings by incorporating titanium nanoparticles (TiO
2 NPs) (30–50 nm) (10 mg/L), which have antimicrobial effects, and rosmarinic acid (RA) (0.005 mg/mL), which has strong antioxidant and antimicrobial activities, into the chitosan matrix using the
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This study aimed to develop and characterize bio-nanocomposite coatings by incorporating titanium nanoparticles (TiO
2 NPs) (30–50 nm) (10 mg/L), which have antimicrobial effects, and rosmarinic acid (RA) (0.005 mg/mL), which has strong antioxidant and antimicrobial activities, into the chitosan matrix using the solvent casting method. The prepared bio-nanocomposite coatings were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM-EDX), and atomic force microscopy (AFM). In the XRD analysis, the crystal structure of the bio-nanocomposite coating material was evaluated, but the absence of the expected TiO
2 NPs diffraction peak in the coating containing TiO
2 NPs was discussed in detail. The TiO
2 NPs decreased the crystallinity, compared to the control film, while rosmarinic acid increased the order of the molecular matrix. FT-IR analysis showed the presences of O–H, C=O, and C–O bonds in the coating materials, and the changes in the positions and intensities of the bands observed in the FTIR spectra of the bio-nanocomposite coatings (CHT and CHTRA) proved that TiO
2 NPs and RA were successfully integrated into the chitosan matrix. The broadening and flattening of the bands belonging to OH groups (3288–3356 cm
−1) indicated that the hydrogen bonds in the chitosan matrix were strengthened during the formation of the bio-nanocomposite structure. The bands representing the C=O stretching vibrations at 1659 cm
−1 (amide I) and the N–H bending vibrations at 1558 cm
−1 (amide II) indicated protein-based features in the structure of chitosan and confirmed the existence of the bio-nanocomposite structure. The SEM-EDX analysis showed that TiO
2 NPs were distributed homogeneously on the chitosan surface, but there was aggregation in places. The AFM images revealed that when TiO
2 NPs and RA were added to the chitosan matrix, the surface topography became more homogeneous, and a topographic pattern was formed in the range of 0–20.4 nm. Therefore, it is concluded that these bio-nanocomposite coatings can be used in antimicrobial surfaces and food packaging areas and should be optimized with different antioxidant and nanoparticle combinations in the future.
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