Interaction mode of polycarbazole–titanium dioxide nanocomposite with DNA: Molecular docking simulation and in-vitro antimicrobial study

• Polycarbazole–titanium dioxide nanocomposite was synthesized.
• DNA binding study of PCz/TiO2 has been performed.
• In-vitro antimicrobial of PCz and PCz/TiO2 were carried out.
• SEM and TEM results show that PCz has polymerized on the surface of the TiO2.

A polycarbazole–titanium dioxide (PCz/TiO2-8) nanocomposite was synthesized for the first time by in-situ oxidative polymerization with APS as an oxidizing agent in the presence of TiO2 nanoparticles which was characterized by SEM, TEM, FT-IR, DTA and TGA techniques. The SEM and TEM results showed that PCz has polymerized on the surface of the TiO2. The results confirmed the incorporation of TiO2 in PCz indicating the formation of nanocomposite due to strong interaction between TiO2 and PCz matrix affecting the properties as compared to pristine PCz. The PCz/TiO2-8 nanocomposite was tested for antimicrobial activity and found to exhibit activity against gram negative and gram positive strains at micromolar concentrations. The four types of 3D molecular field descriptors or field points as extrema of electrostatic, steric, and hydrophobic fields were explained. These field points were used to define the properties necessary for a molecule to bind in a characteristic way into a specified active site. A molecular docking simulation was used to predict the modes of interactions of the drugs (PCz and PCz/TiO2-8) with DNA. The molecular docking conclusion indicated that the modes of interactions between two (PCz and PCz/TiO2-8) and DNA helix can be regarded as minor groove binder. The K value (3.55 × 104 M− 1 and 2.13 × 105 M− 1) obtained from fluorescence data are indicative of binding of PCz and PCz/TiO2-8 with DNA helix.

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