In-situ polymerization of polycarbazole-zinc oxide nanocomposite: An in silico docking model and in vitro antibacterial biomaterial

Abstract

The current study focuses on the synthesis of polycarbazole-zinc oxide (PCz/ZnO) nanocomposite and its application as an in vitro antibacterial biomaterial as well as an in silico docking model. The synthesized pristine polymer, polycarbazole (PCz) and its nanocomposite PCz/ZnO were characterized by Fourier transform infrared (FT-IR), Thermo-gravimetry/Differential Thermo-gravimetry (TG-DTG), X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Brunauer-Emmett-Teller (BET), Energy-dispersive X-ray (EDX), Raman and X-ray photoelectron spectroscopic (XPS) techniques. FT-IR, XRD, FE-SEM, and XPS studies revealed that the polymerization of Cz has been successfully achieved on the surfaces of ZnO nanoparticles, indicating the strong interfacial interaction between PCz and ZnO nanoparticles. However, TG-DTG studies revealed that the nanocomposite, PCz/ZnO, proved thermally more stable compared to the pristine polymer, PCz. Further, the pristine PCz and PCz/ZnO nanocomposite were evaluated for antibacterial activity against Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus. The nanocomposite PCz/ZnO showed the highest zone of inhibition against K. Pneumoniae (17 mm), followed by P. aeruginosa (16 mm), then S. aureus (14 mm) and E. coli (19 mm) at 80 mg ml−1. Significantly, the in silico molecular docking predicts the modes of interactions of PCz and PCz/ZnO with B-DNA. Briefly, the results obtained from in silico molecular docking studies of the pristine PCz and PCz/ZnO nanocomposite with negative free binding energies (-7.1 kcal mol−1 of PCz and −6.23 kcal mol−1 of PCz/ZnO) imply an excellent and favourable binding affinity vis-à-vis interaction modes of both pristine PCz and PCz/ZnO nanocomposite (drugs) with B-DNA bases (target).