Biogenic Synthesis and Characterization of Chitosan-CuO Nanocomposite and Evaluation of Antibacterial Activity against Gram-Positive and -Negative Bacteria

Abstract

Chitosan-copper oxide (CHT-CuO) nanocomposite was synthesized using olive leaf extract (OLE) as reducing agent and CuSO4⋅5H2O as precursor. CHT-CuO nanocomposite was prepared using an in situ method in which OLE was added to a solution of chitosan and CuSO4⋅5H2O mixture in the ratio of 1:5 (v/v) and heated at a temperature of 90 °C. The obtained CHT-CuO nanocomposite was characterized using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectrophotometry, energy-dispersive X-ray spectroscopy (EDAX), Fourier transform infrared spectroscopy (FTIR), and high-resolution transmission electron microscopy (TEM). TEM results indicated that CHT-CuO nanocomposite are spherical in shape with size ranging from 3.5 to 6.0 nm. Antibacterial activity of the synthesized nanocomposites was evaluated against Gram-positive (Bacillus cereus, Staphyloccous haemolytica and Micrococcus Luteus) and Gram-negative (Escherichia coli, Pseudomonas citronellolis, Pseudomonas aeruginosa, kliebisella sp., Bradyrhizobium japonicum and Ralstonia pickettii) species by cup platting or disc diffusion method. Overall, against all tested bacterial strains, the diameters of the inhibition zone of the three nanocomposites fell between 6 and 24 mm, and the order of the antimicrobial activity was as follows: CuO-1.0 > CuO-0.5 > CuO-2.0. The reference antibiotic amoxicillin and ciprofloxacin showed greater activity based on the diameter of zones of inhibition (between 15–32 mm) except for S. heamolytica and P. citronellolis bacteria strains. The nanocomposites MIC/MBC were between 0.1 and 0.01% against all tested bacteria, except S. heamolityca (>0.1%). Based on MIC/MBC values, CuO-0.5 and CuO-1.0 were more active than CuO-2.0, in line with the observations from the disc diffusion experiment. The findings indicate that these nanocomposites are efficacious against bacteria; however, Gram-positive bacteria were less susceptible. The synthesized CHT-CuO nanocomposite shows promising antimicrobial activities and could be utilized as an antibacterial agent in packaging and medical applications.

Corrosion Inhibition Evaluation of Chitosan–CuO Nanocomposite for Carbon Steel in 5% HCl Solution and Effect of KI Addition

“…The mixture was heated on a magnetic hot plate to a constant temperature of 90 • C for 96 h while being constantly stirred. A gradual change in colour indicated the formation of chitosan-CuO nanocomposite, which was confirmed by UV-vis measurement [32].…”

“…Aqueous Olive leaf extract (OLE) was used as the reductant while CuSO 4 •5H 2 O served as the CuO nanoparticles precursor. Details of preparation and characterization of chitosan-CuO nanocomposite are documented in our earlier publication [32]. Briefly, chitosan with masses of 0.5, 1.0, and 2.0 g was weighed into a conical flask (250 mL capacity) and 100 mL distilled water containing 1 mL of acetic acid was added.…”

Comparative analysis of phyto-fabricated chitosan, copper oxide, and chitosan-based CuO nanoparticles: antibacterial potential against Acinetobacter baumannii isolates and anticancer activity against HepG2 cell lines

“…Similarly, Rashki et al (2022) reported the absorption peak for the chitosan nanoparticles to be around 300 nm. For the CH-CuO nanoparticles, Umoren et al (2022) characterized the CH-CuO nanocomposites and reported the spectral absorbance peak for the nanocomposite at around 285 nm, while Maheo et al (2022) reported the absorption peak for the green- synthesized CH-CuO nanoparticles at 278 nm.…”

PPy and CQDs‐doped novel CuO nanocomposites for enhanced antibacterial activity against drug‐resistant bacteria.**

“…Therefore, the nanoparticles of CuO has been combined with polymers or coated on the surface to enable the antibacterial applications. [24,25] Polypyrrole is an organic compound with antibacterial activity due to the strong electrostatic interaction between the positive charges in the polymer structure and the negatively charged bacterial cell wall/membrane. [26][27][28] Positive charges in a form of =NH + can disrupt the bacterial cell wall, interact with the bacterial cell membrane, break the balance of proton transfer, and inhibit cellular respiration, and ultimately lead to cell death.…”

“…Despite of the antimicrobial effect, nanoparticles of copper oxide have shown some deficiencies such as easy to aggregate, insufficient dispersibility and insolubility in water. Therefore, the nanoparticles of CuO has been combined with polymers or coated on the surface to enable the antibacterial applications [24,25] . Polypyrrole is an organic compound with antibacterial activity due to the strong electrostatic interaction between the positive charges in the polymer structure and the negatively charged bacterial cell wall/membrane [26–28] .…”