Blood proteins self-assembly, staphylococcal enterotoxins-interaction, antibacterial synergistic activities of biogenic carbon/FeSO4/Cu/CuO nanocomposites modified with three antibiotics

Abstract

Introduction: Nanocomposites based on copper, iron, and carbon materials are novel nanomaterials with both antibacterial and biocompatibility properties considerable to fight against multidrug-resistant bacteria.

Methods: In this study, phytogenic carbon/FeSO₄/Cu/CuO nanocomposites modified by three antibiotics including tetracycline, amoxicillin, and penicillin were employed to hinder antibiotic resistant bacteria of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Interaction of albumin and hemoglobin as major blood proteins with these nanocomposites were evaluated by SEM, FTIR, and AFM techniques. As in silico study, molecular docking properties of staphylococcal enterotoxin toxin A and B with (Z)-α-Bisabolene epoxide, (E)-Nerolidol, α-Cyperone, daphnauranol C, nootkatin, and nootkatone as major secondary metabolites of Daphne mucronata were obtained by AutoDock Vina program.

Results: Physicochemical characterization of nanocomposites showed (Zeta potential (- 5.09 mV), Z-average (460.2 d.nm), polydispersity index (0.293), and size range of 44.58 ± 6.78 nm). Results of both in vitro and in silico surveys disclosed significant antibacterial activity of antibiotic functionalized carbon/FeSO₄/Cu/CuO nanocomposites compared to antibiotics alone towards Gram-negative and Gram-positive bacteria.

Conclusion: Synergistic activity of bio-fabricated carbon/FeSO₄/Cu/CuO nanocomposites with antibiotics may be affected by main parameters of concentration and ratio of antibacterial agents, physicochemical properties of nanocomposites, bacterial type (Gram-negative or Gram-positive), antibacterial mechanisms, and chemical structure of antibiotics.

Keywords: Albumin; Antibacterial synergism; Antibiotic-functionalized nanocomposites; Hemoglobin; Self-assembly; carbon/FeSO4/Cu/CuO nanocomposites.

Fig. 1

3D structures of staphylococcal enterotoxin A (ID: 1ESF) with related seven cavities (a, b) and enterotoxin B (ID: 1GOZ) by related ten cavities (c, d). Spectra for UV–Vis at the periodicity of 20 min for CuNCs (e), XRD with related indices of CuNCs (f), and FTIR for CuNCs, CuNCs-Am, CuNCs-Pe, and CuNCs-Te (g)

Fig. 2

Size distribution (a), zeta potential distribution (b), and bright field TEM photographs in the scale bars of 40 nm (c) and 10 nm (d) for carbon/FeSO₄/Cu/CuO NCs green synthesized by D. mucronata

Fig. 3

Different IZDs for CuNPs (a), CuNPs/Am (b), CuNPs/Pe (c), and CuNPs/Te (d) toward E. coli, S. aureus, and P. aeruginosa. B MIC and C MBC present results of NCs. SEM images illustrate control group (D) and cell wall deformation and disruption of S. aureus under CuNCs/Te treatment (E)

Fig. 3

Different IZDs for CuNPs (a), CuNPs/Am (b), CuNPs/Pe (c), and CuNPs/Te (d) toward E. coli, S. aureus, and P. aeruginosa. B MIC and C MBC present results of NCs. SEM images illustrate control group (D) and cell wall deformation and disruption of S. aureus under CuNCs/Te treatment (E)

Fig. 4

SEM photographs illustrate control group (a; scale bar of 2 µm) and cell envelop deformation and disruption of E. coli under CuNCs/Te treatment (b; scale bar of 5 µm, c, d; scale bar of 10 µm). e Schematic image showing three main probable pathways for antibacterial activity of CuNCs/Te (I), CuNCs (II), and tetracycline (III) f antibacterial mechanisms of CuNCs/Te and CuNCs [61]

Fig. 5

Interaction of (Z)-α-Bisabolene epoxide (a), (E)-Nerolidol (b), α-Cyperone (c), daphnauranol C (d), nootkatin (e), and nootkatone (f) with amino acids of enterotoxin A. Interaction of (Z)-α-Bisabolene epoxide (g), (E)-Nerolidol (h), α-Cyperone (i), daphnauranol C (j), nootkatin (k), and nootkatone (l) with amino acids of enterotoxin B

Fig. 6

Docking of (Z)-α-Bisabolene epoxide (a), (E)-Nerolidol (b), α-Cyperone (c), daphnauranol C (d), nootkatin (e), and nootkatone (f) with enterotoxin A. Docking of (Z)-α-Bisabolene epoxide (g), (E)-Nerolidol (h), α-Cyperone (i), daphnauranol C (j), nootkatin (k), and nootkatone (l) in yellow color with enterotoxin B

Fig. 7

AFM results of CuNC/Te-A (a) and CuNCs/Te-H (b) with related roughness (nm) ± SD for each nanocomplex (c), and d FTIR spectra for CuNC/Te-A (blue line) and CuNC/Te-H (red line)

Fig. 8

SEM photographs for the interaction of albumin (a–c) and hemoglobin proteins (d–f) with CuNPs-Te NCs