Escherichia coli-based synthesis of cadmium sulfide nanoparticles, characterization, antimicrobial and cytotoxicity studies

Abstract

The present research describes the synthesis of cadmium sulfide (CdS) nanoparticles from Escherichia coli under the influence of bacterial enzyme sulphate reductase and study on their cytotoxicity for applications in cancer therapy. Escherichia coli cells were used to synthesize CdS nanoparticles under different concentrations of cadmium chloride and sodium sulfide. The morphology of the nanoparticles was analysed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) was used for elemental analysis of nanoparticles. Fourier-transform infrared spectroscopy analysis (FTIR) was performed to assess the functional groups of the nanoparticles. Crystalline nature of nanoparticles was assessed using powder X-ray diffraction (XRD). Antibacterial studies of CdS nanoparticles were carried out on foodborne pathogens and cytotoxicity studies were carried out on Mus musculus skin melanoma (B16F10) and human epidermoid carcinoma (A431) cell lines. CdS nanoparticle showed more cytotoxic effect on cancer cells compared with standard 5-aminolevulinic acid (5-ALA). The Escherichia coli-synthesized CdS nanoparticles showed highest zone of inhibition in the ratio 4:1 of cadmium chloride and sodium sulfide on all tested bacterial strains. The nanoparticles were also tested for haemolytic activity on RBC cells, which exhibited lower cytotoxicity than sodium dodecyl sulphate which was used as positive control. The cytotoxicity of CdS nanoparticles assessed on A431 cells showed an inhibition of 81.53% at 100 μM concentration while the cytotoxicity assessed on B16F10 cells showed an inhibition of 75.71% at 200 μM concentration which was much efficient than 5-ALA which showed an inhibition of 31.95% at a concentration against B16F10 cells and 33.45% against A431 cells at a concentration of 1 mM. Cadmium sulfide nanoparticles were thus found to be highly toxic on cancer cells compare with standard anticancerous drug 5-ALA.

Keywords: 5-Aminolevulinic acid; Antimicrobial activity; Cadmium sulfide nanoparticles; Cytotoxicity.

Fig. 1

SEM image of CdS nanoparticles synthesized using different ratios of cadmium chloride and sodium sulfide (a 1:1, b 2:1, c 3:1, d 4:1)

Fig. 2

Antibacterial activity of Escherichia coli-synthesized CdS nanoparticles against 1(a) Pseudomonas aeruginosa, 1(b) Bacillus licheniformis, 1(c) Bacillus cereus, 1(d) Escherichia coli and 1(e) Staphylococcus aureus; Antibacterial activity of standard antibiotics against food borne pathogens. 2(a) Pseudomonas aeruginosa, 2(b) Bacillus licheniformis, 2(c) Bacillus cereus, 2(d) Escherichia coli and 2(e) Staphylococcus aureus

Fig. 3

Antifungal activity of Escherichia coli-synthesized CdS nanoparticles against 1(a) Fusarium oxysporum, 1(b) Aspergillus flavus and 1(c) Penicillum expansum; Antifungal activity of standard fluconazole against 2(a) Fusarium oxysporum, 2(b) Aspergillus flavus and 2(c) Penecillium expansum

Fig. 4

Haemolytic activity of CdS nanoparticles synthesized from Escherichia coli (CDEC) and Bacillus licheniformis (CDBL)

Fig. 5

a Percentage inhibition of B16F10 cells from CdS nanoparticles. b Cytotoxicity of positive control (5-ALA) against B16F10 cells. c Percentage inhibition of A431 cells from CdS nanoparticles. d Cytotoxicity of positive control (5-ALA) against A431 cells