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

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.

Photodynamic therapy on skin melanoma and epidermoid carcinoma cells using conjugated 5-aminolevulinic acid with microbial synthesised silver nanoparticles.

The present research work describes the use of photodynamic therapy (PDT) of drug 5-aminolevulinic acid (5-ALA) conjugated with microbial synthesised silver nanoparticles on skin melanoma (B16F10) and epidermoid carcinoma (A431) cell lines. Silver nanoparticles were synthesised using the bacterial strain Bacillus licheniformis. The morphology of the nanoparticles was studied using scanning electron microscopy (SEM) and elemental analysis of nanoparticles was carried out using energy dispersive X-ray spectroscopy (EDX). Fourier-transform infrared spectroscopy (FTIR) analysis was performed to assess the functional groups of the nanoparticles. Crystalline nature of nanoparticles was assessed using powder X-ray diffraction (XRD).The cytotoxicity of pure nanoparticles and conjugated nanoparticles with 5-ALA using polyethylene glycol (PEG) was assessed on B16F10 and A431 cell lines and also compared with standard 5-ALA. Production of ROS molecules was measured using a 2,7-dichlorofluorescein-diacetate (DCFH-DA) probe. The results showed that the 5-ALA-silver nanoparticles conjugate had higher cytotoxicity on both the cell lines than the pure ALA and silver nanoparticles. Antimicrobial activity of silver nanoparticles was also carried out on food borne pathogens and nanoparticles showed comparable antimicrobial activity with standard antibiotics.