Toxic effects of gold nanoparticles on Salmonella typhimurium bacteria

Abstract

Nanometer-sized gold, due to its beautiful and bountiful color and unique optical properties, is a versatile material for many industrial and societal applications. We have studied the effect of gold nanoparticles on Salmonella typhimurium strain TA 102. The gold nanoparticles in solution prepared using the citrate reduction method is found not to be toxic or mutagenic but photomutagenic to the bacteria; however, careful control experiments indicate that the photomutagenicity is due to the co-existing citrate and Au3+ ions, not due to the gold nanoparticle itself. Au3+ is also found to be photomutagenic to the bacteria at concentrations lower than 1 µM, but toxic at higher concentrations. The toxicity of Au3+ is enhanced by light irradiation. The photomutagenicity of both citrate and Au3+ is likely due to the formation of free radicals, as a result of light-induced citrate decarboxylation or Au3+ oxidation of co-existing molecules. Both processes can generate free radicals that may cause DNA damage and mutation. Studies of the interaction of gold nanoparticles with the bacteria indicate that gold nanoparticles can be absorbed onto the bacteria surface but not able to penetrate the bacteria wall to enter the bacteria.

Impact of nanosilver on various DNA lesions and HPRT gene mutations – effects of charge and surface coating

“…In our study, we found a strong mutagenic effect of sodium citrate at a concentration 0.002 % w/v and of Tween 80 at a concentration of 0.008 % w/v. Similar findings were already reported by Wang et al , who have shown that photo-mutagenic effects of gold ENMs are related not only to ENMs but also to citrate ions used as a stabilizer [ 40 ]. Our results have an implication for the ‘safety by design’ approach, indicating that stabilizers with mutagenic potency should not be used in ENM synthesis.…”

Evaluation of Anti biofilm and Antibiotic Synergistic Activities of Silver Nano particles Against Some Common Bacterial Pathogens

“…14 To confirm the latter idea, Wang et al found that gold nanospheres can attach to the membrane of Salmonella typhimurium, but unable to be digested by the bacteria. 15 AgNPs with a concentration range of 1.6-6.25 ug/mL exhibited more than 90% inhibitory effects on biofilm formation of the examined species (Table 1). Generally, the inhibition of the biofilm formation relates to the inhibition of bacterial growth.…”

Alternative Antimicrobial Approach: Nano-Antimicrobial Materials

“…A burst of ROS causes, via severe oxidative stress, damage to all the cell's macromolecules, leading to lipid peroxidation, alteration of proteins, inhibition of enzymes, and RNA and DNA damage. At high concentrations the ROS lead to cell death and at low doses cause severe DNA damage and mutations [ 17 , 18 ]. In some cases, where the production of ROS is induced by visible or UV light [ 19 ] the toxicity of NM is photocatalytic.…”