Cytotoxicity of nanoparticles - Are the size and shape only matters? or the media parameters too?: a study on band engineered ZnS nanoparticles and calculations based on equivolume stress model

Abstract

Size dependent cytotoxicity of ZnS nanoparticles (NPs) was investigated in Human embryonic kidney (HEK-293) cell lines by MTT assay. The cells were incubated with varying concentration of ZnS NPs of sizes 4 nm, 10 nm and 25 nm for 48 h under different (cell culture) media viscosity conditions. The results showed that the toxicity is decreased with the particle size while it is negatively correlated with the viscosity of the media. Theoretical calculations were performed, by assuming equivolume stress model and the same is explained with schematics. Similarly, the effect of particle size and shape on toxicity is explained based on the theoretical calculation of the stress. The calculations showed that out of the possible cellular entry mechanisms for the cubic or cage shaped NPs, the highest toxicity is predicted for the entry through the corners while the lowest toxicity is predicted for the entry through the faces. The experimental observations depicting the cytotoxicity as a function of the viscosity of cell culture media was also validated by stress calculations and are found to be consistent. Studies on size and shape dependence of semiconductor NPs like ZnS is rather scarce, while the role of viscosity of cell culture media on the cytotoxicity is being reported for the first time. In summary, the study indicates that the cytotoxicity is an integral function of size and shape of NPs, physical parameters of the cell culture media in addition to the post entry biochemical interactions with the host cell.

Keywords:

• Nanoparticles
• co-precipitation method
• optical characteristics
• MTT assay

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Rajendra P. and Swapna S. Nair, Central University of Kerala, India acknowledges for the establishments and facilities and DBT India for the funding (6242-P52/RGCB/PMD/DBT/RPKT/2015). Rajendra P. also acknowledges DST-SERB India (DST No: SB/YS/LS-366/2013) and University Grants Commission (UGC, India) for the funding (UGC BSR Start-up F.20-1/2013) and Department of Science and Technology (DST, Govt. of India, Fast Track–YSS/2014/000436) and Department of Biotechnology, Govt. of India. Manikanta B. acknowledges E-Grantz provided by Kerala Government for the fellowship. Prajit J. acknowledges CSIR Ref No: [09/1108(0005)/2015-EMR-I] for JRF and SRF fellowship. Neeli Chandran acknowledges Kerala State Council for Science and Technology and Environment (Ref No: 077/FSHP-PSS/2015/KSCSTE) for the research fellowship. Ranjeet D. acknowledges Rajiv Gandhi National Fellowship (RGNF) (Ref No: RGNF-2012-13-ST-ORI-30084) for research fellowship. Unnikrishnan U. acknowledges CSIR Grant (Controlling Fibrosisin Systematic Sclerosis), National Medical Research Council, Singapore.