title: Enhanced preferential cytotoxicity through surface modification: synthesis, characterization and comparative in vitro evaluation of TritonX-100 modified and unmodified zinc oxide nanoparticles in human breast cancer cell (MDA-MB-231).
abstract: BACKGROUND
  Nanoparticles (NPs) are receiving increasing interest in biomedical research owing to their comparable size with biomolecules, novel properties and easy surface engineering for targeted therapy, drug delivery and selective treatment making them a better substituent against traditional therapeutic agents. ZnO NPs, despite other applications, also show selective anticancer property which makes it good option over other metal oxide NPs. ZnO NPs were synthesized by chemical precipitation technique, and then surface modified using Triton X-100. Comparative study of cytotoxicity of these modified and unmodified NPs on breast cancer cell line (MDA-MB-231) and normal cell line (NIH 3T3) were carried out.
  
  
  RESULTS
  ZnO NPsof average size 18.67 ± 2.2 nm and Triton-X modified ZnO NPs of size 13.45 ± 1.42 nm were synthesized and successful characterization of synthesized NPs was done by Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction (XRD), transmission electron microscopy (TEM) analysis. Surface modification of NPs was proved by FT-IR analysis whereas structure and size by XRD analysis. Morphological analysis was done by TEM. Cell viability assay showed concentration dependent cytotoxicity of ZnO NPs in breast cancer cell line (MDA-MB-231) whereas no positive correlation was found between cytotoxicity and increasing concentration of stress in normal cell line (NIH 3T3) within given concentration range. Half maximum effective concentration (EC50) value for ZnO NPs was found to be 38.44 µg/ml and that of modified ZnO NPs to be 55.24 µg/ml for MDA-MB-231. Crystal violet (CV) staining image showed reduction in number of viable cells in NPs treated cell lines further supporting this result. DNA fragmentation assay showed fragmented bands indicating that the mechanism of cytotoxicity is through apoptosis.
  
  
  CONCLUSIONS
  Although use of surfactant decreases particle size, toxicity of modified ZnO NPs were still less than unmodified NPs on MDA-MB-231 contributed by biocompatible surface coating. Both samples show significantly less toxicity towards NIH 3T3 in concentration independent manner. But use of Triton-X, a biocompatible polymer, enhances this preferentiality effect. Since therapeutic significance should be analyzed through its comparative effect on both normal and cancer cells, possible application of biocompatible polymer modified nanoparticles as therapeutic agent holds better promise.Graphical abstractSurface coating, characterization and comparative in vitro cytotoxicity study on MDA-MB 231 and NIH 3T3 of ZnO NPs showing enhanced preferentiality by biocompatible surface modification.
authors.affiliation: Department of Biotechnology, School of Science, Kathmandu University, Dhulikhel, Nepal.
authors.forename: Biplab
authors.initials: B
authors.lastname: Kc
authors.affiliation: Department of Biotechnology, School of Science, Kathmandu University, Dhulikhel, Nepal.
authors.forename: Siddhi Nath
authors.initials: SN
authors.lastname: Paudel
authors.affiliation: Department of Biotechnology, School of Science, Kathmandu University, Dhulikhel, Nepal.
authors.forename: Sagar
authors.initials: S
authors.lastname: Rayamajhi
authors.affiliation: Department of Biotechnology, School of Science, Kathmandu University, Dhulikhel, Nepal.
authors.forename: Deepak
authors.initials: D
authors.lastname: Karna
authors.affiliation: Department of Biotechnology, School of Science, Kathmandu University, Dhulikhel, Nepal.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Adhikari
authors.affiliation: Department of Biotechnology, School of Science, Kathmandu University, Dhulikhel, Nepal.
authors.forename: Bhupal G
authors.initials: BG
authors.lastname: Shrestha
authors.affiliation: Department of Chemical Science and Engineering, School of Engineering, Kathmandu University, Dhulikhel, Nepal.
authors.forename: Gunjan
authors.initials: G
authors.lastname: Bisht
keywords: Cytotoxicity; Surface modification; Triton X; ZnO nanoparticles