Contents lists available at ScienceDirect Colloids and Surfaces B: Biointerfaces journal homepage: www.elsevier.com/locate/colsurfb Evaluation of biological response induced by molybdenum oxide nanocolloids on in vitro cultured NIH/3T3 fibroblast cells by micro-Raman spectroscopy Enza Fazio a, ⁎ , Antonio Speciale b, ⁎⁎ , Salvatore Spadaro a , Martina Bonsignore a , Francesco Cimino b , Mariateresa Cristani b , Domenico Trombetta b , Antonella Saija b , Fortunato Neri a a Department of Mathematical and Computational Sciences, Physical Science and Earth Science, University of Messina, Italy b Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Italy ARTICLE INFO Keywords: Molybdenum oxide colloids Pulsed laser ablation Micro-Raman scattering Fibroblast cells Biocompatibility Antioxidants ABSTRACT Tailored colloids of uniformly sized and engineered molybdenum oxide nanoparticles were produced, for the first time, by pulsed laser ablation in water. This green technique ensures the formation of contaminant-free na- nostructures and the absence of by-products, very useful issues in biological applications. A selective tuning of MoeO chemical bonding configurations and a suitable control of nanoparticles size distributions were achieved during the ablation processes by varying the water temperature and by applying an external electric field. The metal redox properties are fundamental factors governing both cell uptake and interaction mode with Mo oxide nanoparticles. Micro-Raman spectroscopy was used to investigate the existence of cellular changes induced by Mo oxide colloids on the fibroblast cell line NIH/3T3 in relation to the molecular vibrations due to proteins, lipids and nucleic acids. The label-free micro-Raman spectroscopy provides an easy and noninvasive method to monitor the harmful effect of toxic agents on cells through ROS production or redox-dependent mechanisms. In view of potential biological applications, molybdenum oxide nanoparticles cytotoxicity towards NIH/3T3 cells was also investigated. A statistical analysis shows that, in the 10–100 μg/mL Mo concentration range, all the colloids are cytotoxic, progressively reducing the cell viability down to 75% upon increasing the concentration. The effect is less pronounced for the oxygen deficient MoO 3 samples where cell viability does not fall below 85%. These results open the way to identify potential bioactive products affecting cellular redox status, by using only the Raman spectral data, even before performing lengthy and expensive specific clinical analyses. 1. Introduction Metal oxide nanostructures can act as nanoprobes for biomedical imaging, drug delivery carriers or as therapeutic agents by themselves. Moreover, they have shown to be excellent antioxidants in vitro and in vivo models, even if their toxicity emerges in some conditions. This is determined by the chemical nature of the metal oxide nanostructures, able to switch between different oxidation states, the surface-to-volume ratio and by the testing conditions (i.e. the experimental environment or the cell lines). Among the investigated metal oxide nanomaterials, molybdenum oxide nanostructures have become an attractive material as potential bioactive products. Recent studies show that Mo oxide nanostructures are effective against cytotoxicity and oxidative stress induced by H 2 O 2 in human breast MCF-7 and fibrosarcoma HT-1080 cells [1]. On the other hand, Mo oxide nanoparticles (NPs) exhibit ex- cellent antimicrobial activity against Candida albicans and Aspergillus niger and potent cytotoxicity against lung and breast cancer cells (MCF- 7 and HEP G2 cell lines) [2]. Moreover, it is known that Mo is in- corporated into the pterin-derived cofactor MoCo required for the cat- alytic functions of several redox enzymes present in many types of cells, including human cells [3]. In biological systems, as part of redox en- zymes activity, Mo acts by shuttling itself between three different oxi- dation states and it results a key factor in the reduction of chemicals at the surfaces of Mo based sulfides or oxides NPs. Despite these unique properties, which make its use very attractive, Mo oxide nanostructures are reactive or catalytic, and thus potentially https://doi.org/10.1016/j.colsurfb.2018.06.028 Received 23 December 2017; Received in revised form 7 May 2018; Accepted 15 June 2018 ⁎ Corresponding author at: Department of Mathematical and Computational Sciences, Physical Science and Earth Science, University of Messina, Viale F. Stagno d’Alcontres, 31, 98166 Messina, Italy. ⁎⁎ Corresponding author at: Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale F. Stagno d’Alcontres, 31, 98166 Messina, Italy. E-mail addresses: enfazio@unime.it (E. Fazio), specialea@unime.it (A. Speciale). Colloids and Surfaces B: Biointerfaces 170 (2018) 233–241 0927-7765/ © 2018 Published by Elsevier B.V. T