The safe implementation of nanotechnology requires nanomaterial hazard assessment in accordance with the material physicochemical properties that trigger the injury response at the nano/bio interface. Since CuO nanoparticles (NPs) are widely used industrially and their dissolution properties play a major role in hazard potential, we hypothesized that tighter bonding of Cu to Fe by particle doping could constitute a safer-by-design approach through decreased dissolution. Accordingly, we designed a combinatorial library in which CuO was doped with 1–10% Fe in a flame spray pyrolysis (FSP) reactor. The morphology and structural properties were determined by XRD, BET, Raman spectroscopy, HRTEM, EFTEM and EELS, which demonstrated a significant reduction in the apical Cu-O bond length while simultaneously increasing the planar bond length (Jahn-Teller distortion). Hazard screening was performed in tissue culture cell lines and zebrafish embryos to discern the change in the hazardous effects of doped vs. non-doped particles. This demonstrated that with increased levels of doping, there was a progressive decrease in cytotoxicity in BEAS-2B and THP-1 cells, as well as an incremental decrease in the rate of hatching interference in zebrafish embryos. The dissolution profiles were determined and the surface reactions taking place in Holtfreter’s solution were validated using cyclic voltammetry (CV) measurements to demonstrate the Cu+/Cu2+ and Fe2+/Fe3+ redox species playing a major role in the dissolution process of pure and Fe doped CuO. Altogether, a safe-by-design strategy was implemented for the toxic CuO particles via Fe doping and has been demonstrated for their safe use in the environment.

The determination of the flat band potential of metal oxide nanoparticles is essential to understand their electrochemical behavior in aqueous environments. The electrochemical behavior determines the possible applications and governs the environmental impact of a nanomaterial. Hence, a new electrode fabrication method is demonstrated that allows determining the flat band potential of nanoparticles in porous nanoparticle electrodes via electrochemical impedance spectroscopy. In such electrodes, the electrolyte is in contact with the substrate material and contributes significantly to the ac response of the entire electrode. To block the substrate–electrolyte contact, the nanoparticle layers were imbibed in a liquid diacrylate monomer, followed by polymerization. To reestablish the contact between the outermost polymer-covered particles and the electrolyte, an O2 plasma treatment was conducted. Based on this new electrode fabrication procedure, the flat band potential of TiO2, WO3, and Co3O4 nanoparticles in porous electrodes was determined with high precision. We believe that this new and economical method will offer an alternative to expensive ultraviolet photoelectron spectroscopy measurements at synchrotron facilities.

The progress in nanomedicine (NM) using nanoparticles (NPs) is mainly based on drug carriers for the delivery of classical chemotherapeutics.A sl ow NM delivery rates limit therapeutic efficacy,a ne ntirely different approach was investigated. Ahomologous series of engineered CuO NPs was designed for dual purposes (carrier and drug) with adirect chemical composition-biological functionality relationship. Model-based dissolution kinetics of CuO NPs in the cellular interior at post-exposure conditions were controlled through Fe-doping for intra/extra cellular Cu 2+ and biological outcome. Through controlled ion release and reactions taking place in the cellular interior,tumors could be treated selectively,invitro and in vivo.L ocally administered NPs enabled tumor cells apoptosis and stimulated systemic anti-cancer immune responses.W ec learly show therapeutic effects without tumor cells relapse post-treatment with 6% Fe-doped CuO NPs combined with myeloid-derived suppressor cell silencing.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.