Toxicological impact of morphology and surface functionalization of amorphous SiO2 nanomaterials

•Characterizations of NMs confirmed the amine-functionalization of SiO2.•Different morphologies of SiO2 influence the toxicological potential of NMs.•Spherical morphology showed higher surface area and toxic potential.•Functionalization potentiates the toxicity of amorphous SiO2 NMs.

Amorphous silica nanomaterials (SiO2NMs) with tubular - nanotube (NT) and spherical - nanohank (NH) morphologies were synthesized. The surfaces of these SiO2NMs were amine functionalized (AF) with 3-[2-(2-aminoetylamine)ethylamine]propyltrimethoxysilane (SiO2NM@AF). The amorphous structure was verified by XRD and the amine functionalization was confirmed by FTIR spectroscopy, surface area, and zeta potential results. The toxicological evaluation of the SiO2NMs was performed using acute and chronic toxicity tests with aquatic microcrustaceans Daphnia magna and a cell viability test with Vero cells. All of the SiO2NH tests showed higher toxicity compared to SiO2NT, due to the spherical shape and larger surface area of the former. The SiO2NM@AF, regardless of the morphology (NT or NH), were more toxic, despite their increased size and reduced surface area. In all cases evaluated, chronic toxicity tests showed a decrease in the reproduction and growth of the organisms, as the NM concentration increased.

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