Effects of biological buffer solutions on the peroxidase-like catalytic activity of Fe3O4 nanoparticles

RAINERI, MARIANA; WINKLER, ELIN; MOLINA, TEOBALDO ENRIQUE; VASQUEZ MANSILLA, MARCELO; NADAL, MARCELA S; ZYSLER, ROBERTO; LIMA, ENIO

Nanoscale

Royal Society of Chemistry

Lugar: Londres; Año: 2019

2040-3364

Iron oxide nanoparticles (IONPs) are frequently used in biomedical applications due to their magnetic properties and putative chemical stability. Nevertheless, their well-known ability to mimic some features of the peroxidase enzyme activity under specific conditions of pH and temperature could lead to the formation of potentially harmful free radical species. In addition to the intrinsic enzymatic-like activity of IONP, there buffer solution is an important external factor that can alter dramatically the IONP activity because buffer species can interact with the surface of the particle. In particular for biomedical applications, it is crucial to determine the catalytic activity of IONPs in physiological buffers. In our study, IONP activity was evaluated in acetate, phosphate, HEPES and HEPES-carbonate buffering solutions under different experimental conditions and predominant free radical species were measured by Electron Paramagnetic Resonance using spin-trap DMPO. The formation kinetics of the reactive oxygen species was studied by UV-visible spectroscopy with TMB and DAB peroxidase substrates. Lower peroxidase-like activities were achieved for phosphate and bicarbonate, the more physiological conditions of pH, salinity and buffering species. In conclusion, our data indicate that biological buffering solutions need to be carefully considered when evaluating IONPs catalytic activity and their potential toxicological effects.