Reactive Oxygen Species Scavenging by Small Gadolinium-Yttrium Orthovanadate Nanocrystals

Oxidative stress induced by reactive oxygen species (hydrogen peroxide, superoxide anion, hydroxyl radical etc.) is the key factor in developing a variety of pathological conditions including diabetes, asthma, atherosclerosis, hypertension mellitus and cancer. To prevent or reduce the cell damages caused by reactive oxygen species, natural or synthetic molecules named antioxidants are commonly used. Recently, various inorganic nanomaterials, such as CeO
2
, Mn
3
O
4
, Co
3
o
4
and Fe
3
O
4
nanocrystals, have attracted growing interest as nano-antioxidants with reactive oxygen species regulating ability. Here, we report on high antioxidant behavior of small gadolinium-yttrium orthovanadate nanocrystals revealed by spectroscopic methods using various reactive oxygen species sensors, and propose the mechanism describing their reactive oxygen species scavenging action. It has been found that in 2 nm gadolinium-yttrium orthovanadate nanocrystals more than 60% vanadium ions are presented in lower V
⁴⁺
and V
³⁺
oxidation states. Switching between
$\mathrm{v}^{3+}\leftrightarrow \mathrm{v}^{4+}$
and
$\mathrm{v}^{4+}\leftrightarrow \mathrm{v}^{5+}$
oxidation states allow gadolinium-yttrium orthovanadate nanocrystals to react with hydrogen peroxide (H
²
O
²
) and superoxide anion (O
2
.) in enzyme-like manner and neutralize hydroxyl radical (·OH), and peroxyl radicals (ROO·), as well. The obtained data and proposed mechanism of gadolinium-yttrium orthovanadate nanocrystals antioxidant action can explain the non-trivial anti-aging and radioprotective effects of gadolinium-yttrium orthovanadate nanocrystals observed earlier in vivo.