Heterogeneities in Fullerene Nanoparticle Aggregates Affecting Reactivity, Bioactivity, and Transport

Abstract

Properties of nanomaterial suspensions are typically summarized by average values for the purposes of characterizing these materials and interpreting experimental results. We show in this work that the heterogeneity in aqueous suspensions of fullerene C60 aggregates (nC60) must be taken into account for the purposes of predicting nanomaterial transport, exposure, and biological activity. The production of reactive oxygen species (ROS), microbial inactivation, and the mobility of the aggregates of the nC60 in a silicate porous medium all increased as suspensions were fractionated to enrich with smaller aggregates by progressive membrane filtration. These size-dependent differences are attributed to an increasing degree of hydroxylation of nC60 aggregates with decreasing size. As the quantity and influence of these more reactive fractions may increase with time, experiments evaluating fullerene transport and toxicity end points must take into account the evolution and heterogeneity of fullerene suspensions.

Production and consumption of reactive oxygen species by fullerenes

“…136-143, 2012 # 2011 SETAC Printed in the USA DOI: 10.1002/etc.711 was reported to be 0.10 in acidic solution and 0.05 at neutral and basic conditions [18], consistent with the value determined using an EPR spin trapping technique [6]. Aqueous fullerenol more efficiently produced 1 O 2 and O À 2 Á than did C 60 in aqueous suspension, with heterogeneities in fullerene nanoparticle aggregates believed to be responsible [19][20][21].…”

Effects of molecular weight-dependent physicochemical heterogeneity of natural organic matter on the aggregation of fullerene nanoparticles in mono- and di-valent electrolyte solutions

“…Elucidating the toxicity and risks of nC 60 requires more detailed studies on its environmental fate and behavior (Lowry et al, 2012;Petosa et al, 2010). This is highly dependent on the size heterogeneity of nC 60 aggregates in the aqueous environment (Chae et al, 2010), which thus highlights the importance of understanding the aggregation process of nC 60 . The inevitable encounter of NOM upon the released nC 60 and other ENPs in the environment has increased the interest in their active interactions (Lowry et al, 2012;Zhang et al, 2009;Xie et al, 2008).…”

Evidence of entropically driven C60 fullerene aggregation in aqueous solution

“…[1][2][3][4] In particular, the link between antibacterial activity and the state and morphology of C 60 fullerene aggregates in solution has recently been discovered, 5,6 suggesting the need for deeper understanding of physicochemical properties of pristine C 60 fullerene aqueous colloid solution (C 60 FAS) and invoking the general question regarding which form of C 60 fullerene is bioactive, namely, a single molecule or its cluster? 5,7,8 It has been recently established that the aggregates of pristine C 60 fullerenes provide an excellent template for formation of highly ordered inclusion complexes with other molecules, resulting in amplified physicochemical or biological properties.…”