Invited Paper AS+BI+EM+NL+NS+SS-ThM1
Surface Analysis as a Critical Step in Translating Nanomaterials to Technologies

Thursday, October 31, 2013, 8:00 am, Room 204

Difficulties assessing human exposure, safety, and possible toxicity from nanotechnologies have prompted questions about how to characterize nanomaterials in various experimental test beds for predictive use. While little consensus is published about human risk/benefit analysis, this is confounded by lack of accepted, sensitive and reliable characterization methods of practical value for nanomaterials in physiological milieu. Relatively few studies are conducted on these materials in biologically relevant media to understand their surface properties and physical states (i.e., sedimentation, aggregation) prior to in vitro or in vivo exposures. Few studies have standard reference materials and analytical protocols established for comparisons to other studies. The current understanding of the fate of nanomaterials of most any size and shape, both in cell culture mediawith serum or inside the mammalian body, is poor at best. Additionally, the collective published scientific record documenting fate of nanomaterials in vivo is consistent with long known tissue-based particle filtration for micro-colloids, with far less success deliberately targeting particles to specific tissue or disease sites (i.e., <5% of a nanoparticle dose reaches a disease site).

To date, most data suggest that size reductions to the nanometer dimension have not significantly changed how nanomaterials interact with physiological systems in vivo, despite in vitro distinctions observed with proteins and in cell cultures. Connecting nanomaterials properties with how they interact with proteins and cells in vitro to affect their biodistribution in vivo allows a more rational approach to designing nanomaterials with specific biomedical and toxicity properties, and to avoid the ubiquitous non-specific tissue scavenging. This is related to materials interactions with whole blood components, including platelets, cells, and plasma proteins, producing fluid transport to tissue sites, particle binding, opsonization and aggregation. However, analytical methods for nanomaterialsare not sufficiently sensitive to study these effects in vivo to alter nanomaterials biodistribution patterns. Additionally, understanding how surface coatings, ligands and contaminants change physiological behavior requires careful analysis.

The nanotechnology field must develop improved, sensitive analytical tools and methods to drive a consensus for how nanomaterials (1) should be fully and reliably characterized for biological and biomedical purposes, and (2) how different nanomaterials properties produce either beneficial (i.e., therapeutic) or toxic responses inside complex physiological systems.