Assessment of Progress - Research Progress on Environmental Health and Safety Aspects of Engineered Nanomaterials - page 32

will require the development of new instrumentation, as described below. The lack of an ontology and a
mechanism for data synthesis led to categorizing this indicator as yellow.
 Progress in developing instrumentation to measure key nanomaterial properties and changes
in them in complex biologic and environmental media
Measurement of nanomaterial transformations in relevant biologic and environmental media has
high priority. In those complex media, a wide array of substantial or subtle changes involving material
composition and structure may occur. Adsorption of natural organic matter, proteins, and lipids may
change the surface coating. Etching, degradation, or agglomeration of nanoparticle cores may transform
the material. Oxidation and dissolution or sulfidation may occur (Liu et al. 2012). Measurements of the
materials are further complicated by their presence at low concentrations and in a wide variety of
compartments.
Little progress has been made in this indicator despite its importance and the recognition that
such measurements are crucial for accelerating nanotechnology EHS research. Several sections in this
chapter describe how analytic techniques are being adapted and used in combination to gain information
about the composition and structure of ENMs in simple well-characterized media. This indicator is
focused on the development of new instrumentation that can measure core and surface compositions and
physical dimensions in complex biologic or environmental matrices and in some cases at a single particle
resolution. The optimal methods would permit measurement of size and composition in the matrices.
Some publications have called for improved detectors to enable single-particle ICP-MS and to improve
the spatial resolution of x-ray microprobes (von der Kammer et al. 2012).
Instruments for measuring airborne ENMs are being developed. J. Wang et al. (2011) have
developed a universal nanoparticle analyzer to measure and characterize airborne nanoparticle
agglomerates. Rhoads et al. (2003) designed an instrument (rapid single-particle mass spectrometry,
RSMS-11) to analyze the chemical composition of airborne nanoparticles (less than 20-nm), and efforts
are directed at developing an instrument to measure nanoparticle-bound reactive oxygen species in real
time (Y. Wang et al. 2011). Despite those developments, overall progress is insufficient.
Considerable progress is required to meet current and future needs in the nanotechnology-EHS
field, and little headway has been made toward the necessary instrumentation. Therefore, this objective is
labeled red by the committee.
 Initiation of interdisciplinary research that can relate native nanomaterial structures to
transformations that occur in organisms and as a result of biologic processes
In its first report, the committee emphasized the importance of processes that lead to
transformations of ENMs in organisms or ecosystems. Adsorption of proteins, lipids, and organic
materials may alter surface properties of ENMs, form a corona, affect mechanisms of cell interactions,
and alter ENM biokinetics. (The corona, a coating that binds to the surface of ENMs, influences the
biodistribution and effects of ENMs [Walczyk et al. 2010].) Although the concept of “differential
adsorption” of lipids and proteins has been described (Müller and Heinemann 1989) and has been
developed in vitro (Cedervall et al. 2007; Walcyzyk et al. 2010), the committee identified a major gap in
understanding of the effects, particularly in vivo effects, of the types and amounts of adsorbed lipids and
proteins.
Some progress has been made by several laboratories in the United States and Europe that are
investigating the adsorption of lipids and proteins on ENMs introduced into organisms or when
interacting with biologic media in vitro. Although in vitro studies have advanced this field of research
considerably (for example, showing that modifying ENM surfaces by coating them with proteins or
surfactants can result in altered cellular responses), confirmatory in vivo studies are lacking. Despite the
progress, much research is needed. The importance of other ENM transformations (altered surfaces,
agglomeration, deagglomeration, aggregation, and solubilization) for biokinetics and effects needs to be