Nanoparticle Aggregation: Challenges to Understanding Transport and Reactivity in the Environment

Abstract

Unique forms of manufactured nanomaterials, nanoparticles, and their suspensions are rapidly being created by manipulating properties such as shape, size, structure, and chemical composition and through incorporation of surface coatings. Although these properties make nanomaterial development interesting for new applications, they also challenge the ability of colloid science to understand nanoparticle aggregation in the environment and the subsequent effects on nanomaterial transport and reactivity. This review briefly covers aggregation theory focusing on Derjaguin-Landau-Verwey-Overbeak (DLVO)-based models most commonly used to describe the thermodynamic interactions between two particles in a suspension. A discussion of the challenges to DLVO posed by the properties of nanomaterials follows, along with examples from the literature. Examples from the literature highlighting the importance ofaggregation effects on transport and reactivity and risk of nanoparticles in the environment are discussed.

Freshwater ecotoxicity characterisation factor for metal oxide nanoparticles: A case study on titanium dioxide nanoparticle

“…ROS generation and dissolution of free ions). On the other hand, it increases the persistence of the ENPs, decreasing the rate of dissolution or degradation (Hotze et al, 2010). Under environ-mental conditions a multimodal size distribution of ENPs is expected and organisms may be exposed to different size ranges of aggregates (Keller et al, 2010;Lin et al, 2010;Sillanpää et al, 2011;Praetorius et al, 2012).…”

Centrifugation-based assay for examining nanoparticle–lipid membrane binding and disruption

“…[34][35][36][37] The extent of nanoparticle-induced biophysical and/or biochemical changes on cell membranes would be dependent on the size, charge, surface reactivity, surface chemistry and compositions of nanoparticles. [38][39][40][41][42] It has been studied that nanoparticles may introduce carcinogenic risks, which may be triggered by the production of reactive oxygen species (ROS) by macrophages attempting to destroy foreign materials on the inflammation sites. The ROS produced in this process, may cause DNA damage as well as inflammatory lesions associated with carcinogenesis.…”

Cobalt Ferrite Nanoparticles Fabricated via Co-precipitation in Air: Overview of Size Control and Magnetic Properties

“…Particles in solution are affected by Brownian motion [13,15,[17][18][22][23][24]. Consequently, particle collisions result and van der waals forces between particles serve as an attractive force between the particles [13,15,[17][18][22][23][24].…”

“…Likewise, magnetic attraction between particles promotes aggregation [22]. These attractive forces must be balanced by a repulsive force or else aggregation will result [13,15,[17][18][22][23][24].…”

“…These attractive forces must be balanced by a repulsive force or else aggregation will result [13,15,[17][18][22][23][24]. An example of a repulsive force is the electrostatic force between particles in solution.…”