Rapid expansion of engineered nanomaterial use in commercial products, pharmaceuticals, and cosmetics, among others, warrants better understanding of nanoparticle fate and transport in the aqueous environment. Confounding this reality is the fact that common biological macromolecules, including biopolymers and/or biosurfactants produced by bacteria and fungi – and ubiquitous in the environment, will likely interact with suspended particles. Rhamnolipid biosurfactants, produced extracellularly by Pseudomonas aeruginosa are not only widely observed in the environment but are also commercially available for experimental studies. In this presentation, I will describe 8nm iron oxide (Fe3O4) nanoparticles with varied surface functional groups and their specific interactions with rhamnolipids through fundamental particle-particle and particle-surface interactions. Specifically, I will quantitatively describe the role of effect of rhamnolipid on particle aggregation processes as a function of pH, ionic strength, and particle surface chemistry. Further, using QCM-D, I will describe the fundamental impact of rhamnolipid on the deposition and release of nanoparticles under the same aqueous matrix. Results from these studies will highlight the crucial role of bio-based surfactants (at low concentrations) with regard to the fate and transport of nanomaterials in the environment.

Adsorption of rhamnolipid biosurfactant and its effect on the aggregation kinetics of iron oxide (Fe3O4) nanoparticles in monovalent and divalent electrolyte solutions

256th National Meeting (2018)

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