Grantee Research Project Results
Influence of Nanoparticle Characteristics on Membrane TransferEPA Grant Number: FP917133
Title: Influence of Nanoparticle Characteristics on Membrane Transfer
Investigators: Garner, Thomas Ross
Institution: Clemson University
EPA Project Officer: Cobbs-Green, Gladys M.
Project Period: August 18, 2010 through August 17, 2013
Project Amount: $111,000
RFA: STAR Graduate Fellowships (2010)
Research Category: Academic Fellowships , Fellowship - Pesticides and Toxic Substances
The explosion of products and applications using nanomaterials has occurred in the absence of detailed knowledge of the interactions of nanoparticles with biological membranes. This lack of knowledge has impeded the development of biomedical applications of nanomaterials and prevented quantitative assessments of the risk of nanoparticles to humans and ecosystems. Many biomedical applications of nanoparticles rely on their ability to cross membranes; for a nanoparticle to be potentially harmful, it typically must cross a membrane. In spite of this information, little deliberate research has been performed to quantitatively characterize the influence of nanoparticle characteristics on membrane transport. The goal of this research is to characterize the influence of particle core chemistry, size, shape and surface chemistry on the movement of nanoparticles across biological membranes.
The nano-tech revolution has occurred in the absence of detailed knowledge concerning the interactions of nanoparticles with the environment. This lack of knowledge has prevented quantitative assessments of the risks nanoparticles pose to humans and ecosystems. This research will characterize the influence that physical and chemical properties of nanoparticles have biological interactions. Results of this project will help predict the uptake of particles in various organisms in the environment.Approach:
This research will test the specific hypothesis that nanoparticle transfer across biological membranes is a function of particle physical and chemical properties. To test this hypothesis, this project will quantify the movement of nanoparticles of across cell membranes: out of the gut tract and into the body of Daphnia magna and across the gut tract of mice. Nanoparticles to be tested in this research vary in core chemistry, shape, size, and surface chemistry. Specifically, carbon dots and gold spheres (4 nm, 18 nm, and 50 nm), gold cubes (50 nm and 75 nm) and gold rods (20 nm × 100 nm and 20 nm × 400 nm) with cationic, anionic, and nonionic surface modifications will be tested. While both gold and carbon particles can be visualized using transmission electron microscopy, gold particles can also be visualized using dark field microscopy, and the autofluorescence of carbon dots makes them amenable to confocal fluorescent microscopy. Bioaccumulation of gold nanoparticles will be further substantiated and quantified by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Use of these complete factorial designs will facilitate the use of Analysis of Variance to analyze the data and quantify primary effects as well as secondary and tertiary factor interactions.Expected Results:
We expect to find that most nanoparticles are poorly bioavailable and do not pass through membranes. However, some nanoparticles, particularly those that are smaller or mimic the charge and size characteristics of ions, prostaglandins, or hormones will be bioavailable as they will pass through either channels or ATP-dependent transporters. We predict that most, if not all, of the nanoparticles that are bioavailable will have similar characteristics. Specifically, we predict that spheres and cubes will show greater bioavailability than rods. Furthermore, we predict that particles that are bioavailable in D. magna will also be bioavailable in mice. We theorize that these particles will pass through the basolateral membranes of the small intestine, travel through the columnar epithelial cells of the small intestine, and exit the apical membranes into the blood. Demonstration of this effect of specific types of nanoparticles is important, as this work would show both basolateral and apical transport in an in vivo system.
Potential to Further Environmental/Human Health Protection:
The potential societal benefits of nanotechnology can only be realized if we adequately understand the interactions of these materials with biological systems. Current research has focused on cellular uptake of nanoparticles, as well as uptake in whole organisms. However, a lack of research quantitatively characterizing the influence of nanoparticle characteristics on their transport within these two systems exists. This research will help bridge the gaps in current research, while also providing a rapid, high volume bioassay that will facilitate future in vitro screenings of varying nanoparticles in the absence of in vivo testing. Results of this research will lay the foundation to develop quantitative structure-activity relationships (QSARs) that can be used to predict nanoparticle absorption in a variety of biological systems. In addition, these same relationships will reduce the uncertainties currently clouding quantitative human and ecological risk assessment.Supplemental Keywords:
nanoparticles, particle characterization, particle uptake, bioaccumulation, gold, carbon dots, cell culture, in vitro screening,