High sensitivity detection of nanoparticles permeation through polymer membranes: A physico-chemical and nuclear imaging measurement approach

Diffusion cells are devices made of donor and acceptor compartments (DC and AC), separated by a membrane. They are widely used in pharmaceutical, cosmetic, toxicology, and protective equipment tests (e.g., gloves) to measure the kinetics of permeants (molecules and nanoparticles) across biological membranes as the skin. However, rarely is the concentration of permeants in the AC measured in continuous or in real-time, and this limitation leads to significant discrepancies in the calculations of kinetic parameters that define the permeation mechanisms. In this study, a diffusion cell compatible with positron emission tomography was used to measure the permeation kinetics of nanoparticles across glove membranes. The technology allows for the measurement of nanoparticle concentration in real-time in the two compartments (DC and AC) and at a detection sensitivity several orders of magnitude higher compared with conventional spectroscopies, thus allowing a much more precise extraction of kinetic parameters. Ultra-small (<10 nm) gold nanoparticles were used as a model nanoparticle contaminant. They were radiolabeled, and their diffusion kinetics was measured in continuous through latex and nitrile polymer membranes. Permeation profiles were recorded at sub-nanomolar sensitivity and in real-time, thus allowing the high precision extraction of kinetic permeation parameters. The technology, methodology, and data extraction process developed in this work could be applied to measure in real-time the kinetics of diffusion of a whole range of potentially toxic molecules and nanoparticles across polymer membranes, including glove membranes.