The characterisation and measurement of biomedically relevant nanomaterials
Bell, Nia C.
Nanomaterial metrology is fundamental to understanding the physical properties of nanomaterials and their environmental interactions. Particles, in the nano and sub-micrometer regimes, are attractive materials for use in biomedical applications such as drug delivery and medical imaging. In order to address concerns regarding their potential for cytotoxicity, particle characterisation before and after exposure to biologically relevant media is critical. Size is one of many particle properties that can influence their behaviour in biomedical applications, including their cellular uptake and circulation lifetime. Therefore, the sizing capabilities of three established (transmission electron microscopy (TEM), scanning mobility particle sizing (SMPS) and dynamic light scattering (DLS)) and three emerging particle sizing techniques (scanning ion occlusion sensing (SIOS), nanoparticle tracking analysis (NTA) and differential centrifugal sedimentation (DCS)) with Stöber silica particles, 100 - 400 nm in diameter, as the test material, were evaluated. When exposed to biological media particles will spontaneously be coated with a film of biomolecules, predominantly proteins, which will subsequently define their biological identities. Being able to quantify and evaluate the composition of these so called "protein coronas" is key to understanding the bio-nano interface. In this study, the amount of immunoglobulin G (IgG) adsorbed onto gold particles, as a function of particle size and protein concentration, was measured, using a combination of techniques including DLS (and ζ-potential), NTA, DCS, and UV-Visible spectroscopy (UV-Vis) plasmonic sensing. ζ-potential was a good indicator of protein corona integrity, and deviations in the protein corona thicknesses measured by NTA and DCS at low protein coverage were observed. Finally, the surface chemistry of an electrospun polymer fibre scaffold was characterised using time of flight-secondary ion mass spectrometry (ToF-SIMS). The concentration of a cell adhesion enhancing peptide was measured to be linearly related to that in the bulk and its co-localisation with the polymers proven through imaging.View Full Article