Characterization and Sizing of Lipid Coated Gold Nanoparticle Cores

Applications of gold nanoparticles are on the forefront of research in many areas, including environmental, industrial, and biomedical sciences. Altering the surface ligands of spherical gold nanoparticles smaller than 100 nm makes them useful for multiple biomedical functions including imaging, colorimetric sensors within the body, and as cell or organelle specific targets for cancer treatment or therapeutic drug delivery. We coated spherical gold nanoparticles ranging in size from 8-40 nm (avg. diameter 23-48nm) with poly(allylamine hydrocholoride) (PAH) and a mixed lipid solution of 1:1 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS) and lysophosphatidylcholine (LPC). The coating process was followed using a NanoSight LM10HS particle sizer which confirmed a gradual increase in size after each step in the coating process. The purified lipid coating thickness of these nanoparticles was consistently 2-3 times that of the PAH coated samples they were layered on to, suggesting a successful, multi-layered coat ranging in size based on the PAH coated core size. UV-Vis spectroscopy revealed a minor red shift, indicating a slight increase in size and change in refractive index, which supported the presence of lipid coating on the PAH coated gold nanoparticle cores