Formvar and carbon

Gold nanostars were characterized using TEM (JEOL JEM-1230) equipped with a Gatan CCD camera and 120 keV accelerating voltage. Samples were prepared by first diluting the nanoparticle solution by 50% using ethanol. This solution was pipetted onto 400 mesh copper grids coated with a thin film of Formvar and carbon (Ted Pella). TEM images were analyzed (Image Pro Analyzer or Image J) to estimate the average overall (ferret) radius before (33.0 ± 8.6 nm, N = 163) and after functionalization (24.8 ± 5.0 nm, N = 149) as well as the tip radius of curvature (before 4.4 ± 0.8 nm, N = 213 and after 4.5 ± 0.5 nm, N = 205 functionalization) where N = the total number of measurements collected, and the average ± standard deviation of these are reported.

TEM was performed using a JEOL TEM-1230 microscope equipped with a Gatan CCD. The nanoparticle solution was diluted by 50% using ethanol, and ~10 μL of this solution was deposited onto 400 mesh copper grids coated with Formvar and carbon (Ted Pella) then dried at room temperature. At least ~200 nanoparticles (N) were analyzed (Image Pro Analyzer) to estimate average nanoparticle diameters. Silica shell thicknesses were determined by propagation of error using Ag@Au and Ag@Au@SiO₂ nanoparticle diameters.