Nanoparticle Morphology Analysis by SEM and TEM

Nanoparticle morphology was analyzed by scanning electron microscopy (SEM). Briefly, nanosuspensions were air dried onto a glass coverslip mounted on an SEM sample stub and sputter coated with approximately 50 nm of gold/palladium alloy. Samples were examined using a FEI Quanta 200 scanning electron microscope (Hillsboro, OR) operated at 5.0 kV. Drug loaded MDM were analyzed by transmission electron microscopy (TEM) after treatment for 8 h. Cells were washed, scraped into PBS, pelleted at 3000 r.p.m. for 8 min at room temperature, and fixed in a solution of 2% glutaraldehyde, 2% paraformaldehyde in 0.1 M Sorenson’s phosphate buffer (pH 6.2). A drop of the fixed cell suspension was placed on a formvar/silicon monoxide 200 mesh copper grid, allowed to settle for 2 min, and the excess solution wicked off and allowed to dry. A drop of NanoVan vanadium negative stain was placed on the grid for 1 min, then wicked away and allowed to dry. Grids were examined on a FEI Tecnai G2 Spirit TWIN transmission electron microscope (Hillsboro, OR) operated at 80 kV, and images were acquired digitally with an AMT digital imaging system (Woburn, MA).