*2.6. TEM Studies of NPs*

Suspension of AuNPs was adsorbed on formvar-coated copper grids for 1 min, then liquid excess was removed by a filter paper, and the grid was air dried. Suspensions of AuNPs-PEI and AuNPs-BSA also were adsorbed on a grid for 1 min, and after removing of liquid excess were contrasted with 2% phosphotungstic acid (EMS, Hatfield, PA, USA), pH 0.5. The samples were examined with a JEM 1400 TEM (JEOL, Japan) equipped with a Veleta digital camera (EM SIS, Muenster, Germany). iTEM program, version 5.2 (EM SIS, Muenster, Germany) was used for direct measurement of NPs sizes.
