Encapsulation of 15 nm citrate-coated GNPs into P6c SAPNs. TEM images of the encapsulation samples that have two different ratios of P6c protein to GNPs, respectively: (a) The P6c protein concentration was 0.05 mg/ml (approximately 4 nmol/ml). The 10 nm GNPs concentration was approximately 2.3×10-3 nmol/ml. (b) The P6c protein concentration was 0.025 mg/ml. The 10 nm GNPs concentration was approximately 2.3×10-3 nmol/ml. The denatured P6c protein was refolded in the GNPs solutions using quick refolding method. After protein refolding, all three samples were dialyzed in buffer containing 20 mM HEPES, 150 mM NaCl, 5% Glycerol. (c) DLS profiles for volume distribution of hydrodynamic sizes of the encapsulation samples.