3.1 Enlarging diameter of AuNPs in ES-SMPS
After mixing the original AuNP solutions and AmAc solution and having the final AmAc concentration of 20 mM, Au-10 and Au-5 suspensions were loaded to ES-SMPS system for the size scanning. Multiple peaks among the size distributions of both AuNP samples were found, as displayed inFigure 2(A) & (D) , and were considered as the influence of the surfactant or other impurity existing in the original AuNP solution. The centrifugal process replaced the most of the solvent in the original AuNP solution with deionized water/AmAc solution, andFigure 2(B) & (E) exhibited the reduction in surfactant/impurity in the AuNP suspensions as the dramatically decrease of NP numbers and disappearance of the peaks positioning at smaller diameters. In according with the size distribution of AuNP samples with centrifugal treatments, the diameters of Au-10 and Au-5 from the original solution were determined as 12.6 nm and 10.6 nm, which presented a respective difference of 26 % and 112 % from the nominal diameter.