The Z-potentials for the GNPs and SNPs prepared at 1 × 10⁻³ M (HAuCl₄ or AgNO₃, respectively) measured 5 days after the synthesis.

Sample	Z-Potential (mV)	Sample	Z-Potential
G20-3	−22.4	S20-3	−29.2
G40-3	−22.4	S40-3	−26.5
G60-3	−24.9	S60-3	−23.6
G80-3	−21.7	S80-3	−24.4
G100-3	−22.0	S100-3	−24.4