The fabrication process of gold nanoparticles (AuNP) is illustrated schematically in Figure (a). The optimal pH for formation of AuNP inside the polymer micelles will be close to the amine's pKa . This is probably because at low pH << pKa the amine group lone electron pairs will almost all be protonated and hence unavailable to complex the gold (III) chloride ions, whereas at high pH >> pKa the micelle core will be very tightly bound due to the hydrophobicity, preventing the gold (III) chloride ions from infiltrating.