to CuO and Au cores . For the synthesis of gold nanoparticles coated with a mesoporous silica shell (Au@SiO2), aqueous solutions of 5.6 mg of CTAB in 0.93 mL of water, 2 mg of L-arginine in 200 µL of water and 0.5 mL of 1x washed and 9x concentrated gold core nanoparticles in water (~4 × 10 12 particles based on estimated NP concentration from AuNP synthesis reaction) were added to 2.17 mL of Milli-Q water. After brief sonication (20 s), the solution was heated to a temperature setpoint of 100 °C for the heating blocks (resulting in an internal temperature of ca.