Rapid Determination of SiO ₂ Shell Thickness on Au Core Nanoparticles via Differential Centrifugal Sedimentation for SHINERS

High Resolution Image Download MS PowerPoint Slide Consistent and reproducible synthesis of SiO 2 -coated Au nanoparticles, which are widely used as shell-isolated nanoparticles for enhanced Raman spectroscopy (SHINERS), is limited by the lack of rapid, routine methods to determine shell thickness and aggregation state. Here, differential centrifugal sedimentation (DCS) is demonstrated as a benchtop, collective-averaged technique capable of evaluating Au–SiO 2 nanoparticles for SHINERS on time scales of under 10 min. Shell thicknesses determined by DCS show close agreement with transmission electron microscopy (TEM) images within the critical 3.5–5.5 nm range governing reliable pinhole free Raman enhancement, while simultaneously revealing early stage aggregation beyond the reach of UV–visible spectroscopy. By converting shell thickness and aggregation assessment into a rapid, decision-ready measurement, DCS enables routine quality control and synthesis-level optimization of reproducible particles for use in SHINERS.