Bifunctional Nanocomposites with Long-Term Stability as SERS Optical Accumulators for Ultrasensitive Analysis

In this work, we have devised and fabricated a magnetic + optical, bifunctional colloidal system that combines flexible handling and efficient SERS analytical capabilities. This system comprises silica-coated magnetic gamma-Fe2O3 (maghemite) cores, coated with a dense monolayer of gold nanorods presenting long-term optical stability and a high density of hot spots per area unit. The magnetic functionality allows for the use of a small number of capsules that can be later concentrated under a magnetic field for SERS analysis thereby increasing the detection limits.