Surface-Enhanced Raman Spectroscopy for Intradermal Measurements

This chapter presents an overview of the current surface-enhanced Raman spectroscopy (SERS) techniques suitable for intradermal measurements. SERS is known for its high chemical specificity and molecular sensitivity. In SERS measurements, the close molecular proximity of intradermal analytes to metal surfaces or nanoparticles is critical. Various approaches have been developed to fulfill this requirement, which include the injection of SERS active nanoparticles, SERS active structures, SERS active acupuncture needles and SERS active microneedles. The principle and experimental validation of each category of approaches are described. Representative methods in all categories are compared in terms of sensing depth, advantages and disadvantages, test models and sensitivity/accuracy. Finally, challenges to be addressed before these techniques could be applied clinically are discussed to provide a guide for future development.