Plasmonic nanomaterial-enhanced fluorescence and Raman sensors: Multifunctional platforms and applications

Plasmonic nanomaterials could improve various optical performance including fluorescence emission, Raman scattering, infrared absorption, etc. Among them, plasmon-enhanced fluorescence (PEF) can realize high-sensitivity sensing and super-resolution imaging quickly, but with inferior multiplexed detection capability. Surface-enhanced Raman scattering (SERS) can offer fingerprint-like spectra for multiplexing, but its imaging speed and resolution are limited. The PEF-SERS integrated sensors could congregate their individual strengths while overcoming inherent weaknesses. Specifically, they can use fluorescence signals to rapidly screen out "suspicious" locations within numerous samples or a broad area, and then conduct multi-peak SERS measurements there to gather more detailed information. Besides, cross-verification of PEF and SERS results is possible to realize self-correction. Hence, many existing issues could be addressed including sensitivity, accuracy, speed, and multiplexing. Attracted by these superior advantages, we review here the interaction between plasmonic nanomaterials and fluorescence/Raman probes to explain enhancement mechanisms, the construction strategies for plasmonic substrates with better PEF-SERS performance, different modes for transforming analyte's information into measurable optical signals, as well as the main application in substance research, disease diagnosis, cell imaging, drug delivery. We believe, a deeper understanding of the state-of-arts of multifunctional plasmonic platforms could provide a generic guideline for their future development and practical application.