Recent Advances in Enhancement of Raman Scattering Intensity for Biological Applications.

Raman scattering spectroscopy has attracted great interest for its significant potential in multiplexed biological imaging and sensing. However, the extremely weak molecular Raman scattering signal raises considerable concerns about its applicability in physiological conditions. Many multidisciplinary attempts, combining optics, materials science, and biology, have been conducted in the past decades to solve the problem of insufficient Raman scattering intensity and to realize the practical application of Raman scattering technology in the field of life science. In addition, to overcome the bottleneck of a single enhancement technology, more and more emphasis has been given to the combination of multiple Raman enhancement technologies. The underlying ideas behind each enhancement mechanism needs to be fully comprehended to effectively combine various techniques for desired signal intensity. Here, we summarize recent strategies developed for the enhancement of the signal strength of Raman scattering. We will also analyze the major advantages and disadvantages of each enhancement technique and provide perspectives for the compatibility and complementarity among different enhancement mechanisms.