Surface-enhanced Raman scattering (SERS) refers to an abnormal surface optical phenomenon that Raman spectra of the analyte adsorbed on metal nanostructures can be significantly enhanced under laser irradiation. In recent years, SERS has been widely used in the substance detection and biological sensing, which has achieved significant development and shown great potential applications in the biomedical field. In this paper, the preparation principle and the latest development of SERS tags used in cell detection are introduced, and their recent applications in cell recognition, imaging, diagnosis and treatment are reviewed, as well as the detection strategies and issues related to SERS tag-based cell detection are discussed.

Contents
1 Introduction
2 SERS tags
2.1 Noble metal nanoparticles
2.2 Raman reporter molecules
2.3 Surface coating for protection
2.4 Biofunction with biomolecules
3 Application of SERS tags in cell
3.1 Cell recognition
3.2 Cell imaging
3.3 Cell pH sensing
3.4 Cancer diagnosis and treatment
4 Conclusions and outlooks