Nanomaterial-based SERS sensing technology has been successfully used to detect intracellular drugs, and various drugs in different locations in a cell show diverse SERS spectra, thus Ramanimaging can be used to observe intracellular drugs via a Raman microscope system.130,131 Compared to typical fluorescence probes with low sensitivity and poor optical stability, Raman imaging based on SERS tags exhibits unique advantages, such as high sensitivity,excellent identification and low interference from water solution, which are prompting rapid development in cell imaging applications. The Raman spectra obtained from different intensities ofexcitation light are almost consistent, which makes SERS imaging believable and stable. Antibody–drug gold nanoantennas capped byDTTC present a high SERS signal for in vivo tumor detection.132Human epidermal growth factor (HER2) cancer markers overexpressed in single MCF7 cells were detected by the use of hollow gold nanosphere SERS sensing.133 Besides, silica-encapsulatedhollow gold nanospheres (SEHGNs) in Fig. 8A were designed and respectively conjugated to three different kinds of Raman reporter-antibody sets, i.e. malachite green isothiocyanate (MGITC),rhodamine B isothiocyanate (RBITC) and bis(2,30-bipyridine)-(5-isothiocyanato-phenanthroline)ruthenium bis(hexafluorophosphate) (RuITC).134 These SEHGNs could image breast cancercells by detecting phenotypic markers and enhance imaging bydetecting specific biological markers with the SERS-based cellimaging technique, shown in Fig. 8B–D.