scalable, costly, and time-consuming nature. Therefore, an assay
that is fast, highly sensitive, and efficient in detecting a trace
number of undifferentiated cells is imperative for assessing the
safety of hPSC-derived products.
Nanoparticle-based surface-enhanced Raman scattering (SERS)
technology is gaining momentum in biomedical applications such
as molecular multiplex detection, pathogen and cell detection, and
in situ imaging [16e21]. When conjugated with biomolecular targeting
ligands, Raman reporter-labelled gold (Au) nanoparticles can
be used to detect specific molecules with high specificity and
sensitivity [19,21e23]. SERS detection produces a sharp,
fingerprint-like spectral pattern that is distinct from other interference
patterns in a complex biological environment. This is
uniquely advantageous when detecting a low number of cells, since
conventional fluorescence signals may be masked by the scattering
signals of background cells [20,21]. In this study, we developed
SERS-based assays targeting the hPSC surface markers stagespecific
embryonic antigen-5 (SSEA-5) and TRA-1-60 to detect residual
undifferentiated hPSCs with high specificity and sensitivity.
Using our newly developed assays, we efficiently detected SSEA-5þ
and TRA-1-60þ cells at sensitivities several orders of magnitude
higher than flow cytometry assays. As such, these assays represent
a rapid, efficient, and economic method for assessing the safety of
hPSC-based products for pre-clinical and clinical applications.