Tracing sialoglycans on cell membrane via surface-enhanced Raman scattering spectroscopy with a phenylboronic acid-based nanosensor in molecular recognition.

Sialoglycan expression is critical for assessing various diseases progression. Especially, its abnormal levels are commonly believed to be associated with tumor and metastatic cancer types. While, complicated structures, multiple types and dynamic distributions make it challenging for in situ investigating sialoglycans at the physiological status. Herein, we developed a 4-mercaptophenylboronic acid (MPBA)-based surface-enhanced Raman scattering (SERS) nanosensor to in situ study sialoglycan levels and dynamic expression processes of different cell types based on molecular recognition between phenylboronic acid and sialoglycans at physiological condition. This nanosensor is designed by the MPBA decorated silver nanoparticle (AgNP), which is unique and multifunctional because of its three-in-one role involving the Raman signal enhancer (AgNP), the sensing reporter of MPBA and the target receptor based on the recognition of phenylboronic acid and sialoglycans. When this nanosensor binds to sialoglycans, the molecular vibrational modes of MPBA will change, which can be traced by ultrasensitive SERS technique. The superiority of this study is that we built the relation between the spectral changes of MPBA (relative intensities) in molecular recognition with the sialoglycan dynamic expression of cells. We believe that our SERS strategy could be further extended to explore crucial physiological processes and significant biological system that glycans are involved in.