Nanoscale Chemical Imaging of Human Cell Membranes Using Tip‐Enhanced Raman Spectroscopy

Lack of appropriate tools for visualizing cell membrane molecules at the nanoscale in a non‐invasive and label‐free fashion limits our understanding of many vital cellular processes. Here, we use tip‐enhanced Raman spectroscopy (TERS) to visualize the molecular distribution in pancreatic cancer cell (BxPC‐3) membranes in ambient conditions without labelling, with a spatial resolution down to ca. 2.5 nm. TERS imaging reveals segregation of phenylalanine‐, histidine‐, phosphatidylcholine‐, protein‐, and cholesterol‐rich BxPC‐3 cell membrane domains at the nm length‐scale. TERS imaging also showed a cell membrane region where cholesterol is mixed with protein. Interestingly, the higher resolution TERS imaging revealed that the molecular domains observed on the BxPC‐3 cell membrane are not chemically “pure” but also contain other biomolecules. These results demonstrate the potential of TERS for non‐destructive and label‐free imaging of cell membranes with nanoscale resolution.