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Abstract
The lack of an appropriate tool for visualizing cell membrane molecules at the nanoscale in a non-invasive and label free fashion limits our understanding of many vital cellular processes. Herein, we demonstrate that tip-enhanced Raman spectroscopy (TERS) is capable of visualizing 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 successfully reveals segregation of phenylalanine-rich and histidine-rich, phosphatidylcholine (PC) lipid-rich and protein-rich, as well as cholesterol-rich BxPC-3 cell membrane domains at the nanometer length-scale. Additionally, TERS imaging also showed a BxPC-3 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 biological cell membranes with nanoscale resolution.
