Measurement of Molecular Height Using Cell Surface Optical Profilometry (CSOP)

Area of Science:

• Cell biology
• Biophysics
• Surface science

Background:

• Cell membranes feature a glycocalyx composed of proteins, glycoproteins, and glycolipids.
• Glycocalyx height influences cell-cell interactions and signal transduction.
• Accurate measurement of molecular heights on native cell surfaces is challenging.

Purpose of the Study:

• To introduce and detail the methodology of Cell Surface Optical Profilometry (CSOP).
• To demonstrate CSOP's capability for nanometer-scale height resolution on cell surfaces.
• To enable precise height measurements of cell surface molecules, including multi-domain proteins.

Main Methods:

• Cell Surface Optical Profilometry (CSOP) utilizes fluorophores at molecule tips and bases.
• Radially averaging across multiple molecules enhances measurement precision.
• CSOP achieves high precision in determining molecular separation on membrane surfaces.

Main Results:

• CSOP provides nanometer-scale height resolution for cell surface molecules.
• The method is effective on both model membrane surfaces and native cell surfaces.
• CSOP overcomes limitations of traditional super-resolution imaging for axial height measurements.

Conclusions:

• CSOP is a simple, rapid, and precise method for measuring molecular heights on cell surfaces.
• This technique offers a valuable tool for studying cell surface architecture and function.
• CSOP enables new investigations into nanometer-scale variations in cell surface protein heights.