Ultrasensitive Label-Free Profiling of Glycans Released from Single Cells

A method of glycan analysis, the method comprising the steps of:

• (a) providing an open tube capillary electrophoresis instrument whose output provides an electrospray input for a mass spectrometer, a glycan release agent solution disposed within a capillary tube of the open tube capillary electrophoresis instrument, and a sample comprising a glycoprotein in an aqueous medium;
• (b) introducing the sample into an inlet of a capillary tube of the open tube capillary electrophoresis instrument, whereby the glycoprotein contacts the glycan release agent solution;
• (c) allowing the glycan release agent to release one or more glycan moieties from the glycoprotein without modification of glycan structure or composition;
• (d) separating the released glycan moieties within the capillary tube using the open tube capillary electrophoresis instrument based on charge and hydrodynamic volume of the released glycan moieties to form a plurality of separated glycan moieties within the capillary tube;
• (e) injecting the separated glycan moieties from an outlet of the capillary tube into the mass spectrometer, whereby the separated glycan moieties are ionized and fragmented to form a plurality of charged glycan fragments;
• (f) separating and detecting the charged glycan fragments based on mass-to-charge ratio using the mass spectrometer;
• and
• (g) analyzing the separated and detected charged glycan fragments, whereby one or more structural characteristics of said plurality of glycan moieties are determined.