Ultrafast analysis of oligosaccharides on microchip with light‐emitting diode confocal fluorescence detection

Abstract

We have developed a new method for the high-speed separation and high-sensitivity detection of complex oligosaccharides based on microchip electrophoresis (nu-CE) with light-emitting diode (LED) confocal fluorescence detection. Oligosaccharides labeled with 8-aminopyrene-1,3,6-trisulfonate (APTS) were found to strongly adsorb to the surface of polymethylmethacrylate (PMMA) microchips. Accordingly, three classes of major dynamic coating additives were systematically investigated, and cellulose derivatives were found to specifically suppress such adsorption and allow high-performance separation on PMMA chips. Additive concentration, buffer pH and applied field strength were found to be key factors in the high-performance separation& of APTS-labeled oligosaccharides on PMMA chips. Under optimal conditions, 15 oligosaccharides in dextrin hydrolysate can be separated within 45 s with an electrophoretic separation efficiency of over 400 000 theoretical plates per meter. The relative standard deviation (RSD) values of migration times of fourteen oligosaccharides were less than 0.50% between six different channels, and the detection limit for APTS-labeled glucose was about 1.98 x 10(-8) mol/L or 8.61 amol with a signal-to-noise ratio (S/N) of 3. The high speed, high efficiency and high sensitivity of this micro-CE-based method indicate that it can be widely applied to analysis of complex oligosaccharides.

A collinear light-emitting diode-induced fluorescence detector for capillary electrophoresis

“…Though the report demonstrated a miniaturized CE system, the separation capillary used was standard scale (48 m i.d.). And the LOD was slightly better than that quoted by Dang et al (19 nM for APTS-labeled glucose) using chipbased CE system [12].…”

“…In previous reports, the optical scheme of LED-FD is usually based on orthogonal configuration for eliminating the interference of excitation beam [3,4]. Some reports described the use of confocal configuration of LED-FD [11,12], but details were not given. Compared with above two schemes, collinear configuration has the advantages such as simple, compact and effective.…”

Surface modification in microchip electrophoresis

“…Dynamic coating methods were applied not only to control EOF and reduce analyte adsorption but also to make the hydrophobic PMMA surface more compatible with a hydrophilic separation medium. Dang et al [54] observed that the separation of oligosaccharides labeled with 8-aminopyrene-1,3,6-trisulfonate (APTS) in PMMA devices is impaired due to strong adsorption of the analytes to the PMMA surface. They systematically investigated different dynamic coating additives which were known to work well in classical CE using fused-silica capillaries.…”

Application of Online Preconcentration Affinity Capillary Electrophoresis Method to Glycans Labeled with 8-Aminonaphthalene-1,3,6-trisulfonic Acid Using Blue Light Emitting Diode-induced Fluorescence Detection

“…Tong and Yeung were the first to report the application of an absorption detection system for a CE separation based on red LEDs. 2 Since then, a number of different types of LED-induced fluorescence detectors for conventional CE [3][4][5][6][7][8] and microfluidic chip based CE [2][3][4] systems have been reported because they possess the advantages mentioned above. Lectins are proteins of non-immune origin that interact specifically with glycans without modifying them.…”