Online Liquid Chromatography–Sheath-Flow Surface Enhanced Raman Detection of Phosphorylated Carbohydrates

Abstract

Online detection and quantification of three phosphorylated carbohydrate molecules: glucose 1-phosphate, glucose 6-phosphate, and fructose 6-phosphate was achieved by coupling sheath-flow surface enhanced Raman spectroscopy (SERS) to liquid chromatography. The presence of an alkanethiol (hexanethiol) self-assembled monolayer adsorbed to a silver SERS-active substrate helps retain and concentrate the analytes of interest at the SERS substrate to improve the detection sensitivity significantly. Mixtures of 2 μM of phosphorylated carbohydrates in pure water as well as in cell culture media were successfully separated by HPLC, with identification using the sheath-flow SERS detector. The quantification of each analyte was achieved using partial least-squares (PLS) regression analysis and acetonitrile in the mobile phases as an internal standard. These results illustrate the utility of sheath-flow SERS for molecular specific detection in complex biological samples appropriate for metabolomics and other applications.

Copper-Oxide-Coated Silver Nanodendrites for Photoelectrocatalytic CO2 Reduction to Acetate at Low Overpotential

“…The shape of the dendrites is well conserved, and the vertices and junctions of the Ag are still evident. The vertices, points, and junctions present in the Ag dendritic structures are responsible for the previously reported enhancement of Raman signals . The thickness of the deposited Cu 2 O/CuO layer is controllable with the deposition time and the pulsed potential during the electrodeposition process.…”

“…The vertices, points, and junctions present in the Ag dendritic structures are responsible for the previously reported enhancement of Raman signals. 45 The thickness of the deposited Cu 2 O/CuO layer is controllable with the deposition time and the pulsed potential during the electrodeposition process. The TEM images obtained from a piece of the dendrite surface in Figure 1b and c show that a thin layer approximately 7 nm thick is formed over the Ag dendrite with a 1 min Cu electrodeposition time and a pulsed potential between −0.35 and −0.4 V versus Ag/AgCl.…”

Untargeted Tumor Metabolomics with Liquid Chromatography–Surface‐Enhanced Raman Spectroscopy

“…In proof‐of‐concept experiments, the detection and disappearance of rhodamine was observed, which indicates fouling is avoidable . Furthermore, coupling the sheath‐flow SERS approach with chromatography techniques (such as CZE and LC) allows for sequential detection of low concentration analytes, such as amino acids, peptides, b‐vitamins, and phosphorylated sugars . In our most recent work, phosphorylated sugars were identified and quantified in the presence of cell culture media, suggesting complex biological matrices are feasible to use as analytes …”

Microfluidics and Surface-Enhanced Raman Spectroscopy: A Perfect Match for New Analytical Tools

“…The SERS effect can be used as an efficient in situ detection tool coupled to flow processes at microscale. In particular, separation methods have largely benefited from microfluidic principles such as liquid chromatography, by introducing variants of the sheath-flow (hydrodynamic flow focusing) method [80], which are also widely used in cytometry. The sheath-flow is based on the splitting of a liquid sample within droplets or slugs thanks to the squeezing of the sample by another fluid (liquid or gas) within a microfluidic channel.…”