Shaorong Liu, Analytical Chemistry

My research interests include development of various chemical separation and analysis methods, integration of these methods into microfabricated devices, and application of these microfabricated devices for high-throughput and cost-effective bioanalysis. I am also interested in understanding the fundamental aspects of micro-fluidics and associated subjects.

Currently, our research is focused on micro devices for high-speed and high-throughput analysis of protein/peptide molecules. Because many proteins can be adsorbed to inner walls of the silica capillaries, the capillary surfaces need to be coated. Many methods have been developed, but still not fully satisfactory. One of our research projects is to address this issue. We have recently made some significant progress in this direction. Figure 1 presents some separation results obtained using the capillaries with our new coatings. The separation efficiencies are very high, and more than 1.4 million plates per meter have been achieved. Figure 2 below presents some typical CIEF separation results.


Fig. 1. Left: CZE separations of protein standard. Protein concentration: 0.25 mg/mL each. Peak identifications: 1 - cytochrome c; 2 - lysozyme; 3 - trypsinogen; 4 – α- chymotrypsinogen A. Right: CZE separation of bovine albumin tryptic digests. The sample contained ~ 0.5 mg/mL of bovine albumin.

Fig. 2. Left: CIEF separation of standard protein pI markers. 1 - trypsinogen (pI 9.30); 2 - lentil lectin-basic band (pI 8.65); 3 - lentil lectin-middle band (pI 8.45); 4 - lentil lectin-acidic band (pI 8.15); 5 - myoglobin-basic band (pI 7.35); 6 - myoglobin- acidic band (pI 6.85); 7 - human carbonic anhydrase B (pI 6.55); 8 - bovine carbonic anhydrase B (pI 5.85); 9 - b-lactoglobulin A (pI 5.20); 10 - trypsin inhibitor (pI 4.55); 11 - amyloglucosidase (pI 3.50). Right: CIEF separation of crude protein extract.

Because the number of proteins in a cell can be many thousands, the associated problem is the limited resolution to resolve all the proteins. An efficient way to improve the resolution is to improve the sieving matrix that will generate high resolutions. We have recently developed a new sieving matrix for high-quality SDS-PAGE. Figure 3 presents a typical high-resolution separation of proteins.

Another active area of research in our group is to discover and investigate the new phenomena associated with nanometer-scale fluidic channels. We are also developing open channel EO pumps for integrated microfluidic systems for bioanalysis.

Fig. 3. (a) Electropherogram of a capillary SDS-PAGE separation of a crude E. Coli cell extract; (b) Electropherogram of a broad MW protein size marker. Protein identification: a - Aprotinin (6.5 kD), b - Lysozyme (14.4 KD), c - Trypsin inhibitor (21.5 kD), d - Carbonic anhydrase (31 kD), e - Ovalbumin (45 kD), f - Serum albumin (66 kD), g - Phosphorylase b (97 kD), h - β-galactosidase (116 kD) and i - Myosin (200 kD).

Selected Publications

"Replaceable Crosslinked Polyacrylamide for High Performance Separation of Proteins", Lu, J. J.; Liu, S.; Pu, Q. Journal of Proteome Research 2005, in press.
"The enhanced PC and PEC oxidation of formic acid in aqueous solution using a Cu–TiO2/ITO film", He, C.; Li, X.; Xiong, Y.; Zhu, X.; Liu, S. Chemosphere 2005, 58, 381–389.
"Fabrication of nanofluidic devices by anodic bonding of amorphous silicon to glass", Datta, A.; Gangopadhyay, S.; Temkin, H.; Pu, Q.; Liu, S. Talanta 2005, in press.
"Cross-Linked Polyacrylamide Coating for Capillary Isoelectric Focusing", Gao, L.; Liu, S. Analytical Chemistry 2004, 76, 7179-7186.
"Electrophoresis Microchips for DNA Analysis", Liu, S.; Guttman, A. Trends in Analytical Chemistry 2004, 23, 422-431.
"Ion-enrichment and ion-depletion effect of nanochannel structures", Pu, W.; Yun, J.; Temkin, H.; Liu, S. Nano Letters 2004, 4, 1099-1103.
"A microfabricated Electroosmotic Pump for Capillary-based Sequential Injection Analysis", Pu, Q.; Liu, S. Analytica Chimica Acta 2004, 511, 105-112.
"A Microfabricated Stand-alone Pump for Microfluidic Systems", Liu, S. Journal of Chromatography A 2003, 1013, 57-64.
"Parallel Sequencing of Real-World Samples Using A Microfabricated Hybrid Device", Liu, S.; Elkin, C.; Kapur, H. Electrophoresis 2003, 24, 3762-3768.
"A Microfabricated Hybrid Device for High Speed and Long Readlength DNA Sequencing", Liu, S. Electrophoresis 2003, 24, 3755-3761.