University of North Florida
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Contact Info

Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Guoquan Liu

Abbrev:
Liu, G.Q.
Other Names:
Address:
Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100080, PR Chinab Institute of Basic Medical Sciences, Beijing 100850, PR China
Phone:
+86-10-62557910
Fax:
+86-10-62559373

Citations 5

"Quartz Crystal Biosensor For Real-time Kinetic Analysis Of Interaction Between Human TNF-α And Monoclonal Antibodies"
Sens. Actuat. B 2004 Volume 99, Issue 2-3 Pages 416-424
Yang Liu, Wei Zhang, Xiao Yu, Hongwu Zhang, Rui Zhao, DiHua Shangguan, Yan Li, Beifen Shen and Guoquan Liu

Abstract: Quartz crystal microbalance (QCM) biosensor integrated in a flow injection analysis (FIA) system was used for the real-time investigation of the interaction between human TNF-α (hTNF-α) and its monoclonal antibodies (mAbs). Biologically active hTNF-α trimer was immobilized on the gold electrodes of the piezoelectric crystals and the binding interactions of the two immobilized antigen with two anti-hTNF-α monoclonal antibodies (Z8 and Z12) were followed as changes in the resonant frequency of the modified crystals. The resultant sensorgrams were rapidly analyzed by using an in-house kinetic analysis software based on genetic algorithm (GA) to derive both the kinetic rate constants (kass and kdiss) and equilibrium dissociation constant (KD) for antigen-antibody interactions. For the interactions, KD were 2.31 x 10^-7 and 5.42 x 10^-7 M for Z8 and Z12, respectively. The generally good agreement found between biosensor data and the affinities known from conventional equilibrium enzyme-linked immunosorbent assay (ELISA) validates this analytical method. The study shows the potential usefulness of QCM biosensor technology for biomolecular interaction analysis.

"Analysis Of Glucose And Lactate In Hippocampal Dialysates Of Rats During The Operant Conditioned Reflex Using Microdialysis"
Neurochem. Int. 2003 Volume 43, Issue 1 Pages 67-72
Yu Dong, Lei Wang, Dihua Shangguan, Xiao Yu, Rui Zhao, Huiwan Han and Guoquan Liu

Abstract: Changes of extracellular glucose and lactate in hippocampus for freely moving rats during the operant conditioned reflex were examined simultaneously. Samples of the dialysate were assayed for both glucose and lactate using in vivo microdialysis and a microbore flow injection analysis-immobilized enzyme reactor-electrochemical detection (FIA-IMER-ECD) system. Microdialysis samplings were conducted in a Skinner box where lights were delivered as conditioned stimuli (CS) paired with foot shocks as unconditioned stimuli (US). In the treatment group the concentration of glucose and lactate showed no fluctuations during the whole process. However, in the control group in which the rats were exposed to many foot shocks, lactate levels decreased by 19% below baseline during the behavioral session and glucose showed a delayed decrease (by 18%). Compared with glucose, lactate can immediately indicate the dynamic changes in brain.

"Quartz Crystal Biosensor For Real-time Monitoring Of Molecular Recognition Between Protein And Small Molecular Medicinal Agents"
Biosens. Bioelectron. 2003 Volume 19, Issue 1 Pages 9-19
Yang Liu, Xiao Yu, Rui Zhao, Di-Hua Shangguan, Zuyi Bo and Guoquan Liu

Abstract: A quartz crystal microbalance (QCM) biosensor integrated into a flow injection analysis (FIA) system was used for the real-time investigation of molecular recognition between a protein and small molecular medicinal agents. Two sulfa-drugs, sulfamethazine (SMZ) and sulfamethoxazole (SMO), were, respectively, immobilized on the gold electrodes of the piezoelectric crystals using appropriate procedures based on self-assembly of the dithiothreitol (DTT). The binding interactions of the two immobilized drug ligands, with various proteins in solution, were followed as changes in the resonant frequency of the modified crystals. Results obtained from this rapid screen analysis clearly indicated that the two drug ligands appeared quite different in this molecular recognition procedure although their structures were similar. SMZ-immobilized sensor showed specific interaction only with IgG, while SMO-immobilized sensor showed negligible specific binding with IgG, but binding with trypsin and chymotrypsin. Further studies on the specific interaction between immobilized SMZ and three different species of IgG--human IgG, goat IgG and mouse IgG were carried out and the marked species-dependent difference was observed. The resultant sensorgrams were rapidly analyzed by using an in-house kinetic analysis software based on genetic algorithm (GA) to derive both the kinetic rate constants (kass and kdiss) and equilibrium association constants (KA) for IgG-SMZ interactions. For the interactions, KA were 5.48 x l05, 2.75 x l05 and 1.86 x l05 M-1 for human IgG, goat IgG and mouse IgG, respectively. The kinetic data provided further insight into the structural/functional relationships of different IgG on a molecular level.

"Real Time Kinetic Analysis Of The Interaction Between Immunoglobulin G And Histidine Using Quartz Crystal Microbalance Biosensor In Solution"
Biosens. Bioelectron. 2003 Volume 18, Issue 11 Pages 1419-1427
Yang Liu, Xiao Yu, Rui Zhao, Di-Hua Shangguan, Zuyi Bo and Guoquan Liu

Abstract: Quartz crystal microbalance (QCM) biosensor integrated in a flow injection analysis (FIA) system was used for the investigation of the specific interaction between immunoglobin G (IgG) and histidine. The histidine was immobilized on the gold electrodes of the piezoelectric crystal using appropriate procedures based on self-assembling of the dithiothreitol (DTT). The specific interaction of the immobilized ligand with IgG in solution was followed as a change in the resonant frequency of the modified crystal and studied in real time without any additional labels. With the mass sensitive biosensor system, the differences in affinity of three different species of IgG: human IgG, goat IgG and mouse IgG were easily distinguished and their respective kinetic rate constants (kass and kdiss) and equilibrium association constants (KA) were determined from the curves of frequency versus time. For the interactions, KA were 2.92 x 104, 3.23 x 104 and 4.08 x 104 M-1 for human IgG, goat IgG and mouse IgG, respectively.

"Analysis Of Glucose And Lactate In Dialysate From Hypothalamus Of Rats After Exhausting Swimming Using Microdialysis"
Biomed. Chromatogr. 2002 Volume 16, Issue 7 Pages 427-431
L. Wang, Y. Dong, X. Yu, D. H. Shangguan, R. Zhao, H. W. Han, G. Q. Liu

Abstract: A microbore flow injection analysis-immobilized enzyme reactor-electrochemical detection (FIA-IMER-ECD) system for glucose and lactate detection was built up. The assays were precise, sensitive and practicable for determination of glucose and lactate levels in hypothalamic dialysate. The method had been used to detect the dynamic changes of glucose and lactate levels during rat exhausting swimming and recovery. The data showed that after exhausting swimming, the concentration of glucose in hypothalamic dialysate that reflected the concentration in the hypothalamic extracellular fluid decreased. The level fell to its nadir at day 1 after the exercise and then went back to the basal level at day 3 after the swimming. However, lactate levels increased to a maximum at day 3 and went back to the basal level at day 5 after the swimming.
Glucose