Welcome to the Bioanalytical Laboratory webpage. We are located in McKinley Hall Room 329. The following introduction gives a brief overview of our research group.
Integrated Microfluidics Systems
Miniaturized lab-chip devices have unique capability in processing extreme edges in analytical chemistry. These analytical extremes include ultra-small sample volumes (pico- to nano-liters), ultra-low concentrations (single molecules or pico- to nano-molars), and ultra-fast analysis. Therefore, lab-chip platforms have the greatest potential to reduce analysis cost, to increase high-throughput screening, and to conduct lab automation. The Gong group designs, fabricates, and tests novel lab-chip devices and integrated microfluidic systems for bioanalytical applications in various areas including chemical separations, biomarker detection, in vivo measurements, and cell-to-cell signaling. Figure 1 shows a typical schematic setup of an integrated microfluidic system. This system is able to perform sequential procedures including microdialysis sampling, fluorogenic derivatization, flow-gated injection, electrophoretic separation, and laser-induced fluorescence detection. Note that multiple modules are interconnected through PDMS interfaces fabricated using a PDMS casting.
Figure 1. Schematic diagram of the PDMS-interconnected microfluidic system (see details in
the text). A, pin hole; B, excitation filter; C, emission filter. Capillaries between
syringes and the mixer have 10 cm x 40 μm ID, the one between the mixer and the second
connector had 32 cm long x 100 μm ID, and the one between the flow gate and the second
connector had 10 cm x 40 μm ID. The separation capillary was 16 cm in length x 10
μm ID. The gating flow was supplied through Tygon tubing with 0.5 mm ID.
Chemical Separations
Electrophoretic separations based on conventional capillaries and microchips are a powerful method in terms of high speed and high resolving power as well as small sample volumes required. Appropriate designs are able to perform sequential and parallel processes and analyses. Coupled with sensitive detectors such as laser-induced fluorescence and mass spectrometry, this technique has seen broad applications in challenging tasks. Upon specific targets, capillary electrophoresis (CE) will be developed for neutral and charged analytes. Factors affecting separations include pH, buffer categories and concentrations, buffer additives, capillary conditions, electric fields, and detector selectivity. All these parameters are required to be optimized for method development. The Gong group develops electrophoretic separations for challenging applications such as in vivo measurements and biomarker detection. Upon these developments, we would promote analytical separations to the next level of analytical extremes in terms of speed and resolving power. Figure 2 shows typical electropherograms for standard and in vivo samples from the rat brain.
Figure 2. (a) Typical electropherogram of 13 standard amino acids. (b) Typical electropherogram of in vitro brain dialysates. Separations were obtained by using 15 cm effective separation length at an electric field of 1000 V/cm. The separation buffer consisted of 10 mM LiTB (lithium tetraborate) and 26 mM LiDS (lithium dodecylsulfate) at pH 9.2. Peak assignments are: 1-Ser; 2- Gln; 3-His; 4-Gly; 5-Cit; 6-Ala; 7-Tau; 8-GABA; 9-Val; 10-Glu; 11-Asp; 12-DA; 13-Arg. Un-marked peaks are un-identified ones. Standard amino acids 5 μM each in aCSF (artificial cerebrospinal fluid).
Brain Connectivity
The brain is a well-organized organ in which different brain regions cooperate in task-oriented functions such as memory and motor tasks. Structurally, various brain regions are interconnected through neural fibers; functionally, remote brain regions cooperate to enhance functional accuracy; and effectively, brain regions have monolateral or bilateral information flow and corresponsive feedback. Thus, the brain has three connectivity levels: structural connectivity, functional connectivity, and effective connectivity, among which the functional and effective connectivity is realized through remote inter-neural signaling. This interneuron communication is often through neurotransmitter release and mass transmission, but conventional techniques (such as fMRI and PET) have difficulty in identifying involved neurotransmitters or other messengers. The Gong group is developing separation-based method coupled with microdialysis to study brain connectivity thus promoting the understanding of neural degenerative diseases such as Parkinson’s. The objective of this research is to identify specific neurotranstmitters involved in brain functional connectivity. The method will be based on multiple-location microdialysis at various brain regions followed by electrophoretic separations on an integrated microfluidic platform. Also, pharmacokinetics and pharmacodynamics will be studied via multiple-location measurements including blood vessel and brain regions.
Biomarker Detection and Discovery
A biomarker is a chemical that exists in the human body between normal ranges for healthy people. These biomarkers can be smaller molecules such as hormones and metabolites of catecholamines, and can also be large molecules such as PSA (Prostate-Specific Antigen) and beta-Amyloid. Concentrations out of their normal range often indicate abnormal situation of the human body. For example, patients with prostate cancer often observe elevated serum PSA concentrations, and pheochromocytoma diagnosis can be performed via chemical testing of catecholamines and methanephrines in blood and urine. Therefore, accurate and rapid determination of biomarkers in biological fluids is valuable for early diagnosis and routine screening of deadly diseases. The Gong group is developing bioanalytical technology and tools to enhance biomarker detection and discovery. The objective is to develop integrated microfluidic tools and technologies for rapid and accurate measurements of PSA and free methanephrine in blood plasma. The platform is based on lab-on-a-chip devices coupled with sensitive detectors. The method will be based immunoassay with Aptamers and electrophoretic separations.