title: Detecting transforming growth factor-β release from liver cells using an aptasensor integrated with microfluidics.
abstract: We developed a cell-culture/biosensor platform consisting of aptamer-modified Au electrodes integrated with reconfigurable microfluidics for monitoring of transforming growth factor-beta 1 (TGF-β1), an important inflammatory and pro-fibrotic cytokine. Aptamers were thiolated, labeled with redox reporters, and self-assembled on gold surfaces. The biosensor was determined to be specific for TGF-β1 with an experimental detection limit of 1 ng/mL and linear range extending to 250 ng/mL. Upon determining figures of merit, aptasensor was miniaturized and integrated with human hepatic stellate cells inside microfluidic devices. Reconfigurable microfluidics were developed to ensure that seeding of "sticky" stromal cells did not foul the electrode and compromise sensor performance. This microsystem with integrated aptasensors was used to monitor TGF-β1 release from activated stellate cells over the course of 20 h. The electrochemical response went down upon infusing anti-TGF-β1 antibodies into the microfluidic devices containing activated stellate cells. To further validate aptasensor responses, stellate cells were stained for markers of activation (e.g., alpha smooth muscle actin) and were also tested for presence of TGF-β1 using enzyme linked immunosorbent assay (ELISA). Given the importance of TGF-β1 as a fibrogenic signal, a microsystem with integrated biosensors for local and continuous detection of TGF-β1 may prove to be an important tool to study fibrosis of the liver and other organs.
authors.affiliation: Department of Biomedical Engineering, University of California , Davis, California 95616, United States.
authors.forename: Zimple
authors.initials: Z
authors.lastname: Matharu
authors.forename: Dipali
authors.initials: D
authors.lastname: Patel
authors.forename: Yandong
authors.initials: Y
authors.lastname: Gao
authors.forename: Amranul
authors.initials: A
authors.lastname: Haque
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhou
authors.forename: Alexander
authors.initials: A
authors.lastname: Revzin
mesh_terms: D000906:Antibodies / Q000276:immunology; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation*; D002460:Cell Line; D055664:Electrochemical Techniques; D004566:Electrodes; D004797:Enzyme-Linked Immunosorbent Assay; D055166:Hepatic Stellate Cells / Q000166:cytology / Q000378:metabolism; D006801:Humans; D044085:Microfluidics / Q000295:instrumentation*; D020349:Surface Plasmon Resonance; D053773:Transforming Growth Factor beta1 / Q000032:analysis* / Q000378:metabolism
chemical_list: D000906:Antibodies; D052157:Aptamers, Nucleotide; D053773:Transforming Growth Factor beta1
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