title: Assessment of mitochondrial membrane potential using an on-chip microelectrode in a microfluidic device.
abstract: The mitochondrial membrane potential is used to generate and regulate energy in living systems, driving the conversion of ADP to ATP, regulating ion homeostasis, and controlling apoptosis, all central to human health and disease. Therefore, there is a need for tools to study its regulation in a controlled environment for potential clinical and scientific applications. For this aim, an on-chip tetraphenylphosphonium (TPP(+)) selective microelectrode sensor was constructed in a microfluidic environment. The concentration of isolated mitochondria (Heb7A) used in a membrane potential measurement was 0.3 ng microL(-1), four orders of magnitude smaller than the concentration used in conventional assays (3 microg microL(-1)). In addition, the volume of the chamber (85 microL) is 2 orders of magnitude smaller than traditional experiments. As a demonstration, changes in the membrane potential are clearly measured in response to a barrage of well-known substrates and inhibitors of the electron transport chain. This general approach, which to date has not been demonstrated for study of mitochondrial function and bio-energetics in generally, can be instrumental in advancing the field of mitochondrial research and clinical applications by allowing high throughput studies of the regulation, dynamics, and statistical properties of the mitochondrial membrane potential in response to inhibitors and inducers of apoptosis in a controlled (microfluidic) chemical environment.
authors.affiliation: Integrated Nanosystems Research Facility, Department of Electrical Engineering & Computer Science, University of California Irvine, Irvine, CA 92697-3940, USA.
authors.forename: Tae-Sun
authors.initials: TS
authors.lastname: Lim
authors.forename: Antonio
authors.initials: A
authors.lastname: Dávila
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Wallace
authors.forename: Peter
authors.initials: P
authors.lastname: Burke
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D006367:HeLa Cells; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000502:physiology*; D008839:Microelectrodes; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*
references.citation: Trends Neurosci. 2000 Apr;23(4):166-74
references.pmid: 10717676
references.citation: Annu Rev Genet. 2005;39:359-407
references.pmid: 16285865
references.citation: J Membr Biol. 1979 Aug;49(2):105-21
references.pmid: 490631
references.citation: Methods Enzymol. 1996;264:484-509
references.pmid: 8965721
references.citation: Anal Biochem. 2006 Jun 1;353(1):37-42
references.pmid: 16643832
references.citation: Methods Cell Biol. 2007;80:283-95
references.pmid: 17445700
references.citation: Physiol Rev. 2007 Jan;87(1):99-163
references.pmid: 17237344
references.citation: J Bioenerg. 1975 May;7(2):61-74
references.pmid: 241748
references.citation: Apoptosis. 2007 May;12(5):803-13
references.pmid: 17294081
references.citation: Methods Enzymol. 2008;442:355-74
references.pmid: 18662579
references.citation: J Membr Biol. 1984;81(2):127-38
references.pmid: 6492133
references.citation: Biochim Biophys Acta. 2003 Sep 30;1606(1-3):137-46
references.pmid: 14507434
references.citation: Arch Biochem Biophys. 1989 Dec;275(2):580-90
references.pmid: 2556969
references.citation: Oncogene. 2006 Aug 7;25(34):4812-30
references.pmid: 16892093
references.citation: Ernst Schering Found Symp Proc. 2007;(4):1-21
references.pmid: 18814355
references.citation: Biosci Rep. 2007 Jun;27(1-3):11-21
references.pmid: 17497220