title: Polyelectrolyte Multilayer-Treated Electrodes for Real-Time Electronic Sensing of Cell Proliferation.
abstract: We report on the use of polyelectrolyte multilayer (PEM) coatings as a non-biological surface preparation to facilitate uniform cell attachment and growth on patterned thin-film gold (Au) electrodes on glass for impedance-based measurements. Extracellular matrix (ECM) proteins are commonly utilized as cell adhesion promoters for electrodes; however, they exhibit degradation over time, thereby imposing limitations on the duration of conductance-based biosensor experiments. The motivation for the use of PEM coatings arises from their long-term surface stability as promoters for cell attachment, patterning, and culture. In this work, a cell proliferation monitoring device was fabricated. It consisted of thin-film Au electrodes deposited with a titanium-tungsten (TiW) adhesion layer that were patterned on a glass substrate and passivated to create active electrode areas. The electrode surfaces were then treated with a poly(ethyleneimine) (PEI) anchoring layer and subsequent bilayers of sodium poly(styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH). NIH-3T3 mouse embryonic fibroblast cells were cultured on the device, observed by optical microscopy, and showed uniform growth characteristics similar to those observed on a traditional polystyrene cell culture dish. The optical observations were correlated to electrical measurements on the PEM-treated electrodes, which exhibited a rise in impedance with cell proliferation and stabilized to an approximate 15 % increase as the culture approached confluency. In conclusion, cells proliferate uniformly over gold and glass PEM-treated surfaces, making them useful for continuous impedance-based, real-time monitoring of cell proliferation and for the determination of cell growth rate in cellular assays.
authors.affiliation: Semiconductor Electronics Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8120.
authors.forename: Geraldine I
authors.initials: GI
authors.lastname: Mijares
authors.affiliation: Semiconductor Electronics Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8120.
authors.forename: Darwin R
authors.initials: DR
authors.lastname: Reyes
authors.affiliation: Semiconductor Electronics Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8120.
authors.forename: Jon
authors.initials: J
authors.lastname: Geist
authors.affiliation: Semiconductor Electronics Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8120.
authors.forename: Michael
authors.initials: M
authors.lastname: Gaitan
authors.affiliation: Formerly of Semiconductor Electronics Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8120.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Polk
authors.affiliation: Department of Bioengineering and Department of Machanical Engineering, University of Maryland College Park, MD 20742.
authors.forename: Don L
authors.initials: DL
authors.lastname: DeVoe
keywords: biosensor; cell growth; electrical monitoring; gold electrodes; impedance spectroscopy; polyelectrolyte multilayers