title: Design, development, and validation of an in-situ biosensor array for metabolite monitoring of cell cultures.
abstract: Conventional pharmaceutical processes involving cell culture growth are generally taken under control with expensive and long laboratory tests performed by direct sampling to evaluate quality. This traditional and well-established approach is just partially adequate in providing information about cell state. Electrochemical enzyme-based biosensors offer several advantages towards this application. In particular, they lend themselves to miniaturization and integration with cheap electronics. In the present work we go through the design, the development, and the validation of a self-contained device for the on-line measurement of metabolites in cell culture media. We microfabricated a sensing platform by using thin film technologies. We exploited electrodeposition to precisely immobilize carbon nanotubes and enzymes on miniaturized working electrodes. We designed and realized the electronics to perform the electrochemical measurements and an Android application to display the measurements on smartphones and tablets. In cell culture media glucose biosensor shows a sensitivity of 4.7 ± 1.3 nA mM(-1)mm(-2) and a detection limit of 1.4mM (S/N = 3σ), while for lactate biosensor the sensitivity is 12.2 ± 3.8 nA mM(-1)mm(-2) and the detection limit is 0.3mM. The whole system was then validated by monitoring U937 cell line over 88 h. Metabolic trends were fully congruent with cell density and viability. This self-contained device is a promising tool to provide more detailed information on cell metabolism that are unprecedented in cell biology.
authors.affiliation: Laboratory of Integrated Systems, EPFL, Lausanne 1015, Switzerland. Electronic address: cristina.boero@epfl.ch.
authors.forename: Cristina
authors.initials: C
authors.lastname: Boero
authors.affiliation: Laboratory of Integrated Systems, EPFL, Lausanne 1015, Switzerland.
authors.forename: Maria Antonietta
authors.initials: MA
authors.lastname: Casulli
authors.affiliation: Laboratory of Integrated Systems, EPFL, Lausanne 1015, Switzerland.
authors.forename: Jacopo
authors.initials: J
authors.lastname: Olivo
authors.affiliation: Laboratory of Integrated Systems, EPFL, Lausanne 1015, Switzerland.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Foglia
authors.affiliation: Department of Electronics Engineering, EIA, Fribourg 1705, Switzerland.
authors.forename: Eric
authors.initials: E
authors.lastname: Orso
authors.affiliation: Department of Electronics Engineering, EIA, Fribourg 1705, Switzerland.
authors.forename: Marco
authors.initials: M
authors.lastname: Mazza
authors.affiliation: Laboratory of Integrated Systems, EPFL, Lausanne 1015, Switzerland.
authors.forename: Sandro
authors.initials: S
authors.lastname: Carrara
authors.affiliation: Laboratory of Integrated Systems, EPFL, Lausanne 1015, Switzerland.
authors.forename: Giovanni
authors.initials: G
authors.lastname: De Micheli
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D018929:Cell Culture Techniques / Q000295:instrumentation*; D003470:Culture Media / Q000737:chemistry / Q000378:metabolism*; D004563:Electrochemistry / Q000295:instrumentation; D004867:Equipment Design; D005947:Glucose / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D019344:Lactic Acid / Q000032:analysis / Q000378:metabolism*; D057230:Limit of Detection; D008839:Microelectrodes; D037742:Nanotubes, Carbon / Q000737:chemistry / Q000648:ultrastructure; D020298:U937 Cells
chemical_list: D003470:Culture Media; D037742:Nanotubes, Carbon; D019344:Lactic Acid; D005947:Glucose
keywords: Carbon nanotubes; Cell culture; Electrochemical biosensor; Glucose deprivation; Metabolite; Oxidase