Indium Tin Oxide devices for amperometric detection of vesicular release by single cells Anne Meunier a , Rémy Fulcrand a , François Darchen b , Manon Guille Collignon a , Frédéric Lemaître a , Christian Amatore a, ⁎ a Ecole Normale Supérieure, Département de Chimie, UMR CNRS-ENS-UPMC 8640 « PASTEUR », 24 rue Lhomond, 75231 Paris cedex 05. France b CNRS/Université Paris Descartes UMR8192, 45 rue des Saints-Pères, 75270, Paris cedex 06, France HIGHLIGHTS ► Microfabrication of three microsys- tems for amperometric detection of exocytosis. ► Effect of collagen treatments on the electrochemical capability. ► Moderate collagen treatment does not induce any alteration of voltammetric responses or degradation of the signal-to-noise ratio. GRAPHICAL ABSTRACT abstract article info Article history: Received 26 October 2011 Received in revised form 9 December 2011 Accepted 18 December 2011 Available online 24 December 2011 Keywords: Exocytosis Amperometry Indium Tin Oxide microelectrode Microsystem Collagen surface treatment The microfabrication and successful testing of a series of three ITO (Indium Tin Oxide) microsystems for am- perometric detection of cells exocytosis are reported. These microdevices have been optimized in order to si- multaneously (i) enhance signal-to-noise ratios, as required electrochemical monitoring, by defining appropriate electrodes geometry and size, and (ii) provide surface conditions which allow cells to be cultured over during one or two days, through apposite deposition of a collagen film. The intrinsic electrochemical quality of the microdevices as well as the effect of different collagen treatments were assessed by investigat- ing the voltammetric responses of two classical redox systems, Ru(NH 3 ) 6 3+/2 + and Fe(CN) 6 3-/4 - . This estab- lished that a moderate collagen treatment does not incur any significant alteration of voltammetric responses or degradation of the excellent signal-to-noise ratio. Among these three microdevices, the most versatile one involved a configuration in which the ITO microelec- trodes were delimited by a microchannel coiled into a spiral. Though providing extremely good electrochem- ical responses this specific design allowed proper seeding and culture of cells permitting either single cell or cell cluster stimulation and analysis. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Vesicular exocytosis is a key biological mechanism allowing cell communication by release of bioactive molecules into extracellular medium. As such, the exact delineation of the main factors which command this crucial phenomenon has been the target of numerous investigations. It is now generally assumed that secretory vesicles filled with specific chemical messengers (neurotransmitters, hor- mones, peptides) are transported via the cytoskeleton network up to cell membranes where they eventually dock and fuse to release their content into the external medium after adequate stimulation [1]. Yet the exact details of each of these steps, especially those which control the fusion mechanism are still not fully understood. This has prompted the development of several specific physico-chemical Biophysical Chemistry 162 (2012) 14–21 ⁎ Corresponding author. Tel.: + 33 1 4432 3388; fax: +33 1 4432 3863. E-mail address: Christian.Amatore@ens.fr (C. Amatore). 0301-4622/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.bpc.2011.12.002 Contents lists available at SciVerse ScienceDirect Biophysical Chemistry journal homepage: http://www.elsevier.com/locate/biophyschem