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Electrochemically Assisted Encapsulation of Bacteria in Sol-Gel Thin Films

Wissam Ghach ,  Mathieu Etienne ,  Frédéric Jorand ,  Alain Walcarius 

Laboratoire de Chimie Physique et Microbiologie pour l'Environnement (LCPME), 405, rue de Vandoeuvre, Nancy 54600, France

Life-span viability accompanied with preserved activity of micro-organisms in solid support has gained considerable interests for bioelectrochemical applications including biofuel cells and biosensors for environmental monitoring. Sol-gel technology has proved its suitable environment for living cells entrapment and ensured their stability and activity enhancement better than free living cells [1]. The development of the electrochemically assisted deposition of sol-gel at the end of the nineties [2] has opened a larger window for bioencapsulation process in thin sol-gel films by using the electrochemical methods [3]. The Electrochemically assisted deposition has several advantages compared to other sol-gel methods that are based on solvent evaporation (spin-, dip-, spray-coatings). It exhibits the ability of film deposition on small electrodes (ultramicroelectrode) or non-flat supports, in-addition to the film deposition on conducting supports for useful electrochemical applications and monitoring. Moreover, the possibility of porosity control by using the template approach [4] and thickness control facilitates the interactions of trapped living cells with the surrounding environment for fluorescent and environmental analysis.

This communication intends to show some recent developments on sol-gel bioencapsulation using electrochemically assisted deposition applied to the immobilization of bacteria. The incorporation of biocompatible organic polymers to the inorganic sol-gel source has proved the mechanical enhancement of sol-gel deposition and stability. Furthermore, additional disaccharide has provided a more hydrophilic environment which is critical for bioencapsulation of micro-organisms in thin sol-gel film. This hybrid composition of sol-gel appeared to be critical for the long-term viability of trapped bacteria according to the bacterial membrane integrity studied by Live/Dead BacLight viability assay.  It proved a better long-term stability of the bacterial membrane integrity than that of inorganic composition of sol-gel [5]. Perspectives of bacterial respiration analysis and bioencapsulation of other complex biological objects with the electrochemically assisted methodology will be discussed later on.

[1] D. Avnir, T. Coradin, O. Lev, J. Livage, J. Mater. Chem., 2006, 16, 1013.
[2] R. Shacham, D. Avnir, D. Mandler, Adv. Mater., 1999, 11, 384.
[3] O. Nadzhafova, M. Etienne, A. Walcarius, Electrochem. Commun., 2007, 9 , 1189.
[4] A. Walcarius, E. Sibotier, M. Etienne, J. Ghanbaja, Nature Mater. 2007, 6, 602.
[5] T. M. Harrell, B. Hosticka,  M . E. Power, L. Cemke, R. Hull, P. M. Norris, J.  Sol-Gel Sci. Technol. 2004, 31, 349.

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Presentation: Poster at SMCBS'2011 International Workshop, by Wissam Ghach
See On-line Journal of SMCBS'2011 International Workshop

Submitted: 2011-08-31 15:49
Revised:   2011-08-31 16:26