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Volume 7, Issue 2 (Suppl) J Biotechnol Biomater
ISSN: 2155-952X JBTBM, an open access journal Biomaterials 2017
March 27-28, 2017
2nd Annual Conference and Expo on
March 27-28, 2017 Madrid, Spain
Tiago Monteiro et al., J Biotechnol Biomater 2017, 7:2 (Suppl)
Co-immobilization of glucose oxidase and catalase on electrodes’ surface: A multifunctional tool for
biosensing applications
Tiago Monteiro, Sara Gomes, Célia Silveira and M Gabriela Almeida
Universidade Nova de Lisboa, Portugal
Real world application of reductase-based electrochemical biosensing devices is limited by the need of anaerobic working
conditions. Molecular oxygen is a main interferent because (a) it can react with many redox mediators in their reduced form, and
(b) the reduction of oxygen at the working electrode surface generates an intense background noise that can mask important redox
processes occurring between -200 and -800 mV (vs SHE). Standard laboratorial oxygen removal strategies, such as argon purging or
vacuum degassing, are incompatible with on-site monitoring. Alternatively, a bi-enzymatic scavenging system that efficiently reduces
the soluble oxygen content in small volume samples, and can maintain anaerobic conditions in an open-air environment for extended
periods of time, was adapted for biosensing purposes. The scavenging system is composed by glucose oxidase (GOx) and catalase (Cat)
in solution and uses the glucose as main substrate, removing oxygen in a two-step cycle. This strategy was successfully employed with
a miniaturized reductase-based biosensing tool to monitor nitrite in real samples. We now aim at making the scavenging system an
integral part of the biosensors, simplifying operating procedures and reducing costs. Therefore, we have immobilized GOx and Cat on
pyrolytic graphite electrodes, using a silica sol-gel matrix, and tested the system’s ability to provide local anaerobic conditions. Several
combinations of GOx/Cat in solution and in the immobilized state were prepared and the electrochemical response, in non-deareated
solutions containing glucose, was monitored by cyclic voltammetry. Our results showed that although the scavenging system was
more effective when in solution, the co-immobilized GOx and Cat were still able to provide a satisfactory anaerobic environment.
Additionally, the configurations containing either immobilized GOx or Cat were explored as biosensing tools to monitor glucose and
hydrogen peroxide, respectively. The GOx-based bioelectrode responded linearly to glucose concentrations from 1.2 – 7 mM.
Biography
Tiago Monteiro is a second year PhD student at the Doctoral Program in Sustainable Chemistry at Faculdade de Ciências e Tecnlogia, Universidade Nova de
Lisboa, Portugal. He has previously obtained a MSc degree in Biotechnology (2013) and a BSc degree in Molecular and Cellular Biology (2011) at the same
institution.