UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2015 Meeting


Section: Biophysics; Medical Physics


Title:
Functionalized carbon nanoparticles as electrical bridges in enzyme loaded biopolymer layer-by-layer glucose biosensors


Authors:
Melinda DAVID (1), Monica FLORESCU (2), Christopher M. A. BRETT (3)


Affiliation:
(1) Facultatea de Fizica, Universitatea din Bucuresti, 077125, Bucuresti; Romania

(2) Facultatea de Medicina, Universitatea Transilvania, 500019, Brasov, Romania

(3) 1Departamento de Química, Faculdade de Ciências e Tecnologia,

Universidade de Coimbra, 3004-535 Coimbra, Portugal


E-mail
melinda.dav@gmail.com


Keywords:
layer-by-layer, quartz crystal microbalance, functionalized carbon nanomaterials, chitosan, glucose biosensors


Abstract:
Glucose oxidase (GOx) was incorporated into a multilayer film on a gold electrode constructed by the layer-by-layer (LbL) technique. Multilayer films containing the enzyme and carbon nanomaterials (CN) dispersed in the biocompatible positively-charged polymer chitosan (chit+(CN+GOx)), together with the negatively charged polymer poly(styrene sulfonate, PSS-), were assembled by alternately immersing a gold electrode substrate in chit+(CN+GOx) and PSS- solutions. A good electronic communication between the electrode and enzyme was ensured by carbon nanomaterials such as graphene (G) or carbon nanotubes (CNT) functionalized in either HNO3 or KOH. Gravimetric monitoring during LbL assembly by an electrochemical quartz microbalance enabled investigation of the adsorption mechanism and deposited mass for each monolayer. Cyclic voltammetry and electrochemical impedance spectroscopy led to identification of the assemblies with the best functionalized CN, KOH_G and HNO3_CNT, confirmed by the analytical properties of the glucose biosensors determined by fixed potential amperometry at 0.2 V vs. Ag/AgCl, exhibiting the highest sensitivities and lowest detection limits. The importance of CN in the biosensor architecture was evaluated by performing a comparative study without CN in the chitosan layer. This study approaches the development of new biosensor architectures, combining the advantages of CN with the LbL technique, for enzyme immobilization.


References:

A new self-assembled layer-by-layer glucose biosensor based on chitosan biopolymer entrapped enzyme with nitrogen doped graphene.” – Madalina M. Barsan, Melinda David, Monica Florescu, Laura Þugulea, Christopher M.A. Brett - Bioelectrochemistry 99 (2014) 46–52, DOI: 10.1016/j.bioelechem.2014.06.004

Acknowledgement:
MD thanks the European Commission for a grant under the Erasmus student exchange programme, and Prof. Dr. Aurel Popescu, University of Bucharest, Faculty of Physics for guidance.