Prussian Blue-modified microelectrodes for selective transduction in enzyme-based amperometric microbiosensors for in vivo neurochemical monitoring

• Published in: Electrochimica acta 2010-09, Vol.55 (22), p.6476-6484
• Main Authors: Salazar, P., Martín, M., Roche, R., O’Neill, R.D., González-Mora, J.L.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biosensor; Biosensors; Biotechnology; Carbon fiber electrodes; Fundamental and applied biological sciences. Psychology; Hydrogen peroxide; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Methods. Procedures. Technologies; Miscellaneous. Technology; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Poly(o-phenylenediamine); Prussian Blue; Various methods and equipments
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2010.06.036

Prussian Blue-modified carbon fiber microelectrodes (CFE/PBs) are proposed as an alternative to the more conventional metal transducers used for H 2O 2-detecting biosensors in brain extracellular fluid (ECF). The main advantages of this approach are the very small dimensions (∼10 μm diameter) and the low applied potentials needed (0.0 V versus SCE). Electrocatalytic and physiochemical properties of PB deposits were studied using cyclic voltammetric (CV), amperometric and spectroscopic methods (FTIR and VIS). Optimized CFE/PB microsensors displayed a H 2O 2 current density of 1.00 ± 0.04 A M −1 cm −2 with a detection limit of 10 −8 M. Furthermore, to improve stability and selectivity properties, several polymeric films were investigated: Nafion, poly(o-phenylenediamine) (PoPD), and a hybrid configuration of these two polymers. Finally, the PoPD film was selected due to its excellent anti-interference properties. The use of this permselective film also enhanced the stability of PB against solubilization at high pH, albeit at the expense of slightly lower H 2O 2 sensitivity (0.48 ± 0.02 A M −1 cm −2) and higher detection limit (∼10 −7 M). However, the use of the PoPD film significantly enhanced the selectivity against the main endogenous brain interference species (ascorbic acid, uric acid, dopamine and 3,4-dihydroxyphenylacetic acid), expressed as the ratio of the sensitivity slopes ( S H 2 O 2 / S interference ), which was close to 600 for all interference molecules studied. A prototype of a CFE/PB-based glucose microbiosensor design is presented, together with preliminary studies of its characteristics in vitro and its functionality in brain ECF in vivo.