Determination of trace metal release during corrosion characterization of FeCo-based amorphous metallic materials by stripping voltammetry. New materials for GMI biosensors F.F. Marzo a, * , A.R. Pierna a , J. Barranco a , A. Lorenzo a , J. Barroso a , J.A. García b , A. Pérez c a Chemical Engineering and Environment Department, University of the Basque Country, UPV-EHU, Plaza de Europa, 20018 San Sebastian, Spain b Department of Physics, University of Oviedo, c/Calvo Sotelo s/n, 33007, Oviedo, Spain c Graphical Expression and Engineering Projects Department, University of the Basque Country, UPV-EHU, La Casilla, No. 3, 48012, Bilbao, Spain article info Article history: Available online 18 October 2008 PACS: 82.45.Bb 81.65.kn 81.65.Rv 82.45.Rr 82.80.Fk Keywords: Alloys Biomaterials Biosensors Corrosion Electrochemical properties Magnetic properties abstract The objective of this investigation has been the study of metal release during corrosion characterization of Fe 2.5 Co 64.5 Cr 3 Si 15 B 15 , Fe 3 Co 67 Cr 3 Si 15 B 12 and Fe 5 Co 70 Si 15 B 10 amorphous metallic alloys, used as based materials to create new type for giant magnetoimpedance (GMI) biosensors. Alloy samples were tested in phosphate buffered saline solutions (PBS, artificial biological solutions) at pH 7.4 and 22 °C. Individual alloy constituents (Fe, Co, Cr, B) released during the electrochemical corrosion tests, were analyzed by dif- ferential pulse stripping voltammetry (DP) using a hanging mercury drop electrode technique (HMDE). In this work, the experimental results obtained are discussed in order to study their corrosion behavior in artificial biological solutions and thus determine their possible use as GMI biosensor prototype materials. Ó 2008 Elsevier B.V. All rights reserved. 1. Introduction Giant magnetoimpedance (GMI) effect has recently been pro- posed for the detection of magnetically labeled biomolecules pro- viding a biosensor-like character to the materials that show such an effect [1–3]. High sensitivity, small size, stability of operation parameters, quick response and resistance to aggressive medium, are some of the requirements for this new generation of biosen- sors. In the reported GMI biosensor prototype [1], stable FeCoMo- SiB ribbon without any protective layer was used as a sensitive element. Co-based amorphous alloys ribbons showed high soft magnetic properties (GMI) with regard to the magnetic field as well as high stability. Corrosion resistance plays a decisive role in determining the successful use of metal alloys as biomaterials and is a vital prop- erty for this kind of application once physiological fluids are chloride containing solutions. Corrosion process can alter the magnetic properties of the sensor altering its GMI effect since this property is mainly a skin effect [4]. Moreover, metal ions re- leased from metallic biomaterials during corrosion are largely responsible for limited biocompatibility and can produce unde- sirable reactions. Thus the quantification of corrosion and metal ion release from Co-based amorphous alloys ribbons is a very important issue in order to study the viability of such materials as sensor elements in GMI biosensors. The aim of the current study is to provide quantitative data of metal release during cor- rosion characterization of Fe 2.5 Co 64.5 Cr 3 Si 15 B 15 , Fe 3 Co 67 Cr 3 Si 15 B 12 and Fe 5 Co 70 Si 15 B 10 biosensor prototype amorphous materials [4–6], in biological phosphate buffered saline solution (PBS) medium by stripping voltammetry. 2. Experimental setup Alloys ingots of Fe 2.5 Co 64.5 Cr 3 Si 15 B 15 (alloy A1), Fe 3 Co 67 Cr 3- Si 15 B 12 (alloy A2), and Fe 5 Co 70 Si 15 B 10 (alloy B) were prepared by induction melting under He atmosphere. From these ingots, amor- phous alloy ribbons of about 2 mm wide and 20–30 lm thick were prepared by planar flow casting method. The amorphous structure of the samples was verified by X-ray diffraction. 0022-3093/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jnoncrysol.2008.08.014 * Corresponding author. Fax: +34 943017130. E-mail address: iapfemaf@sp.ehu.es (F.F. Marzo). Journal of Non-Crystalline Solids 354 (2008) 5169–5171 Contents lists available at ScienceDirect Journal of Non-Crystalline Solids journal homepage: www.elsevier.com/locate/jnoncrysol