Natural polymer coated magnetic nanoparticles for biosensing
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Natural polymer coated magnetic nanoparticles for biosensing Gloria Longinotti1, Paulina Lloret1, Regina Peter-Gauna2, Mariano Roberti3, Laura Malatto3, Diego Rey-Serantes4, Andrés Ciocchini4, Laura Hermida2, Gabriel Ybarra1, Liliana Fraigi3 and Carlos Moina1. 1
Instituto Nacional de Tecnología Industrial, INTI-Procesos Superficiales, Argentina. Instituto Nacional de Tecnología Industrial, INTI-Química, Argentina. 3 Instituto Nacional de Tecnología Industrial, INTI-Electrónica e Informática, Argentina. 4 Instituto de Investigaciones Biotecnológicas, UNSAM, Argentina. 2
ABSTRACT Superparamagnetic iron oxide nanoparticles coated with natural polymers have found many applications in the field of biosensors as magnetic carriers due to the combination of two characteristics: the possibility of controlling the particles movement by applying external magnetic fields and attaching biomolecules to the particle through a chemical bond. The aim of this work was to prepare long-term stabilized particles with acid groups available to be used as magnetic carriers of biomolecules. In this study, we present the synthesis of maghemite nanoparticles coated with alginate, a natural polymer. Particles were characterized by electron microscopy. Magnetic properties were studied by vibrating sample magnetometry, which revealed the superparamagnetic behavior of maghemite nanoparticles. Horseradish peroxidase (HRP) was chemically bonded to the maghemite-alginate particles and the enzymatic activity of HRP was determined by a colorimetric technique. The maghemite-alginate particles were immobilized onto the surface of a gold electrode by means of a magnet and the HRP activity was followed electrochemically, showing that these particles can be successfully used in amperometric sensors. Furthermore, maghemite-alginate particles were also used for the diagnosis of the foot-and-mouth disease by means of an enzyme-linked immunoassay with electrochemical detection. 3ABC protein, a non-structural protein of the virus, was linked to the maghemite-alginate particles and used to selectively detect anti-3ABC antibodies in cattle sera. Keywords: biological; magnetic; sensor INTRODUCTION Alginate is a natural, biocompatible polymer composed by β-D mannuronic acid and α-L guluronic acid units that can be found in cell walls of seaweeds [1]. It is used in pharmaceutical applications in the form of microspheres for drug delivery after crosslinking with divalent metals [2]. Superparamagnetic iron oxide nanoparticles (SPIONs) are used in drug delivery, magnetic resonance imaging contrast, and hyperthermia [3]. The interest of synthesizing superparamagnetic iron oxide nanoparticles coated with natural polymers is clear: such particles can be used as magnetic carriers, whose movement can be controlled by external magnetic fields, while biomolecules can be bonded to the polymer via a covalent bond. These particles may find many applications in the biosensors field, such as enzymatic electrodes, a type of biosensors formed by an electrode on whose surface a red
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