Nanostructured Fe3O4 satellite gold nanoparticles to improve biomolecular detection

摘要

Fe3O4 satellite gold nanoparticles (Fe3O4@Au) have proved to be very useful in biomedical and technolog-ical applications because of their unique optical, magnetic, and catalytic properties. The electrocatalyticproperties of Fe3O4@Au nanoparticles enable them to be used as mediator agents during the redoxof electroactive species. In this study, Fe3O4@Au were synthesized in the presence of generation fourpolyamidoamine (PAMAM G4). The Fe3O4@Au nanoparticles were immobilized by layer-by-layer (LbL)technique to develop dopamine sensors by alternately depositing layers of Fe3O4@Au nanoparticles andpoly(vinyl sulfonic acid) as polyanionic polymer onto an indium tin oxide electrode. The electrochemicalperformances of the indium tin oxide/poly(vinyl sulfonic acid) and indium tin oxide/gold nanoparti-cle/poly(vinyl sulfonic acid) electrodes were also investigated for comparison. The modified electrodeswere characterized using ultraviolet-vis absorption spectroscopy, Fourier transform infrared spec-troscopy, X-ray diffraction and cyclic voltammetry. The electrocatalytic properties of the iron oxide/goldnanoparticles configured throughout the indium tin oxide-iron oxide/gold/poly(vinyl sulfonic acid) archi-tecture promoted a dopamine oxidation process at a potential of 0.30 V, which is lower compared withthose observed for the other sensors. The dopamine sensor provided linear responses to dopamine inthe 4-100µM range with detection limit and quantification values as 3.94 × 10−8M and 15.5 × 10−8M,respectively. Furthermore, the main interferents to dopamine detection were ascorbic and uric acids,whose cyclic voltammograms showed oxidation peaks that, were displaced by 0.2 and 0.39 V in theirrespective binary mixtures with dopamine. The immobilized iron oxide/gold nanoparticles in the layer-by-layer-fabricated films exhibited an efficient electron transfer, which could be useful when such filmsare combined with other conjugated materials to detect electroactive species that are highly relevant inmedical applications.