Abstract
In this article, it is shown that the efficiency of an electrochemical aptasensing device is influenced by the use of different nanoparticles (NPs) such as gold nanoparticles (Au), silver nanoparticles (Ag), hollow gold nanospheres (HGN), hollow silver nanospheres (HSN), silver–gold core shell (Ag@Au), gold–silver core shell (Au@Ag), and silver–gold alloy nanoparticles (Ag/Au). Among these nanomaterials, Ag@Au core shell NPs are advantageous for aptasensing applications because the core improves the physical properties and the shell provides chemical stability and biocompatibility for the immobilization of aptamers. Self-assembly of the NPs on a cysteamine film at the surface of a carbon paste electrode is followed by the immobilization of thiolated aptamers at these nanoframes. The nanostructured (Ag@Au) aptadevice for Escherichia coli as a target shows four times better performance in comparison to the response obtained at an aptamer modified planar gold electrode. A comparison with other (core shell) NPs is performed by cyclic voltammetry and differential pulse voltammetry. Also, the selectivity of the aptasensor is investigated using other kinds of bacteria. The synthesized NPs and the morphology of the modified electrode are characterized by UV-Vis absorption spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis, and electrochemical impedance spectroscopy.
Highlights
It is well known that the properties of detection systems composed of nano-dimensional elements are different from those of common bulky ones [1]
This work reports on the joint action of aptamers and Ag@Au core shell NPs on a carbon paste electrode (CPE) for the detection of E. coli
Experimental details can be found in the supporting information including materials, sequence of aptamers, bacterial strains, culture conditions, procedure for the synthesis of nanoparticles, and preparation of the aptasensor
Summary
It is well known that the properties of detection systems composed of nano-dimensional elements are different from those of common bulky ones [1]. Of particular interest are binary metallic nanostructures showing multiple characteristics [3] In this case, core/shell nanoparticle architectures, in which a layer of metal surrounds another NP core, have shown specific properties different from those of their monometallic counterparts and even alloys [4]. Core/shell nanoparticle architectures, in which a layer of metal surrounds another NP core, have shown specific properties different from those of their monometallic counterparts and even alloys [4] In this structure, the stability and surface chemistry of the shell nanoparticles can be improved along with accessing the physicochemical nature of the core layer. This work reports on the joint action of aptamers and Ag@Au core shell NPs on a carbon paste electrode (CPE) for the detection of E. coli.
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