Unique Properties of Core Shell Ag@Au Nanoparticles for the Aptasensing of Bacterial Cells

Abstract

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.

Antitumor Activity of Alloy and Core-Shell-Type Bimetallic AgAu Nanoparticles

“…Such physicochemical parameters as size, shape, composition, and charge greatly influence biological activity of NPs [ 9 – 12 ]. These properties of bimetallic AgAu NPs have been also shown to be advantageous in a development of aptamer-based biosensors [ 13 ]. However, many aspects of gold and silver NP-based systems remain unexplored, limiting the efficiency of their application.…”

Silver Nanoparticles for Water Pollution Monitoring and Treatments: Ecosafety Challenge and Cellulose-Based Hybrids Solution

“…The well-assessed bottom up approach is based on a wet reduction of Ag + ions in the presence of capping agents. Generally, hydrophilic AgNPs can be synthesized starting from water solution of AgNO 3 in presence of ligand molecule, and adding a reducing agent, such as sodium borohydride or formic acid [ 24 , 68 , 69 , 70 , 71 ].…”

“…Engineered nanomaterials (ENMs) are typically defined as materials smaller than 100 nm in at least one dimension, and they have specific surface functionalizations and size-dependent properties, such as high reactivity and large surface-to-volume ratio, that satisfy their wide range of applications, including in sensing [1][2][3][4][5], optics [6][7][8][9][10], energy [11][12][13][14][15], catalysis [16][17][18][19], biotechnology [20][21][22][23][24] and so on.…”

Electrochemical Immunosensors and Aptasensors

“…Marrazza and coworkers [14] propose the use of affibodies immobilized on magnetic particles to detect, with screen printed electrodes, the human epidermal growth factor receptor 2 (HER2) which is overexpressed by breast cancer cells. De Wael et al [15] study the immobilization of aptamers on core-shell nanoparticles for improving the electrochemical detection of bacteria. Aptamers are also studied by Casalis and coworkers [16] who exploit an approach based on atomic force microscopy to control the bioaffinity properties of the sensor at the nanoscale.…”