ABSTRACT
The definition of nanoparticles (NPs) differs depending upon the materials, fields, and applications concerned. In general, they are regarded as particles smaller than 10-20 nm and sometimes particles from 1 nm to 1 μm [1, 2]. As Itamar and Wang stated, the progress in electroanalytical methods for enhancing the sensitivity and selectivity of electroanalysis recently trends to advances accomplished by the chemical modification and functionalization of electrodes, while in the old years, the development of new electrochemical techniques such as alternating current (AC) voltammetry, pulse voltammetry, and stripping voltammetry, were important in the same manner [3]. In recent years, the chemical modification and functionalization of electrodes have been done by introducing miniature materials like nanotubes, nanoballs, nanodots, and, in particular, NPs into the structure [4-8]. The reason behind this intense interest in NPs, as stated above, can be attributed to their unique optical, magnetic, electronic, and chemical properties, which are not shared by bulk materials [8]. Regarding electroanalysis, the modification of an electrode with one of these NPs provides a high effective surface area, mass transport, catalysis, and control over the local microenvironment [8]. Among these nanomaterials, metallic NPs are of great interest due to their important properties and their numerous possible applications [9, 10]. The use of metal NP superstructures for the organization of electrochemical sensing devices is an extremely promising prospect. In electroanalytical applications, metal NPs provide some important functions, including roughening of the conductive sensing interface and some catalytic properties that result with amplification of the electrochemical signal. Besides, the conductivity properties of NPs at nanoscale dimensions allow the electrical contact of redox centers in proteins with electrode surfaces. On the other hand, metal oxide NPs have profound applications in optics, optoelectronics, sensors, and actuators due to their semiconducting, piezoelectric, and pyroelectric properties [11-15]. When modified with electrodes, these NPs not only possesses a high surface area, nontoxicity, good biocompatibility, and chemical stability but also show fast electron transfer that is very important in terms of electroanalytic applications [11, 13, 15, 16].
