Continuous progress in the domain of nano and material science has led to modulation ofthe properties of nanomaterials in a controlled and desired fashion. In this sense, nanomaterials,including carbon-based materials, metals and metal oxides, and composite/hybrid materials haveattracted extensive interest with regard to the construction of electrochemical biosensors. Themodification of a working electrode with a combination of two or three nanomaterials in the formof nano-composite/nano-hybrids has revealed good results with very good reproducibility, stability,and improved sensitivity. This review paper is focused on discussing the possible constructs ofnano-hybrids and their subsequent use in the construction of electrochemical glucose biosensors.
Propyl
gallate (PG) as one of the important synthetic antioxidants
is widely used in the prevention of oxidative deterioration of oils
during processing and storage. Determination of PG has received extensive
concern because of its possible toxic effects on human health. Herein,
we report a photoelectrochemical (PEC) sensor based on ZnO nanorods
and MoS2 flakes with a vertically constructed p–n
heterojunction. In this system, the n-type ZnO and p-type MoS2 heterostructures exhibited much better optoelectronic behaviors
than their individual materials. Under an open circuit potential (zero
potential) and visible light excitation (470 nm), the PEC sensor exhibited
extraordinary response for PG determination, as well as excellent
anti-inference properties and good reproducibility. The PEC sensor
showed a wide linear range from 1.25 × 10–7 to 1.47 × 10–3 mol L–1 with
a detection limit as low as 1.2 × 10–8 mol
L–1. MoS2/ZnO heterostructure with proper
band level between MoS2 and ZnO could make the photogenerated
electrons and holes separated more easily, which eventually results
in great improvement of sensitivity. On the other hand, formation
of a five membered chelating ring structure of Zn(II) with adjacent
oxygen atoms of PG played significant roles for selective detection
of PG. Moreover, the PEC sensor was successfully used for PG analysis
in different samples of edible oils. It demonstrated the ability and
reliability of the MoS2/ZnO-based PEC sensor for PG detection
in real samples, which is beneficial for food quality monitoring and
reducing the risk of overuse of PG in foods.
Thin films of organic moiety functionalized carbon nanotubes (CNTs) from a very well-dispersed aqueous solution were designed on a screen printed transducer surface through a single step directed assembly methodology. Very high density of CNTs was obtained on the screen printed electrode surface, with the formation of a thin and uniform layer on transducer substrate. Functionalized CNTs were characterized by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) surface area analyzer methodologies, while CNT coated screen printed transducer platform was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The proposed methodology makes use of a minimum amount of CNTs and toxic solvents, and is successfully demonstrated to form thin films over macroscopic areas of screen printed carbon transducer surface. The CNT coated screen printed transducer surface was integrated in the fabrication of electrochemical aptasensors for breast cancer biomarker analysis. This CNT coated platform can be applied to immobilize enzymes, antibodies and DNA in the construction of biosensor for a broad spectrum of applications.
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