Role of Au(NPs) in the enhanced response of Au(NPs)-decorated MWCNT electrochemical biosensor

Abstract

BackgroundThe combination of Au-metallic-NPs and CNTs are a new class of hybrid nanomaterials for the development of electrochemical biosensor. Concentration of Au(nanoparticles [NPs]) in the electrochemical biosensor is crucial for the efficient charge transfer between the Au-NPs-MWCNTs modified electrode and electrolytic solution.MethodsIn this work, the charge transfer kinetics in the glassy carbon electrode (GCE) modified with Au(NPs)–multiwalled carbon nanotube (MWCNT) nanohybrid with varied concentrations of Au(NPs) in the range 40–100 nM was studied using electrochemical impedance spectroscopy (EIS). Field emission scanning electron microscopy and transmission electron microscopy confirmed the attachment of Au(NPs) on the surface of MWCNTs.ResultsThe cyclic voltammetry and EIS results showed that the charge transfer mechanism was diffusion controlled and the rate of charge transfer was dependent on the concentration of Au(NPs) in the nanohybrid. The formation of spherical diffusion zone, which was dependent on the concentration of Au(NPs) in nanohybrids, was attributed to result in 3 times the increase in the charge transfer rate ks, 5 times increase in mass transfer, and 5% (9%) increase in Ipa (Ipc) observed in cyclic voltammetry in 80 nM Au(NP) nanohybrid-modified GCE from MWCNT-modified GCE. The work was extended to probe the effect of charge transfer rates at various concentrations of Au(NPs) in the nanohybrid-modified electrodes in the presence of Escherichia coli. The cyclic voltammetry results clearly showed the best results for 80 nM Au(NPs) in nanohybrid electrode.ConclusionThe present study suggested that the formation of spherical diffusion zone in nanohybrid-modified electrodes is critical for the enhanced electrochemical biosensing applications.

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“…Additionally, the CNTs/GCEand Au@CNTs/GCE comparisons demonstrate how Au nanostructures enhance catalytic activity, and the mixture of Au NPs and CNTs has produced a new category of hybrid nanostructures with effective ionic diffusion, that also led to an increase in charge transport due to the formation of globular diffusion regions from around electrode materials. 18 Additional research was done to assess the stability of the electrodes' response to the additional PNS. First and 40th DPV curve for the GCE,CNTs/GCE, Au@CNTs/GCE, and Au-PPy NPs@CNTs within 0.1M PBS containing 5µM PNS are shown in Figure 3 at scan rates of 10mV/s and potential ranges of -0.1 to 0.5V, respectively.…”

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“…Moreover, taking into account the effect of the concentration of Au solution on the composition of the MWCNT complex, Mehmood et al [ 101 ] studied the charge transfer kinetics in the GCE modified with AuNP-MWCNT nanohybrid at varied concentrations of AuNPs in the range of 40–100 nM. The results of cyclic voltammetry and EIS demonstrated that the diffusion control, charge transfer mechanism, and concentration of AuNPs are critical factors for the charge transfer rate.…”

Hybrid Nanobioengineered Nanomaterial-Based Electrochemical Biosensors

“…Metal nanostructures are generally defined as isolable particles between 1 and 50 nm in size, usually protected within shells to avoid agglomeration. Such nanoparticles have physical, electronic, and chemical properties different from bulk metals due to their small size [43]. Metallic nanostructures (MNS) (e.g., Au, Pt, Cu, Ir, Zn, Ag, Fe, Pd, and their different alloys) have been used in electrochemical biosensing devices to improve their conductive properties [29,33,44] as mediators of the signal from target-bioreceptor recognition [45] and to promote a better contact between bioreceptors and transducers, thus improving the sensitivity of the resultant devices.…”