Electroanalytical applications of a graphite–Au nanoparticles composite included in a sonogel matrix

Simultaneous Detection of Glucose and Fructose in Synthetic Musts by Multivariate Analysis of Silica-Based Amperometric Sensor Signals

“…A similar trend was also observed for glucose oxidation, in this case resulting in a broad oxidation peak increasing from 0.0 to +0.2 V, similarly to what was observed in the CV responses reported previously [ 30 ].…”

“…As discussed in [ 30 ], AuNPs in SNG/C-AuNPs are effective in activating electrocatalytic processes that allow the oxidation, thus the detection, of glucose. Although the oxidation of this analyte is also possible at neutral pH values with this electrode system, the sensitivity is higher in alkaline media.…”

“…The origin of the positive contribution of glucose concentration to the current values in the potential range between −0.5 and +0.2 V is easily ascribable to the first step of glucose oxidation [ 39 ]. Conversely, it is difficult to give a ratio of the process occurring in the signal region between +0.2 and +0.6 V, where a current decrease is observed when passing from the blank electrolyte solution to solutions with increasing concentration values of glucose; this leads to solutions that contain a concentration of sugar higher than 2 mM, i.e., higher than those tested in Section 3.2 , to the negative peaks centred at +0.4 V with a shoulder at about +0.3 V. However we need to remember that oxidation of glucose at Au surfaces occurs with a peculiar electrochemical process, where positive current values are normally recorded also in the scan toward negative potentials when reasonably high concentrations of sugars are analysed [ 25 , 30 ]. This can explain the negative values obtained in this potential region when adopting DPV as the investigation technique and after subtraction of the background signal from the response due to glucose/fructose oxidation.…”

“…SNG/C-AuNPs electrodes were obtained as reported in [ 30 ], starting from methyltrimethoxysilane, natural graphite powder (99.999 % pure, dimension < 74 μm) by Alfa-Aesar (Johnson Matthey GmbH, London, UK) and AuNPs encapsulated with citrate (16.3 nm mean diameter). They were made as schematized in Figure 1 , by pouring 0.50 g of the C-AuNPs composite [ 30 ] in 0.6 mL of SNG solution; glass capillary tubes with 1.15 mm internal diameter were used as the body of the electrode.…”

“…In previous work, we reported the performance of silica-based electrodes including a graphite-Au nanoparticles composite (C-AuNPs) [ 30 ]; they were synthesized by means of an innovative sonogel process [ 31 ]. The resulting SNG/C-AuNPs devices showed peculiar electrocatalytic activity toward glucose oxidation, reduced surface passivation and simple and reproducible surface renewal.…”