A class-selective and reliable electrochemical monosaccharide index in honeys, as determined using nickel and nickel-copper nanowires

Evaluation of Antioxidants Using Electrochemical Sensors: A Bibliometric Analysis

The imbalance of oxidation and antioxidant systems in the biological system can lead to oxidative stress, which is closely related to the pathogenesis of many diseases. Substances with antioxidant capacity can effectively resist the harmful damage of oxidative stress. How to measure the antioxidant capacity of antioxidants has essential application value in medicine and food. Techniques such as DPPH radical scavenging have been developed to measure antioxidant capacity. However, these traditional analytical techniques take time and require large instruments. It is a more convenient method to evaluate the antioxidant capacity of antioxidants based on their electrochemical oxidation and reduction behaviors. This review summarizes the evaluation of antioxidants using electrochemical sensors by bibliometrics. The development of this topic was described, and the research priorities at different stages were discussed. The topic was investigated in 1999 and became popular after 2010 and has remained popular ever since. A total of 758 papers were published during this period. In the early stages, electrochemical techniques were used only as quantitative techniques and other analytical techniques. Subsequently, cyclic voltammetry was used to directly study the electrochemical behavior of different antioxidants and evaluate antioxidant capacity. With methodological innovations and assistance from materials science, advanced electrochemical sensors have been fabricated to serve this purpose. In this review, we also cluster the keywords to analyze different investigation directions under the topic. Through co-citation of papers, important papers were analyzed as were how they have influenced the topic. In addition, the author’s country distribution and category distribution were also interpreted in detail. In the end, we also proposed perspectives for the future development of this topic.

Screen-Printed Electrodes Modified with Metal Nanoparticles for Small Molecule Sensing

Recent progress in the field of electroanalysis with metal nanoparticle (NP)-based screen-printed electrodes (SPEs) is discussed, focusing on the methods employed to perform the electrode surface functionalization, and the final application achieved with different types of metallic NPs. The ink mixing approach, electrochemical deposition, and drop casting are the usual methodologies used for SPEs' modification purposes to obtain nanoparticulated sensing phases with suitable tailor-made functionalities. Among these, applications on inorganic and organic molecule sensing with several NPs of transition metals, bimetallic alloys, and metal oxides should be highlighted.

Microchip in situ electrosynthesis of silver metallic oxide clusters for ultra-FAST detection of galactose in galactosemic newborns' urine samples

This work describes for the first time the coupling of microfluidic chips (MC) to electrosynthetized silver metallic oxide clusters (AgMOCs). As an early demonstration of this novel approach, the ultrafast detection of galactose in galactosemic newborns' urine samples is proposed. AgMOCs were in situ electrosynthetized on integrated microchip platinum electrodes using a double pulse technique and characterized in full using scanning electronic microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and electrochemical techniques revealing the presence of silver oxides and electrocatalysis towards galactose as a galactosemia biomarker. Galactose detection in galactosemic newborns' urine samples proceeded in less than 30 s, differentiating between ill and healthy urine samples and requiring negligible urine sample consumption. The significance of the newborns' urine samples confirmed the analytical potency of the MC-AgMOCs approach for future implementation of screening for rare disease diagnosis such as galactosemia.

Galvanostatic electrodeposition of copper nanoparticles on screen-printed carbon electrodes and their application for reducing sugars determination

In this work, a novel method for the galvanostatic electrodeposition of copper nanoparticles on screen-printed carbon electrodes was developed. Nanoparticles of spherical morphology with sizes between 60 and 280nm were obtained. The electrocatalytic effect of these copper nanospheres towards the oxidation of different sugars was studied. Excellent analytical performance was obtained with the nanostructured sensor: low detection limits and wide linear ranges (1-10,000µM) were achieving for the different reducing sugars evaluated (glucose, fructose, arabinose, galactose, mannose, xylose) with very similar calibration slopes, which demonstrates the possibility of total sugar detection. The reproducibility of these sensors was 4.4% (intra-electrode) and 7.2% (inter-electrode). The stability of the nanostructured electrodes was at least 30 days, even using the same device on different days. Several real samples (honey, orange juice and normal and sugar-free soft drinks) were evaluated to study the reliability of the nanostructured sensor.

Vertically-Oriented and Shape-Tailored Electrocatalytic Metal Nanowire Arrays for Enzyme-Free Galactosemia Rapid Diagnosis

Metallic catalytic nanowires such as nickel and copper nanowires (NWs) for electrochemical detection of carbohydrates involved in metabolic rare diseases are proposed. NWs were electrodeposited using a polycarbonate membrane template, which was cut with the desired shape, stuck in double-sided adhesive tape, pasted into a non-conductive substrate and in situ removed. This simple and versatile approach allowed to obtain NWs vertically oriented (v-NWs), which are contained in the double-sided adhesive tape, becoming highly versatile. The high specific surface of working electrode in which the transduction is supported exclusively by the nanomaterial yielded a high analytical performance [extremely low fouling for galactose (RSD<2 %; n=25)]. Likewise, v-NWs exhibited a superior analytical performance with respect to commercial sputtered thick-film electrodes showing also a clear advantage related with the price, as well as with non-need clean room facilities. The analytical potency of the new approach was clearly demonstrated towards the fast and reliable diagnosis of galactosemia using precious newborn urine samples compared to standard clinical diagnosis. These results revealed new opportunities for future enzyme-free diagnosis and development of future point-of-care applications.

Glucose sensing on graphite screen-printed electrode modified by sparking of copper nickel alloys

Electric spark discharge was employed as a green, fast and extremely facile method to modify disposable graphite screen-printed electrodes (SPEs) with copper, nickel and mixed copper/nickel nanoparticles (NPs) in order to be used as nonenzymatic glucose sensors. Direct SPEs-to-metal (copper, nickel or copper/nickel alloys with 25/75, 50/50 and 75/25wt% compositions) sparking at 1.2kV was conducted in the absence of any solutions under ambient conditions. Morphological characterization of the sparked surfaces was performed by scanning electron microscopy, while the chemical composition of the sparked NPs was evaluated with energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The performance of the various sparked SPEs towards the electro oxidation of glucose in alkaline media and the critical role of hydroxyl ions were evaluated with cyclic voltammetry and kinetic studies. Results indicated a mixed charge transfer- and hyroxyl ion transport-limited process. Best performing sensors fabricated by Cu/Ni 50/50wt% alloy showed linear response over the concentration range 2-400μM glucose and they were successfully applied to the amperometric determination of glucose in blood. The detection limit (S/N 3) and the relative standard deviation of the method were 0.6µM and <6% (n=5, 2µM glucose), respectively. Newly devised sparked Cu/Ni graphite SPEs enable glucose sensing with distinct advantages over existing glucose chemical sensors in terms of cost, fabrication simplicity, disposability, and adaptation of green methods in sensor's development.

Electrodeposition of nickel nanoflowers on screen-printed electrodes and their application to non-enzymatic determination of sugars

Nickel nanoflowers were electrodeposited on screen-printed carbon electrodes for the non-enzymatic catalytic detection of sugars.

Microchip electrophoresis-copper nanowires for fast and reliable determination of monossacharides in honey samples

Microchip electrophoresis (ME) with electrochemical detection has been demonstrated to be a powerful tool in food analysis. However, the coupling of ME with electrochemical detection and nanotechnologies is still in its infancy, knowing that nanomaterials can significantly improve the ME analytical performance. This work reports the coupling between ME and copper nanowires (CuNWs) for the selective analysis of monosaccharides in honey samples. Also, in terms of real applicability, the study of analytical reliability of ME is an issue of paramount importance. To this end, a representative group of nine honey samples were analyzed and the results were compared with those previously obtained by HPLC-refractive index. ME-CuNWs approach allowed the separation of glucose and fructose in <250 s under optimized separation (20 mM NaOH + 10 mM H3 BO3 , pH 12; separation voltage + 1000 V) and detection (E = +0.70 V in 20 mM NaOH + 10 mM H3 BO3 , pH 12) conditions. An excellent stability of EOF during sample analysis was achieved with RSDs for migration times <2% and for amperometric currents <9%. The quantitative contents for individual glucose and fructose obtained using ME-CuNWs in comparison with those obtained by HPLC-refractive index were highly in agreement with errors <10% indicating the reliability of the approach. The excellent analytical performance obtained confirms the analytical potency of ME-CuNWs approach, enhancing the maturity of the microchip technology and opening new avenues for future implementation of applications in the field of food analysis.

Enzymeless determination of total sugar by luminol-tetrachloroaurate chemiluminescence on chip to analyze food samples

Chemiluminescence (CL) emission from luminol-tetrachloroaurate ([AuCl(4)](-)) system studied in presence of monosaccharide sugars such as glucose and fructose was investigated on a microfluidic chip fabricated by the soft lithography technique. CL emission from the luminol-[AuCl(4)](-) system at 430 nm was intensified remarkably by the catalytic activity of glucose and fructose at room temperature. Under optimized conditions, the CL emission intensity of the system was found to be linearly related to the concentration of the sugars. Based on this observation, nonenzymatic determination of total sugar (glucose, fructose, or hydrolyzable sucrose) was performed in a rapid and sensitive analytical method. The results revealed that the linearity ranged from 9 to 1,750 μM for glucose and 80 to 1,750 μM for fructose, with a limit of detection of 0.65 and 0.69 μM, respectively. The relative standard deviations determined at 250 μM based on six repetitive injections were 1.13 and 1.15% for glucose and fructose, respectively. The developed method was successfully applied for determination of the total sugar concentration in food and beverages.