Search

The development of an electrochemical aptasensor for the detection of CA125 as an ovarian cancer biomarker using gold nanostructures (GNs) modified electrodes is reported. The GNs were deposited on the surface of fluorine-doped tin oxide electrodes using a simple electrochemical method and the effects of pH and surfactant concentration on the topography and electrochemical properties of the resulting GNs modified electrodes were investigated. The electrodes were characterized using field-emission scanning electron microscopy and X-ray diffraction, cyclic voltammetry, and electrochemical impedance spectroscopy. The best electrode, in terms of the uniformity of the deposited GNs and the increase in electroactive surface area, was used for development of an aptasensor for CA125 tumor marker detection in human serum. Signal amplification was done by using aptamer-conjugated gold nanorods resulting in the detection limit of 2.6 U/ml and a linear range of 10 to 800 U/ml. The results showed that without the need for expensive antibodies, the developed aptasensor could specifically measure the clinically relevant concentrations of the tumor marker in human serum., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

The core-shell non-enzymatic glucose sensors are generally fabricated by chemical synthesis approaches followed by a binder-based immobilization process. Here, we have introduced a new approach to directly synthesis the core-shell of Au@Cu and its Au@Cu x O oxides on an FTO electrode for non-enzymatic glucose detection. Physical vapor deposition of Au thin film followed by thermal annealing has been used to fabricate Au nanocores on the electrode. The Cu shells have been deposited selectively on the Au cores using an electrodeposition method. Additionally, Au@Cu 2 O and Au@CuO have been synthesized via post thermal annealing of the Au@Cu electrode. This binder-free and selective-growing approach has the merit of high electrooxidation activity owing to improving electron transfer ability and providing more active sites on the surface. Electrochemical measurements indicate the superior activity of the Au@Cu 2 O electrode for glucose oxidation. The high sensitivity of 1601 μAcm -2  mM -1 and a low detection limit of 0.6 μM are achieved for the superior electrode. Additionally, the sensor indicates remarkable reproducibility and supplies accurate results for glucose detection in human serums. Moreover, this synthesis approach can be used for fast, highly controllable and precise fabrication of many core-shell structures by adjusting the electrochemical deposition and thermal treatment parameters., (© 2022. The Author(s).)

A bimetallic nanostructure of Co/Cu for the non-enzymatic determination of glucose is presented. The heterostructure includes cobalt thin film on a porous array of Cu nanocolumns. Glancing angle deposition (GLAD) method was used to grow Cu nanocolumns directly on a fluorine-doped tin oxide (FTO) substrate. Then a thin film of cobalt was electrodeposited on the Cu nanostructures. Various characterization studies were performed in order to define the optimum nanostructure for the determination of glucose. The results showed remarkable boosting of the electrocatalytic activity of Co/Cu bimetallic structure compare to the responses achieved by the monometallic structures of Co or Cu. The sensor showed two linear response ranges for the determination of glucose at 0.55 V in 0.1 M NaOH, from 5 μM-1 mM and 2-9 mM. The sensitivity was 1741 (μA mM -1  cm -2 ) and 626 (μA mM -1  cm -2 ), respectively, while the detection limit for a signal-to-noise ratio of 3 was found to be 0.4 μM. The sensor exhibited excellent selectivity and was successfully applied to the determination of glucose in real human blood serum samples. Graphical Abstract Schematic representation of fabrication process of the glucose sensor of Co (Cobalt)/Cu (Copper) on Fluorine doped Tin Oxide (FTO). The current voltage plots show higher electrooxidation activity of the bimetallic nanostructure of Co/Cu/FTO relative to the bare Co/FTO.

[Display omitted] • Cu-Ag nanostructures are fabricated by combining GLAD and galvanic replacement. • Various morphologies are fabricated by controlling galvanic replacement parameters. • Ag nanoshells deposited on Cu nanocolumns show the best electrocatalytic performance. • Best electrodes have the sensitivity of 3802 μAcm−2 mM−1 and detection limit of 1.33 μM. A scalable and repeatable synthetization method is introduced to fabricate Cu-Ag bimetallic nanostructures as a stable, robust, fast-response and enzyme-free glucose sensor. Cu nanocolumns were constructed on the FTO substrate using the glancing angle deposition (GLAD). Then a thin layer of Ag is deposited on the Cu nanocolumns through a galvanic replacement reaction. The Cu-Ag nanostructures with different morphologies were developed by tuning the concentration and the reaction time of the galvanic replacement process. Various electrochemical characterizations, including cyclic voltammetry and electrochemical impedance spectroscopy (EIS), were performed to determine the superior electrocatalytic activity of the electrodes. The results reveal that the superior electrocatalytic performance toward glucose oxidation was achieved with Cu-Ag fabricated under the AgNO 3 concentration of 5 mM and with a reaction time of 30 s. The sensor exhibits a fast response of ∼2 s with an excellent sensitivity of 3802 and 712 μAcm−2 mM−1 in two wide linear ranges of 0.01–3 mM and 3–8 mM and an optimum potential of 0.65 V. The proposed Cu-Ag sensor showed considerable enhancement of electrocatalytic activity compared to Cu or Ag monometallic structures due to the synergistic effect. In addition, the current bimetallic sensor regarding its outstanding precision and its reproducibility provides a promising method for large scale fabrication of non-enzymatic glucose sensors. [ABSTRACT FROM AUTHOR]

• We have produced porous Cu nanostructures by glancing angle deposition. • The Cu nanostructures deposited on FTO provide a sensitive glucose sensor. • Impressive electrochemical responses from the electrode were measured. • A high glucose detection sensitivity of 1862 μAcm−2 mM−1 was obtained. • The fabrication method proposes excellent reproducibility and selectivity. In this work, we have proposed a proper method to fabricate porous Cu nanostructured electrodes for non-enzymatic glucose detection. The glancing angle deposition (GLAD) has been used to produce Cu nanostructures on the FTO substrates. To optimize the sensing performance of the electrode, the effects of vapor deposition angle and azimuthal substrate rotation speed have been investigated. As a result, the superior electrocatalitic activity is obtained under the deposition angle of θ = 82° and the substrate rotation speed of φ ̇ = 20 rpm, respectively. By controlling the GLAD deposition parameters, an excellent sensing performance against glucose with a high sensitivity of 1862 μAcm−2 mM−1, a low detection limit of 0.048 μM and two wide linear ranges of detection of 10 μM–2 mM and 2–8 mM have been achieved at the applied potential of 0.5 V. Considering the high selectivity, excellent reproducibility and accurate measuring of the glucose levels in human serums, the proposed Cu-based sensor has a remarkable potential for large-scale production as a non-enzymatic glucometer. [ABSTRACT FROM AUTHOR]

[Display omitted] • We have fabricated nickel-gold bimetallic nanostructures by a novel method. • The Ni/Au@FTO electrodes provide a high stability for glucose determination. • These electrodes show a good glucose sensitivity of 893 μA mM−1 cm−2. • The low detection limit for glucose determination is 0.7 μM. • The fabrication procedure proposes excellent reproducibility. Bimetallic nanostructured electrodes are promising candidates for non-enzymatic glucose detection due to their excellent selectivity and high sensitivity. In this work, a bimetallic Ni/Au non-enzymatic glucose sensor was developed by the electrodeposition of nickel nanostructures on Au nanoparticles (NP). Physical vapor deposition followed by thermal annealing was used for the growth of seeding Au (NP) on fluorine doped tin oxide (FTO) substrates. The electrochemical growth of Ni nanostructures on the Au-seeded substrates led to enhanced electrochemical responses from the modified electrodes. Cyclic voltammetry results showed considerable improvement of the electrocatalytic activity of the Ni/Au bimetallic structure in comparison to monolithic Ni and Au structures due to the synergistic effect. The sensor showed two linear ranges of 5 μM–3.5 mM and 3.5–7 mM for glucose detection with the sensitivity of 893 (μA mM−1 cm−2). The low detection limit of 0.7 μM and the fast response time of 5 s was achieved. The selectivity, reproducibility and accuracy of the fabricated sensor in determination of human serum glucose suggest its potential for large-scale production as commercial non-enzymatic glucose detection. [ABSTRACT FROM AUTHOR]