Cobalt-copper bimetallic nanostructures prepared by glancing angle deposition for non-enzymatic voltammetric determination of glucose

Precision in cancer diagnostics: ultra-sensitive detection of MCF-7 breast cancer cells by gold nanostructure-enhanced electrochemical biosensing

Timely identification of cancers is pivotal in optimizing treatment efficacy and reducing their widespread impact. This study introduces a novel biosensor for the sensitive electrochemical detection of cancer cells overexpressing mucin 1 (MUC1), a well-established model for breast cancer. The sensor substrate comprises gold columnar nanostructures obtained through glancing angle deposition (GLAD) of copper nanostructures, subsequently replaced by gold via a facile galvanic replacement process. Functionalizing these gold nanostructures with aptamers targeting the MUC1 glycoproteins, a prominent cancer biomarker, enables specific recognition of MCF-7 breast cancer cells. The proposed electrochemical sensing platform offers several advantages, including high selectivity, a wide linear range of detection, a low detection limit of 30 cells per mL, and long-term stability, rendering this sensor highly desirable for definitive breast cancer diagnosis.

Facile preparation of a CoNiS/CF electrode by SILAR for a high sensitivity non-enzymatic glucose sensor

The nanomaterials for non-enzymatic electrochemical sensors are usually pre-synthesized and coated onto electrodes by ex situ methods. In this work, amorphous cobalt-nickel sulfide (CoNiS) nanoparticles were facilely prepared on copper foam (CF) by the in situ successive ionic layer adsorption and reaction (SILAR) method, and as-prepared CoNiS/CF was studied as an electrode for non-enzymatic glucose sensing. It was analyzed by field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDAX) and X-ray photoelectron spectroscopy (XPS). The electrochemical performance was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). This binary sulfide electrode showed better performance toward glucose oxidation compared to the corresponding single sulfide and showed a wide linear range of 0.005 to 3.47 mM, a high sensitivity of 2298.7 μA mM-1 cm-2 and a low detection limit of 2.0 μM. The sensor exhibited high sensitivity and good repeatability and stability and was able to detect glucose in an actual sample. This work provides a simple and fast in situ electrode preparation method for a high-sensitivity glucose sensor.

Anti-galvanic reaction induced interfacial engineering to reconstruct ternary colloid satellite platform for exceptionally high-performance redox-responsive sensor

The anti-galvanic reaction (AGR), which is a classic galvanic reaction (GR) with an opposite effect, is a unique phenomenon associated with the quantum size effect. This reaction involves the interaction between metal ions and nanoclusters, offering opportunities to create well-defined nanomaterials and diverse reductive behavior. In hence, in our work, we utilize the AGR to generate gold (Au), silver (Ag), and copper (Cu) satellite nanoclusters which have superior electromagnetic properties for Surface-enhanced Raman spectroscopy (SERS) sensor. As the AGR process, weak oxidant Cu2+ is selected to etched matrix Au@Ag NPs, reduced to Cu(0) or Cu(1) and generated the ultrasmall metal nanoparticles (Ag). To facilitate the AGR, we introduce the nucleophilic thiol 4-mercaptopyridine (4-Mpy) to bridge the metal ions or ultrasmall metal nanoparticles to reconstruct the satellite nanoclusters. These experimental displays that the AGR based biosensors has highly sensitivity for reductive molecule glucose. The liner ranges from 1 mmol/L to 1 nmol/L and alongs with a correlation coefficient and detection limit (LOD) of 0.999 and 0.14 nmol/L. Moreover, the AGR based biosensors exhibits remarkable stability and high repeatability with RSD 1.3 %. The food samples are tested to further investigate the accuracy and reliability of the method, which provides a novel and effective SERS method for the reduction molecules detection.

Stable, reproducible, and binder-free gold/copper core-shell nanostructures for high-sensitive non-enzymatic glucose detection

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_xO 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@Cu₂O 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@Cu₂O 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.

Electrochemical fabrication of Co(OH)2 nanoparticles decorated carbon cloth for non-enzymatic glucose and uric acid detection

Cobalt hydroxide nanoparticles (Co(OH)₂ NPs) were uniformly deposited on flexible carbon cloth substrate (Co(OH)₂@CC) rapidly by a facile one-step electrodeposition, which can act as an enzyme-free glucose and uric acid sensor in an alkaline electrolyte. Compositional and morphological characterization were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), which confirmed the deposited nanospheres were Co(OH)₂ nanoparticles (NPs). The electrochemical oxidation of glucose and uric acid at Co(OH)₂@CC electrode was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry methods. The results revealed a remarkable electrocatalytic activity toward the single and simultaneous determination of glucose and uric acid at about 0.6 V and 0.3 V (vs. Ag/AgCl), respectively, which is attributed to a noticeable synergy effect between Co(OH)₂ NPs and CC with good repeatability, satisfactory reproducibility, considerable long-term stability, superior selectivity, outstanding sensitivity, and wide linear detection range from 1 uM to 2 mM and 25 nM to 1.5 uM for glucose and UA, respectively. The detection limits were 0.36 nM for UA and 0.24 μM for glucose (S/N = 3). Finally, the Co(OH)₂@CC electrode was utilized for glucose and uric acid determination in human blood samples and satisfying results were obtained. The relative standard derivations (RSDs) for glucose and UA were in the range 6 to 14% and 0 to 3%, respectively. The recovery ranges for glucose an UA were 97 to 103% and 95 and 101%, respectively. These features make the novel Co(OH)₂@CC sensor developed by a low-cost, efficient, and eco-friendly preparation method a potentially practical candidate for application to biosensors.

Non-Enzymatic Glucose Sensors Involving Copper: An Electrochemical Perspective

Non-enzymatic glucose sensors based on the use of copper and its oxides have emerged as promising candidates to replace enzymatic glucose sensors owing to their stability, ease of fabrication, and superior sensitivity. This review explains the theories of the mechanism of glucose oxidation on copper transition metal electrodes. It also presents an overview on the development of among the best non-enzymatic copper-based glucose sensors in the past 10 years. A brief description of methods, interesting findings, and important performance parameters are provided to inspire the reader and researcher to create new improvements in sensor design. Finally, several important considerations that pertain to the nano-structuring of the electrode surface is provided.

Highly improved supercapacitance properties of MnFe2O4 nanoparticles by MoS2 nanosheets

Manganese ferrite (MnFe₂O₄) nanoparticles were synthesized via a hydrothermal method and combined with exfoliated MoS₂ nanosheets, and the nanocomposite was studied as a supercapacitor. X-ray diffractometry and Raman spectroscopy confirmed the crystalline structures and structural characteristics of the nanocomposite. Transmission electron microscopy images showed the uniform size distribution of MnFe₂O₄ nanoparticles (~ 13 nm) on few-layer MoS₂ nanosheets. UV-visible absorption photospectrometry indicated a decrease in the bandgap of MnFe₂O₄ by MoS₂, resulting in a higher conductivity that is suitable for capacitance. Electrochemical tests showed that the incorporation of MoS₂ nanosheets largely increased the specific capacitance of MnFe₂O₄ from 600 to 2093 F/g (with the corresponding energy density and power density of 46.51 Wh/kg and 213.64 W/kg, respectively) at 1 A/g, and led to better charge-discharge cycling stability. We also demonstrated a real-world application of the MnFe₂O₄/MoS₂ nanocomposite in a two-cell asymmetric supercapacitor setup. A density functional theory study was also performed on the MnFe₂O₄/MoS₂ interface to analyze how a MoS₂ monolayer can enhance the electronic properties of MnFe₂O₄ towards a higher specific capacitance.

Construction of an MnO2 nanosheet array 3D integrated electrode for sensitive enzyme-free glucose sensing

MnO₂ based electrochemical enzyme-free glucose sensors remain significantly limited by their low electronic conductivity and associated complex preparation. In this paper, an MnO₂ nanosheet array supported on nickel foam (MnO₂ NS/NF) was prepared using a simple hydrothermal synthesis and employed as a 3D integrated electrode for enzyme-free glucose detection. It was found that MnO₂ NS/NF shows high performance with a wide linear range from 1 μM to 1.13 mM, a high sensitivity of 6.45 mA mM^-1 cm^-2, and a low detection limit of 0.5 μM (S/N = 3). Besides, MnO₂ NS/NF shows high selectivity against common interferences and good reliability for glucose detection in human serum. This work demonstrates the promising role of MnO₂ NS/NF as an efficient integrated electrode in enzyme-free glucose detection with high performance.