Penicillamine-modified sensor for the voltammetric determination of Cd(II) and Pb(II) ions in natural samples

Construction and Application of an Electrochemical Sensor for Determination of D-Penicillamine Based on Modified Carbon Paste Electrode

D-penicillamine (D-PA) is a sulfur-containing drug that has been used for various health conditions. However, like any medication, overdosing on D-PA can have adverse effects and may require additional treatment. Therefore, developing simple and sensitive methods for sensing D-PA can play a crucial role in improving its efficacy and reducing its side effects. Sensing technologies, such as electrochemical sensors, can enable accurate and real-time measurement of D-PA concentrations. In this work, we developed a novel electrochemical sensor for detecting D-PA by modifying a carbon paste electrode (CPE) with a multi-walled carbon nanotube-Co3O4 nanocomposite, benzoyl-ferrocene (BF), and ionic liquid (IL) (MWCNT-Co3O4/BF/ILCPE). Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CHA) were employed to explore the electrochemical response of D-PA on the developed sensor, the results of which verified a commendable electrochemical performance towards D-PA. Under optimized conditions, the developed sensor demonstrated a rapid response to D-PA with a linear dynamic range of 0.05 μM-100.0 μM, a low detection limit of 0.015 μM, and a considerable sensitivity of 0.179 μA μM-1. Also, the repeatability, stability, and reproducibility of the MWCNT-Co3O4/BF/ILCPE sensor were studied and showed good characteristics. In addition, the detection of D-PA in pharmaceutical and biological matrices yielded satisfactory recoveries and relative standard deviation (RSD) values.

Poly(Thionine)-Modified Screen-Printed Electrodes for CA 19-9 Detection and Its Properties in Raman Spectroscopy

Polythionine (PTH) is an electroactive compound known for its excellent electron transfer capacity. It has stable and redox centers in its structure, and it can also be generated by electropolymerization of thionine (TH). Due to its properties, it has been used in a large number of applications, including the construction of electrochemical biosensors. In this work, PTH is explored for its ability to generate electrons, which allows it to act as an electrochemical probe in a biosensor that detects CA 19-9 on two different substrates, carbon and gold, using differential pulse voltammetry (DPV) as a reading technique in phosphate buffer (PhB). The analytical features of the resulting electrodes are given, showing linear ranges from 0.010 to 10 U/mL. The Raman spectra of PTH films on gold (substrates or nanostars) and carbon (substrates) are also presented and discussed as a potential use for SERS readings as complementary information to electrochemical data.

Design of a dual-signal sensing platform for d-penicillamine based on UiO-66-NH2 MOFs and APBA@Alizarin Red

Herein, we designed a diversified sensing platform for d-penicillamine based on amino-functionalized Zr-based metal-organic frameworks (UiO-66-NH₂ MOFs) and 3-aminophenylboronic acid (APBA)@Alizarin Red (ARS). The boronic acid group of 3-aminophenylboronic acid could react with Alizarin Red to form an APBA@ARS complex with a yellow fluorescence emission at 580 nm and ultraviolet absorption at 435 nm. APBA@ARS can greatly quench the fluorescence of UiO-66-NH₂ MOFs at 450 nm via fluorescence resonance energy transfer (FRET). When copper ions were present in the reaction system of APBA and Alizarin Red, the copper ions could complex with Alizarin Red to prevent the generation of APBA@ARS, and the absorption of Cu@ARS at 530 nm occurred. Thus, the absorbance of APBA@ARS at 435 nm declined, restoring the fluorescence of UiO-66-NH₂ MOFs. Nevertheless, when d-penicillamine and copper ions coexist in the APBA and Alizarin Red reaction system, the copper ions would complex with the sulfhydryl group of d-penicillamine and no longer hinder the generation of APBA@ARS, and the fluorescence of UiO-66-NH₂ MOFs is quenched again. Meanwhile, the absorbance of APBA@ARS at 435 nm enhanced and the absorbance at 530 nm decreased. Thus, a fluorescence and colorimetric dual-signal sensing platform was constructed for d-penicillamine detection, which could detect d-penicillamine in the 1-20 μM and 2-50 μM ranges with the limit of detection (LOD) values of 0.46 μM and 1.38 μM, respectively. Furthermore, this sensing platform could also realize the intelligent RGB detection via mobile phones due to the obvious color change of the reaction system.

MnO2@Reduced Graphene Oxide Nanocomposite-Based Electrochemical Sensor for the Simultaneous Determination of Trace Cd(II), Zn(II) and Cu(II) in Water Samples

The rapid detection of trace metals is one of the most important aspect in achieving environmental monitoring and protection. Electrochemical sensors remain a key solution for rapid detection of heavy metals in environmental water matrices. This paper reports the fabrication of an electrochemical sensor obtained by the simultaneous electrodeposition of MnO₂ nanoparticles and RGO nanosheets on the surface of a glassy carbon electrode. The successful electrodeposition was confirmed by the enhanced current response on the cyclic voltammograms. The XRD, HR-SEM/EDX, TEM, FTIR, and BET characterization confirmed the successful synthesis of MnO₂ nanoparticles, RGO nanosheets, and MnO₂@RGO nanocomposite. The electrochemical studies results revealed that MnO₂@RGO@GCE nanocomposite considerably improved the current response on the detection of Zn(II), Cd(II) and Cu(II) ions in surface water. These remarkable improvements were due to the interaction between MnO₂ nanomaterials and RGO nanosheets. Moreover, the modified sensor electrode portrayed high sensitivity, reproducibility, and stability on the simultaneous determination of Zn(II), Cd(II), and Cu(II) ions. The detection limits of (S/N = 3) ranged from 0.002–0.015 μg L⁻¹ for the simultaneous detection of Zn(II), Cd(II), and Cu(II) ions. The results show that MnO₂@RGO nanocomposite can be successfully used for the early detection of heavy metals with higher sensitivity in water sample analysis.

Simultaneous Voltammetric Determination of Acetaminophen, Ascorbic Acid and Uric Acid by Use of Integrated Array of Screen-Printed Electrodes and Chemometric Tools

In the present work, ternary mixtures of Acetaminophen, Ascorbic acid and Uric acid were resolved using the Electronic tongue (ET) principle and Cyclic voltammetry (CV) technique. The screen-printed integrated electrode array having differentiated response for the three oxidizable compounds was formed by Graphite, Prussian blue (PB), Cobalt (II) phthalocyanine (CoPc) and Copper oxide (II) (CuO) ink-modified carbon electrodes. A set of samples, ranging from 0 to 500 µmol·L⁻¹, was prepared, using a tilted (3³) factorial design in order to build the quantitative response model. Subsequently, the model performance was evaluated with an external subset of samples defined randomly along the experimental domain. Partial Least Squares Regression (PLS) was employed to construct the quantitative model. Finally, the model successfully predicted the concentration of the three compounds with a normalized root mean square error (NRMSE) of 1.00 and 0.99 for the training and test subsets, respectively, and R² ≥ 0.762 for the obtained vs. expected comparison graphs. In this way, a screen-printed integrated electrode platform can be successfully used for voltammetric ET applications.

Diagnosis of penicillin allergy: a MOFs-based composite hydrogel for detecting β-lactamase in serum

A MOFs-based composite hydrogel 1@SA is presented for the diagnosis of penicillin anaphylaxis. This composite hydrogel reflects the enzymatic hydrolysis profiles of penicillin via β-lactamase. The determination of β-lactamase by this hydrogel was achieved through an “ON–OFF–OFF–ON” fluorescence trigger pattern. The potency of 1@SA was further demonstrated for its selectivity, sensitivity and convenient visual detection.

Green Synthesis of Ag Nanoparticles Using Grape Stalk Waste Extract for the Modification of Screen-Printed Electrodes

The chemical synthesis of silver nanoparticles (Ag-NPs) by using an environmentally friendly methodology for their preparation is presented. Thus, considering that plants possess components that can act as reducing agents and stabilizers in nanoparticles’ production, the synthesis of Ag-NPs by using an extract aqueous solution of grape stalk waste as a reducing and capping agent is studied. First, the total polyphenols and reducing sugars contained in the produced extracts at different conditions are characterized. After that, Ag-NPs are synthesized regarding the interaction of Ag ions (from silver nitrate) and the grape stalk extract. The effect of temperature, contact time, extract/metal solution volume ratio and pH solution in the synthesis of metal nanoparticles are also studied. Different sets of nanoparticle samples are characterized by means of Electron Microscopy coupled with Energy Dispersive X-Ray for qualitative chemical identification. Ag-NPs with an average diameter of 27.7 ± 0.6 nm are selected to proof their suitability for sensing purposes. Finally, screen-printed electrodes modified with Ag-NPs are tested for the simultaneous stripping voltammetric determination of Pb(II) and Cd(II). Results indicate good reproducibility, sensitivity and limits of detection around 2.7 µg L⁻¹ for both metal ions.

Multi-element determination of metals and metalloids in waters and wastewaters, at trace concentration level, using electroanalytical stripping methods with environmentally friendly mercury free-electrodes: A review

Nowadays, water is no longer regarded as an inexhaustible resource and the excessive release and proliferation of toxic metal(loid)s into aquatic environments has become a critical issue. Therefore, fast, accurate, simple, selective, sensitive and portable methodologies to detect multiple elements in natural waters is of paramount importance. Electrochemical stripping analysis is an efficient tool for trace metal(loid)s determinations and bring new prospects for answering the current environmental concerns. This review presents a survey of the advancements made between 2003 and 2016 on the development and application of non-toxic mercury free electrodes on the simultaneous analysis of metals and metalloids in waters and wastewaters by means of electroanalytical stripping techniques. The advantages, limitations, improvements and real applications of these "green" sensors are discussed from a critical point of view.

Ag Nanoparticles Drop-Casting Modification of Screen-Printed Electrodes for the Simultaneous Voltammetric Determination of Cu(II) and Pb(II)

A new silver nanoparticle modified screen-printed electrode was developed and applied to the simultaneous determination of Pb(II) and Cu(II). Two different types of silver nanoparticles with different shapes and sizes, Ag nanoseeds and Ag nanoprisms, were microscopically characterized and three different carbon substrates, graphite, graphene and carbon nanofibers, were tested. The best analytical performance was achieved for the combination of Ag nanoseeds with a carbon nanofiber modified screen-printed electrode. The resulting sensor allowed the simultaneous determination of Pb(II) and Cu(II) at trace levels and its applicability to natural samples was successfully tested with a groundwater certified reference material, presenting high reproducibility and trueness.

Simultaneous electrochemical detection of Cd(II), Pb(II), As(III) and Hg(II) ions using ruthenium(II)-textured graphene oxide nanocomposite

Simultaneous determination of Cd(II), Pb(II), As(III) and Hg(II) metal ions was carried out based on the synergistic effect of graphene oxide (GO) textured with redox active ruthenium(II) bipyridine complex ([Ru(bpy)₃]²⁺). [Ru(bpy)₃]²⁺-GO nanocomposite on the modified gold (Au) electrode acts as an electrocatalyst and favours the sensitive and selective detection of metal ions. Also, it exhibited an enhanced electron transfer rate with a low solution resistance examined by cyclic voltammetry and impedance analysis. The inherent electrochemical and electrocatalytic behaviours of [Ru(bpy)₃]²⁺-GO on gold electrode were demonstrated for simultaneous detection of heavy metal ions in water matrix. The proposed sensor exhibited a higher sensitivity towards Cd(II), Pb(II), As(III) and Hg(II) metal ions with a lowest detection limit of 2.8, 1.41, 2.3 and 1.6nM respectively. The observed detection limits were less than the World Health Organization standards and hence the developed sensor can be deployed for detecting heavy metal ions in water bodies. Simultaneous electrochemical detection of heavy metal ions in river and tap water was carried out using the developed sensor and the observed results were validated with atomic absorption spectroscopy.

Glutathione modified screen-printed carbon nanofiber electrode for the voltammetric determination of metal ions in natural samples

This work reports the development of a glutathione modified electrode via electrografting on a screen-printed carbon nanofiber substrate (GSH-SPCNFE). GSH-SPCNFE was compared to a classical screen-printed carbon electrode modified with glutathione (GSH-SPCE) for the simultaneous voltammetric determination of Cd(II) and Pb(II). Their electrochemical characterization and analytical performance suggest that SPCNFE could be a much better support for GSH immobilization. The applicability of GSH-SPCNFE for the determination of low concentration levels of Pb(II) and Cd(II) ions in environmental samples was successfully tested in a certified wastewater reference material by means of stripping voltammetry with a very high reproducibility and good trueness.