Sustainable Engineering of a Surfactant-Free Nanocomposite Based on Bacterial Nanocellulose Produced from Beer Waste and MWCNTs-AgNPs for Electrochemical Sensing of Furosemide

Due to their high toxicity, potential for bioaccumulation and carcinogenicity, heavy metal pollutants have harmed the environment. Cadmium is a dangerous heavy metal that can accumulate easily in the human body. Long‐term exposure to cadmium‐contaminated environments can result in numerous diseases. A novel electrochemical sensor based on multi‐walled carbon nanotubes (MWCNTs)–imprinted polymer and reduced graphene oxide–titanium oxide (rGO@TiO2) is reported which was used to detect cadmium ions in actual samples in a highly sensitive and precise method. By using the surface imprinting technique to adhere the imprinted polymer to the surface of the MWCNTs, the template removal rate and cavity utilization rate are increased. At the same time, the electron transfer rate is increased by the MWCNTs’ superior electrochemical performance and higher conductivity. Transmission electron microscopy was used to characterize the composite's morphology. Cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy were used to describe the imprinted polymer's electrochemical behavior. The findings demonstrate the sensor's excellent cadmium ion selectivity. Under ideal experimental conditions, the electrochemical sensor has a good linear relationship in the range of 10−9 to 10−6 mol L−1, and the detection limit is 1.12 × 10−9 mol L−1. The novel sensor offers outstanding repeatability and stability in addition to good selectivity and sensitivity. Eventually, real samples were successfully used to apply the electrochemical sensor for the detection of trace Cd(II) (river water, tap water and rice). © 2023 Society of Industrial Chemistry.

The analysis of pathogens in foods is of critical importance to ensure consumer safety and quality assurance, as contaminants pose serious risks to public health. Mycotoxins are naturally occurring carcinogenic toxins that arise from specific strains of fungi as they contaminate food. They are found in a wide variety of grains, cereals, and dairy products, causing cancer in both humans and animals. Thus, there is a growing demand for simple, sensitive and inexpensive sensors for mycotoxin detection in lieu of conventionally employed large-scale instrumentation. In this study, the development of electrochemical sensors for the detection of aflatoxin B1 (AFB1), zearalenone (ZEN) and ochratoxin A (OTA) in foods was investigated and presented as three case studies, respectively. In the first case study, an ultrasensitive aptasensor was developed for the indirect detection of AFB1 in the presence of a ferri/ferrocyanide ([Fe(CN)6]3-/4-) redox probe solution. The sensor was constructed by immobilizing an anti-AFB1 aptamer (Apt) to a carboxylated multiwalled carbon nanotube (cMWCNT) and iron oxide (Fe3O4) nanoparticle (NP) composite using a glassy carbon electrode (GCE). This resulted in the development of the GCE/cMWCNTsFe3O4 NP/Apt sensor. An electrochemical response was exhibited from AFB1 applying cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV), respectively, utilizing a [Fe(CN)6]3-/4- redox probe prepared in phosphatebuffered saline (PBS) solution with reference to the Ag/AgCl reference electrode under optimized conditions. DPV findings reported very low limits of detection (LOD) and quantification (LOQ) of 0.43 fg mL-1 and 1.44 fg mL-1 respectively in comparison to current literature, over a calibration range of 0.50 fg mL-1 to 5.00 fg mL-1. For real sample analysis, excellent spike recoveries from 95% to 105% were obtained for corn and rice flour. Density functional theory (DFT) was used to propose a reaction scheme by ascertaining the electronic properties of the redox-active functional groups of AFB1. This supported the experimental anodic response findings of DPV. The second case study focused on how PEGylated Fe3O4 NPs and cMWCNTs fabricated on a GCE could be used for the design of an electrochemical sensor for ZEN analysis. The qualitative and quantitative analyses of ZEN were completed using CV, EIS and DPV, respectively, under optimized conditions in a sodium phosphate buffer solution. The developed sensor reported significantly low LODs and LOQs of 0.34 fg mL-1 and 1.12 fg mL-1 respectively, over a calibration range of 1.00 fg mL-1 to 10.00 fg mL-1 by DPV. Excellent spike recoveries ranging from 92% to 106% were obtained for rice and corn flour. The Monte Carlo (MC) adsorption simulation studies predicted the strong interaction of ZEN with the constructed sensor. In the final case study, an OTA electrochemical sensor was designed using a nickel metalorganic framework (Ni-MOF) and carboxylated reduced graphene oxide (cRGO) on a GCE. The detection of OTA was achieved under optimized conditions in PBS solution with the developed GCE/Ni-MOF/cRGO electrode, employing CV, EIS and DPV as electrochemical tools. Applying DPV, the sensor reported very low LODs and LOQs of 3.29 fg mL-1 and 10.97 fg mL-1 respectively, over a calibration range of 10.00 fg mL-1 to 90.00 fg mL-1. Regarding real sample analysis, excellent spike recoveries from 95% to 105% were obtained for corn and rice flour. Molecular dynamics (MD) studies predicted that the Ni-MOF exhibited a strong electrostatic interaction with the OTA analyte, in agreement with the experimental findings. The synthesized nanomaterials (cMWCNTs-Fe3O4 NP, PEG-Fe3O4 NPs/cMWCNTs, and NiMOF/cRGO) utilized in this study were characterized by an array of techniques, including single particle inductively coupled plasma-mass spectrometry (spICP-MS), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), multidetector asymmetrical flow field-flow fractionation (AF4), and Fourier transform infrared spectroscopy (FTIR). Finally, computational modelling studies were undertaken to establish a synergy with the experimental approaches employed in each case study. These methodologies included DFT, docking studies, MC adsorption and MD simulations, which were aimed at predicting and assessing the atomic and molecular interactions between the mycotoxins and their respective electrode systems.

An electrochemical sensor for creatinine based on carbon nanotubes/folic acid /silver nanoparticles modified electrode

A new electrochemical sensor based on a neutral red (NR) and multiwalled carbon nanotubes (CNT) modified glassy carbon electrode (GCE) with NR electropolymerized in ternary deep eutectic solvents (DES), has been developed. Cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy were used to characterize the performance of the sensor. Differential pulse voltammetry was utilized to evaluate the analytical performance of acetaminophen (APAP) oxidation on the modified electrode (PNR/CNT/GCE) in Britton-Robinson buffer aqueous solution. The combined use of PNR prepared by electropolymerization in novel green DES on CNT led to a large electroactive surface area and a synergistic effect attributed to π–π electronic interactions and resulted in improved performance towards APAP detection, with a high sensitivity (56.4 µA µM−1 cm−2) in the range 2.0–70 µM and a low limit of detection (0.015 µM). The constructed sensor displayed outstanding selectivity to detect APAP in the presence of dopamine, and good repeatability, reproducibility and stability. The sensor was successfully applied to the determination of APAP in pharmaceutical samples, with good recoveries.

Selective detection of dopamine in the presence of uric acid using a gold nanoparticles-poly(luminol) hybrid film and multi-walled carbon nanotubes with incorporated β-cyclodextrin modified glassy carbon electrode

In this work, we report the first molecularly imprinted polymer (MIP) based electrochemical sensor for the determination of the antidiabetic drug Linagliptin (LNG) in pure sample, tablets, and spiked human urine and serum samples. Using a graphite electrode, differential pulse voltammetry (DPV) was applied to study the electrochemical behavior of LNG in a Britton Robinson (BR) universal buffer of pH 8 with Ag/AgCl electrode and Pt wire. The sensor is based on the modification of the traditional carbon paste sensor with Itaconic acid (IA) as monomer, which cross-linked using ethylene glycol dimethacrylate (EGDMA) and multiwalled carbon nanotubes (MWCNTs) as a modifier. The different factors were optimized, such as ratio of MIP components, percentage of multiwalled carbon nanotubes (MWCNT), pH, accumulation time, accumulation potential and scan rate. The proposed sensor was characterized morphologically using: Scanning electron Microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and Brunauer–Emmett–Teller (BET) and electrochemically applying electrochemical impedance spectroscopy (EIS)and cyclic voltammetry (CV). DPV was applied to obtain the calibration curve and optimization of different factors, the proposed sensor shows a wide linear range of 1 × 10−12M (0.47 ng l−1) to 1 × 10−7M (47.26 μg l−1) and limit of detection (LOD)1 × 10−13M (0.05 ng l−1) while the limit of quantification (LOQ)was found to be 3.3 × 10−13M (0.16 ng l−1) in addition to good reproducibility and selectivity.

The electroanalytical sensing of linezolid is reported using a multiwalled carbon nanotubes (MWCNTs)/bromocresol green (BCG) modified carbon paste electrode.

Fabrication of a new electrochemical sensor based on Au[sbnd]Pt bimetallic nanoparticles decorated multi-walled carbon nanotubes for determination of diclofenac

Highly sensitive and selective determination of methylergometrine maleate using carbon nanofibers/silver nanoparticles composite modified carbon paste electrode

Synthesis and characterization of a highly sensitive and selective electrochemical sensor based on molecularly imprinted polymer with gold nanoparticles modified screen-printed electrode for glycerol determination in wastewater

Novel electrochemical sensor based on molecularly imprinted polymer combined with L-His-MWCNTs@PDMS-5 nanocomposite for selective and sensitive assay of tetracycline

Selenite (Se4+), a significant source of water pollution above the permissible limits, is considered a valuable metal by environmentalists. In this study, we described a novel electrochemical sensor that utilized a carbon paste electrode (CPE) that was modified using multiwall carbon nanotubes (MWCNTs) and poly(1-aminoanthraquinone) (p-AAQ) for finding Se4+ in water samples. Electrochemical quantification of Se4+ depends on the formation of a selective complex (piaselenol) with p-AAQ. In this work, we prepared a CPE modified by physical embedding of MWCNTs and 1-aminoanthraquione (AAQ), while the polymer film was formed by anodic polymerization of AAQ by applying a constant potential of 0.75 V in 0.1 M HCl for 20 s followed by cyclic voltammetry (CV) from −0.2 to 1.4 V for 20 cycles. The modified CPE was used for differential pulse voltammetry (DPV) of Se4+ in 0.1 M H2SO4 from 0 to 0.4 V with a characteristic peak at 0.27 V. Further, the proposed sensor was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and electrochemical impedance spectroscopy (EIS). The analytical conditions regarding the electrode performance and voltammetric measurements were optimized, with the accumulation time and potential, supporting electrolyte, differential-pulse period/time, and amplitude. The EIS results indicated that the p-AAQ/MWCNTs-modified CPE sensor (p-AAQ/MWCNTs/CPE) that also exhibited low charge-transfer resistance (Rct) toward the anodic stripping of Se4+, exhibited good analytical performance toward different concentrations of Se4+ in a linear range of 5–50 μg L−1 Se4+ with a limit of determination (LOD) of 1.5 μg L−1 (3σ). Furthermore, differential-pulse voltammetry was employed to determine different concentrations of Se4+ in a linear range of 1–50 μg L−1 Se4+, and an LOD value of 0.289 μg L−1 was obtained. The proposed sensor demonstrated good precision (relative standard deviation = 4.02%) at a Se4+ concentration of 5 μg L−1. Moreover, the proposed sensor was applied to analyze Se4+ in wastewater samples that were spiked with Se, and it achieved good recovery values.

We report on a glassy carbon electrode that was modified with a composite made from graphene oxide (GO) and multiwalled carbon nanotubes (MWCNT) that enables highly sensitive determination of L-tyrosine. The sensor was characterized by transmission electron microscopy and electrochemical impedance spectroscopy, and its electrochemical properties by cyclic voltammetry, chronocoulometry and differential pulse voltammetry. The GO/MWCNT hybrid exhibits strong catalytic activity toward the oxidation of L-tyrosine, with a well defined oxidation peak at 761 mV. The respective current serves as the analytical information and is proportional to the L-tyrosine concentration in two ranges of different slope (0.05 to 1.0 μM and 1.0 to 650.0 μM), with limits of detection and quantification as low as 4.4 nM and 14.7 nM, respectively. The method was successfully applied to the analysis of L-tyrosine in human body fluids. The excellent reproducibility, stability, sensitivity and selectivity are believed to be due to the combination of the electrocatalytic properties of both GO and MWCNT. They are making this hybrid electrode a potentially useful electrochemical sensing platform for bioanalysis.

The electrochemical performances of porous niobium pentoxide with multi-walled carbon nanotubes nanocomposite incorporated with glassy carbon electrode for the sensing of chloramphenicol

A novel paraoxon imprinted electrochemical sensor based on MoS2NPs@MWCNTs and its application to tap water samples