Preparation of chitosan grafted graphite composite for sensitive detection of dopamine in biological samples

Recent Advances in Biodegradable Green Electronic Materials and Sensor Applications

As environmental issues have become the dominant agenda worldwide, the necessity for more environmentally friendly electronics has recently emerged. Accordingly, biodegradable or nature-derived materials for green electronics have attracted increased interest. Initially, metal-green hybrid electronics are extensively studied. Although these materials are partially biodegradable, they have high utility owing to their metallic components. Subsequently, carbon-framed materials (such as graphite, cylindrical carbon nanomaterials, graphene, graphene oxide, laser-induced graphene) have been investigated. This has led to the adoption of various strategies for carbon-based materials, such as blending them with biodegradable materials. Moreover, various conductive polymers have been developed and researchers have studied their potential use in green electronics. Researchers have attempted to fabricate conductive polymer composites with high biodegradability by shortening the polymer chains. Furthermore, various physical, chemical, and biological sensors that are essential to modern society have been studied using biodegradable compounds. These recent advances in green electronics have paved the way toward their application in real life, providing a brighter future for society.

Electrochemical Biosensors for Whole Blood Analysis: Recent Progress, Challenges, and Future Perspectives

Whole blood, as one of the most significant biological fluids, provides critical information for health management and disease monitoring. Over the past 10 years, advances in nanotechnology, microfluidics, and biomarker research have spurred the development of powerful miniaturized diagnostic systems for whole blood testing toward the goal of disease monitoring and treatment. Among the techniques employed for whole-blood diagnostics, electrochemical biosensors, as known to be rapid, sensitive, capable of miniaturization, reagentless and washing free, become a class of emerging technology to achieve the target detection specifically and directly in complex media, e.g., whole blood or even in the living body. Here we are aiming to provide a comprehensive review to summarize advances over the past decade in the development of electrochemical sensors for whole blood analysis. Further, we address the remaining challenges and opportunities to integrate electrochemical sensing platforms.

Detection and modulation of neurodegenerative processes using graphene-based nanomaterials: Nanoarchitectonics and applications

Neurodegenerative disorders (NDDs) are caused by progressive loss of functional neurons following the aggregation and fibrillation of proteins in the central nervous system. The incidence rate continues to rise alarmingly worldwide, particularly in aged population, and the success of treatment remains limited to symptomatic relief. Graphene nanomaterials (GNs) have attracted immense interest on the account of their unique physicochemical and optoelectronic properties. The research over the past two decades has recognized their ability to interact with aggregation-prone neuronal proteins, regulate autophagy and modulate the electrophysiology of neuronal cells. Graphene can prevent the formation of higher order protein aggregates and facilitate the clearance of such deposits. In this review, after highlighting the role of protein fibrillation in neurodegeneration, we have discussed how GN-protein interactions can be exploited for preventing neurodegeneration. A comprehensive understanding of such interactions would contribute to the exploration of novel modalities for controlling neurodegenerative processes.

Ultrasensitive detection of hydrogen peroxide and dopamine using copolymer-grafted metal-organic framework based electrochemical sensor

We reported the synthesis of a copolymer- and metal-organic framework-based electrochemical sensor, UiO-66-NH₂@P(ANI-co-ANA) using the polymerization method for the highly sensitive and selective detection of hydrogen peroxide (H₂O₂) and dopamine (DA). The as-synthesized material was characterized via Fourier transform infrared spectroscopy, X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The electrochemical characteristics of the proposed sensor were evaluated via impedance spectroscopy and cyclic voltammetry (CV). The electrochemical oxidation of DA and the reduction of H₂O₂ were determined via CV, square-wave voltammetry, and chronoamperometric techniques. The fabricated sensor exhibited a wide linear range of 25-500 μM, with a sensitivity of 1396.1 μAμM^-1cm^-2 and a limit of detection of 0.6 μM, for the electrochemical reduction of H₂O₂. Additionally, it exhibited a wide linear range of 10-110 μM, with a sensitivity of 1110.2 μAμM^-1cm^-2 and a limit of detection of 0.3 μM, for the electrochemical detection of DA. The practical utility of the fabricated sensor was evaluated via the detection of H₂O₂ in milk samples and DA in human urine samples.

Brilliant red X-3B uptake by a novel polycyclodextrin-modified magnetic cationic hydrogel: Performance, kinetics and mechanism

A novel polycyclodextrin-modified magnetic cationic hydrogel (PCD-MCH) was developed and its performance, kinetics and mechanism for the removal of reactive brilliant red X-3B (X-3B) were studied. The results showed that the zeta-potential of PCD-MCH was 32.8 to 16.7mV at pH3.0-10.5. The maximum X-3B adsorption capacity of PCD-MCH was 2792.3mg/g. The adsorption kinetics could be well-described by the Weber-Morris model and the homogeneous surface diffusion model (HSDM). Diffusion stages corresponding to surface or film diffusion, intra-particle or wide mesopore diffusion, and narrow mesopore/micropore diffusion occurred at 0-120, 120-480 and 480-1200min, respectively. The latter two diffusion stages were rate-controlling for X-3B adsorption kinetics. At the initial X-3B concentration of 600mg/L, the diffusion coefficient (D_s) and external mass transfer coefficient in the liquid phase (k_F) were 3×10^-11cm²/min and 4.68×10^-6cm/min, respectively. X-3B approaching the center of PCD-MCH particles could be observed at 360min. At the end of the third diffusion stage, the C_p at q/q_e=0 was 45.20mg/L, which was close to the homogeneous C_p value of 46mg/L along the radius of PCD-MCH particles. At pH3.0-10.0, PCD-MCH showed stable X-3B adsorption capacities. After five regeneration-reuse cycles, the residual adsorption capacity of regenerated PCD-MCH was higher than 892.7mg/g. The corresponding adsorption mechanism was identified as involving electrostatic interactions, cyclodextrin cavities and hydrogen bonds, of which cyclodextrin cavities showed prominent capture performance towards dye molecules through the formation of inclusion complexes.

A novel amperometric determination of flufenamic acid using CuMOF ribbons incorporated with activated carbon

Electrochemical detection of FFA using AC–CuMOF modified electrode.

Novel Design of a Layered Electrochemical Dopamine Sensor in Real Samples Based on Gold Nanoparticles/β-Cyclodextrin/Nafion-Modified Gold Electrode

Change in the level of dopamine (DA) concentration in the human body causes critical diseases such as schizophrenia and Parkinson's disease. Therefore, the determination of DA concentration and monitoring its level in human body fluids is of great importance. An electrochemical sensor based on modification of the gold electrode surface with Nafion (NF), β-cyclodextrin (CD), and gold nanoparticles (AuNPs) was fabricated for the determination of DA in biological fluids. Combined impact of all the modifiers enhances the catalytic activity of the sensor. Gold nanoparticles increase the surface area of the sensor and enhance the electron transfer rate. CD plays a main role in enhancing the accumulation of protonated DA and forming stable complexes via electrostatic interactions and hydrogen bond formation. In addition, extra preconcentration of positively charged DA is achieved through ionic selectivity of NF. High electrocatalytic activity was achieved using the modified sensor for determination of DA in real urine samples in a wide concentration range, 0.05-280 μM with a low detection limit of 0.6 nM in the small linear dynamic range, 0.05-20 μM. Furthermore, common overlapped oxidation peaks of DA in presence of biologically interfering compounds at the gold electrode were resolved by using the modified sensor. Excellent recovery results were obtained using the proposed method for determination of DA in real urine samples.

Sonochemical synthesis of gum guar biopolymer stabilized copper oxide on exfoliated graphite: Application for enhanced electrochemical detection of H2O2 in milk and pharmaceutical samples

A novel and cost-effective synthesis of biopolymer-based organic and inorganic composite materials have received substantial attention in a broad range application including electroanalysis of small molecules. In this perspective, we report the synthesis of gum guar (guar) biopolymer stabilized cupric oxide decorated on exfoliated graphite (GR-guar/CuO) composite. Different physicochemical characterization methods were used to confirm the successful exfoliation of graphite and formation of the GR-guar/CuO composite. A simple sonochemical method has been used for the preparation of guar stabilized exfoliated graphite (GR-guar). The flower-like CuO on GR-guar and guar stabilized CuO (CuO-guar) composites were synthesized using a hydrothermal method. Cyclic voltammetric studies revealed that the GR-guar/CuO composite modified screen-printed carbon electrode (SPCE) had enhanced electro-reduction ability towards H₂O₂ than GR-guar and pristine graphite/CuO-guar modified SPCEs. Under optimized experimental conditions, the GR-guar/CuO composite modified electrode detects H₂O₂ in the response ranges from 0.02 to 1296.6 µM. The sensor shows a lower detection limit of 5.8 nM with high sensitivity. The as-prepared GR-guar/CuO composite sensor is highly reproducible and had excellent selectivity and practicality towards the detection of H₂O₂. Consequently, the fabricated sensor can be used for the accurate detection of H₂O₂ in real samples.

Recent development in chitosan nanocomposites for surface-based biosensor applications

Recent years have witnessed ever expanding use of biosensors in the fields of environmental monitoring, homeland security, pharmaceutical, food and bioprocessing, and agricultural industries. To produce effective and reliable biosensors, good quality immobilization of biological recognition elements is critical. Chitosan and its nanocomposites emerge as an excellent immobilization matrix on biosensor surface. As a natural polysaccharide, chitosan has many useful characteristics, such as high permeability and mechanical strength, biocompatibility and non-toxicity, availability, and low cost. Due to the presence of amino and hydroxyl groups on chitosan, chitosan can easily crosslink with a variety of nanomaterials. This investigation of chitosan nanocomposite-based biosensors presents recent development and innovations in the preparation of chitosan nanocomposites in coordination with biosensors for various bio-detection applications, including chitosan nanocomposites formed with carbon nanomaterials, various inorganic and biological complexes. These chitosan nanocomposite based biosensors have demonstrated good sensitivity selectivity and stability for the detection of different types of targets ranging from glucose, proteins, DNAs, small biomolecules to bacteria. It is in our hope that this review will offer guidance for the development of novel biosensors and open up opportunities in the field of biosensor research.

Electrochemically reduced graphene oxide and gold nanoparticles on an indium tin oxide electrode for voltammetric sensing of dopamine

The authors describe an electrochemical dopamine sensor that is based on the use of electrochemically co-reduced graphene oxide (Er-GO) and gold nanoparticles (AuNPs) on an indium-tin oxide (ITO) electrode. The synergistic effects of Er-GO and Er-AuNPs promote electron transport in the modified ITO. This results in an excellent performance for voltammetric sensing of dopamine (DA). Under the optimum conditions and a typical working potential of -0.05 V (vs. Ag/AgCl), the ITO electrode has a linear response in the 0.02-200 μM DA concentration range and a low detection limit of 15 nM. The sensor also showed a good selectivity over ascorbic acid and uric acid. The feasibility of the method was studied by analyzing DA in cerebrospinal fluid of rats. Graphical abstract Schematic presentation of one-step electrochemical co-reduction of graphene oxide (GO) and gold nanoparticles (AuNPs) on an ITO electrode for voltammetric sensing of dopamine.

Simultaneous cationic Cu (II)‒anionic Sb (III) removal by NH2-Fe3O4-NTA core-shell magnetic nanoparticle sorbents synthesized via a facile one-pot approach

In this study, a regenerable magnetic core-shell nanoparticles NH₂-Fe₃O₄-NTA which include 3-aminopropyltriethoxysilane (APTES) and nitrilotriacetic acid (NTA) crosslinked to Fe₃O₄ was developed by one-pot method for simultaneous removal of cationic and anionic metals. Another nanocomposite NH₂-Fe₃O₄-NTA_II was prepared by multi-step method for comparison. NH₂-Fe₃O₄-NTA had positive zeta potential values of 35.1-0.8 mV at pH 1.8-11.0, with the saturation magnetization and surface area up to 40.56 emu/g and 56.94 m²/g, respectively. The maximum sorption capacities of NH₂-Fe₃O₄-NTA for cationic Cu (II) and anionic Sb (III) were 55.56 and 51.07 mg/L, respectively, which were superior to that of NH₂-Fe₃O₄-NTA_II. Based on screening in terms of characterization and metal sorption capacity, NH₂-Fe₃O₄-NTA with a feasible synthesis scheme was chosen for further evaluation. The Cu (II) removal by NH₂-Fe₃O₄-NTA was favored with increasing pH, while the Sb (III) removal preferred low pH (2-3). Simultaneous sorption of Cu (II) and Sb (III) exhibited same removal performance with the sole sorption under high dosage (>1 g/L). In real wastewater applications of NH₂-Fe₃O₄-NTA, multiple metals in actual wastewater could be removed to well below the regulation levels. Nonspecific electrostatic interactions, inner-sphere complexation, ligand exchange, chelation and coordination complexation were responsible for Cu (II) and Sb (III) removal.

Trace level electrochemical determination of the neurotransmitter dopamine in biological samples based on iron oxide nanoparticle decorated graphene sheets

The trace level electrochemical determination of dopamine in biological samples based on an iron oxide nanoparticle-capped graphene sheet modified electrode.

Simple strategy for sensitive detection of dopamine using CdTe QDs modified glassy carbon electrode

BACKGROUND

Cellular and brain metabolism of dopamine can be correlated with a number of neurodegenerative disorders, our study was to explore a simple and efficient method to detect dopamine in real samples.

METHODS

A new quantum dots (CdTe QDs) could be prepared using the hydrothermal method, the electrochemical biosensor was established by dropping CdTe QDs on the surface of glassy carbon electrode (GCE).

RESULTS

The CdTe QDs/GCE exhibited the excellent electrochemical catalytic activity toward dopamine (DA) with good stability and high sensitivity in presence of interfering substances. The detection limit of DA was calculated by differential pulse voltammetry (DPV) as low as 0.3 μmol L^-1 with a linear dynamic range of 1 μmol L^-1 to 400 μmol L^-1 .

CONCLUSION

In this paper, the proposed electrochemical biosensor could be effectively used for the direct and rapid detection of DA in human serum and urine samples.

New Approach for Porous Chitosan-Graphene Matrix Preparation through Enhanced Amidation for Synergic Detection of Dopamine and Uric Acid

Amide-functionalized materials have emerged as promising nonprecious catalysts for electrochemical sensing and catalysis. The covalent immobilization of chitosan (CS) onto graphene sheet (GS) (denoted as CS-GS) has been done via higher degree of amidation reaction to develop an electrochemical sensing matrix for simultaneous determination of dopamine (DA) and uric acid (UA). The enhanced amidation between CS and GS has not been reported previously. However, electrochemical results have revealed that the CS-GS enhances the electrocatalytic performance in terms of the oxidation potential and peak current due to the higher degree of amide functionalization compared to that of CS/GS, which has a lower amidation. Differential pulse voltammetry-based studies have indicated that the CS-GS matrix works at a lower detection limit (0.14 and 0.17 μM) (S/N = 3) and over a longer linear range (1-700 and 1-800 μM), with a comparatively higher sensitivity (2.5 and 2.0 μA μM^-1 cm^-2), for DA and UA, respectively. In addition, the CS-GS matrix demonstrates good selectivity toward the detection of DA and UA in the presence of a 10-fold higher concentration of AA and glucose. The as-prepared three-dimensional porous CS-GS also endows selective determination toward DA and UA in various real samples.

Nanomolar electrochemical detection of caffeic acid in fortified wine samples based on gold/palladium nanoparticles decorated graphene flakes

Amalgamation of noble metal nanomaterials on graphene flakes potentially paves one way to improve their physicochemical properties. This paper deals with the simultaneous electrochemical deposition of gold and palladium nanoparticles on graphene flakes (Au/PdNPs-GRF) for the sensitive determination of caffeic acid (CA). The physiochemical properties of the prepared Au/PdNPs-GRF was characterized by using numerous analytical techniques such as scanning electron microscopy, electron dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction, Raman spectroscopy and electrochemical impedance spectroscopy. The enhanced electrochemical determination of CA at Au/PdNPs deposition on GRF were studied by using cyclic voltammetry and differential pulse voltammetry. In results, Au/PdNPs-GRF electrode exhibited an excellent electrocatalytic activity towards CA with wide linear range and low limit of detection of 0.03-938.97µM and 6nM, respectively. Eventually, the Au/PdNPs-GRF was found as a selective and stable active material for the sensing of CA. In addition, the proposed sensor showed the adequate results in real sample analysis.

Magnetism-assisted modification of screen printed electrode with magnetic multi-walled carbon nanotubes for electrochemical determination of dopamine

A simple and sensitive dopamine (DA) electrochemical sensor was fabricated based on magnetism-assisted modification of screen printed electrode (SPE) with magnetic multi-walled carbon nanotubes (mMWCNTs). The mMWCNTs modified electrodes (mMWCNTs/SPE) combines the advantages of SPE and the simultaneous contribution of magnetic nanoparticles (MNPs) and MWCNTs, increasing sensitivity and selectivity of DA detection. The linearity was found between 5μM to 180μM, with the limit of detection (LOD) of 0.43μM. In the mean time, this modified electrode exhibited excellent selectivity for DA detection with almost no interference from ascorbic acid (AA), which co-exists with DA in many bio-samples and causes common interference. Finally, this novel electrode has been applied to determine DA concentration in spiked human blood serum and satisfactory recovery was found in the range of 97.43-102.94% with the RSDs of less than 2.27%. This work developed a sensitive and reliable electrochemical analytical method based on mMWCNTs/SPE, which exhibits great potential for diagnosis of the diseases related to DA.

High sensitivity chlorogenic acid detection based on multiple layer-by-layer self-assembly films of chitosan and multi-walled carbon nanotubes on a glassy carbon electrode

A chlorogenic acid sensor based on a chitosan (CS) and multi-walled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE) was fabricated via a layer-by-layer (LBL) self-assembly method.