A systematic review on electrochemical sensors for the detection of acetaminophen

Considerable progress has been made in the electrochemical determination of acetaminophen (AP) over the past few decades. Nanomaterials or enzymes as electrode modifiers greatly improve the performance of AP electrochemical sensors. This review focuses on the development potential, detection principles and techniques for the electrochemical analysis of AP. In particular, the design and construction of AP electrochemical sensors are discussed from the perspective of non-enzyme materials (such as nanomaterials, including precious metals, transition metals and non-metals) and enzyme substances (such as aryl acylamidase, polyphenol oxidase and horseradish peroxidase). Moreover, the influencing factors for AP electrochemical sensors and the simultaneous detection of AP and other targets are summarized, and the future prospective of AP electrochemical sensors is outlined. This review provides a reference and guidance for the development and application of electrochemical sensors for AP detection.

Design of self-healing nanocomposite hydrogels and the application to the detection of human exercise and ascorbic acid in sweat

Hydrogel sensors have broad application prospects in human motion monitoring and sweat composition detection. However, hydrogel-based sensors are faced with challenges such as low accuracy and poor mechanical properties of analytes detection. Based on mussel-inspired chemistry, we synthesized mesoporous silica@polydopamine-Au (MPS@PDA-Au) nanomaterials and designed a self-healing nanocomposite hydrogel to monitor human movement and ascorbic acid detection in sweat. Mesoporous silica (MPS) possess orderly mesoporous structure. Dopamine (DA) polymerized on the surface of MPS to generate polydopamine (PDA), forming the composite material MPS@PDA-Au. This composite was then embedded into polyvinyl alcohol (PVA) hydrogels through a simple freeze-thaw cycle process. The hydrogels have achieved excellent deformable ability (508.6%), self-healing property (90.5%) and mechanical strength (2.9 MPa). The PVA/MPS@PDA-Au hydrogel sensors had the characteristics of fast response time (123.2 ms), wide strain sensing range (0-500%), excellent fatigue resistance and stability in human detection. The detection range of ascorbic acid (AA) in sweat was wide (8.0 μmol/L-100.0 μmol/L) and the detection limit was low (3.3 μmol/L). Therefore, these hydrogel sensors have outstanding application prospects in human motion monitoring and sweat composition detection.

Graphene derivative-based ink advances inkjet printing technology for fabrication of electrochemical sensors and biosensors

The field of biosensing would significantly benefit from a disruptive technology enabling flexible manufacturing of uniform electrodes. Inkjet printing holds promise for this, although realizing full electrode manufacturing with this technology remains challenging. We introduce a nitrogen-doped carboxylated graphene ink (NGA-ink) compatible with commercially available printing technologies. The water-based and additive-free NGA-ink was utilized to produce fully inkjet-printed electrodes (IPEs), which demonstrated successful electrochemical detection of the important neurotransmitter dopamine. The cost-effectiveness of NGA-ink combined with a total cost per electrode of $0.10 renders it a practical solution for customized electrode manufacturing. Furthermore, the high carboxyl group content of NGA-ink (13 wt%) presents opportunities for biomolecule immobilization, paving the way for the development of advanced state-of-the-art biosensors. This study highlights the potential of NGA inkjet-printed electrodes in revolutionizing sensor technology, offering an affordable, scalable alternative to conventional electrochemical systems.

Macromolecule-Nanoparticle-Based Hybrid Materials for Biosensor Applications

Biosensors function as sophisticated devices, converting biochemical reactions into electrical signals. Contemporary emphasis on developing biosensor devices with refined sensitivity and selectivity is critical due to their extensive functional capabilities. However, a significant challenge lies in the binding affinity of biosensors to biomolecules, requiring adept conversion and amplification of interactions into various signal modalities like electrical, optical, gravimetric, and electrochemical outputs. Overcoming challenges associated with sensitivity, detection limits, response time, reproducibility, and stability is essential for efficient biosensor creation. The central aspect of the fabrication of any biosensor is focused towards forming an effective interface between the analyte electrode which significantly influences the overall biosensor quality. Polymers and macromolecular systems are favored for their distinct properties and versatile applications. Enhancing the properties and conductivity of these systems can be achieved through incorporating nanoparticles or carbonaceous moieties. Hybrid composite materials, possessing a unique combination of attributes like advanced sensitivity, selectivity, thermal stability, mechanical flexibility, biocompatibility, and tunable electrical properties, emerge as promising candidates for biosensor applications. In addition, this approach enhances the electrochemical response, signal amplification, and stability of fabricated biosensors, contributing to their effectiveness. This review predominantly explores recent advancements in utilizing macrocyclic and macromolecular conjugated systems, such as phthalocyanines, porphyrins, polymers, etc. and their hybrids, with a specific focus on signal amplification in biosensors. It comprehensively covers synthetic strategies, properties, working mechanisms, and the potential of these systems for detecting biomolecules like glucose, hydrogen peroxide, uric acid, ascorbic acid, dopamine, cholesterol, amino acids, and cancer cells. Furthermore, this review delves into the progress made, elucidating the mechanisms responsible for signal amplification. The Conclusion addresses the challenges and future directions of macromolecule-based hybrids in biosensor applications, providing a concise overview of this evolving field. The narrative emphasizes the importance of biosensor technology advancement, illustrating the role of smart design and material enhancement in improving performance across various domains.

Novel nickel(II) phthalocyanine/reduced graphene oxide: an electrochemical sensing platform for analysis of hydroquinone and chloramphenicol in environmental samples

Novel tetra-2-(biphenyl-4-yl)-1,3-benzoxazol-carboxamide nickel(II) phthalocyanine (NiTBPBXCAPc) and rGO were confirmed using FT-IR, UV-vis, XRD, TGA and Raman spectra. The NiTBPBXCAPc and rGO nanocomposite has been developed to detect hydroquinone (HQN) and chloramphenicol (CPC). NiTBPBXCAPc has been examined using cyclic voltammetry (CV), linear sweep voltammetry (LSV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) analysis. The simultaneous CV analysis of HQN and CPC demonstrated the ability of NiTBPBXCAPc@rGO/GCE to execute simultaneous redox reactions. The voltammetric and amperometric limit of detection for HQN and CPC was determined to be 4.5 and 3.5 nM respectively, with a sensitivity of 0.446 and 0.416 μA M-1 cm-2. The amperometric LOD was observed to be 5 and 4 nM with a sensitivity of 0.235 and 0.288 μA M-1 cm-2. Additionally, the NiTBPBXCAPc@rGO/GC electrode is also used for real sample analysis with outstanding recovery. The long-term storage stability, reusability, and real-world sample analysis of the NiTBPBXCAPc@rGO/GC electrode demonstrated its use in environmental analysis.

A novel MWCNT-encapsulated (2-aminoethyl)piperazine-decorated zinc(II) phthalocyanine composite: development of an electrochemical sensor for detecting the antipsychotic drug promazine in environmental samples

A nanocomposite of (2-aminoethyl)piperazine ligand substituted with zinc(II) tetra carboxylic acid phthalocyanine (ZnTEPZCAPC) and MWCNTs was constructed and employed to develop an electrochemical sensor with outstanding sensitivity and a low detection limit. The macrocyclic complex ZnTEPZCAPC was first synthesized and then employed for the electrochemical determination of the antipsychotic drug promazine (PMZ). The as-prepared ZnTEPZCAPC and MWCNT nanocomposite was characterized using different techniques, such as Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), UV-visible spectroscopy (UV-Vis), field emission scanning electron microscopy (FE-SEM), and thermogravimetric analysis (TGA). Further, the prepared ZnTEPZCAPC@MWCNT nanocomposites were modified on a glassy carbon electrode (GCE) surface, and the electrochemical activity was investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CA) tests in pH 7.0 phosphate buffer solution (PBS) in the potential window of 0.0-1 V. The ZnTEPZCAPC@MWCNTs displayed a superior electrochemical performance because of their high electrochemical active surface area (0.453 cm2), good conductivity, and a synergetic effect. The developed electrochemical sensor exhibited a broad linear range of 0.05-635 μM and the lowest detection limit of 0.0125 nM, as well as excellent sensitivity, repeatability, and reproducibility. Finally, the fabricated sensor was successively used for the real-time detection of PMZ in environmental and biological samples and displayed feasible recoveries.

DNA-functionalized carbon quantum dots for electrochemical detection of pyocyanin: A quorum sensing molecule in Pseudomonas aeruginosa

The electrochemical biosensing strategy for pyocyanin (PYO), a virulent quorum-sensing molecule responsible for Pseudomonas aeruginosa infections, was developed by mimicking its extracellular DNA interaction. Calf thymus DNA (ct-DNA) functionalized amine-containing carbon quantum dots (CQDs) were used as a biomimetic receptor for electrochemical sensing of PYO as low as 37 nM in real urine sample. The ct-DNA-based biosensor enabled the selective measurement of PYO in the presence of other interfering species. Calibration and validation of the PYO sensor platform were demonstrated in buffer solution (0-100 μM), microbial culture media (0-100 μM), artificial urine (0-400 μM), and real urine sample (0-250 μM). The sensor capability was successfully implemented for point-of-care (POC) detection of PYO release from Pseudomonas aeruginosa strains during lag and stationary phases. Cross-reactivity of the sensing platform was also tested in other bacterial species such as Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Shigella dysenteriae, Staphylococcus aureus, and Streptococcus pneumoniae. Potential clinical implementation of the ct-DNA-based sensor was manifested in detecting the PYO in P. aeruginosa cultured baby diaper and sanitary napkin. Our results highlight that the newly developed ct-DNA-based sensing platform can be used as a potential candidate for real-time POC diagnosis of Pseudomonas aeruginosa infection in clinical samples.

Enzyme-Mimics for Sensitive and Selective Steroid Metabolite Detection

We present an enzyme-like functional polymer that recognizes nonelectroactive targets and catalyzes their redox reactions for simple, selective steroid metabolite detection. Measuring steroid metabolites, such as cortisol, has been widely adopted to diagnose stress and chronic diseases. Conventional detection method based on competitive immunoassay requires time-consuming labeling processes for signal transduction and unstable biological receptors for biorecognition yet with limited selectivity. Inspired by natural enzymes' target specificity and catalytic nature, we report an enzyme-mimic using electrocatalytic molecularly imprinted polymers (EC-MIP) to achieve label-free, external redox reagent-free, sensitive, and selective electrochemical detection of cortisol. The EC-MIP sensor contains molecularly imprinted cavities for specific cortisol binding and embedded copper phthalocyanine tetrasulfonate (CuPcTS) for electrocatalytic reduction of the ketones on the captured cortisol into alcohols. The direct sensing approach resolves the intrinsic limitations of conventional MIP-based sensors, most notably the use of external redox probes and weak sensing signals. The sensor exhibited a detection limit of 181 pM with significantly enhanced selectivity using a differential sensing mechanism. The new enzyme-like sensor can be modified to detect other targets, offering a simple, robust approach to future health monitoring technologies.

Electrochemical, Ultrasensitive, and Selective Detection of Nitrite and H2O2: Novel Macrostructured Phthalocyanine with Composite MWCNTs on a Modified GCE

In the current study, the synthesis of tetra-4-(2-methoxyphenoxy) carboxamide cobalt(II) amide-bridged phthalocyanine (CoTMePhCAPc) is described, as well as its characterization by Fourier transform infrared (FT-IR), UV-visible, and mass spectroscopy; powder X-ray diffraction (PXRD); thermogravimetric analysis (TGA); scanning electron microscopy (SEM); and electrochemistry. Sensing of nitrite (NO₂^-) and hydrogen peroxide (H₂O₂) simultaneously was done on CoTMePhCAPc with the composite multiwalled carbon nanotube (MWCNT)-modified glassy carbon electrode (CoTMePhCAPc/MWCNT/GCE) in the range of linear absorption (NO₂^- and H₂O₂: CV 50-750, differential pulse voltammetry (DPV) 50-750, CA 50-500 nmol L^-1), lower detection limit (NO₂^- and H₂O₂: CV 10.5 and 12.5, DPV 10.5 and 11.2, CA 6.0 and 5.5 nmol L^-1), and sensitivity (NO₂^- and H₂O₂: CV 0.379 and 0.529, DPV 0.043 and 0.049, CA 0.033 and 0.040 μA nM^-1 cm^-2). The composite electrode exhibits improved electrocatalytic behavior compared to modified electrodes for nitrite and H₂O₂. The CoTMePhCAPc/MWCNT/GCE sensor displays good selectivity even in the presence of an excess of interfering metal ions and biomolecules at the applied potentials of +400 mV (nitrite) and -400 mV (H₂O₂). Moreover, the fabricated sensor was studied with various phosphate-buffered saline (PBS) (pH 5-9) electrolyte solutions. The unknown H₂O₂ concentration in blood samples and apple juice and nitrite concentration in drinking water and butter leaf lettuce were all measured using the usual addition method. Docking analysis clearly indicates that the ligand shows excellent inhibition activity toward the three subjected protein molecules.

Recent Advances in the Use of CoPc-MWCNTs Nanocomposites as Electrochemical Sensing Materials

Cobalt phthalocyanine multiwalled carbon nanotubes (CoPc-MWCNTs), a nanocomposite, are extraordinary electrochemical sensing materials. This material has attracted growing interest owing to its unique physicochemical properties. Notably, the metal at the center of the metal phthalocyanine structure offers an enhanced redox-active behavior used to design solid electrodes for determining varieties of analytes. This review extensively discusses current developments in CoPc-MWCNTs nanocomposites as potential materials for electrochemical sensors, along with their different fabrication methods, modifying electrodes, and the detected analytes. The advantages of CoPc-MWCNTs nanocomposite as sensing material and its future perspectives are carefully reviewed and discussed.

Mechanistic insight into the photocatalytic degradation of organic pollutants and electrochemical behavior of modified MWCNTs/Cu–Co3O4 nanocomposites

The present work reported the physical, chemical and electrical properties of Cu doped Co3O4.

Novel Schiff base iron(ii) phthalocyanine with composite MWCNTs on modified GCE: electrochemical sensor development for paracetamol

Paracetamol is one of the most commonly consumed medicines to deal with minor pain, body ache, headache, fever etc. It can also be used for getting temporary relief from arthritis pain.

A novel electrochemical sensor based on TAPT-TFP-COF/COOH-MWCNT for simultaneous detection of dopamine and paracetamol

In this work, a covalent organic framework (COF) TAPT-TFP-COF containing a triazine ring was prepared by a typical Schiff base condensation reaction of 1,3,5-tris-(4-aminophenyl)triazine (TAPT) and 1,3,5-triformyl phloroglucinol (TFP). The TAPT-TFP-COF and carboxyl-functionalized multi-wall carbon nanotubes (COOH-MWCNTs) were drip-coated on glassy carbon electrode respectively to develop a novel and simple electrochemical sensor in order to simultaneously detect dopamine (DA) and paracetamol (PA). COOH-MWCNTs interconnected the TAPT-TFP-COF and acted as bridges between the COF particles, which had a good synergistic effect and accelerated electron transfer. Under optimal conditions, linear responses were obtained over the concentration range 1-190 μM for DA and PA with limits of detection (LOD) of 0.14 μM and 0.19 μM, respectively. Furthermore, the fabricated sensor possesses outstanding repeatability and high selectivity, and can be applied for the determination of DA and PA in dopamine injection and acetaminophen drugs with satisfactory recoveries.

Novel Schiff base cobalt(ii) phthalocyanine with appliance of MWCNTs on GCE: enhanced electrocatalytic activity behaviour of α-amino acids

A novel tetra-4-{(E)-[(8-aminonaphthalen-1-yl)imino]methyl}-2-methoxyphenol Co(ii) phthalocyanine (CoTANImMMPPc) was synthesized using a precursor protocol and characterized via electroanalytical and spectroscopic techniques. The FT-IR spectra of the synthesized compounds showed significant peaks corresponding to the functional groups of the precursors and phthalocyanine (Pc) compound. The mass and NMR spectra confirmed the formation of the target precursor compounds. A film of CoTANImMMPPc was deposited on the surface of an electrode and applied for the detection and monitoring of l-alanine and l-arginine. The cyclic voltammetric studies of l-alanine and l-arginine using the (CoTANImMMPPc/MWCNTs/GC) electrode showed a linear response in the range of 50–500 nM and the limit of detection was found to be 1.5 and 1.2 nM, respectively. Differential pulse voltammetry and chronoamperometry showed that the catalytic response for l-alanine and l-arginine is in the range of 50–500 nM with an LoD of 1.8 and 2.3 nM, respectively. The oxidation-active CoTANImMMPPc film significantly enhanced the current response in the chronoamperometric method and displayed a selective and sensitive response towards l-alanine and l-arginine in the presence of various other bio-molecules. The developed electrode showed good working stability and was applied for the analysis of real samples, which yielded satisfactory results. Therefore, CoTANImMMPPc-MWCNTs/GCE shows good analytical performance, is economical and produced via a simple synthetic method and can be applied as a sensor for the detection of l-alanine and l-arginine.

A novel CoTANImMMPPc complex was synthesized using a precursor protocol and characterized via electroanalytical and spectroscopic techniques with enhanced electrocatalytic behaviour of α-amino acids.