Screen-printed analytical strip constructed with bacteria-templated porous N-doped carbon nanorods/Au nanoparticles for sensitive electrochemical detection of dopamine molecules

Single iron catalyst with bi-atomic matching site to construct electrochemical chip for on-site inspection of antibiotic chloramphenicol

Chloramphenicol (CAP) as an amide-alcohol antibiotic is extensively used in aquaculture industries and can accumulate in the human body through the food chain and water sources, leading to various diseases. On-site inspection of CAP remains a challenge due to the lack of portable and sensitive sensing platforms. Herein, a bi-atomic matching catalyst that comprises atomic Fe uniformly distributed on an N-doped graphene matrix (A-Fe-NG) is synthesized. An electrochemical sensor based on A-Fe-NG is constructed for CAP, demonstrating a high sensitivity of 164.2 μA μM-1 cm-2 and a fast response time of 1.2 s, among the best of Fe-based electrochemical CAP sensors. The high performance should be attributed to the high active site density of A-Fe-NG as well as the bi-atomic matching-catalysis mechanism. A portable electrochemical chip based on A-Fe-NG is also built, delivering accurate monitoring of CAP in river water for practical on-site inspection.

Gold Nanoparticles: Diagnostic and Therapeutic Applications in Neurodegenerative Disorders

Neurodegenerative disorders (NDDs), including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and prion diseases, pose a significant and escalating health challenge in the context of an aging population. Gold nanoparticles (GNPs) have emerged as promising agents in the diagnostic and therapeutic realms of NDDs, due to their unique ability to enhance drug delivery across the blood-brain barrier (BBB). This paper presents a comprehensive review of the application of GNPs in the context of NDDs diagnosis and therapy, highlighting their potential to transform patient management. Additionally, we systematically address the critical challenges associated with the use of GNPs in the treatment and diagnosis of NDDs, focusing on pharmacokinetics and metabolism, toxicity, long-term biocompatibility, regulatory challenges, and cost-effectiveness. Furthermore, we synthesize ongoing clinical studies to provide a holistic perspective on the current state of research in this field. We also explore the prospective trajectories and clinical translational potential of GNPs, which may usher in a new era in the treatment of NDDs.

COF-Derived Carbon Materials: Synthesis Strategies and Emerging Applications

Covalent organic framework (COF)-derived carbon materials seamlessly inherit the periodic porous architecture and high specific surface area of their precursors, while simultaneously enabling the confinement of nanoparticles in designated regions. This unique feature mitigates agglomeration, enhances intrinsic properties, and imparts novel functionalities to the resulting materials. Consequently, COF-derived carbon materials have garnered significant attention across diverse fields, including energy, environmental remediation, and biomedical applications. Despite this burgeoning interest, a comprehensive review encompassing the synthesis, classification, and multifaceted applications of these materials remains scarce. In this context, the state-of-the-art advancements in COF-derived carbon materials are reviewed systematically here. It categorizes the materials, delineates their primary synthesis strategies, and highlights their versatile applications in catalysis, electrochemical energy storage, water treatment, sensing, and cancer therapy. Lastly, fresh insights into the challenges and future prospects of COF-derived carbon materials, paving the way for their expanded exploration and utilization are offered here.

Copper Nanoclusters Anchored on Crumpled N-Doped MXene for Ultra-Sensitive Electrochemical Sensing

Simultaneous detection of dopamine (DA) and uric acid (UA) is essential for diagnosing neurological and metabolic diseases but hindered by overlapping electrochemical signals. We present an ultrasensitive electrochemical sensor using copper nanoclusters anchored on nitrogen-doped crumpled Ti3C2Tx MXene (Cu-N/Ti3C2Tx). The engineered 3D crumpled architecture prevents MXene restacking, exposes active sites, and enhances ion transport, while Cu nanoclusters boost electrocatalytic activity via accelerated electron transfer. Structural analyses confirm uniform Cu dispersion (3.0 wt%), Ti-N bonding, and strain-induced wrinkles, synergistically improving conductivity. The sensor achieves exceptional sensitivity (1958.3 and 1152.7 μA·mM-1·cm-2 for DA/UA), ultralow detection limits (0.058 and 0.099 μM for DA/UA), rapid response (<1.5 s), and interference resistance (e.g., ascorbic acid). Differential pulse voltammetry enables independent linear detection ranges (DA: 2-60 μM; UA: 5-100 μM) in biofluids, with 94.4% stability retention over 7 days. The designed sensor exhibits excellent capabilities for DA and UA detection. This work provides a novel design strategy for developing high-performance electrochemical sensors.

A multidimensional luminescent sensor for specific and in situ visual detection of dopamine

Dopamine (DA) is a neurotransmitter with biologically important properties that play an important role in the function of the central nervous and cardiovascular systems. Abnormal DA concentrations in human biological fluids are thought to be associated with many neurological disorders. Luminescence have now become an effective method for the detection of DA. Ratiometric luminescent sensors with self-calibration exhibit higher sensitivity and selectivity than conventional single-emission sensors. In addition, Ln-MOFs sensors constructed based on lanthanide ions doping have the significant advantages of simple synthesis, green, and high stability. In this study, EuxTbyGd1-x-y-dpdf with tunable emission properties was developed by introducing Eu3+ and Tb3+ ions, which emit red and green light, as the luminescent centers. Then the framework was doped with inert Gd³⁺ to tune the energy levels. The introduction of Gd3+ realizes multiple emission centers from both the visible and UV regions. Ratiometric luminescence detection of DA was achieved by using the ligand-based peak (390 nm) as an internal reference and the emission centers of Tb3+ (545 nm) and Eu3+ (617 nm) as indicators. The optimized Tb0.24Eu0.16Gd0.6-dpdf showed excellent sensitivity and low detection limit for DA in aqueous solution. In addition, nanofiber films of probes were prepared by electrostatic spinning technique for visual detection of DA, demonstrating the potential for practical applications. This work provides a novel design strategy for ratiometric luminescent probes, which can be doped with inert Ln3+ and regulate the ratio between different ions to achieve energy level matching. The ratiometric luminescent sensor constructed based on this method significantly improves the selectivity and sensitivity of DA detection, which provides valuable implications for biomedical and clinical diagnosis.

Implementation of π-π interaction in AuNPs@GDY to boost the bioelectrocatalysis in enzymatic biofuel cells

The main challenges (sluggish electron transfer, low energy density) hinder the future application of enzymatic biofuel cells (EBFCs), which urgent to take effective measures to solve these issues. In this work, a composite of Au nanoparticles decorated graphdiyne (AuNPs@GDY) is fabricated and employed as the carrier of enzyme (G6PDH), and a mechanism based on π-π interaction of electron transfer is proposed to understand bioelectrocatalysis processes. The results show that the AuNPs@GDY composite exhibits the highest current density among the three materials (GDY, AuNPs, and AuNPs@GDY), which is 3.4 times higher than that of GDY and 2.5 times higher than that of AuNPs. Furthermore, the results reveal that the AuNPs could increase the loading of enzymes and provide more active site for reaction, while GDY provides highly π-conjugated structure and unique sp/sp2-hybridized linkages interface. This work provides new insights to explore a theoretical basis for the development of more efficient bioelectrocatalytic systems.

Co4+ in porous ZIF-67-derives intercalating-bridging adsorption of 2-reaction sites for simultaneous 2-electron transfer toward sensitive detection of uric acid

Metal-organic frameworks (MOFs) have been used to detect uric acid (UA), but still very challenging to achieve a low detection limit due to the low inferior conductivity of MOFs. Herein, three different N-doped ZIF-67-derived carbons were synthesized for the first time by one-step co-pyrolysis of 2-methylimidazole with cobalt nitrate (CN), cobalt acetate (CA) or cobalt chloride (CC) toward UA sensing. Afterwards, the cobalt nitrate-derived Co particle (Co/CN) supported by N-doped ZIF-67-derived carbon displays extremely low detection limit and high sensitivity for UA, outperformed all reported MOFs-based UA sensors. More interestingly, it was discovered that the high valence Co4+ within the Co/CN sample produced in high-acidic environment can intercalate in the frame for a bridge adsorption between two reaction sites, which boosted simultaneous 2-electron transfer, while Co3+ only allows an end-adsorption structure for one-electron transfer being the rate determining step. Furthermore, the bridge adsorption mode of UA on Co4+ -based catalyst was also verified by theoretical DFT calculations and XPS experiment. This work holds great promise for a selective and sensitive UA sensor for practical bioscience and clinic diagnostic applications while shedding lights in fundamental research for innovative designs and developments of high-sensitive electrochemical sensors.

Integrated Sandwich-Paper 3D Cell Sensing Device to In Situ Wirelessly Monitor H2O2 Released from Living Cells

Point-of-care testing (POCT) has attracted great interest because of its prominent advantages of rapidness, precision, portability, and real-time monitoring, thus becoming a powerful biomedical device in early clinical diagnosis and convenient medical treatments. However, its complicated manufacturing process and high expense severely impede mass production and broad applications. Herein, an innovative but inexpensive integrated sandwich-paper three-dimensional (3D) cell sensing device is fabricated to in situ wirelessly detect H2O2 released from living cells. The paper-based electrochemical sensing device was constructed by a sealed sandwiched bottom plastic film/fiber paper/top hole-centered plastic film that was printed with patterned electrodes. A new (Fe, Mn)3(PO4)2/N-doped carbon nanorod was developed and immobilized on the sensing carbon electrode while cell culture solution filled the exposed fiber paper, allowing living cells to grow on the fiber paper surrounding the electrode. Due to the significantly shortening diffusion distance to access the sensing sites by such a unique device and a rationally tuned ratio of Fe2+/Mn2+, the device exhibits a fast response time (0.2 s), a low detection limit (0.4 μM), and a wide detection range (2-3200 μM). This work offers great promise for a low-cost and highly sensitive POCT device for practical clinic diagnosis and broad POCT biomedical applications.

Graphdiyne chelated AuNPs for ultrasensitive electrochemical detection of tyrosine

Tyrosine (Tyr) is a kind of amino acid that can regulate emotions and stimulate the nervous system, and it is of great importance to realize its ultrasensitive detection. A unique material of graphdiyne chelated AuNPs (GDY@AuNPs) is designed and developed to realize high-performance electrochemical sensing of Tyr. GDY promotes the absorption of Tyr via π-π interaction, and its CC strongly chelates with AuNPs for greatly improved sensitivity. GDY@AuNPs delivers a sensitivity of up to 181.2 μA mM-1 cm-2 and a wide range of 0.1-600 μM, among the best for carbon or AuNPs-based materials for the detection of Tyr. It demonstrates the accurate detection of Tyr in human sweat for potential practical applications.

Electroactive Microorganisms in Advanced Energy Technologies

Large-scale production of green and pollution-free materials is crucial for deploying sustainable clean energy. Currently, the fabrication of traditional energy materials involves complex technological conditions and high costs, which significantly limits their broad application in the industry. Microorganisms involved in energy production have the advantages of inexpensive production and safe process and can minimize the problem of chemical reagents in environmental pollution. This paper reviews the mechanisms of electron transport, redox, metabolism, structure, and composition of electroactive microorganisms in synthesizing energy materials. It then discusses and summarizes the applications of microbial energy materials in electrocatalytic systems, sensors, and power generation devices. Lastly, the research progress and existing challenges for electroactive microorganisms in the energy and environment sectors described herein provide a theoretical basis for exploring the future application of electroactive microorganisms in energy materials.

Single-Atom Indium Boosts Electrochemical Dopamine Sensing

A rational design of high-efficiency electrocatalysts and thus achieving sensitive electrochemical sensing remains a great challenge. In this work, single-atom indium anchored on nitrogen-doped carbon (In₁-N-C) with an In-N₄ configuration is prepared successfully through a high-temperature annealing strategy; the product can serve as an advanced electrocatalyst for sensitive electrochemical sensing of dopamine (DA). Compared with In nanoparticle catalysts, In₁-N-C exhibits high catalytic performance for DA oxidation. The theoretical calculation reveals that In₁-N-C has high adsorption energy for hydroxy groups and a low energy barrier in the process of DA oxidation compared to In nanoparticles, indicating that In₁-N-C with atomically dispersed In-N₄ sites possesses enhanced intrinsic activity. An electrochemical sensor for DA detection is established as a concept application with high sensitivity and selectivity. Furthermore, we also verify the feasibility of In₁-N-C catalysts for the simultaneous detection of uric acid, ascorbic acid, and DA. This work extends the application prospect of p-block metal single-atom catalysts in electrochemical sensing.

Polyoxometalate-cyclodextrin supramolecular entities for real-time in situ monitoring of dopamine released from neuroblastoma cells

Optimized and sensitive biomarker detection has recently been shown to have a critical impact on quality of diagnosis and medical care options. In this research study, polyoxometalate-γ-cyclodextrin metal-organic framework (POM-γCD MOF) was utilized as an electrocatalyst to fabricate highly selective sensors to detect in-situ released dopamine. The POM-γCD MOF produced multiple modes of signals for dopamine including electrochemical, colorimetric, and smartphone read-outs. Real-time quantitative monitoring of SH-SY5Y neuroblastoma cellular dopamine production was successfully demonstrated under various stimuli at different time intervals. The POM-CD MOF sensor and linear regression model were used to develop a smartphone read-out platform, which converts dopamine visual signals to digital signals within a few seconds. Ultimately, POM-γCD MOFs can play a significant role in the diagnosis and treatment of various diseases that involve dopamine as a significant biomarker.

Screen printed electrodes on interfacial Pt-CuO/carbon nanofiber functional ink for real-time qualification of cell released hydrogen peroxide

Screen printed electrode (SPE) on carbon-based inks exhibits promising applications in biosensing, environment protection and food safety. We report here a unique carbon-based material comprising Pt-CuO nanocrystal interfacially anchored on functionalized carbon nanofiber (Pt-CuO@FCNF) and its functional ink to build SPE for ultrasensitive detection of cell released H₂O₂. Pt-CuO@FCNF is fabricated using a one-pot and mass production method through direct pyrolysis of Pt and CuO precursors together with FCNF. FCNF with 1-D structure and high electrical conductivity can interfically anchor Pt-CuO nanocrystal, which synergically promotes rich active site and catalytic activity towards H₂O₂. Pt-CuO@FCNF exhibits a wide linear response of 0.4 μM-11 mM, a low detection limit of 17 nM, a fast response time of 1.0 s, and good selectivity. Eventually, Pt-CuO@FCNF SPE realizes real-time and ultrasensitive qualification of H₂O₂ released from both normal and cancer cells.

Interfacial Regulation of ZIF-67 on Bacteria to Generate Bifunctional Sensing Material on Chip for Qualifying Cell-Released Reactive Oxygen Species

Cell's activities are highly dependent on signal molecules, of which reactive oxygen species of the superoxide anion (O₂^•-) and hydrogen peroxide (H₂O₂) are important ones that always work together to regulate biological processes such as apoptosis and oxidative stress. It is of significance to realize simultaneous qualification of O₂^•- and H₂O₂ but it still faces challenges particularly in live-cell assay with a complex environment. We report the design of a bifunctional sensing material by interfacially regulating ZIF-67 on bacteria Shewanella putrefaciens to generate cobalt nanoparticles/nitrogen-doped porous carbon nanorods (Co/N-doped CNRs) and its sensing chip for qualifying cell-released O₂^•- and H₂O₂. Co/N-doped CNRs exhibit unique properties including porous structure for significantly increased reaction surface area and coordinating Co nanoparticles for rich active sites. The bifunctional Co/N-doped CNRs is used to fabricate the electrochemical sensing chip, which achieves a fast response time (0.5 s for O₂^•-, 1.9 s for H₂O₂), a low detection limit (0.69 nM for O₂^•-, 2.25 μM for H₂O₂), and a remarkably high sensitivity (792.30 μA·μM^-1·cm^-2 for O₂^•-, 153.91 μA·mM^-1·cm^-2 for H₂O₂), among the best of reported bifunctional nanozymes.

Point-of-care biochemical assays using electrochemical technologies: approaches, applications, and opportunities

Against the backdrop of hidden symptoms of diseases and limited medical resources of their investigation, in vitro diagnosis has become a popular mode of real-time healthcare monitoring. Electrochemical biosensors have considerable potential for use in wearable products since they can consistently monitor the physiological information of the patient. This review classifies and briefly compares commonly available electrochemical biosensors and the techniques of detection used. Following this, the authors focus on recent studies and applications of various types of sensors based on a variety of methods to detect common compounds and cancer biomarkers in humans. The primary gaps in research are discussed and strategies for improvement are proposed along the dimensions of hardware and software. The work here provides new guidelines for advanced research on and a wider scope of applications of electrochemical biosensors to in vitro diagnosis.

Review—Recent Progress in Graphene Based Modified Electrodes for Electrochemical Detection of Dopamine

Graphene and its derivatives have been widely used for the electrochemical detection of dopamine (DA) neurotransmitter, thanks to its high surface area and excellent conductivity. Modified graphene and graphene-based nanocomposites have shown improved catalytic activity towards DA detection. Various modification approaches have been taken, including heteroatom doping and association with other nanomaterials. This review summarizes and highlights the recent advances in graphene-based electrodes for the electrochemical detection of DA. It also aims to provide an overview of the advantages of using polymer as a linker platform to form graphene-based nanocomposites applied to electrochemical DA sensors.

Vanadium pentoxide flat-nanofiber networked thin layer-structure to initiate intercalated polymerization for rapidly producing superior conductive hydrogel and its biomimetic hydrogen peroxide sensing application

Poly(3,4-ethylenedioxythiophene) (PEDOT)-based hydrogel has been studied extensively due to its low cost, good chemical/mechanical stability, printability and high biocompatibility, but still suffers from its relatively low conductivity and complex synthesis method. In this work, we use vanadium pentoxide (V₂O₅) flat-nanofiber networked thin layer-structure to boost EDOT-intercalation reaction for rapidly producing fiber-reinforced conductive gel (FCG), achieving superior conductivity of 10 S cm^-1 and extremely fast production time (10 s). The superior FCG formation mechanism is ascribed to the V₂O₅ flat-nanofiber networked thin layer-structure allowing EDOT rapidly penetrating to inter-layers and replacing inside water molecules for polymerization to high-conductive FCG. The FCG can be used to print various patterns and are further used to fabricate a flexible biomimetic hydrogen peroxide (H₂O₂) sensor, delivering a high sensitivity of 2100 µA mM^-1 cm^-2, ranking the best among all flexible enzyme-free H₂O₂ sensors. More importantly, this flexible biomimetic H₂O₂ sensor is successfully applied to real-time detect living cells-secreted H₂O₂, demonstrating its application for in situ monitoring of small biomolecules released from living cells. This work offers a universal approach to synthesize high-conductive printable hydrogels by designing precursors meriting from both physics and chemistry, while holding great promise for mass-manufacturing inexpensive hydrogels in applications of sensing or wearable devices.

Wearable Electrochemical Sensors in Parkinson's Disease

Parkinson’s disease (PD) is a neurodegenerative disorder associated with widespread aggregation of α-synuclein and dopaminergic neuronal loss in the substantia nigra pars compacta. As a result, striatal dopaminergic denervation leads to functional changes in the cortico-basal-ganglia-thalamo-cortical loop, which in turn cause most of the parkinsonian signs and symptoms. Despite tremendous advances in the field in the last two decades, the overall management (i.e., diagnosis and follow-up) of patients with PD remains largely based on clinical procedures. Accordingly, a relevant advance in the field would require the development of innovative biomarkers for PD. Recently, the development of miniaturized electrochemical sensors has opened new opportunities in the clinical management of PD thanks to wearable devices able to detect specific biological molecules from various body fluids. We here first summarize the main wearable electrochemical technologies currently available and their possible use as medical devices. Then, we critically discuss the possible strengths and weaknesses of wearable electrochemical devices in the management of chronic diseases including PD. Finally, we speculate about possible future applications of wearable electrochemical sensors in PD, such as the attractive opportunity for personalized closed-loop therapeutic approaches.

Fabrication of ionic liquid stabilized MXene interface for electrochemical dopamine detection

Development of MXene (Ti3C2Cl2)-based sensing platforms by exploiting their inherent active electrochemistry is highly challenging due to their characteristic poor stability in air and water. Herein, we report a cost-effective methodology to deposit MXene on a conductive graphitic pencil electrode (GPE). MXenes can provide active surface area due to their clever morphology of accordion-like sheets; however, the disposition to stack together limits their potential applications. A task-specific ionic liquid (1-methyl imidazolium acetate) is utilized as a multiplex host material to engineer MXene interface via π-π interactions as well as to act as a selective binding site for biomolecules. The resulting IL-MXene/GPE interface proved to be a highly stable interface owing to good interactions between MXene and IL that inhibited electrode leaching and boosted electron transfer at the electrode-electrolyte interface. It resulted in robust dopamine (DA) oxidation with amplified faradaic response and enhanced sensitivity (9.61 µA µM-1 cm-2) for DA detection. This fabricated sensor demonstrated large linear range (10 µM - 2000 µM), low detection limit (702 nM), high reproducibility, and good selectivity. We anticipate that such platform will pave the way for the development of stable and economically viable MXene-based sensors without sacrificing their inherent properties. Scheme 1 Schematic illustration of the IL-MXene/GPE fabrication and oxidative process towards non-enzymatic dopamine sensor.

Green synthesis of magnetically recyclable Mn0.6Zn0.4Fe2O4@Zn1-xMnxS composites from spent batteries for visible light photocatalytic degradation of phenol

Magnetic binary heterojunctions are a kind of promising photocatalysts due to their high catalytic activity and easy magnetic separation; however, their synthesis may involve high costs or secondary environmental impacts. In this work, the magnetically recyclable Mn_0.6Zn_0.4Fe₂O₄@Zn_1-xMn_xS (MZFO@Zn_1-xMn_xS, x = 0.00-0.07) photocatalysts are synthesized from spent batteries via a green biocheaching and egg white-assisted hydrothermal method. The as-synthesized photocatalysts have been comprehensively characterized in phase, morphology, texture, optics, photoelectrochemistry and photocatalytic activity. Characterization results indicate that the desired core-shell structure MZFO@Zn_1-xMn_xS composites are successfully synthesized, theirs absorption intensity in the visible light region is greatly enhanced compared to Zn_1-xMn_xS. In addition, doped Mn²⁺ in ZnS host lattice and the staggered bandgap alignment of MZFO and Zn_1-xMn_xS greatly enhances electron transfer and charge separation in the binary heterojunction system. The optimized MZFO@Zn_0.95Mn_0.05S shows the highest photodegradation performance toward phenol under the visible light irradiation, with a complete degradation of 25 mg L^-1 of phenol within 120 min, and its reactive kinetic constants is about 5.2 and 13.3 times higher than that of pure Zn_0.95Mn_0.05S and MZFO, respectively. Furthermore, the mechanism and pathways for the degradation of phenol are proposed. In addition, MZFO@Zn_0.95Mn_0.05S also exhibits a good reusability and high magnetic separation properties after 5 successive cycles. This new material has the advantages of low costs, simple reuse and great potential in application.

Construction of a Au@MoS2 composite nanosheet biosensor for the ultrasensitive detection of a neurotransmitter and understanding of its mechanism based on DFT calculations

MoS₂ nanosheets can be applied as electrochemical biosensors to selectively and sensitively respond to the surrounding environment and detect various biomolecules due to their large specific surface area and unique physicochemical properties. In this paper, single-layer or few-layer MoS₂ nanosheets were prepared by an improved liquid phase stripping method, and then combining the unique material characteristics of MoS₂ and the metallic property of Au nanoparticles (AuNPs), Au@MoS₂ composite nanosheets were synthesized based on MoS₂ nanosheets. Then, the structure and properties of MoS₂ nanosheets and Au@MoS₂ composite nanosheets were comprehensively characterized. The results proved that AuNPs were successfully loaded on MoS₂ nanosheets. At the same time, on the basis of the successful preparation of Au@MoS₂ composite nanosheets, an electrochemical biosensor targeting dopamine was successfully constructed by cyclic voltammetry. The linear detection range was 0.5–350 μM, and the detection limit was 0.2 μM. The high-sensitive electrochemical detection of dopamine has been achieved, which provides a new idea for the application of MoS₂-based nanomaterials in the biosensing of neurotransmitters. In addition, density functional theory (DFT) was used to explore the electrochemical performance of Au@MoS₂ composite nanosheets. The results show that the adsorption of Au atoms on the MoS₂ 2D structure improves the conductivity of MoS₂ nanosheets, which theoretically supports the possibilities of its application as a platform for the ultrasensitive detection of neurotransmitters or other biomolecules in the field of disease diagnosis.

An electrochemical biosensor based on Au@MoS₂ composite nanosheets was successfully prepared for the high-sensitivity detection of dopamine.

Highly stable branched cationic polymer-functionalized black phosphorus electrochemical sensor for fast and direct ultratrace detection of copper ion

Copper ions (Cu²⁺) is an indispensable trace element in the process of metabolism and intake of excessive Cu²⁺ may lead to fatal diseases such as Alzheimer's disease. It is highly demanding to develop a sensitive, selective and convenient method for Cu²⁺ detection. In this work, thin-layer structured polyethyleneimine (PEI) decorated black phosphorus (BP) nanocomposite is one-step synthesized for an electrochemical sensor toward direct detection of Cu²⁺. This sensor achieves a wide detection range of 0.25-177 μM, a low detection limit of 0.02 μM much below the Environmental Protection Agency (EPA) maximum contaminant levels for drinking water (20 μM for Cu²⁺), and much faster response (1.5 s response time) and simpler operation than the conventional tedious anodic stripping voltammetry, ranking one of the best among all reported Cu²⁺ sensor. The great sensing enhancement is mainly due to a synergistic effect of BP and PEI of the composite, of which the former offers the reactivity while the latter splits the thick BP to thin-layer structured PEI-BP composite for larger reaction area. Meanwhile, a flexible sensor has been successfully fabricated and applied in detecting of Cu²⁺ in real samples of river, confirming the application feasibility of PEI-BP sensor in water environment control.