A proof-of-concept electroreduction-free anodic stripping voltammetry analysis of Ag(I) based on S,N-Ti3C2Tx MXene nanoribbons.

Herein, by preparing sulfur and nitrogen co-doped Ti3C2Tx MXene nanoribbons (S,N-Ti3C2TxR) as a sensing material, a sensitive and novel electroreduction-free anodic stripping voltammetry strategy was designed to detect Ag(I) (Ag+) for the first time, which can successfully avoid the power-consuming electroreduction step, achieving simple, sensitive and efficient detection for Ag+ with a low detection limit and wide linearity.

Target-Controlled Redox Reaction and Ru(II) Release of a Smart Metal-Organic Framework Nanomaterial for Highly Sensitive Ratiometric Homogeneous Electroanalysis of Cadmium(II).

In this work, a highly sensitive ratiometric homogeneous electroanalysis (HEA) strategy of cadmium(II) (Cd2+) was proposed via a Cd2+-controlled redox reaction and Ru(bpy)32+ (Ru(II)) release from a smart metal-organic framework (MOF) nanomaterial. For achieving this purpose, Ru(II) was entrapped ingeniously into the pores of an MOF material (UiO-66-NH2) and subsequently gated by the double-strand hybrids of a Cd2+-aptamer (Apt) and its complementary sequences (CP) to form a novel smart nanomaterial (denoted as Ru@UiO-66-NH2); meanwhile, Fe(III) was selected as an additional probe present in electrolyte to facilitate the Ru(II) redox reaction: Fe(III) + Ru(II) → Fe(II) + Ru(III). Owing to the strong binding effect of the Cd2+ target to the specific Apt, the Apt-CP hybridization at Ru@UiO-66-NH2 would be destroyed in the presence of Cd2+, and the related Apt was further induced away from the smart nanomaterial, leading to the opening of the gate and release of Ru(II). Meanwhile, the released Ru(II) was quickly oxidized chemically by Fe(III) to Ru(III). On the basis of the generated Ru(III) and consumed Fe(III), the ratio of the reduction currents between Ru(III) and Fe(III) exhibits an enhancement and it is dependent on the level of Cd2+; thus, a novel HEA strategy of Cd2+ was then designed. Under the optimal conditions, the HEA sensor shows a wide linearity ranging from 10.0 pM to 500.0 nM, and the achieved detection limit of Cd2+ is 3.3 pM. The as-designed ratiometric HEA strategy not only offers a unique idea to realize a simple and sensitive assay for Cd2+ but also possesses significant potential as an effective tool to be introduced for other target analysis just via altering the specific Apt.

High Peroxidase-Mimicking Metal-Organic Frameworks Decorated with Platinum Nanozymes for the Colorimetric Detection of Acetylcholine Chloride and Organophosphorus Pesticides via Enzyme Cascade Reaction.

The sensitive detection of acetylcholinesterase (AChE) and organophosphorus pesticides (OPs) is very important for the protection of human health. Herein, a hybrid material, Pt NPs/Fe-MOF, consisting of a metal-organic framework (MIL-88B-NH2, Fe-MOF) decorated with platinum nanoparticles (Pt NPs), was prepared first and exhibited remarkably improved and excellent peroxidase-mimicking activity compared to the Fe-MOF material resulting from the synergistic catalysis effect between Fe-MOF and Pt NPs, which can effectively catalyze 3,3',5,5'-tetramethylbenzidine (TMB) oxidation to generate a blue product (oxidized TMB, oxTMB). Interestingly, in the presence of AChE and acetylcholinesterase, the peroxidase-mimicking activity from Pt NPs/Fe-MOF was inhibited obviously, and thus, a colorimetric sensing platform for AChE can be constructed; more importantly, after the addition of OPs, this nanozyme activity can be recovered, inducing the further successful construction of a sensitive colorimetric sensing platform for OPs. The related sensing mechanism and condition optimization were studied, and the as-prepared Pt NPs/Fe-MOF nanozyme-based colorimetric method for AChE and OP detection displayed superior analytical performances with wide linearities and low detection limits. Furthermore, the designed method offers satisfactory real application ability. We expect the as-proposed Pt NPs/Fe-MOF nanozyme-based colorimetric sensing platform for AChE and OPs via the enzyme cascade reaction to show great potential application.

Homogeneous voltammetric sensing strategy for lead ions based on aptamer gated methylthionine chloride@UiO-66-NH2 framework as smart target-stimulated responsive nanomaterial.

Herein an innovative electrochemical method is proposed for the determination of lead ions (Pb2+) based on a homogeneous voltammetric (HVC) sensing strategy using an aptamer gated methylthionine chloride@UiO-66-NH2 framework as a smart target-stimulated responsive material. The proposed HVC sensor exhibits excellent sensing performance: ultralow detection limit (0.166 pM) and wide linearity (5.0 pM-500.0 nM), simultaneously, it avoids electrodeposition processes and it is simple to modify the electrode compared to previous electrochemical methods for Pb2+ detection. Thus our method shows great potential in the highly efficient detection of Pb2+ and other heavy metal ions by simply altering the related specific aptamer.

Colorimetric method transforms into highly sensitive homogeneous voltammetric sensing strategy for mercury ion based on mercury-stimulated Ti3C2Tx MXene nanoribbons@gold nanozyme activity.

Nanozymes were emerged as the next generation of enzyme-mimics which exhibit great applications in various fields, but there is rarely report in the electrochemical detection of heavy metal ions. In this work, Ti3C2Tx MXene nanoribbons@gold (Ti3C2Tx MNR@Au) nanohybrid was prepared firstly via a simple self-reduction process and its nanozyme activity was studied. The results showed the peroxidase-like activity of bare Ti3C2Tx MNR@Au is extremely weak, while in the presence of Hg2+, the related nanozyme activity is stimulated and improved remarkably, which can easily catalyze oxidation of several colorless substrates (e.g., o-phenylenediamine) to form colored products. Interestingly, the product of o-phenylenediamine exhibits a strong reduction current which is considerably sensitive to the Hg2+ concentration. Based on this phenomenon, an innovative and highly sensitive homogeneous voltammetric (HVC) sensing strategy was then proposed to detect Hg2+ via transforming the colorimetric method into electrochemistry since it can exhibit several unique advantages (e.g., rapid responsiveness, high sensitivity and quantificational). Compared to the conventional electrochemical sensing methods for Hg2+, the designed HVC strategy can avoid the modification processes of electrode coupled with enhanced sensing performances. Therefore, we expect the as-proposed nanozyme-based HVC sensing strategy provides a new development direction for detecting Hg2+ and other heavy metals.

Nitrogen-doped Ti3C2 MXene quantum dots as an effective FRET ratio fluorometric probe for sensitive detection of Cu2+ and D-PA.

In this work, a ratiometric fluorescence sensing platform was established to detect Cu2+ and D-PA (d-penicillamine) based on nitrogen-doped Ti3C2 MXene quantum dots (N-MODs) that was prepared via a simple hydrothermal method and exhibited strong fluorescent and photoluminescence performance as well as excellent stability. Since the oxidation reaction between o-phenylenediamine (OPD) and Cu2+ induced the formation of 2,3-diaminophenazine (ox-OPD) which not only can emerge an emission peak at 570 nm, but also inhibit the fluorescence intensity of N-MQDs at 450 nm, a ratiometric reverse fluorescence sensor via fluorescence resonance energy transfer (FRET) was designed to sensitively detect Cu2+, where N-MQDs acted as energy donor and ox-OPD as energy acceptor. More importantly, another considerably interesting phenomenon was that their catalytic oxidation reaction can be restrained in the presence of D-PA because of the coordination of Cu2+ with D-PA, further triggering the obvious changes in ratio fluorescent signal and color, thus a ratiometric fluorescent sensor of determining D-PA was proposed also in this work. After optimizing various conditions, the ratiometric sensing platform showed rather low detection limits for Cu2+ (3.0 nM) and D-PA (0.115 µM), coupled with excellent sensitivity and stability.

N and P co-doped MXenes nanoribbons for electrodeposition-free stripping analysis of Cu(II) and Hg(II).

The present electrochemical stripping analysis (ESA) for multiple heavy metal ions (HMI) generally requires an electrodeposition process at a very low potential below -1.0 V, which inevitably makes the sensing procedures more complex, inefficient and power-wasting. Meanwhile, the emerging MXenes rising-star materials have been studied in various fields recently. While there are only few reports focusing on the heteroatom doping of MXenes, especially no doping-MXenes for electroanalysis. Based on these issues, a novel multifunctional heteroatoms-doped MXenes nanomaterial, N and P co-doped Ti3C2Tx MXenes nanoribbons (N,P-Ti3C2TxR), was prepared herein for the first time, and then N,P-Ti3C2TxR was used as electrode material to propose an electrodeposition-free ESA strategy for multiple HMI (Cu2+, Hg2+). Owing to the unique spontaneous adsorption and reducing capacities of N,P-Ti3C2TxR towards Cu2+ and Hg2+ coupled with the excellent sensing performances, Cu2+ and Hg2+ can undergo self-reduction to be preconcentrated on N,P-Ti3C2TxR surface with the form of Cu0 and Hg0, thus a simple and ultrasensitive electrodeposition-free ESA platform was developed successfully for the simultaneous detection of Cu2+and Hg2+. This work opened a new pathway for the detection for multiple HMI and the preparation/application of heteroatoms doping MXenes.

Free-electrodeposited anodic stripping voltammetry sensing of Cu(II) based on Ti3C2Tx MXene/carbon black.

A proof-of-principle concept for free-electrodeposited anodic stripping voltammetry (ASV) sensing of Cu2+ is proposed by using Ti3C2Tx MXene/carbon black (Ti3C2Tx@CB) nanohybrids as electrode materials. Owing to the high adsorption and reduction capability of Ti3C2Tx towards Cu2+, Ti3C2Tx MXene enables Cu2+ to be immobilized and self-reduced directly to form Cu0 on the Ti3C2Tx@CB electrode surface. As a result an oxidation peak current appears from the re-oxidation of Cu0 via differential pulse voltammetry. Carbon black (CB) was introduced to prevent Ti3C2Tx Mxene aggregation and improve the related electron transfer as well as enhance their surface area. After optimizing various conditions, a considerable low limit of detection (4.6 nM) and a wide linear range (0.01-15.0 µM) for Cu2+ were achieved at the working potential from - 0.3 V to 0.0 V (vs SCE). Relative standard deviation (RSD) of eight individual Ti3C2Tx@CB electrodes is 3.72%, and the recoveries from tap water sample and lake water sample were in the ranges of 97.0-108% and 104-107%, respectively.

Novel methodology for anodic stripping voltammetric sensing of heavy-metal ions using Ti3C2Tx nanoribbons.

Conventional anodic stripping voltammetry (ASV) sensing of heavy-metal ions (HMIs) generally includes a two-step approach: (a) preconcentration via electrodeposition and (b) re-oxidation, while the requirement of the electrodeposition step makes the detection processes more complex. Herein, a novel methodology using self-reduction instead of electrodeposition was developed for the ASV sensing of HMIs (selecting Cd2+ as a representative analyte) by introducing Ti3C2Tx MXene nanoribbons (Ti3C2Tx NR) as a sensing element that can exhibit direct adsorption and reduction capabilities towards HMIs. Compared with conventional ASV technology, the proposed methodology is simpler and power-saving, and has a significant low detection limit (0.94 nM) and wide linear range (0.005-3.0 µM).

Fluorescent and Colorimetric Dual-signal Enantiomers Recognition via Enzyme Catalysis: The Case of Glucose Enantiomers Using Nitrogen-doped Silicon Quantum Dots/Silver Probe Coupled with ß-D-Glucose Oxidase.

Chiral enantiomer recognition is important but facing tough challenges in the direct quantitative determination for complex samples. In this work, via chosing nitrogen-doped silicon quantum dots (N-SiQD) as optical nanoprobe and constructing N-SiQD/silver (N-SiQD/Ag NPs) complex, ß-D-GOx as model enzyme and glucose enantiomers as analytes, a fluorescent and colorimetric dual-signal chiral sensing strategy was proposed herein for chiral recognition based on specific enzyme-catalyzed reaction. N-SiQD can exhibit intense fluorescence, while it can be quenched by Ag NPs owing to the formation of N-SiQD/Ag NPs. In the presence of glucose isomer, D-glucose is catalytically hydrolyzed by ß-D-GOx to form H2O2 owing to the specific enzyme catalyzed reaction between D-glucose and ß-D-GOx, and H2O2 can etch Ag NPs from the N-SiQD/Ag NPs probe to change the solution color from brown to colorless and restore the N-SiQD fluorescence; while these phenomena cannot be caused by L-glucose, a dual-signal sensing method was thus constructed for recognizing glucose enantiomers. It is believed that the chiral enantiomers recognition strategy via enzyme catalysis has great application for selective and quantificational detection of enantiomers in the complex sample system.

ß-Cyclodextrin functionalized molybdenum disulfide quantum dots as nanoprobe for sensitive fluorescent detection of parathion-methyl.

Through modifying molybdenum disulfide quantum dots (MoS2 QDs) with 3-aminophenyl boronic acid and functionalizing further with hydropropyl-ß-cyclodextrin (ß-CD), a novel nanoprobe based on ß-CD functionalized MoS2 QDs (ß-CD-MoS2 QDs) was developed for the fluorescent detection of parathion-methyl (MP). ß-CD-MoS2 QDs was characterized with various technologies including transmission electron microscopy, X-ray photoelectron spectroscopy, fluorescence and UV-Vis absorption spectra. As for MP detection, MP was hydrolyzed to p-nitrophenol (p-NP) under the alkaline conditions, and p-NP can enter into the ß-CD cavity due to the host-guest recognition capability of ß-CD, which then results the fluorescence quenching of nanoprobe. Based on this principle, an enzyme-free fluorescence sensing platform were constructed for MP. Under the optimal conditions, ß-CD-MoS2 QDs nanoprobe exhibits wide detection scope (0.01-18.0 ppm) and low detection limits (3.3 ppb) for MP detection. In addition, the nanoprobe has excellent selectivity for MP, and it can be applied to detect MP in real samples.

3-Aminobenzeneboronic Acid Functionalized MoS2 Quantum Dot as Fluorescent Nanoprobe for the Determination of o-Dihydroxybenzene.

In this work, by functionalizing MoS2 quantum dot with 3-aminobenzeneboronic acid, a novel multifunctional quantum dot (denoted as B-MoS2 QD) was obtained and used successfully for a fluorescence nanoprobe for detecting o-dihydroxybenzene (o-DHB). Transmission electron microscopy, fluorescence spectrum, UV-vis spectrum and fluorescence lifetime were used to investigate the prepared nanoprobe. The results show that the B-MoS2 QD nanoprobe can exhibit strong fluorescence and excellent light fastness owing to the coupled effect from the MoS2 QDs and boronic acid; interestingly, the vicinal diols structure from its surface can bridge covalently with o-DHB, resulting in the fluorescence quenching of B-MoS2 QDs and selective recognition toward o-DHB. With the increasing of o-DHB concentration, the nanoprobe fluorescence would gradually decrease. By measuring the fluorescence intensity of B-MoS2 QDs, a wide linear range from 0.1 to 200.0 µM with a low detection limit of 0.025 µM was obtained for o-DHB analysis; meanwhile, this fluorescence nanoprobe possesses excellent selectivity for the selective detection of o-DHB from its analogues.

Electrochemical recognition of tryptophan enantiomers using a multi-walled carbon nanotube@polydopamine composite loaded with copper(II).

The work describes a voltammetric method for the recognition of tryptophan (Trp) enantiomers. A glassy carbon electrode (GCE) was modified with polydopamine-coated multiwalled carbon nanotubes and subsequently loaded with copper(II) ions. The morphology and structure of the material were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and electrochemical methods. The recognition of Trp enantiomers by the modified GCE was investigated by differential pulse voltammetry. Under optimum conditions, the sensor revealed a linear range from 1.0 to 100.0 µM with the limit of detection values of 0.15 µM and 0.20 µM for D-Trp and L-Trp, respectively. The recognition efficiency for the Trp enantiomers (with a chiral separation factor of 5.4 for L-Trp over D-Trp) is much higher than that of other electrodes. This is assumed to be due to the unique features of MWCNTs, PDA and Cu(II). After optimizing various experimental conditions, the method was successfully applied to chiral sensing of Trp isomers in a racemic mixture. The potential application to chiral separation of the amino acids phenylalanine and tyrosine was also evaluated, with a chiral separation factor of 2.14 and 1.33 for L-/D-phenylalanine and L-/D-tyrosine, respectively. Graphical abstract Schematic presentation of the synthesis of a multi-walled carbon nanotubes@polydopamine composite loaded with copper(II), and its application in electrochemical enantiorecognition of tryptophan enantiomers.

Highly sensitive and selective "off-on" fluorescent sensing platform for ClO- in water based on silicon quantum dots coupled with nanosilver.

We present a new "off-on" fluorescence probe for detecting hypochlorite (ClO-) based on silicon quantum dots coupled with silver nanoparticles (SiQDs/AgNPs) as nanocomplexes. Via introducing N-[3-(trimethoxysilyl)propyl]ethylenediamine and catechol as initial reactants, silicon quantum dots (SiQDs) with excellent properties were synthesized through a simple hydrothermal method. Transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to characterize the morphology and structure of quantum dots. The fluorescence of SiQDs could be quenched by the silver nanoparticles (AgNPs) by surface plasmon-enhanced energy transfer (SPEET) from SiQDs (donor) to AgNPs (acceptor). The AgNPs could be etched by adding ClO-, thus freeing the SiQDs from the AgNP surfaces and restoring the SiQDs' fluorescence. The sensing system exhibits many advantages, such as wide linear response range, high sensitivity, and excellent selectivity. Under optimized conditions, wide linear ranges (from 0.1 to 100.0 µM) and low detection limits (0.08 µM) were obtained for ClO-. Graphical Abstract.

Silicon quantum dot-coated onto gold nanoparticles as an optical probe for colorimetric and fluorometric determination of cysteine.

Silicon quantum dots (SiQDs) were synthesized from N-[3-(trimethoxysilyl)propyl]-ethylenediamine and catechol by a hydrothermal method. Transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to characterize the morphology and structure of quantum dots. The SiQDs were then placed on gold nanoparticles (AuNPs). When Cys is added to this solution, Cys will penetrate the SiQDs "shell" of the SiQDs/AuNP composite. This is due to the interaction and conformational differences of Cys and other substance with AuNPs and leads to the dispersion of the aggregated SiQD/AuNPs. A color change from purple to red can be visually observed, and the (green) fluorescence of SiQDs (with excitation/emission peaks at 430/520 nm) is restored. This dual-readout nanoprobe was successfully applied to the selective and sensitive detection of cysteine (Cys) in (spiked) serum and urine samples. The detection limit is 3.5 nmol·L-1 (at an S/N ratio of 3), and the method works on the 0.01 to 2 µM Cys concentration range. Graphical abstract Schematic illustration of a method for synthesizing silicon quantum dots (SiQDs) and coating them on gold nanoparticles (AuNPs) as an optical probe for colorimetric and fluorometric determination of cysteine.

Dual-Signal Electrochemical Enantiospecific Recognition System via Competitive Supramolecular Host-Guest Interactions: The Case of Phenylalanine.

For developing highly selective and sensitive electrochemical sensors for chiral recognition, taking advantage of the synthetical properties of ß-cyclodextrin (ß-CD, strong host-guest recognition) and carbon nanotubes wrapped with reduced graphene oxide (CNTs@rGO, excellent electrochemical property and large surface area), as well as the differences in binding affinity between ß-CD and guest molecules, a dual signal electrochemical sensing strategy was proposed herein for the first time in chiral recognition based on the competitive host-guest interaction between probe and chiral isomers with ß-CD/CNTs@rGO. As a model system, rhodamine B (RhB) and phenylalanine enantiomers (d- and l-Phe) were introduced as probe and target enantiomers, respectively. Due to the host-guest interactions, RhB can enter into the ß-CD cavity, showing remarkable oxidation peak current of RhB. In the presence of l-Phe, competitive interaction with the ß-CD cavity occurs and RhB are replaced by l-Phe owing to the stronger binding affinity between l-Phe and ß-CD, which results in the peak current of RhB decreasing and the peak current of l-Phe appears, and interestingly, the changes of both signals linearly correlate with the concentration of l-Phe. As for d-Phe, it cannot replace RhB owing to the weaker binding affinity between d-Phe and ß-CD. Based on this, a dual-signal electrochemical sensor was developed successfully for recognizing Phe. This dual-signal sensing strategy can provide highly selective and sensitive recognition compared to single-signal sensor and has important potential applications in chiral recognition.

A novel ratiometric fluorescent probe for the detection of uric acid in human blood based on H2O2-mediated fluorescence quenching of gold/silver nanoclusters.

In this work, a ratiometric fluorescent probe (RF-probe) for highly sensitive and selective detection of uric acid was reported for the first time toward H2O2 based on inner filter effect (IFE) between bimetallic gold/silver nanoclusters (Au/Ag NCs) and 2,3-diaminophenazine (DAP). For this RF-probe, uric acid was degraded to allantoin and H2O2. Upon the addition of HRP, o-phenylenediamine (OPD) could be catalytically oxidized to DAP in the presence of H2O2, then the fluorescence intensity corresponding to DAP at 580 nm increased dramatically with a fluorescence quenching of BSA-Au/Ag NCs at 690 nm, resulting in a RF-probe toward uric acid. This RF-probe allowed for the sensitive detection of uric acid in range of 5.0 × 10-6 M to 5.0 × 10-5 M with a detection limit (S/N = 3) as low as 5.1 × 10-6 M. At the same time, it has been successfully used for uric acid levels detection in human serum, and the results are consistent with those of the hospital. RF-probe built may provide a ratiometric fluorescence universal platform for detection of various species involving in the production of H2O2 in other biological systems.

Electrochemical sensing of 4-nitrochlorobenzene based on carbon nanohorns/graphene oxide nanohybrids.

Owing to the harmful nature of 4-nitrochlorobenzene (4-NCB, one toxic organic pollutant) and the low cost, high sensitivity and ease of operation of electrochemical method, it is highly desirable to develop effect electrochemical sensor for the detection of 4-NCB. Herein, by partially unzipping carbon nanohorns (CNHs) via a simple wet-chemistry method, CNHs and graphene oxide (GO) (CNHs/GO) nanohybrids were produced for sensing 4-NCB with synergistic properties. While the retained CNHs offer a path for rapid electron transport, the GO sheets formed by partially unzipping CNHs provide abundant active sites, further increase in surface area as well as improved dispersibility of the CNHs/GO. Our results show that the CNHs/GO modified electrode has excellent sensitivity to 4-NCB with a wide linear response range and a detection limit as low as 10 nM.

An ultrasensitive competitive immunosensor using silica nanoparticles as an enzyme carrier for simultaneous impedimetric detection of tetrabromobisphenol A bis(2-hydroxyethyl) ether and tetrabromobisphenol A mono(hydroxyethyl) ether.

Based on our produced polyclonal antibody capable of recognizing tetrabromobisphenol A bis(2-hydroxyethyl) ether (TBBPA-DHEE) and tetrabromobisphenol A mono(hydroxyethyl) ether (TBBPA-MHEE) (cross-reactivity, 100% for TBBPA DHEE; 98.7% for TBBPA MHEE), an important derivative and byproduct of tetrabromobisphenol A (TBBPA), respectively, a novel ultrasensitive competitive immunosensor was established using an electrochemical impedimetric strategy for the simultaneous detection of both chemicals. A significantly amplified electrochemical impedance spectroscopy (EIS) for quantitative target analysis was obtained through (i) the biocatalytic precipitation of 4-chloro-1-naphthol (CN) on the electrode surface triggered by horseradish peroxidase (HRP) and (ii) increased amounts of the enzyme with HRP-loaded silica nanoparticles carrying poly-brushes (SiO2@PAA) as labels, achieving a remarkable improvement in catalytic performance. Under the optimized conditions, the immunosensor showed satisfactory accuracy (recovery, 84.6-118%) and a good linear range (0.21- 111.31ng/mL) with a limit of detection (LOD) of 0.08ng/mL (S/N = 3) for TBBPA DHEE and TBBPA MHEE. In addition, the proposed approach was used to analyse real environmental water samples, and our results indicated that this immunosensor had great potential for the determination of the trace pollutants in aquatic environments.

Sensitive and Simultaneous Electrochemical Sensing for Three Dihydroxybenzene Isomers Based on Poly(L-arginine) Modified Glassy Carbon Electrode.

The simultaneous and sensitive electrochemical detection of dihydroxybenzene isomers (hydroquinone, HQ; catechol, CC; resorcinol, RS) is of great significance because such isomers can be awfully harmful to the environment and human health. In this paper, by preparing poly(L-arginine) modified glassy carbon electrode (P-L-Arg/GCE) with a simple method, a highly sensitive electrochemical sensor for simultaneously detecting HQ, CC and RS was constructed successfully due to the large surface area, good electronic properties and catalytic ability of P-L-Arg/GCE and the electrostatic action between P-L-Arg (positive) and targets (negative). Under the optimized conditions, the results show that the P-L-Arg/GCE has a wide linear range from 0.1 to 110.0 µM for HQ ,CC and RS. The detection limits for HQ, CC and RS are 0.01, 0.03 and 0.1 µM, respectively. Finally, the proposed sensor was successfully applied in real sample analysis.