2D/3D hierarchical porous structure of mNPC/SMOH@C to construct an electrochemical sensor for the simultaneous determination of p-acetylaminophenol and p-aminophenol.

BACKGROUND: As persistent organic pollutants (POPs), the accumulation of p-acetylaminophenol (PAT) and p-aminophenol (PAP) in water can seriously damage the health of plants and animals, ultimately leading to threats to human health and safety. Electrochemical sensors have the advantages of being fast, inexpensive, and accurate compared to the complex, expensive, and cumbersome conventional analytical methods. In this study, we designed and synthesized composites with two-dimensional/three-dimensional (2D/3D) porous structures to construct an efficient electrochemical platform for the simultaneous detection of PAT and PAP. RESULTS: In this work, a novel 3D foamy birnessite Na0.55Mn2O4·1.5H2O@C (SMOH@C) was synthesized, which was composited with 2D ordered mesoporous nanosheets (mNPC) to construct electrochemical sensors detecting PAT and PAP simultaneously. The prepared 2D/3D porous structure of mNPC/SMOH@C increased the exposure of active sites due to its large specific surface area. The introduction of a 3D carbon skeleton altered the charge transfer rate of SMOH@C, and the rich pore structure and oxygen-rich vacancies created favorable conditions for the diffusion and adsorption of PAP and PAT, which enabled the sensitive detection of PAT and PAP. The constructed mNPC/SMOH@C electrochemical sensor could simultaneously detect PAT (1 × 10-7 - 1 × 10-4 M) and PAP (5 × 10-8 - 1 × 10-4 M) with detection limits of 20.4 nM and 30.1 nM, respectively. The sensor has good repeatability (RSD <4 %) and reproducibility (RSD <4 %), and satisfactory recoveries (96.7-102.8 %) were obtained in the analysis of natural water samples. SIGNIFICANCE: In this paper, for the first time, we present the synthesis of 3D foam birnessite and its composite with mNPC for the electrochemical simultaneous detection of PAT and PAP. Our proposed strategy for fabricating 2D/3D porous composites lays the foundation for the design and synthesis of other porous materials. In addition, this study provides new ideas for developing efficient and practical electrochemical sensors for detecting pollutants in aquatic environments.

Electrochemical sensing platform using reduced graphene oxide and Sn MOF-derived hollow cubic composites for sensitive detection of catechol in environmental water samples.

Catechol, a polyphenolic molecule and significant organic chemical intermediate, is a highly dangerous environmental contaminant due to its unpredictable nature and potential harm to both humans and the environment. This study presents the development of Sn MOF@rGO-650, identified as a hollow cube by SEM and TEM, created by carbonizing rGO on the surface of Sn MOF after in situ encapsulation. The Sn MOF@rGO-650 modified glassy carbon electrode was successfully constructed for the electrochemical detection of catechol. Under optimal conditions, the sensor exhibited a detection limit of 33 nM, a linear range of 0.20 µM-28 µM, and good long-term stability and reproducibility. This work proves for the first time that Sn MOF@rGO-650 composites can effectively detect catechol in real environmental water samples, achieving recoveries between 95.7 % and 104.8 %, and is validated in UV spectroscopy, which highlights its potential for practical applications.

Ultra-sensitive electrochemical sensor based on in situ grown ultrafine HKUST-1 nanoparticles @ graphite nanosheets and core-shell structured MoO3-polypyrrole nanowires for the detection of rutin in orange juice.

Rutin extracted from natural plants has important medical value, so developing accurate and sensitive quantitative detection methods is one of the most important tasks. In this work, HKUST-1@GN/MoO3-Ppy NWs were utilized to develop a high-performance rutin electrochemical sensor in virtue of its high conductivity and electrocatalytic activity. The morphology, crystal structure, and chemical element composition of the fabricated sensor composites were characterized by SEM, TEM, XPS, and XRD. Electrochemical techniques including EIS, CV, and DPV were used to investigate the electrocatalytic properties of the prepared materials. The electrochemical test conditions were optimized to achieve efficient detection of rutin. The 2-electron 2-proton mechanism, consisting of several rapid and sequential phases, is postulated to occur during rutin oxidation. The results show that HKUST-1@GN/MoO3-Ppy NWs have the characteristics of large specific surface area, excellent conductivity, and outstanding electrocatalytic ability. There is a significant linear relationship between rutin concentration and the oxidation peak current of DPV. The linear range is 0.50-2000 nM, and the limit of detection is 0.27 nM (S/N = 3). In addition, the prepared electrode has been confirmed to be useful for rutin analysis in orange juice.

In-situ synthesized MgIn2S4/CdWO4 type-II heterojunction as a light-driven photoelectrochemical sensor for ultrasensitive detection of catechol in environmental water samples.

As an essential chemical intermediate, catechol (CC) residues may have adverse effects on human health. Herein, an effective and facile photoelectrochemical sensor platform based on MgIn2S4/CdWO4 composite is constructed for monitoring CC. MgIn2S4 increases light absorption range and activity, while CdWO4 enhances photoelectronic stability, and the type-II heterojunction formed can significantly enhance photocurrent response. Due to the autoxidation process, CC is converted into oligomeric products, which increase the spatial site resistance and attenuate the overall photocurrent response. It is worth noting that the cauliflower-like structure of MgIn2S4 can provide a large specific surface area, and the presence of Mg2+ promotes autoxidation, thus providing a suitable condition for detecting CC. Under optimal conditions, the MgIn2S4/CdWO4/GCE photoelectrochemical sensor has a prominent linear relationship in the range of CC concentration from 2 nM to 7 µM, with a limit of detection of 0.27 nM. With satisfactory selectivity, excellent stability, and remarkable reproducibility, this sensor provides a crucial reference value for effectively and rapidly detecting pollutants in environmental water samples.

Multilayer Ti3C2-CNTs-Au Loaded with Cyclodextrin-MOF for Enhanced Selective Detection of Rutin.

In this work, multi-layer Ti3C2 - carbon nanotubes - gold nanoparticles (Ti3C2-CNTs-Au) and cyclodextrin metal-organic framework - carbon nanotubes (CD-MOF-CNTs) have been prepared by in situ growth method and used to construct the ultra-sensitive rutin electrochemical sensor for the first time. Among them, the large number of metal active sites of Ti3C2, the high electron transfer efficiency of CNTS, and the good catalytic properties of AuNPs significantly enhance the electrochemical properties of the composite carbon nanomaterials. Interestingly, CD-MOF has a unique host-guest recognition and a large number of cavities, molecular gaps, and surface reactive groups, which gives the composite outstanding accumulation properties and selectivity for rutin. Under the optimized conditions, the constructed novel sensor has satisfactory detection performance for rutin in the range of 2 × 10-9 to 8 × 10-7 M with a limit of detection of 6.5 × 10-10 M. In addition, the sensor exhibits amazing anti-interference performance against rutin in some flavonoid compounds and can be used to test natural plant samples (buckwheat, Cymbopogon distans, and flos sophorae immaturus). This work has promising applications in the field of environmental and food analysis, and exploring new directions for the application of Mxene-based composites.

Detection of gallic acid in food using an ultra-sensitive electrochemical sensor based on glass carbon electrode modified by bimetal doped carbon nanopolyhedras.

Gallic acid is widely used as an antioxidant in food because of its good antioxidant function, but excessive intake induces side effects in humans, so it is essential to devise a highly responsive technique for detecting gallic acid. In this work, we synthesized ZIF-67@FePc by the one-pot method. The synthesized material is more stable at high temperatures compared to ZIF-67 and maintains its original morphology during pyrolysis, when iron was introduced as a second metal active site during the synthesis process. Subsequently, Co/FeOX@NC-800 was employed to fabricate a GA sensor on a GCE. The developed sensor exhibited remarkable sensitivity towards GA, featuring a low LOD of 1.30 nM and a linear range spanning from 5 to 4500 nM. The electrochemical sensors we have prepared also showed good selectivity, stability, and reproducibility. It has been successfully employed for detecting GA in actual samples such as apples, grapes, tomatoes, and red wine.

An ultrasensitive dietary caffeic acid electrochemical sensor based on Pd-Ru bimetal catalyst doped nano sponge-like carbon.

Caffeic acid (CA) is widely present in the human daily diet, and a reliable CA detection method is beneficial to food safety. Herein, we constructed a CA electrochemical sensor employing a glassy carbon electrode (GCE) which was modified by the bimetallic Pd-Ru nanoparticles decorated N-doped spongy porous carbon obtained by pyrolysis of the energetic metal-organic framework (MET). The high-energy bond N-NN in MET explodes to form N-doped sponge-like carbon materials (N-SCs) with porous structures, boosting the adsorptive capacity for CA. The addition of Pd-Ru bimetal improves the electrochemical sensitivity. The linear range of the PdRu/N-SCs/GCE sensor is 1 nM-100 nM and 100 nM-15 µM, with a low detection limit (LOD) of 0.19 nM. It has a high sensitivity (55 µA/µM) and repeatability. The PdRu/N-SCs/GCE sensor has been used to detect CA in actual samples of red wine, strawberries, and blueberries, providing a novel approach for CA detection in food analysis.

Electrochemical Behavior of ß-Cyclodextrin-Ni-MOF-74/Reduced Graphene Oxide Sensors for the Ultrasensitive Detection of Rutin.

Rutin, as a biological flavonoid glycoside, has very important medicinal value. The accurate and rapid detection of rutin is of great significance. Herein, an ultrasensitive electrochemical rutin sensor based on ß-cyclodextrin metal-organic framework/reduced graphene oxide (ß-CD-Ni-MOF-74/rGO) was constructed. The obtained ß-CD-Ni-MOF-74 was characterized by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and nitrogen adsorption and desorption. The ß-CD-Ni-MOF-74/rGO presented good electrochemical properties benefiting from the large specific surface area and good adsorption enrichment effect of ß-CD-Ni-MOF-74 and the good conductivity of rGO. Under optimal conditions for the detection of rutin, the ß-CD-Ni-MOF-74/rGO/GCE showed a wider linear range (0.06-1.0 µM) and lower detection limit (LOD, 0.68 nM, (S/N = 3)). Furthermore, the sensor shows good accuracy and stability for the detection of rutin in actual samples.

An electrochemical sensor based on Ce-MOF-derived Ce-doped poly(3,4-ethylenedioxythiophene) composite for efficient determination of rutin in food.

As a common antioxidant and nutritional fortifier in food chemistry, rutin has positive therapeutic effects against novel coronaviruses. Here, Ce-doped poly(3,4-ethylenedioxythiophene) (Ce-PEDOT) nanocomposites derived through cerium-based metal-organic framework (Ce-MOF) as a sacrificial template have been synthesized and successfully applied to electrochemical sensors. Due to the outstanding electrical conductivity of PEDOT and the high catalytic activity of Ce, the nanocomposites were used for the detection of rutin. The Ce-PEDOT/GCE sensor detects rutin over a linear range of 0.02-9 µM with the limit of detection of 14.7 nM (S/N = 3). Satisfactory results were obtained in the determination of rutin in natural food samples (buckwheat tea and orange). Moreover, the redox mechanism and electrochemical reaction sites of rutin were investigated by the CV curves of scan rate and density functional theory. This work is the first to demonstrate the combined PEDOT and Ce-MOF-derived materials as an electrochemical sensor to detect rutin, thus opening a new window for the application of the material in detection.

A light-driven photoelectrochemical sensor for highly selective detection of hydroquinone based on type-II heterojunction formed by carbon nanotubes immobilized in 3D honeycomb CdS/SnS2.

The ecological environment and public safety are seriously threatened by the typical phenolic contaminant hydroquinone (HQ). Here, using a straightforward physical mixing technique, we created an n-n heterojunction by uniformly immobilizing cadmium sulfide (CdS) nanoparticles on the surface of a three-dimensionally layered, flower-like structure made of tin sulfide (SnS2). Then, as photosensitizers, carbon nanotubes (CNTs) were added to the CdS/SnS2 complex to create a type-II heterostructure of CdS/SnS2/CNTs with synergistic effects. Subsequently, the detector HQ was bound to the modified photoelectrodes, which was accompanied by the hole oxidation of the bound HQ, leading to a significant increase in the photocurrent signal, thus allowing specific and sensitive detection of HQ. Under optimized detection conditions, the proposed photoelectrochemical sensor shows a wide detection range of 0.2 to 100 µM for HQ with a detection limit as low as 0.1 µM. The high accuracy of the sensor was demonstrated by comparison with the detection results of UV-vis spectrophotometry. In addition, the photoelectrochemical sensor exhibits good reproducibility, stability, selectivity, and specificity, providing a light-driven method to detect HQ.

Anomalous concentrations of rare earth elements in acid mine drainage and implications for rare earth resources from late Permian coal seams in northern Guizhou.

Rare earth elements (REEs) have attracted much attention in recent decades due to their growing applications in high-tech industries. Coal and acid mine drainage (AMD) are considered promising alternative sources due to their high concentrations of REEs. Here, AMD with anomalous REEs concentrations was reported in a coal-mine area in northern Guizhou, China. The AMD had a total concentration as high as 22.3 mg/l, suggesting that regional coal seams may be enriched with REEs. Five segments from borehole samples, which contained coal, rocks from the roof and floor of the coal seam were collected from the coal mine site to investigate the abundance, enrichment, and occurrence of REE-bearing minerals. Elemental analysis showed that the REE contents in the coal, mudstone and limestone from the coal seam roof, and claystone from the floor (all dating to the late Permian) varied greatly, with averages of 388, 549, 60.1 mg/kg and 2030 mg/kg, respectively. Encouragingly, the REEs content in the claystone is over an order of magnitude higher than the average content reported in most other coal-based materials. The enrichment of REEs resources in regional coal seams is particularly associated with the contribution of REEs in the claystone that comprises the coal seam floor, rather than just the coal, as considered in previous studies. The minerals in these claystone samples were dominated by kaolinite, pyrite, quartz and anatase. Two types of REE-bearing minerals, bastnaesite and monazite, were detected in the claystone samples by SEM-EDS analysis, and they were found to be adsorbed by a large amount of clay minerals, mainly kaolinite. Additionally, the results of chemical sequential extraction also confirmed that the majority of the REEs in the claystone samples are mainly in their ion-exchangeable, metal oxide and acid-soluble forms, which are viable prospects for REE extraction. Therefore, the anomalous concentrations of REEs and most of them are in extractable phases, which demonstrates that the claystone from the floor of the late Permian coal seam should be a potential secondary source of REEs. Future studies will further consider the extraction model and the economic benefits of REEs from the floor claystone samples.

A "Special" Solvent to Prepare Alloyed Pd2Ni1 Nanoclusters on a MWCNT Catalyst for Enhanced Electrocatalytic Oxidation of Formic Acid.

Herein, an electrocatalyst with Pd2Ni1 nanoclusters, supporting multiwalled carbon nanotubes (MWCNTs) (referred to Pd2Ni1/CNTs), was fabricated with deep eutectic solvents (DES), which simultaneously served as reducing agent, dispersant, and solvent. The mass activity of the catalyst for formic acid oxidation reaction (FAOR) was increased nearly four times compared to a Pd/C catalyst. The excellent catalytic activity of Pd2Ni1/CNTs was ascribed to the special nanocluster structure and appropriate Ni doping, which changed the electron configuration of Pd to reduce the d-band and to produce a Pd-Ni bond as a new active sites. These newly added Ni sites obtained more OH- to release more effective active sites by interacting with the intermediate produced in the first step of FAOR. Hence, this study provides a new method for preparing a Pd-Ni catalyst with high catalytic performance.

A novel photoelectrochemical sensor based on flower-like SnS2, sea urchin-like AgBiS2 and graphene oxide nanocomposite film for efficient and sensitive detection of acetaminophen in lake water samples.

As an emerging detection technology, photoelectrochemical sensors have been widely noticed for their unique technical features. Among others, the technology has been widely used in the fields of drug, biological antibody or antigen and contaminant detection. Secondly, acetaminophen, as a novel environmental pollutant, is difficult to be degraded in the ecosystem, which in turn causes serious impacts on the ecosystem. Therefore, in this work, we designed a photoelectrochemical sensor based on a composite film of flower-like SnS2, sea urchin-like AgBiS2 and graphene oxide for the detection of acetaminophen in water samples. Among them, graphene oxide, as a two-dimensional carbon-based material, can immobilize other photoelectric materials well. In addition, the flower-like SnS2 and sea urchin-like AgBiS2 can enhance the intensity of the photoelectric response due to their synergistic effect. Notably, the combination of graphene oxide with SnS2 and AgBiS2 revealed an exponential increase in the photoresponse intensity, indicating that SnS2/AgBiS2/GO has a satisfactory photoresponse intensity. At the same time, the photoelectrochemical sensor exhibited sensitive detection performance (LOD = 4 nM) and a wide detection range (0.01-50 µM) for acetaminophen under optimal detection conditions. Moreover, it also showed excellent detection performance in the detection of actual water samples, indicating that it can be applied to the detection of acetaminophen in lakes.

Ultrasensitive Determination of Natural Flavonoid Rutin Using an Electrochemical Sensor Based on Metal-Organic Framework CAU-1/Acidified Carbon Nanotubes Composites.

Rutin, a natural flavonol glycoside, is widely present in plants and foods, such as black tea and wheat tea. The antioxidant and anti-inflammatory effects of flavonoids are well known. In this study, a new electrochemical rutin sensor was developed using multiwalled carbon nanotubes/aluminum-based metal-organic frameworks (MWCNT/CAU-1) (CAU-1, a type of Al-MOF) as the electrode modification material. The suspension of multiwalled carbon tubes was dropped on the surface of the GCE electrode to make MWCNT/GCEs, and CAU-1 was then attached to the electrode surface by electrodeposition. MWCNTs and CAU-1 were characterized using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Due to the synergistic effect of CAU-1 and MWCNT-COOH, the prepared sensor showed an ultrasensitive electrochemical response to rutin. Under optimized conditions, the sensor showed a linear relationship between 1.0 × 10-9~3.0 × 10-6 M with a detection limit of 6.7 × 10-10 M (S/N = 3). The sensor also showed satisfactory stability and accuracy in the detection of real samples.

An ultrasensitive high-performance baicalin sensor based on C3N4-SWCNTs/reduced graphene oxide/cyclodextrin metal-organic framework nanocomposite.

Baicalin (Bn) obtained from natural plants has been found to exhibit significant antiviral activity against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Herein, a novel ultrasensitive Bn electrochemical sensor was proposed based on graphitized carbon-nitride - single-walled carbon nanotube nanocomposites (C3N4-SWCNTs), reduced graphene oxide (rGO) and electrodeposited cyclodextrin-metal organic framework (CD-MOF). The sensing nanomaterials were characterized by X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. Under optimal conditions, the sensor exhibited sensitive detection of Bn in a wide linear range of 1 × 10-9-5 × 10-7 M with an LOD of 4.6 × 10-10 M and a sensitivity of 220 A/M, and it showed satisfactory stability and accuracy for detecting Bn in real samples (human serum and bear bile scutellaria eye drops). In addition, the electrochemical reaction sites and redox mechanism of Bn were revealed through electrochemical behavior and density functional theory. This work provided an insightful solution for detecting Bn, and extensive potential applications could be further expected.

Ultrasensitive catechin electrochemical sensor based on uniform ordered mesoporous carbon hollow spheres (MCHSs) advanced carbon-based conductive materials.

Catechin is one of the flavonoids with antioxidant activity and has attracted great interest. A rapid and accurate detection of catechin is of great significance. Herein, an ultrasensitive catechin electrochemical sensor based on uniform ordered mesoporous carbon hollow spheres (MCHSs) advanced carbon-based conductive material modified glass carbon electrode was constructed. The MCHSs were synthesized by pyrolysis using nitrogen protection and template removal methods, and they exhibited excellent electrochemical detection for catechin owing to their high conductivity and uniform and small spheres with a large specific surface area and hollow structure. Under optimal conditions for the detection of catechin, the MCHSs/GCE showed a wider linear range (10 -1400 nM) and lower detection limit (LOD, 2.82 nM, (S/N = 3)). Furthermore, the electrochemical reaction sites and redox mechanisms of catechin were revealed by electrochemical behavior and density flooding theory. Moreover, the sensor we constructed exhibited good accuracy and stability for the detection of catechin in actual sample detections.

Determination of luteolin in Chrysanthemum tea with a ultra-sensitive electrochemical sensor based on MoO3/poly(3,4-ethylene dioxythiophene)/gama-cyclodextrin metal-organic framework composites.

Chrysanthemum tea is a tranditional Chinese health drink, which contains luteolin, a flavonoid with vesatile health benefit activities. Herein, A sensitive electrochemical sensor based on composite materials consisting of MoO3 nanorods, poly (3, 4-ethylene dioxyethiophene)(PEDOT), and γ-cyclodextrin metal-organic framework(CD-MOF) was prepared.The materials were characterized and analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). Due to the synergisticeffects of the materials, the sensor showed a wide linear range of 0.4 nM -1800 nM and a low detection limit (LOD) of 0.1 nM (S/N = 3) for luteolin under optimized conditions. Besides, the influences of some coexistent phenolic compounds and common metal ions on luteolin detection were evaluated and no significant interference was observed. Finally, the sensor was successfully applied to the detection of luteolin in real Chrysanthemum tea samples.

An ultrasensitive luteolin electrochemical sensor based on a glass carbon electrode modified using multi-walled carbon nanotube-supported hollow cobalt sulfide (CoSx) polyhedron/graphene quantum dot composites.

Luteolin (LU), belonging to the group of flavonoids with rich biological activities, has attracted considerable attention. Herein, a novel ultrasensitive LU electrochemical sensor based on hollow cobalt sulfide polyhedron-multi-walled carbon nanotube nanocomposites (CoSx-MWCNTs) and graphene quantum dots (GQDs) was proposed. The hollow CoSx polyhedrons derived from ZIF-67 showed excellent electrochemical sensing performance, which was attributed to the abundant surface active sites endowed by the special hollow structure. When detecting LU using the DPV model, the CoSx-MWCNTs/GQDs/GCE showed a linear range of 5 nM-2000 nM under optimal conditions, and the corresponding detection limit (LOD) was 1.2 nM (S/N = 3). In addition, the sensor exhibited satisfactory sensitivity and accuracy for detecting LU in real samples from Chrysanthemum extracts.

Correlation Between Resting Theta Power and Cognitive Performance in Patients With Schizophrenia.

Objective: Schizophrenia is a mental disorder that is characterized by progressive cognitive impairment. Objective measures of cognitive function may provide reliable neurobiomarkers for patients with schizophrenia. The goal of the current work is to explore the correlation between resting theta power and cognitive performance in patients with schizophrenia. Methods: Twenty-two patients with schizophrenia and 23 age-, sex-, and education-matched healthy controls were included in this study. The MATRICS Consensus Cognitive Battery (MCCB) was used for cognitive evaluation and the Positive and Negative Syndrome Scale (PANSS) for evaluation of clinical symptoms. EEGs were acquired in the resting state with closed and opened eyes. Between the two groups, we compared the relative theta power and examined their relationship with cognitive performance. Results: Compared to healthy controls, patients with schizophrenia showed significantly higher theta power, both with eyes closed and open (P < 0.05). When the eyes were open, negative correlations were found in patients with schizophrenia between theta power in the central and parietal regions with processing speed scores, and between the theta power of the Pz electrode and verbal learning and reasoning and problem-solving scores (r ≥ -0.446). In the control group, theta power over the Fz electrode was negatively correlated with processing speed (r = -0.435). Conclusions: Our findings showed that theta activity increased in certain brain regions during resting state in schizophrenia. Negative associations between resting theta power (increased) over the parietal-occipital regions with MCCB domains scores (decreased) suggest that altered theta activity can be used as a neurobiological indicator to predict cognitive performance.

A non-enzymatic photoelectrochemical sensor based on g-C3N4@CNT heterojunction for sensitive detection of antioxidant gallic acid in food.

Gallic acid (GA) is found in a wide range of natural plants and is relevant to the health of human beings. Here, a photoelectrochemical sensing platform based on g-C3N4@CNT heterojunction has been prepared for the highly sensitive and selective detection of GA. Under the light of xenon lamp, the photocurrent of g-C3N4@CNT is 7 times higher than that of g-C3N4. And the sensor generates 4 times more photocurrent in the presence of GA than without GA. This sensor has a wide linear range from 10 nM to 10 µM with a limit of detection as low as 2 nM. Also, the abundant amino groups of g-C3N4 provide excellent selectivity for the sensor. Furthermore, the sensor can be used for the analysis of GA in black tea samples, which provides a novel and rapid method for the detection of GA in food samples.