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Novel tributyl phosphate-based hydrophobic deep eutectic solvent: application in simultaneous liquid–liquid microextraction of parabens and their metabolite in surface water samples.

Gastric cancer is a malignant tumor, and its early diagnosis remains challenging due to the lack of simple and sensitive detection methods and specific biomarkers. In this work, to improve the detection reliability, we developed a dual-mode detection strategy for the detection of two biomarkers associated with it. First, an N- and S-doped carbon dots-N-rich porous carbon nanoenzyme (N/S-CDs@NC) was prepared by a two-step pyrolysis of thiourea-penetrated zinc-based zeolite imidazole framework. It was then combined with the 3,3',5,5'-tetramethylbenzidine-H

Molecularly imprinted polymers (MIPs) are widely used as artificial recognition element in sensing field, but their electrochemical sensing performances are generally affected by their poor catalytic activity and unruly condition change. In this work, an MIP film with catalysis (Fe-DMMIP) is constructed by electrodeposition of Fe-coordinated aminophenanthroline and 3,4-ethylenedioxythiophene on N, S doped C material, using cannabinoid (CBD) as template molecule. Due to the presence of Fe-N active sites, the obtained Fe-DMMIP possesses enzyme-like catalytic activity besides conventional recognition capability. Accordingly, the sensor exhibits high electrocatalytic activity and selectivity. Moreover, the Fe-DMMIP can produce a stable and well-defined signal as an internal reference around 0 V (vs. Ag/AgCl) for ratiometric sensing. Under the optimal conditions, the ratiometric signal is linear to CBD concentration in the range of 0.004-0.8 μmol L

In this work, a ratiometric electrochemical sensor was developed for the detection of perphenazine (PPZ). The sensor was constructed by electrodepositing Cu-coordinated molecularly imprinted polymer (Cu-MIP) on Ag nanoparticles (NPs) modified flexible porous carbon cloth. The Cu-MIP showed highly electrochemical response because of the enhanced adsorptive ability and electronic properties of Cu

In this work, a smart tetracycline (TC) imprinted material (DSMIP@Mn

Organic-inorganic hybrid materials are rarely applied in photoelectrochemical (PEC) sensing because of the serious charge-carrier recombination in organic conjugated polymers. In this work, a series of poly(3,4-ethylenedioxythiophene) (PEDOT)/ZnIn

Efficient photocatalytic reduction of electron acceptors is highly desirable for cathodic photoelectrochemical (PEC) sensors. Here, we report a facile and controllable strategy to tailor surface ox...

In this work, a simple and sensitive method based on Fe3O4/multi-walled carbon nanotubes/ionic liquid (Fe3O4/MWCNTs/IL) as the adsorbent for magnetic solid phase extraction coupled with high performance liquid chromatography was developed for the determination of trace fluoroquinolones in foods. After a simple one-pot solvothermal synthesis, Fe3O4/MWCNTs were further modified with an amine-terminated ionic liquid to enhance their dispersibility and extraction capacity. The morphology, structure and magnetic properties of the composite adsorbent were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction spectrometry and vibrating-sample magnetometry. Under the optimized extraction and detection conditions, the studied fluoroquinolones were enriched effectively and separated well and their UV signals were linear to their concentrations in the range of 4–1000 ng mL−1, with correlation coefficients ranging from 0.9958 to 0.9990. The enrichment factors were 29.1–43.9 fold and the limits of detection were 0.33–0.78 ng mL−1. The spiked recoveries were 85.4–105.9% for milk and 85.2–103.7% for pork samples, with relative standard deviations of 0.8–5.7%. The developed method provided a fast, sensitive and reliable determination platform for fluoroquinolones in complex real samples.

A novel electrochemiluminescence (ECL) sensing platform was developed for the detection of neuron-specific enolase (NSE), based on the nanocomposite of mesoporous silica encapsulated CuO

Conventional molecularly imprinted polymers (MIP)-based electrochemical sensors are generally susceptible to the changes of personal operation, electrode surface, and solution conditions. Herein, a ratiometric strategy was employed through introducing Cu

Chlortetracycline (CTC) is a widely used broad-spectrum antibiotic, its residue likely occurs in the environment and foods, bringing some negative effects to human health. Hence the detection and quantification of CTC in environmental and food samples is relevant. Herein, a novel electrochemical sensor based on surface molecularly imprinted polymer (SMIP) was constructed for the quantitative detection of CTC. The SMIP was synthesized by using ionic liquid (IL) functionalized MWCNT (MWCNT-IL) as supporter, 1-carboxymethyl-3-vinylimidazolium bromide (IL

In this work, a novel signal on/off ratiometric electrochemical sensor for the selective detection of chlorpromazine (CPZ) was developed. The sensor was constructed by electrodepositing dual-monomer molecularly imprinted polymer (DMMIP) film on the surface of Pt/Co

A novel plasmon enhanced electrochemiluminescence (ECL) sensor was fabricated for the highly sensitive detection of glutathione (GSH). First, Au nanoparticles (AuNPs) were coated with silica dioxide to prevent the direct contact of AuNPs and luminophore Ru(bpy) 3 2+ ; then Ru(bpy) 3 2+ -containing silica layer (RuDS) was allowed to grow onto the obtained Au@SiO 2 . Owing to the high luminescence efficiency of RuDS and the surface plasmon resonance of AuNPs, the nanocomposite Au@SiO 2 @RuDS exhibited large ECL signal. As free radical scavenger, GSH could react with tri-n-propylamine radical (i.e. TPA +• ) and effectively suppress the excitation of Ru(bpy) 3 2+ , thus made the ECL signal significantly decrease. By using Nafion as immobilization reagent, the resulting Au@SiO 2 @RuDS/GCE sensor showed wide linear response ranges (1.0 fM–1.0 nM and 1.0 nM–1.0 μM) and low detection limit (0.5 fM, S/N=3) for GSH. In addition, it had excellent stability, repeatability and reproducibility. The sensor was applied to the detection of GSH in human serum samples and satisfactory results were achieved.

A ternary WO3/Au/CdS photocatalyst was prepared by reversible redox and ionic adsorption for the first time. The photocatalyst exhibited high photocatalytic activity and good photoelectrochemical (PEC) property in comparison with WO3, CdS, WO3/Au and WO3/CdS, because the localized surface plasmon resonance (LSPR) effect of Au nanoparticles (Au NPs) and the sensitization of CdS benefited the spatial separation of photogenerated electron-hole pairs and the absorption of visible light. Thus, its photocurrent response intensity was quite high, up to about 218-fold of WO3 and 87-fold of CdS under 430 nm LED light irradiation. Based on the large anodic photocurrent and the specific recognition between carcinoembryonic antigen (CEA) and anti-CEA, a novel PEC immunosensor was constructed for the sensitive and selective detection of CEA. Under the selected conditions, the change of photocurrent intensity was linear to the logarithm of CEA concentration over the range from 0.01 to 10 ng/mL, and the detection limit was down to 1 pg/mL. The immunosensor also showed good stability, reproducibility and repeatability. It was successfully applied to the detection of CEA in serum samples.

A type I core/shell structured Bi2S3@ZnS photocatalyst was synthesized by an electrostatic interaction mechanism and used for the photoelectrochemical detection of Cu2+. The Bi2S3@ZnS composite showed excellent photoelectrochemical activity and stability due to the high photoelectrochemical activity of Bi2S3 and the anti-photocorrosion function of the ZnS shell. In addition, the ZnS shell also provided a transfer platform for the photogenerated holes through its acceptor states (i.e. VZn and IS) and suppressed the recombination of photogenerated carriers. The photocurrent signal of the obtained Bi2S3@ZnS/ITO electrode was much higher than that of pure Bi2S3 under visible-light irradiation. When it was used for the photoelectrochemical sensing of Cu2+, a wide detection range (0.003–30.0 μM) and a low detection limit (0.001 μM) were observed. The sensor also displayed high stability and acceptable selectivity. It was applied to detect real samples and good results were achieved.

Oxytetracycline (OTC) residue in food and environment has potential threats to ecosystem and human health, thus its sensitive monitoring and effective elimination are very important. In this work, a new molecularly imprinted polymer (MIP) composite was prepared through atom transfer radical polymerization by using OTC as template, gold nanoparticles modified carbon nanospheres (Au-CNS) as supporter, ionic liquids (IL) as functional monomer and cross-linking agent. The obtained MIP-IL@Au-CNS composite was characterized by Fourier transform infrared absorption spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. It displayed high imprinting factor (5.50) and adsorption capacity (56.7 mg g

A novel water-based deep eutectic solvent was synthesized and used for the ultrasound-assisted liquid-liquid microextraction of parabens in edible oil and for their determination by high performance liquid chromatography. Herein, the water-based deep eutectic solvent was formulated at room temperature by tetrabutylammonium chloride as hydrogen bond acceptor and water as hydrogen bond donor at the molar ratio of 1:5. As component, water has the effect on tailoring the physicochemical properties of water-based deep eutectic solvent and assisting tetrabutylammonium chloride (hydrogen bond acceptor) capturing parabens (hydrogen bond donor) through in-situ deep eutectic solvent formation. The developed method has satisfactory linearity (1.5-500 μg/L), limits of detections (0.2-0.4 μg/L), precisions (RSDs ≤ 5.8%), and was fruitfully applied to detect parabens in edible oil with excellent recoveries (85.1-106.8%). The feature of the procedure lies in simplicity, low cost and high sensitivity, and this can be extended for the efficient separation of other hydrophobic compounds.

A novel dual-dummy templates imprinted electrochemical sensor has been fabricated for the detection of patulin. Herein, 2-oxindole (2-oxin) and 6-hydroxynicotinic acid (6-HNA) as the dummy templates, 4-aminothiophenol as functional monomer, and ionic liquid (IL) as electropolymerization electrolyte are employed to prepare molecularly imprinted polymer (MIP) film. 2-Oxin and 6-HNA have multiple groups and the obtained MIP possesses different types of imprinted sites, thereby achieving a better recognition capacity than that of single-dummy imprinted film. ILs can regulate the density of molecularly imprinted film and facilitate effective molecular recognition. The composite of PtPd decorated N-doped porous carbon has good conductivity and large surface area, and can amplify the signal. With the aid of electrochemical probe [Fe(CN)6]3-/4- (0.16 V vs. SCE) patulin can be detected. Under the optimal conditions, this sensor shows a detection range from 0.01 to 10 μg L−1, with a detection limit of 7.5 × 10−3 μg L−1 (S/N = 3). Two spiked juice samples were analyzed by this method, and the recovery ranges from 94 to 99.8% with RSD values of 2.4–4.6% (n = 3), indicating that this method can be applied for the detection of patulin in real samples.

Zearalenone (ZEN) is a nonsteroidal estrogenic mycotoxin, and its accurate detection in complex biological samples is still a challenge. Herein, an antifouling ratiometric electrochemical sensor has been developed for its detection. In this system, black phosphorus-graphene oxide is used as substrate to amplify the signal; ionic liquid doped molecularly imprinted polymer (MIP) endows the sensing surface not only high recognition ability but also high capability to resist nonspecific adsorption. During MIP preparation a magnetic field is introduced to regulate polymer structure for improving the recognition efficiency of the sensor. The signals of ZEN and poly methylene blue (MB) serve as response signal and internal reference signal, respectively. The peak current of ZEN increases with the increase of ZEN concentration, while the peak current of poly(MB) decreases simultaneously; their ratio changes with ZEN concentration variation. The obtained ratiometric sensor shows a wide linear response range of 0.05-13 μM and a low limit of detection of 12.7 nM (S/N = 3). Furthermore, it has high selectivity, stability and reproducibility, thanks to the advanced antifouling MIP and the built-in correction of poly(MB). The sensor has been successfully applied to determine ZEN in human serum.

Synthesizing novel cathodic photoactive materials with high photoelectrochemical (PEC) performance is urgently important for the development of photocathodic sensors. Herein, a novel photocathode material, Bi self-doped Bi

In this work, a novel signal on/off ratiometric electrochemical sensor for the selective detection of chlorpromazine (CPZ) was developed. The sensor was constructed by electrodepositing dual-monomer molecularly imprinted polymer (DMMIP) film on the surface of Pt/Co3O4 nanoparticles modified glassy carbon electrode, using CPZ as template molecule, methylene blue and catechol as functional monomers. The copolymerization of two monomers increased the diversity of functional groups for binding template molecules, and enhanced stability. The quantitative detection of CPZ was performed by differential pulse voltammetry, using the peak current of poly (methylene blue) as reference signal and the peak current of CPZ as indicating signal. The results showed that the developed DMMIP sensor not only possessed high selectivity and sensitivity, but also exhibited satisfactory anti-interference ability. Under the optimum conditions, a linear detection range of 0.005–9 μmol L-1 (R2 = 0.9962) was obtained, and the limit of detection was 2.6 nmol L-1. Moreover, the sensor showed good reproducibility and stability toward CPZ detection. It was applied to detect CPZ in serum and pharmaceutical samples, and satisfactory recoveries (ranging from 95.3% to 108.0%) were achieved.

A solid-state electrochemiluminescence (ECL) sensor for the highly selective and sensitive detection of 17β-estradiol (E2) is presented. The sensor is constructed with Ru(bpy)32+ doped vinyl-SiO2 nanoparticles (Ru@ethyl-SiO2) and E2 imprinted polypyrrole (MIP). The Ru@ethyl-SiO2 nanoparticles act as luminophores, while the MIP provides recognition sites for E2. As the adsorbed template molecules can act as co-reactant for Ru@ethyl-SiO2, the ECL intensity increases with the adsorption amount of E2 rising, which depends on its concentration in the solution. Owing to the well combination/or synergy of the smart MIP and the high-effective ECL material, the resulting sensor exhibits highly selective and ultrasensitive response to E2. Under the selected conditions, the ECL intensity increment (ΔI) is linear to the logarithm of E2 concentration over the range from 0.01 to 100 pg mL−1, and the detection limit is down to 0.005 pg mL−1 (S/N = 3). The ECL sensor also shows good reproducibility and repeatability. It has been successfully applied to the detection of E2 in tea and oral solution samples and the recoveries are 87.7%–115.3%.

A plasmonic WO3/Au photocatalyst was successfully synthesized by a reversible charging and discharging mechanism. The photocatalyst showed much higher photocatalytic activity and photoelectrochemical (PEC) performance than pure WO3, due to the localized surface plasmonic resonance (LSPR) enhancement of Au nanoparticles (Au NPs). In addition, Au NPs also could enhance the absorption of visible light and suppress the recombination of photogenerated electron-hole pairs. Hg2+ ions could make the effects of Au NPs weak through forming amalgam with Au at WO3/Au surface, thus the photocurrent response of the resulting WO3/Au/ITO electrode decreased. Hence, the electrode could be used for the selective detection of Hg2+ although no special recognition element was introduced. The wide linear range of 4.2 pM‒840 pM and quite low detection limit of 2.0 pM made it suitable for the detection of ultra-micro Hg2+ in real samples. Thus, the WO3/Au based PEC sensor had active effect on solving some tough issues, such as complicated operation and rigorous measurement conditions, in the detection of ultra-micro Hg2+.

A ZnIn2S4/CdS photocatalyst was synthesized based on an electrostatic interaction mechanism and was used to construct a photoelectrochemical (PEC) sensor for the highly sensitive and selective dete...

Tremella-like ZnIn2S4 (ZISt) and flower-like microsphere ZnIn2S4 (ZISm) were synthesized via a straightforward hydrothermal method. It was found that the ZISt was superior to ZISm for photoelectrochemical (PEC) sensing because of its large surface area and high photocatalytic activity. A composite of ZISt and graphene (GR) was prepared and used for the PEC sensing of dopamine (DA). Here DA acted as an electron donor to scavenge the hole and inhibit the charge recombination. The GR enhanced visible light absorption and accelerated electron transfer, amplifying the photocurrent signal. The strong chelating coordination interaction between DA and Zn(II) in ZISt guaranteed the selective adsorption of target analyte. Thus the resulting ZISt/GR photoelectrode showed sensitive and selective PEC response to DA. Under the optimized conditions, the linear response range was from 0.01 to 20 μM, and the detection limit was down to 0.001 μM. Additionally, the sensor had good stability and reproducibility, and it could be used for the detection of DA in real samples.

We report the electrochemical fabrication of a poly(2,2-bithiophene-co-3-methylthiophene)-graphene composite coating and its application in the headspace solid-phase microextraction and gas chromatography determination of benzenes (i.e., bromobenzene, 4-bromotoluene, 2-nitrotoluene, 3-nitrotoluene and 1,2,4-trichlorobenzene). The coating was uniform and showed cauliflower-like microstructure. It had high thermal stability (up to 375°C) and could be used for at least 180 times of solid-phase microextraction without a decrease in extraction performance. Furthermore, it presented high extraction capacity for the benzenes due to the hydrophobic effect and π-π interaction between the analytes and the coating. Under optimized extraction conditions, good linearity (correlation coefficients higher than 0.9946), wide linear range (0.01-50 μg/L), and low limits of detection (5.25-12.5 ng/L) were achieved for these analytes. The relative standard deviation was lower than 5.7% for five successive measurements with one fiber, and the relative standard deviation for fiber-to-fiber was 4.9-6.8% (n = 5). The solid-phase microextraction and gas chromatography method was successfully applied for the determination of three real samples, and the recoveries for standards added were 89.6-106% for nail polish, 85.8-110% for hair dye, and 90-106.2% for correction fluid, respectively.

A novel electrochemical sensor was prepared for the detection of bisphenol A (BPA), and it was based on a molecularly imprinted polymer/carbon nanotubes-Au nanoparticles/boron-doped ordered mesoporous carbon composite. The composite showed a porous 3D structure and had a large surface area, good recognition capacity and high electrocatalysis to BPA; thus the sensor presented a sensitive and selective electrochemical response to it. Under optimal conditions, the sensor showed a large linear range of 0.01–10 μM and a low detection limit of 5 nM determined by using differential pulse voltammetry. It was applied to detect BPA in milk samples successfully.

Citrinin can cause serious human diseases, thus its detection in foods is necessary. Herein, a molecularly imprinted polymer-based ratiometric electrochemical sensor (MIP-RECS) was presented for citrinin detection. The sensor was fabricated by electropolymerization, using thionine as monomer and citrinin as template. The ionic liquid decorated boron and nitrogen co-doped hierarchical porous carbon (BN-HPC) as supporter, provided large surface for anchoring thionine and citrinin. Poly(thionine) not only acted as MIP, but also acted as reference probe. When [Fe(CN)6] 3-/4- was adopted as indicating probe, the resulting sensor demonstrated a wide linear detection range (i.e. 1 × 10-3–10 ng mL−1) and a low detection limit (i.e. 1 × 10-4 ng mL−1).The sensor was applied to the detection of spiked citrinin in real samples, and satisfactory recovery (i.e. 97% – 110%) was obtained. Hence, it was promising for citrinin detection.

Doping, as an important strategy, can change the conductivity type of semiconductor and has been used to construct p-n homojunction. However, the effect of doping style on the conductivity type has not been well ascertained. Herein, taking Bi2WO6 with layered crystal structure as the model, the effect of Bi doping type on the conductivity type of Bi2WO6 is studied through density functional theory (DFT) and experiments. Detailed investigations reveal that Bi substitutes W site rather than fills O site or interlayer, is critical for changing the conductivity type of Bi2WO6 (i.e. from n to p), thus producing a p-n homojunction structure in Bi2WO6 and enabling it cathodic photoelectrochemical (PEC) performance. To further study and improve the PEC properties of Bi-doped Bi2WO6 (marked as Bi2+xWO6), a novel p-n/n homo/heterojunction photocathode material of Z-scheme Bi2+xWO6/Bi2S3 has been synthesized by an in-situ ion-exchange reaction. Benefiting from the internal built-in electric field of homojunction and Z-scheme heterojunction, the bulk and interface charges of Bi2+xWO6/Bi2S3-3 (i.e. treated with 1 mM of Na2S) are sufficiently separated and transferred, and thus a quite high cathodic photocurrent response occurs, which is about 5 and 100 times of those induced by Bi2+xWO6 and Bi2S3, respectively. To explore the applicability of this homo/heterojunction structure, a novel “signal-on” cathodic PEC immunosensor is constructed with Z-scheme Bi2+xWO6/Bi2S3-3 as substrate and self-assembled 3D Ti3C2@Au as label for the ultrasensitive detection of neuron-specific enolase (NSE). The immunosensor exhibits high sensitivity and selectivity.

In this work, an organic/inorganic hybrid nanorod array (P(33DT-co-3TPCA)/[BMIM]Cl-ZnO NRAs) composed of poly(3,3'-dithiophene-co-3-thiophenecarboxylic acid) (P(33DT-co-3TPCA)), 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) and zinc oxide (ZnO) was synthesized by simple electrochemical method through in-situ growing on indium tin oxide (ITO). Due to the introduction of molecularly imprinted conducting polymer (MICP) with good recognition ability and the use of ionic liquid [BMIM]Cl instead of KCl during ZnO growth to regulate and control its micromorphology and photoelectrochemical property, the developed photoelectrochemical (PEC) sensor exhibited good PEC performance for aflatoxin B1 (AFB1) detection. Under the optimized conditions, the MICP-PEC sensor could linearly response to the target molecule AFB1 in the range of 0.10 ng mL−1-10 ng mL−1 with a detection limit of 0.058 ng mL−1 (S/N = 3). Furthermore, the practicability of the developed MICP-PEC sensor was demonstrated by determining AFB1 in rice and peanut samples. This work provided a new promising organic/inorganic hybrid MICP-PEC sensing platform for toxic small molecule detection.

MoS2/graphene-carbon nanotubes (MoS2/GN-CNTs) nanocomposite was prepared by hydrothermal method. The nanocomposite combined the high catalysis of MoS2 with the superior electronic conductivity of GN-CNTs, and exhibited high electrochemical sensitivity towards luteolin. A molecularly imprinted polymer (MIP) film deposited by electropolymerization, based on carbazole monomer and luteolin template, was used to improve the selectivity. Thus the resulting electrochemical sensor MIP/MoS2/GN-CNTs/GCE showed high performance. Its linear detection range and limit of detection were 0.040–2.0 μM and 9.0 nM (S/N = 3), respectively, while its sensitivity was 381.3 μA μM−1 cm−2. In addition, 1000-fold K+, Na+, Ca2+, Mg2+, NO3−, Cl−, SO42− and CO32− 500-fold glucose and mannitol, 250-fold cystein, glycine, lysine, citric acid and oxalic acid, and 100-fold urea, ascorbic acid and dopamine did not interfere with the determination of luteolin. Moreover, 5-fold analogs rutin, catechin and naringenin, and 2-fold kaempferide, quercetin and morin also did not influence on its determination. The sensor was applied to the determination of luteolin in carrot and chrysanthemum tea samples and the results were in good agreement with those obtained through HPLC.

A novel molecularly imprinted electrochemical sensor for quercetin (QR) was fabricated via electropolymerization of para -aminobenzoic acid (p-ABA) on a three-dimensional (3D) Pd nanoparticles-porous graphene-carbon nanotubes composite (Pd/pGN-CNTs) modified glassy carbon electrode. The 3D Pd/pGN-CNTs composite was prepared by a facile one-pot hydrothermal method and it exhibited high conductivity, large surface as well as excellent electrocatalysis. The imprinting factor (IF) of MIP sensor toward QR was 3.14, which is higher than those of its analogues (i. e. morin, catechin, rutin, luteolin, and kaempferide). Based on the synergistic effect of the nanocomposite and the molecularly imprinted poly(p-ABA), the resulting electrochemical sensor presented high sensitivity and selectivity. Its linear response range was 0.01–0.50 μM, and the low detection limit was 5.0 nM (S/N = 3). The sensor also showed good reproducibility and stability. It was successfully applied to the detection of QR in food and medicine samples. In addition, theoretical calculations based on density functional theory (DFT) was conducted, and the result indicated that there was strong hydrogen bond between the QR and p-ABA.

A quercetin (QR) sensor based on Pd/MoS 2 -ionic liquid functionalized ordered mesoporous carbon (Pd/MoS 2 -IL-OMC) composite is developed. The Pd/MoS 2 -IL-OMC composite is prepared by using IL as anchor and OMC as substrate. MoS 2 nanosheets are in situ grown on IL-OMC surface and then Pd nanoparticles are prepared on MoS 2 nanosheets via chemical reduction method. As the nanocomposite combines the high conductivity of IL-OMC and the electrocatalytic activity of Pd nanoparticles and MoS 2 , the resulting sensor exhibits good performance towards QR, better than MoS 2 -IL-OMC and Pd/IL-OMC nanocomposites modified electrodes. The electrochemical sensor allows for the selective determination of QR, with a detection limit of 8.0 nM (S/N = 3), a linear range of 0.020 μM–10 μM, and a sensitivity of 150.1 μA μM −1 cm −2 . It also shows good reproducibility and stability, and can be applied to the detection of QR in real samples.

A hollow CuCo2O4 polyhedron/porous reduced graphene oxide (PrGO) composite was prepared by simple thermolysis-induced transformation of heterobimetallic zeolitic imidazolate frameworks/porous graphene oxide (Cu-Co-ZIFs/PGO). In this strategy, the PGO was suitable for Cu-Co-ZIFs growing and anchoring, and the framework acted as sacrificial template during the formation of morphology-inherited hollow polyhedrons. In the obtained composite, PrGO sheets not only provided conduction path, but also served as protective agent to prevent the aggregation of crystals. The hollow rhombic dodecahedral CuCo2O4 possessed plentiful active sites and high electrocatalytic activity. When the composite was optimized and used for glucose sensing, it displayed good performance with a wide linear range of 0.5–3354 μM, a low detection limit of 0.15 μM (S/N = 3), a high sensitivity of 2426 μA mM−1 cm−2 and short response time (