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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

Herein, a dual-mode electrochemical competitive immunosensor was constructed for the detection of 17β-estradiol (E2) based on differential pulse voltammetry (DPV) and chronoamperometry (

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

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

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

In this article, the catalyst Au/γ-Fe2O3@hydroxyapatite (Au/γ-Fe2O3@HAP) consisting of Au nanoparticles supported on the core–shell structure γ-Fe2O3@HAP was prepared through a deposition–precipitation method. The catalyst was characterized by transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, N2 adsorption–desorption and atomic absorption spectrometry. The as-prepared Au/γ-Fe2O3@HAP exhibited excellent performance for the reduction of 4-nitrophenolate (4-NP) to 4-aminophenolate (4-AP) in the presence of NaBH4 at room temperature. Thermodynamic and kinetic data on the reduction of 4-NP to 4-AP catalyzed by the as-prepared catalyst were studied. The as-prepared catalyst could be easily separated by a magnet and recycled 6 times with over 92% conversion of 4-NP to 4-AP. In addition, the as-prepared catalyst showed excellent catalytic performance on other nitrophenolates. The TOF value of this work on the reduction of 4-NP to 4-AP was 241.3 h−1. Au/γ-Fe2O3@HAP might have a promising potential application on the production of 4-AP and its derivatives.

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.

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.

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.

In this article, the catalyst Au/γ-Fe

A stable gold nanoparticles (AuNPs) and barium coordination polymer (BaCP) doped polypyrrole (Ppy) solid phase microextraction coating was prepared by electrodeposition. It was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetry. The obtained coating exhibited broccoli-shape with many particles attached on it, and it could bear 300 °C. Five nitropolycyclic aromatic hydrocarbons (NPAHs) were selected as models to test its extraction property. Due to the π-π, metal ion-π interaction, hydrogen bonding and hydrophobic interaction between the target analytes and the coating, high extraction efficiency was observed. Under the selected conditions, by coupling with GC-FID detection limits of 0.92 ~ 4.16 ng/L (S/N = 3) and linear ranges of 10 ~ 3500 ng/L were achieved. The relative standard deviation for different coatings was 4.20 ~ 10.2%, and the relative standard deviation for the same coatings was 2.86 ~ 5.70%. The detection of the five NPAHs in water samples was successfully performed by using this method and the recoveries ranged from 80.3% to 115.6%.