Search

Escherichia coli O157:H7 (E. coli O157:H7) emerges as a foodborne pathogen, emphasizing the imperative for creating precise detection tools. An ultrasensitive electrochemiluminescence/fluorescence (ECL/FL) dual-signal mode aptasensor was constructed for the detection of E. coli O157:H7. Ultrafine silver nanoparticles were loaded on the surface of hydrogen-bonded organic skeleton materials by in-situ photoreduction method, and then combined with aptamers that can identify specific targets to prepare HOF-101@AgNPs@Apt, greatly simplifying the ECL/FL dual-signal mode probe fabrication process and improving sensing reliability. HOF-101@AgNPs@Apt had both strong ECL luminescence and fluorescence, resulting in a high detection sensitivity. The low limit of detection (LOD) for ECL and FL were 0.48 CFU mL -1 and 2.39 CFU mL -1 , respectively. Moreover, the proposed dual-signal mode aptasensor has been successfully applied to determine E. coli O157:H7 levels in tap water and milk with superior accuracy and high antiinterference capability, providing a promising method for food safety monitoring., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

An all-fiber-optic system for rapid detection of antibiotic concentration, based on an optical enzyme biosensor with microfiber interferometer (MFI) and fiber gratings (FBGs) power variation, is proposed and experimentally validated. During the experiment, β-lactamase(β-LS) is fixed on the polyaniline (PANI)-coated optical fiber by cross-linking through glutaraldehyde (GA) covalent bonding. β-LS can hydrolyze β-lactam antibiotics to generate acidic by-products that transform polyaniline from the form of the emerald base to emerald salt, which results in the surface refractive index (RI) variation of MFI, to convert MFI wavelength and FBGs power macroscopic change for feedbackingly detecting the concentration of β-lactam antibiotics. The detection of amoxicillin (AMX) in deionized water at concentrations in the range of 0.01-100 nM resulted in a wavelength change sensitivity of 0.6 nm/nM, and FBGs power difference change sensitivity of 1.3 dB/nM, with a detection limit LOD = 0.04 nM in real food and urine samples. The sensing system by the same calibration technique can detect antibiotic concentrations in different substances (tap water, milk and artificial urine). This developed all-fiber-optic system can be used as a rapid solution for the measurement of β-lactam antibiotic residues in food and the environment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

An ingenious and universal design of fluorescent/electrochemical dual-signal mode sensing platform was constructed for the sensitive, selective and accurate detection of tetracycline (TET). Apt-functionalized nano-magnetic beads (Fe 3 O 4 -Apt) as capture probe, Apt-complementary short-chain functionalized fluorescent MOF loaded with methylene blue (MB) (cDNA-MOF-MB) as dual-signal tag were prepared. The sensing platform (Fe 3 O 4 -Apt/cDNA-MOF-MB) was formed based on the base complementary pairing of Apt and cDNA. With the help of Apt for target recognition, together with magnetic separation technology, a dual-signal mode biosensor was constructed. The dual-signal mode biosensor exhibited a wide linear concentration range from 1.00 × 10 -9 g/mL to 1.00 × 10 -4 g/mL with a low limit of detection (LOD) of 1.69 × 10 -10 g/mL (fluorescence mode assay) and 1.15 × 10 -10 g/mL (electrochemical mode assay). The proposed biosensor had been successfully applied to the determination of TET content in real samples with satisfactory recoveries (94.99-101.30%)., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

A universal design of turn-on fluorescent aptasensor based on aptamer functionalized gold nanoparticles (AuNPs) and luminescent metal-organic frameworks (LMOFs) complex (AuNPs-Apt/NH 2 -MIL-125(Ti)) was realized for bisphenol A (BPA) detection. LMOF NH 2 -MIL-125(Ti) was prepared using facial hydrothermal method. BPA aptamer functionalized AuNPs were prepared and adsorbed on the surface of NH 2 -MIL-125(Ti) to obtain platform of the fluorescent aptasensor. The fabrication process, sensing performance and applicability of the proposed aptasensor were characterized and investigated carefully. Linear detection range of the constructed aptasensor was from 1 × 10 -9 mol L -1 to 1 × 10 -4 mol L -1 with good selectivity, repeatability, stability and reproducibility under optimal experimental conditions. Meanwhile, the fluorescent aptasensor was successfully utilized for BPA detection in real samples with the recoveries of 95.80%-103.12%. The proposed aptasensor based on AuNPs-Apt/NH 2 -MIL-125(Ti) holds significant potential for BPA detection in environmental and food samples, promoting the construction and application of LMOFs-based aptasensor., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

A novel metal-organic framework (MOF)/covalent-organic framework (COF) heterostructure hybrid composite (NH 2 -UiO-66/TpPa-1-COF) with excellent photoactivity was developed, which further acted as the photoelectrochemical sensitized layer of a molecularly imprinted photoelectrochemical (MIP-PEC) sensor for extremely sensitive and selective determination of dibutyl phthalate (DBP). The NH 2 -UiO-66/TpPa-1-COF was synthesized using a simple one-step solvothermal method, which showed improved photocurrent response owing to heterojunction formation, favorable energy-band configuration and strong light absorption capacity. To improve the sensing performance, molecularly imprinted polymer (MIP) was developed by sol-gel polymerization method as the recognition component of PEC sensor. The specific binding of imprinting sites towards DBP could block the electron transfer, causing decreased photocurrent response of the MIP-PEC sensor. The MIP-PEC sensor showed a wide detection range from 0.1 nmol L -1 to 100 μmol L -1 with a limit of detection of 3.0 × 10 -11  mol L -1 under optimal conditions. Meanwhile, the proposed MIP-PEC sensor showed good stability, selectivity, reproducibility, and applicability in real samples. This is the first attempt to apply MOF/COF heterostructure hybrid composite for MIP-PEC sensor construction, providing new insight into the potential applications of microporous crystalline framework heterostructure hybrid composite in the sensing field., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

A novel label-free point-of-care quartz crystal microbalance (QCM) aptasensing platform based on metal-organic frameworks (MOFs) and gold nanoparticles (AuNPs) was fabricated for tetracycline (TC) detection. MOFs (HKUST-1) and AuNPs were modified onto the sensing interface of QCM sensor to enhance the sensing performance of the QCM aptasensor. TC aptamer with sulfhydryl group was fixed through Au-S bond. The recognition performance of the aptasensor was predicted and verified by the computer simulation. At the optimal conditions, the frequency change of the sensor was adopted for quantitative detection of TC. The prepared QCM aptasensor exhibited a wide linear range from 1 × 10 -10  g mL -1 to 1 × 10 -5  g mL -1 with low limit of detection (0.8 × 10 -11  g mL -1 ). High sensitivity, good selectivity, acceptable recoveries (87.6-91.4%) in real samples were obtained. For the first time, MOFs were utilized in the construction of QCM aptasensing platform, providing a promising application way of MOFs in the QCM sensing., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

In order to solve inherent problems of traditional molecularly imprinted electrochemical sensors (MIECS), a novel platform of surface molecularly imprinted magnetic metal-organic frameworks (mMOFs@MIPs) was coupled with magneto electrode to establish magnetic MIECS for the recognition of oxytetracycline (OTC). mMOFs@MIPs were synthesized using layer-by-layer modification method for the recognition of OTC. With the help of magneto electrodes, mMOFs@MIPs can be magnetically modified on the electrode surface, forming the electrochemical sensing interface. The imprinted cavities of mMOFs@MIPs can act as the electron channel of the probe to realize label-free detection of OTC. A linear response was obtained within the OTC concentration range of 1.0 × 10 -9 g mL -1 -1.0 × 10 -4 g mL -1 . The applicability of the sensor was estimated using the spiking and recovery method in milk samples with the recoveries ranging from 89.0% to 103.1%. It has potential applications in food safety analysis with high throughput detection capability, high specificity and good stability., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

In this work, a molecularly imprinted photoelectrochemical (MIP-PEC) sensor based on a novel PEC composite of metal-organic frameworks (MOFs) and TiO 2 (NH 2 -MIL-125(Ti)-TiO 2 ) was established for the ultrasensitive and selective detection of oxytetracycline (OTC). This is the first attempt of applying MOFs in the construction of MIP-PEC sensor. The NH 2 -MIL-125(Ti)-TiO 2 was synthesized by a simple one-step solvothermal method and modified onto the surface of indium tin oxide (ITO) electrode as the photosensitive layer. Subsequently, molecularly imprinted polymer (MIP) was modified as recognition element by electropolymerization. The NH 2 -MIL-125(Ti)-TiO 2 showed an enhanced photocurrent response due to stronger light absorption capacity and matched energy band. Furthermore, MIP greatly improved the selectivity and sensitivity of the constructed PEC sensor. The photocurrent response of the MIP-PEC sensor was reduced after OTC recognition because the specific binding of OTC to the imprinted cavities blocked the electron transfer of the electrode. Under optimal experimental conditions, the MIP-PEC sensor exhibited a wide detection range from 0.1 nM to 10 μM with a low limit of detection (LOD) of 60 pM, as well as certain reproducibility, stability and good applicability in real samples. The proposed sensor provides ideas for the application of MOFs in the construction of PEC sensors and will offer an alternative method for the detection of other pollutants in the field of food safety., (Copyright © 2021 Elsevier B.V. All rights reserved.)

A simple, efficient and sensitive molecularly imprinted electrochemiluminescence sensor (MIECLS) based on reduced graphene oxide (rGO) and upconversion nanoparticles (UCNPs) was developed for determination of clenbuterol (CLB). In this study, rGO generated by electrodeposition of graphene oxide not only acted as carrier for immobilizing UCNPs, but also had a significant impact in boosting electrochemiluminescence (ECL) response of UCNPs thanks to its high conductivity, superior electron transport rate and large specific surface area. UCNPs as an advanced ECL emitter possessed wonderful ECL performance. Furthermore, the introduction of molecularly imprinted polymers (MIP) endowed the ECL sensor a new character of specifically identifying analyte CLB. Under the optimal experimental conditions, the ECL signal was proportional to the logarithm of CLB concentration in the range of 10nM to 100µM with a low detection limit of 6.3nM. The proposed MIECLS combining the advantages of UCNPs-ECL and MIP exhibited good sensitivity, desirable selectivity and favorable stability, indicating enormous potential in the future of food safety detection., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A novel fluorescence material with thermo-sensitive for the enrichment and sensing of protein was successfully prepared by combining molecular imprinting technology with upconversion nanoparticles (UCNPs) and metal-organic frameworks (MOFs). Herein, the UCNPs acted as signal reporter for composite materials because of its excellent fluorescence property and chemical stability. MOFs were introduced to molecularly imprinted polymer (MIP) due to its high specific surface area which increases the rate of mass transfer relative to that of traditional bulk MIP. The thermo-sensitive imprinted material which allows for swelling and shrinking with response to temperature changes was prepared by choosing Bovine hemoglobin (BHB) as the template, N-isopropyl acrylamide (NIPAAM) as the temperature-sensitive functional monomer and N,N-methylenebisacrylamide (MBA) as the cross-linker. The recognition characterizations of imprinted material-coated UCNPs/MOFs (UCNPs/MOFs/MIP) were evaluated, and the results showed that the fluorescence intensity of UCNPs/MOFs/MIP reduced gradually with the increase of BHB concentration. The fluorescence material was response to the temperature. The adsorption capacity was as much as 167.6 mg/g at 28°C and 101.2mg/g at 44°C, which was higher than that of traditional MIP. Therefore, this new fluorescence material for enrichment and sensing protein is very promising for future applications., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Quinoxaline-2-carboxylic acid (QCA) is difficult to measure since only trace levels are present in commercial meat products. In this study, a rapid, sensitive and selective molecularly imprinted electrochemical sensor for QCA determination was successfully constructed by combination of a novel modified glassy carbon electrode (GCE) and differential pulse voltammetry (DPV). The GCE was fabricated via stepwise modification of multi-walled carbon nanotubes (MWNTs)-chitosan (CS) functional composite and a sol-gel molecularly imprinted polymer (MIP) film on the surface. MWNTs-CS composite was used to enhance the electron transfer rate and expand electrode surface area, and consequently amplify QCA reduction electrochemical response. The imprinted mechanism and experimental parameters affecting the performance of MIP film were discussed in detail. The resulting MIP/sol-gel/MWNTs-CS/GCE was characterized using various electrochemical methods involving cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and DPV. The sensor using MIP/sol-gel/MWNTs-CS/GCE as working electrode showed a linear current response to the target QCA concentration in the wide range from 2.0×10(-6) to 1.0×10(-3)molL(-1) with a low detection limit of 4.4×10(-7)molL(-1) (S/N=3). The established sensor with excellent reproductivity and stability was applied to evaluate commercial pork products. At five concentration levels, the recoveries and standard deviations were calculated as 93.5-98.6% and 1.7-3.3%, respectively, suggesting the proposed sensor is promising for the accurate quantification of QCA at trace levels in meat samples., (Copyright © 2013 Elsevier B.V. All rights reserved.)