Search Results (27)

Based on dual-template molecular imprinting polymerization technology, a fluorescent molecularly imprinted polymer doped with CdSe/ZnS quantum dots was developed to construct a “Turn-on” fluorescence sensor for the rapid, sensitive, and specific detection of two biogenic amines. The biogenic amines bind to the quantum dots, which eliminates surface defects and enhances the fluorescence emission intensity of the quantum dots. By optimizing both the polymerization and detection processes, the results demonstrate that the sensor can detect biogenic amines within the range of 0.01–10 mmol/L, with a low detection limit of 14.57 μmol/L and a detection time of only ten minutes. Moreover, the sensor is cost-effective and does not require specialized instrument operation, offering a practical approach for the rapid detection of biogenic amines in complex food matrices. This study advances the development of simultaneous recognition and rapid detection technologies for multiple target molecules. Full article

Developing a catalyst with excellent electrical conductivity and catalytic performance for on-site testing of residual imidacloprid is significant and challenging. In situ growth of Mo₂C nanodots on Co-induced N-doped carbon nanotubes (Co/Mo₂C/N-CNT) was synthesized to construct a molecularly imprinted electrochemical sensor for the detection of imidacloprid. The results proved that the catalytic performance of Co/Mo₂C/N-CNT for imidacloprid was over two times higher than those of Co/N-CNT and commercial CNT. This improvement was attributed to the formation of a heterostructure between Co species, Mo₂C, and N-CNT, which facilitated highly exposed catalytic active sites. Additionally, the abundant Mo₂C nano-dots promoted interfacial charge transfer to achieve optimal dynamics. The optimum preparation parameters of the catalysts were obtained by response surface methodology. By analyzing the relationship between different pH values and peak potential, as well as the influence of different scanning rates on peak potential, it was deduced that the possible electrocatalytic mechanism of imidacloprid involved the reduction of the nitro group to a hydroxylamine group and H₂O. Under optimal conditions, the limit of detection (LOD) was 0.033 × 10⁻⁶ mol·L⁻¹ (R² = 0.99698), and the linear range was 0.1 × 10⁻⁶~100 × 10⁻⁶ mol·L⁻¹. The application effect of the prepared sensor was evaluated by measuring the imidacloprid in two kinds of tea, indicating that the sensor possessed good sensitivity and selectivity, and was capable of meeting the requirements of on-site detection. Full article

In this work, a new surface plasmon resonance (SPR) sensor based on sulphur-doped titanium dioxide (S-TiO₂) nanostructures and molecularly imprinted polymer (MIP) was presented for thiram (THI) determination in milk samples. Firstly, the S-TiO₂ nanomaterial with a high product yield was prepared by using a facile sol-gel hydrolysis technique with a high product yield. After that, UV polymerization was carried out for the preparation of the THI-imprinted SPR chip based on S-TiO₂ using a mixture including ethylene glycol dimethacrylate (EGDMA) as the cross-linker, N,N′-azobisisobutyronitrile (AIBN) as the initiator, and methacryloylamidoglutamicacid (MAGA) as the monomer. The reliability of the sensor preparation procedure has been successfully proven by characterization studies of the prepared nanomaterials and SPR chip surfaces through spectroscopic, microscopic, and electrochemical methods. As a result, the prepared SPR sensor showed linearity in the range of 1.0 × 10⁻⁹–1.0 × 10⁻⁷ M with a detection limit (LOD) of 3.3 × 10⁻¹⁰ M in the real samples, and a sensor technique for THI determination with high sensitivity, repeatability, and selectivity can be included in the literature. Full article

Dimethoate (DIM) as an organophosphorus pesticide is widely utilized especially in the cultivation of vegetables and fruits due to its killing effect on harmful insects. However, unconscious use of DIM in large amounts can also cause serious health problems. For these reasons, rapid and reliable detection of DIM from food samples is significant. In this study, a novel quartz crystal microbalance (QCM) sensor based on erbium molybdate incorporating sulfur-doped graphitic carbon nitride (EM/S-g-C₃N₄) and a molecularly imprinting polymer (MIP) was designed for DIM detection in apple juice samples. Firstly, an EM/S-g-C₃N₄ nanocomposite with high purity was prepared under hydrothermal conditions at high temperatures over a long period of time. After the modification of the EM/S-g-C₃N₄ nanocomposite on a QCM chip, the polymerization solution including N,N′-azobisisobutyronitrile (AIBN) as an initiator, ethylene glycol dimethacrylate (EGDMA) as a cross-linker, methacryloylamidoglutamic acid (MAGA) as a monomer, and DIM as an analyte was prepared. Then, the polymerization solution was dropped on an EM/S-g-C₃N₄ nanocomposite modified QCM chip and an ultraviolet polymerization process was applied for the formation of the DIM-imprinted polymers on the EM/S-g-C₃N₄ nanocomposite modified QCM chip. After the polymerization treatment, some characterization studies, including electrochemical, microscopic, and spectroscopic methods, were performed to illuminate the surface properties of the nanocomposite and the prepared QCM sensor. The values of the limit of quantification (LOQ) and the detection limit (LOD) of the prepared QCM sensor were as 1.0 × 10⁻⁹ M and 3.3 × 10⁻¹⁰ M, respectively. In addition, high selectivity, stability, reproducibility, and repeatability of the developed sensor was observed, providing highly reliable analysis results. Finally, thanks to the prepared sensor, it may be possible to detect pesticides from different food and environmental samples in the future. Full article

Paper-based test strips with on-site visual detection have become a hot spot in the field of target detection. Yet, low specific surface area and uneven deposition limit the further application of test strips. Herein, a novel “turn-on” ratio of molecularly imprinted membranes (Eu@CDs-MIMs) was successfully prepared based on a Eu complex-doped polyvinylidene fluoride membrane for the selective, rapid and on-site visual detection of norfloxacin (NOR). The formation of surface-imprinted polymer-containing carbon dots (CDs) improves the roughness and hydrophilicity of Eu@CDs-MIMs. Fluorescence lifetimes and UV absorption spectra verified that the fluorescence enhancement of CDs is based on the synergistic effect of charge transfer and hydrogen bonding between CDs and NOR. The fluorescent test strip showed a linear fluorescent response within the concentration range of 5–50 nM with a limit of detection of 1.35 nM and a short response time of 1 min. In comparison with filter paper-based test strips, Eu@CDs-MIMs exhibit a brighter and more uniform fluorescent color change from red to blue that is visible to the naked eye. Additionally, the applied ratio fluorescent test strip was combined with a smartphone to translate RGB values into concentrations for the visual and quantitative detection of NOR and verified the detection results using high-performance liquid chromatography. The portable fluorescent test strip provides a reliable approach for the rapid, visual, and on-site detection of NOR and quinolones. Full article

In this work, $\mathrm{F}{\mathrm{e}}_2{\mathrm{O}}_3$ was investigated as a doping agent for poly(methyl methacrylate) (PMMA) in order to enhance the plasmonic effect in sensors based on D-shaped plastic optical fibers (POFs). The doping procedure consists of immerging a premanufactured POF sensor chip in an iron (III) solution, avoiding repolymerization and its related disadvantages. After treatment, a sputtering process was used to deposit a gold nanofilm on the doped PMMA in order to obtain the surface plasmon resonance (SPR). More specifically, the doping procedure increases the refractive index of the POF’s PMMA in contact with the gold nanofilm, improving the SPR phenomena. The doping of the PMMA was characterized by different analyses in order to determine the effectiveness of the doping procedure. Moreover, experimental results obtained by exploiting different water–glycerin solutions have been used to test the different SPR responses. The achieved bulk sensitivities confirmed the improvement of the plasmonic phenomenon with respect to a similar sensor configuration based on a not-doped PMMA SPR-POF chip. Finally, doped and non-doped SPR-POF platforms were functionalized with a molecularly imprinted polymer (MIP), specific for the bovine serum albumin (BSA) detection, to obtain dose-response curves. These experimental results confirmed an increase in binding sensitivity for the doped PMMA sensor. Therefore, a lower limit of detection (LOD), equal to 0.04 μM, has been obtained in the case of the doped PMMA sensor when compared to the one calculated for the not-doped sensor configuration equal to about 0.09 μM. Full article

In order to achieve simple, rapid, and highly sensitive detection of trimethoprim (TMP), a magnetic molecularly imprinted carbon paste electrode (MCPE) was prepared by drop-coating magnetic molecularly imprinted polymer (MIP@Fe₃O₄@MWNTs) on the surface of reduction graphene oxide (rGO)/MCPE doped with Fe₃O₄@MWNTs. The introduction of multi-walled carbon nanotubes (MWNTs) and rGO served as dual signal-amplification materials, which can improve the response sensitivity of the sensor. In addition, the magnetic interaction between the substrate electrode and the molecularly imprinted material was beneficial to increasing the stability of the sensor. As expected, the electrochemical sensor not only showed sensitivity and selectivity for the detection of TMP, but it also possessed good stability. The detection range for TMP was 4.0 × 10⁻⁹~5.0 × 10⁻⁴ mol/L, and the detection limit was 1.2 × 10⁻⁹ mol/L. The response performance varied within 10% when the sensor was placed for more than 2 months and used more than 60 times. The spiked recoveries of TMP in environmental water samples, urine samples, and pharmaceuticals (drugs) were between 91% and 110%, and the relative standard deviation (RSD) was within 5%. Full article

Polymeric materials have recently attracted a lot of attention due to their potential applications in many fields, ranging from biomedicine, the food industry and environmental monitoring to electronic, energy storage and sensing devices. Their versatility, functionalization capability, chemical/physical stability, reusability, long shelf-life, as well as good mechanical and thermal properties, also make them idoneous candidates for use in forensic sciences, which deal with the investigation of crimes, finding relations between evidence and criminals. In particular, molecularly imprinted polymers (MIPs), designed based on the principle of generating template-specific polymeric cavities fitted to the target molecules in the presence of selected chemicals via non-covalent or covalent interactions, are highly suitable for forensic analysis. In addition, their combination with other compounds such as carbon nanomaterials can provide composites with improved properties to be used in the analysis of illicit drugs, doping substances, biological agents, toxins and so forth. In this article, recent applications of polymeric materials in the field of forensic analysis are discussed. The goal is to summarize their current uses and put forth a projection of their potential as promising alternatives for standard competitors. Full article

The choice of carrier material is critical in the study of natural drug release preparations and glycosylated magnetic molecularly imprinted materials. The stiffness and softness of the carrier material affect the efficiency of drug release and the specificity of recognition. The dual adjustable aperture-ligand in molecularly imprinted polymers (MIPs) provides the possibility of individualized design for sustained release studies. In this study, a combination of paramagnetic Fe₃O₄ and carboxymethyl chitosan (CC) was used to enhance the imprinting effect and improve drug delivery. A combination of tetrahydrofuran and ethylene glycol was used as a binary porogen to prepare MIP-doped Fe₃O₄-grafted CC (SMCMIP). Salidroside serves as the template, methacrylic acid acts as the functional monomer, and ethylene glycol dimethacrylate (EGDMA) serves as the crosslinker. Scanning and transmission electron microscopy were used to observe the micromorphology of the microspheres. The structural and morphological parameters of the SMCMIP composites were measured, including the surface area and pore diameter distribution. In an in vitro study, we found that the SMCMIP composite had a sustained release property of 50% after 6 h of release time in comparison to the control SMCNIP. The total amounts of SMCMIP released at 25 °C and 37 °C were 77% and 86%, respectively. In vitro results showed that the release of SMCMIP followed Fickian kinetics, meaning that the rate of release is dependent on the concentration gradient, with diffusion coefficients ranging from 3.07 × 10⁻² cm²/s to 5.66 × 10⁻³ cm²/s. The results of cytotoxicity experiments showed that the SMCMIP composite did not have any harmful effects on cell growth. The survival rates of intestinal epithelial cells (IPEC-J2) were found to be above 98%. By using the SMCMIP composite, drugs may be delivered in a sustained manner, potentially leading to improved therapeutic outcomes and reduced side effects. Full article

Magnetic nanocomposites (MNCs) combine the features of magnetic nanoparticles and a second material, which provide distinct physical, chemical, and biological properties. The magnetic core for nanocomposite synthesis is extensively used due to its high saturation magnetization, chemical stability, large surface area, and easy functionalization. Moreover, magnetic nanoparticles (MNPs) have great potential for magnetic resonance imaging (MRI), magnetic particle imaging (MPI), hyperthermia, and targeted drug and gene delivery by an external magnetic field. Numerous composing units exist, which leads to the outstanding application of composites. This review focuses on nucleic acid-based bioapplications of MNCs with polymeric, organic, inorganic, biomolecules, and bioinspared surface coating. In addition, different forms, such as core–shell, doping, multilayer, yolk–shell, and Janus-shaped hybrids, are discussed, and their unique properties are highlighted. The unique types of nanocomposites as magnetic molecularly imprinted polymer (MMIP) properties are presented. This review presents only the synthesis of MNCs using ready-made magnetic cores. These restrictions are associated with many materials, the quantitative and qualitative magnetic core composition, and synthesis procedures. This review aims to discuss the features of nucleic acid-based MNC information available to researchers in this field and guide them through some problems in the area, structure variation, and surface functionalization possibilities. The most recent advancements of MNCs and imprinted polymers in nucleic acid-based therapy, diagnostics, theranostics, magnetic separation, biocatalytic, and biosensing are introduced. Full article

Roxarsone (ROX) as an organoarsenic feed additive has been widely used in livestock breeding and poultry industry, but ROX can degrade into highly toxic inorganic arsenic species in natural environments to threaten to the environment and human health. Therefore, there is a considerable interest in developing convenient, selective and sensitive methods for the detection of ROX in livestock breeding and poultry industry. In this work, a fluorescent molecularly imprinted polymer (MIPs) probe based on amino-modified Mn-ZnS quantum dots (QDs) has been developed by sol–gel polymerization for specific recognition of ROX. The synthesized MIPs-coated Mn-ZnS QDs (MIPs@Mn-ZnS QDs) have highly selective recognition sites to ROX because there are multi-interactions among the template ROX, functional monomer phenyltrimethoxysilane and the amino-functionalized QDs such as the π–π conjugating effect, hydrogen bonds. Under the optimal conditions, an obvious fluorescence quenching was observed when ROX was added to the solution, and the quenching mechanism could be explained as the photo-induced electron transfer. The MIPs@Mn-ZnS QDs sensor exhibited sensitive response to ROX in the linear range from 3.75 $\times$ 10⁻⁸ M to 6.25 $\times$ 10⁻⁷ M (R² = 0.9985) and the limit of detection down to 4.34 nM. Moreover, the fluorescence probe has been applied to the quantitative detection of ROX in feed samples, and the recovery was in the range of 91.9% to 108.0%. The work demonstrated that the prepared MIPs@Mn-ZnS QDs probe has a good potential for rapid and sensitive determination of ROX in complicated samples. Full article

We report the proof-of-concept of molecularly imprinted polymer (MIP) functionalized Bi2S₃/Ti₃C₂T_X MXene nanocomposites for photoelectrochemical (PEC)/electrochemical (EC) dual-mode sensing of chlorogenic acid (CGA). Specifically, the in-situ growth of the Bi₂S₃/Ti₃C₂T_X MXene served as a transducer substrate for molecularly imprinted polymers such as PEC and EC signal generators, due to its high surface area, suitable bandwidth and abundant active sites. In addition, the chitosan as a binder was encapsulated into MIP by means of phase inversion on a fluorine-doped tin dioxide (FTO) electrode. In the determination of CGA as an analytical model, the dual-mode sensor based on MIP functionalized Bi₂S₃/Ti₃C₂T_X MXene nanocomposites had good selectivity, excellent stability and acceptable reproducibility, which displayed a linear concentration range from 0.0282 μM to 2824 μM for the PEC signal and 0.1412 μM to 22.59 μM for the EC signal with a low detection limit of 2.4 nM and 43.1 nM, respectively. Importantly, two dual-response mode with different transduction mechanisms could mutually conform to dramatically raise the reliability and accuracy of detection compared to single-mode detection. This work is a breakthrough for the design of dual-mode sensors and will provide a reasonable basis for the construction of dual-mode sensor platforms. Full article

In this study, a novel fluorescent molecularly imprinted nanosensor (N, S-GQDs@ZIF-8@MIP) based on the nitrogen and sulfur co-doped graphene quantum dots decorated zeolitic imidazolate framework-8 was constructed for the detection of octopamine (OA). Herein, ZIF-8 with a large surface area was introduced as a supporter of the sensing system, which effectively shortened the response time of the sensor. Meanwhile, high green luminescent N, S-GQDs and a maximum emission wavelength of 520 nm under 460 nm excitation and a 12.5% quantum yield were modified on the surface of ZIF-8 as a signal tag that can convert the interactions between the sensor and OA into detectable fluorescent signals. Finally, N, S-GQDs@ZIF-8@MIP was acquired through the surface molecular imprinting method. Due to the synergy of N, S-GQDs, ZIF-8, and MIP, the obtained sensor not only demonstrated higher selectivity and sensitivity than N, S-GQDs@ZIF-8@NIP, but also displayed faster fluorescence response than N, S-GQDs@MIP. Under optimal conditions, the developed sensor presented a favorable linear relationship in the range of 0.1–10 mg L⁻¹ with a detection limit of 0.062 mg L⁻¹. Additionally, the proposed N, S-GQDs@ZIF-8@MIP strategy was effectively applied to the detection of OA in fermented samples, and the obtained results had a satisfactory correlation with those of HPLC. Full article

C-reactive protein (CRP) is a non-specific biomarker of inflammation and may be associated with cardiovascular disease. In recent studies, systemic inflammatory responses have also been observed in cases of coronavirus disease 2019 (COVID-19). Molecularly imprinted polymers (MIPs) have been developed to replace natural antibodies with polymeric materials that have low cost and high stability and could thus be suitable for use in a home-care system. In this work, a MIP-based electrochemical sensing system for measuring CRP was developed. Such a system can be integrated with microfluidics and electronics for lab-on-a-chip technology. MIP composition was optimized using various imprinting template (CRP peptide) concentrations. Tungsten disulfide (WS₂) was doped into the MIPs. Doping not only enhances the electrochemical response accompanying the recognition of the template molecules but also raises the top of the sensing range from 1.0 pg/mL to 1.0 ng/mL of the imprinted peptide. The calibration curve of the WS₂-doped peptide-imprinted polymer-coated electrodes in the extended-gate field-effect transistor platform was obtained and used for the measurement of CRP concentration in real human serum. Full article

In this work, high-temperature pyrolysis was used to prepare both the core and shell of lantha-nide-doped UCNPs with lithium yttrium tetrafluoride (LiYF₄) to enhance the green luminescence. Merocyanine 540 (MC540)-grafted magnetic nanoparticles were incorporated in the PD-L1 pep-tide-imprinted poly(ethylene-co-vinyl alcohol) particles, which were formed by precipitation in a non-solvent. UCNPs in the non-solvent bath were thus entrapped in the imprinted particles to generate composite nanoparticles for the targeting and photodynamic therapy of PD-L1 in tumor cells. Finally, the in vitro cytotoxicity of the nanoparticles in HepG2 human liver cancer cells was evaluated with the continuous administration of MC540/MNPs@MIPs/UCNPs under irradiation by an NIR laser. To understand the delivery of the UCNP-embedded molecularly imprinted pol-ymers, the intrinsic and extrinsic pathways were also investigated. Full article