Preparation and recognition performance of cytisine alkaloid-imprinted material prepared using novel surface molecular imprinting technique

Portably and Visually Sensing Cytisine through Smartphone Scanning Based on a Post-Modified Luminescence Center Strategy in Zinc-Organic Frameworks

Cytisine (CTS) is a useful medicine for treating nervous disorders and smoking addiction, and exploring a convenient method to detect CTS is of great significance for long-term/home medication to avoid the risk of poisoning, but it is full of challenges. Here, a modified metal-organic framework sensor Tb@Zn-TDA-80 with dual emission centers was prepared using a post-modified luminescence center strategy. The obtained Tb@Zn-TDA-80 can serve as a CTS sensor with high sensitivity and selectivity. To achieve portable detection, Tb@Zn-TDA-80 was further fabricated as a membrane sensor, M-Tb@Zn-TDA-80, which displayed an obvious CTS-responsive color change by simply dropping a CTS solution onto its surface. Benefiting from this unique functionality, M-Tb@Zn-TDA-80 successfully realized the visual detection and quantitative monitoring of CTS in the range of 5.26-52.6 mM by simply scanning the color with a smartphone. The results of nuclear magnetic resonance spectroscopy and theoretical computation illustrated that the high sensing efficiency of Tb@Zn-TDA-80 for CTS was attributed to the N-H⋅⋅⋅π and π⋅⋅⋅π interactions between the ligand and CTS. And luminescence quenching may result from the intramolecular charge transfer. This study provides a convenient method for ensuring long-term medication safety at home.

Highly sensitive determination of L-glutamic acid in pig serum with an enzyme-free molecularly imprinted polymer on a carbon-nanotube modified electrode

Through electrochemical polymerization using L-glutamic acid (L-Glu) as a template and 4,6-diaminoresorcinol as a functional monomer, an enzyme-free molecularly imprinted polymer (MIP) based L-Glu sensor with multi-walled carbon nanotubes (MWCNTs) decorated on a glassy carbon electrode (GCE), namely G-MIP/MWCNTs/GCE, was developed in this work. The reaction conditions were optimized as follows: electrochemical polymerization of 23 cycles, pH of 3.0, molar ratio of template/monomer of 1 : 4, volume ratio of elution reagents of acetonitrile/formic acid of 1 : 1, and elution time of 2 min. The prepared materials and molecularly imprinted polymer were characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) as well as electrochemical methods. The electrochemical properties of different electrodes were investigated via differential pulse voltammetry (DPV), showing that the electrode of G-MIP/MWCNTs/GCE exhibited excellent catalytic oxidation activity towards L-Glu. A good linear relationship between peak-currents and L-Glu concentrations in a range from 1.00 × 10-8 to 1.00 × 10-5 mol L-1 was observed, with a detection limit of 5.13 × 10-9 mol L-1 (S/N = 3). The imprinted sensor possesses excellent selectivity, high sensitivity, and good stability, which have been successfully applied for the detection of L-Glu in pig serum samples with a recovery rate of 97.4-105.5%, being comparable to commercial high-performance liquid chromatography, demonstrating a simple, rapid, and accurate way for the determination of L-Glu in the fields of animal nutrition and biomedical engineering.

Delayed Addition of Template Molecules Enhances the Binding Properties of Diclofenac-Imprinted Polymers

It has been reported that in the molecular imprinting technique, the use of preformed oligomers instead of functional monomers increases the stability of the non-covalent interactions with the template molecule, providing a sharp gain in terms of binding properties for the resulting imprinted polymer. Based on this theory, we assumed that the delayed addition of template molecules to a polymerization mixture enhances the binding properties of the resulting polymer. To verify this hypothesis, we imprinted several mixtures of 4-vinylpyridine/ethylene dimethacrylate (1:6 mol/mol) in acetonitrile by adding diclofenac progressively later from the beginning of the polymerization process. After polymerization, the binding isotherms of imprinted and non-imprinted materials were measured in acetonitrile by partition equilibrium experiments. Binding data confirm our hypothesis, as imprinted polymers prepared by delayed addition, with delay times of 5 and 10 min, showed higher binding affinity (K_eq = 1.37 × 10⁴ L mol⁻¹ and 1.80 × 10⁴ L mol⁻¹) than the polymer obtained in the presence of template at the beginning (K_eq = 5.30 × 10³ L mol⁻¹). Similarly, an increase in the imprinting factor measured vs. the non-imprinted polymer in the binding selectivity with respect to mefenamic acid was observed. We believe that the delayed addition approach could be useful in prepar imprinted polymers with higher binding affinity and increased binding selectivity in cases of difficult imprinting polymerization.

Core-shell nanoparticles for gas phase detection based on silver nanospheres coated with a thin molecularly imprinted polymer adsorbed on a chemiresistor

We present a novel gas phase detection prototype based on assembling core-shell nanospheres made of a silver core and coated with a molecularly imprinted polymer (MIP) adsorbed onto an interdigitated array (IDA) electrode chemiresistor (CR). The core-shell nanospheres, AgNP@MIPs, were imprinted with linalool, a volatile terpene alcohol, as a model system. The thickness of the MIP layer was tuned to a few nanometers to enable the facile ingress and egress of the linalool, as well as to enhance the electrical transduction through the Ag core. The AgNP@MIPs were spread onto the IDA-CR modified with various positively charged polymers, by drop casting and dip-coating. The AgNP@MIPs were characterized by various techniques such as extra high-resolution scanning and tunnelling electron microscopy and X-ray diffraction. The MIP recognition event was transduced into a measurable increase in the resistance. The response to linalool exposure and removal was fast and the device was fully recovered and could be reused. Finally, the difference in the resistance change between imprinted and non-imprinted nanospheres was substantial.

Selective determination of monosodium glutamate (Ajinomoto) in food samples using a potentiometric method with a modified multiwalled carbon nanotube based molecularly imprinted polymer

A molecularly imprinted polymer based on modified multiwalled carbon nanotubes was synthesized and used for the determination of MSG in food samples.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

Electrochemical sensor based on magnetic graphene oxide@gold nanoparticles-molecular imprinted polymers for determination of dibutyl phthalate

A novel composite of magnetic graphene oxide @ gold nanoparticles-molecular imprinted polymers (MGO@AuNPs-MIPs) was synthesized and applied as a molecular recognition element to construct dibutyl phthalate (DBP) electrochemical sensor. The composite of MGO@AuNPs was first synthesized using coprecipitation and self-assembly technique. Then the template molecules (DBP) were absorbed at the MGO@AuNPs surface due to their excellent affinity, and subsequently, selective copolymerization of methacrylic acid and ethylene glycol dimethacrylate was further achieved at the MGO@AuNPs surface. Potential scanning was presented to extract DBP molecules from the imprinted polymers film rapidly and completely. As a consequence, an electrochemical sensor for highly sensitive and selective detection of DBP was successfully constructed as demonstration based on the synthesized MGO@AuNPs-MIPs composite. Under optimal experimental conditions, selective detection of DBP in a linear concentration range of 2.5 × 10(-9)-5.0 × 10(-6)mol/L was obtained. The new DBP electrochemical sensor also exhibited excellent repeatability, which expressed as relative standard deviation (RSD) was about 2.50% for 30 repeated analyses of 2.0 × 10(-6)mol/L DBP.

Electrochemical sensor for dopamine based on a novel graphene-molecular imprinted polymers composite recognition element

A novel composite of graphene sheets/Congo red-molecular imprinted polymers (GSCR-MIPs) was synthesized through free radical polymerization (FRP) and applied as a molecular recognition element to construct dopamine (DA) electrochemical sensor. The template molecules (DA) were firstly absorbed at the GSCR surface due to their excellent affinity, and subsequently, selective copolymerization of methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) was further achieved at the GSCR surface. Potential scanning was presented to extract DA molecules from the imprinted polymers film, and as a result, DA could be rapidly and completely removed by this way. With regard to the traditional MIPs, the GSCR-MIPs not only possessed a faster desorption and adsorption dynamics, but also exhibited a higher selectivity and binding capacity toward DA molecule. As a consequence, an electrochemical sensor for highly sensitive and selective detection of DA was successfully constructed as demonstration based on the synthesized GSCR-MIPs nanocomposites. Under experimental conditions, selective detection of DA in a linear concentration range of 1.0 × 10(-7)-8.3 × 10(-4)M was obtained, which revealed a lower limit of detection and wider linear response compared to some previously reported DA electrochemical MIPs sensors. The new DA electrochemical sensor based on GSCR-MIPs composites also exhibited excellent repeatability, which expressed as relative standard deviation (RSD) was about 2.50% for 30 repeated analyses of 20 μM DA.