Computational Design and Preparation of MIPs for Atrazine Recognition on a Conjugated Polymer-Coated Microtiter Plate

Synthesis and characterization of tetracycline-imprinted membranes: A detailed positron annihilation lifetime spectroscopy investigation

Molecularly imprinted thin membranes for selective removal of tetracycline from real water samples were prepared using the radiation-induced polymerization method. The chemical and physical characterization of the membranes was conducted by FTIR, XPS, AFM and SEM analyses. The effect of the template on the size and the size distribution of the pores in the membrane structure was investigated by positron annihilation lifetime spectroscopy (PALS) experiments. The presence of the template molecule causes the formation of larger cavities, which have a strong correlation to the molecular size of the template molecule. The density of the free volume holes in the imprinted network shows a significant increase due to the presence of the template molecule. The binding performances of the membranes were tested against various factors such as pH, time and initial concentration of template molecules. The specific selectivity of the membranes was investigated by cross-reactivity experiments. The binding capacity of the imprinted membranes was obtained at 14.5 μmol g^-1 , with the highest imprinting factor (2.84) for tetracycline. The imprinting factor was obtained at 1.44, 1.25 and 1.57 for oxytetracycline hydrochloride, doxycycline hyclate and chlortetracycline, respectively. The binding capability of the imprinted membranes in real water samples was promising for the application of the membranes as a filter material for removal of tetracycline with high binding capacity. Tetracycline binding percentage of the membranes was determined at 92.4, 81.1., 75.0 and 68.7 for ultra-pure water, tap water and natural water samples collected from different sources, respectively.

Molecularly Imprinted Nanoparticles Assay (MINA) in Pseudo ELISA: An Alternative to Detect and Quantify Octopamine in Water and Human Urine Samples

In 2004, octopamine was added to the list of drugs banned by the world anti-doping agency (WADA) and prohibited in any sport competition. This work aims to develop a new analytical method to detect octopamine in water and human urine samples. We proposed a pseudo-enzyme-linked immunosorbent assay (pseudo-ELISA) by replacing traditional monoclonal antibodies with molecularly imprinted polymer nanoparticles (nanoMIPs). NanoMIPs were synthesised by a solid-phase approach using a persulfate initiated polymerisation in water. Their performance was analysed in pseudo competitive ELISA based on the competition between free octopamine and octopamine-HRP conjugated. The final assay was able to detect octopamine in water within the range 1 nmol·L⁻¹–0.1 mol·L⁻¹ with a detection limit of 0.047 ± 0.00231 µg·mL⁻¹ and in human urine samples within the range 1 nmol·L⁻¹–0.0001 mol·L⁻¹ with a detection limit of 0.059 ± 0.00281 µg·mL⁻¹. In all experiments, nanoMIPs presented high affinity to the target molecules and almost no cross-reactivity with analogues of octopamine such as pseudophedrine or l-Tyrosine. Only slight interference was observed from the human urine matrix. The high affinity and specificity of nanoMIPs and no need to maintain a cold chain logistics makes the nanoMIPs a competitive alternative to antibodies. Furthermore, this work is the first attempt to use nanoMIPs in pseudo-ELISA assays to detect octopamine.

Development of a quantum dot molecularly imprinted polymer sensor for fluorescence detection of atrazine

Atrazine is a common agricultural pesticide which has been reported to occur widely in surface drinking water, making it an environmental pollutant of concern. In the quest for developing sensitive detection methods for pesticides, the use of quantum dots (QDs) as sensitive fluorescence probes has gained momentum in recent years. QDs have attractive and unique optical properties whilst coupling of QDs to molecularly imprinted polymers (MIPs) has been shown to offer excellent selectivity. Thus, the development of QD@MIPs based fluorescence sensors could provide an alternative for monitoring herbicides like atrazine in water. In this work, highly fluorescent CdSeTe/ZnS QDs were fabricated using the conventional organometallic synthesis approach and were then encapsulated with MIPs. The CdSeTe/ZnS@MIP sensor was characterized and applied for selective detection of atrazine. The sensor showed a fast response time (5 min) upon interaction with atrazine and the fluorescence intensity was linearly quenched within the 2-20 mol L^-1 atrazine range. The detection limit of 0.80 × 10^-7  mol L^-1 is comparable to reported environmental levels. Lastly, the sensor was applied in real water samples and showed satisfactory recoveries (92-118%) in spiked samples, hence it is a promising candidate for use in water monitoring.

Synthesis, characterization, and theoretical study of an acrylamide-based magnetic molecularly imprinted polymer for the recognition of sulfonamide drugs

In this work, a magnetic molecularly imprinted polymer (MION-MIP) was prepared for the recognition and extraction of sulfadiazine (SDZ). The acrylamide-based MIP was imprinted directly onto the surface of 3-(trimethoxysilyl)propyl methacrylate-modified magnetic iron oxide nanoparticles. The synthesized MION-MIP with a diameter about 100 nm possesses fast adsorption kinetics and high adsorption capacity. The results also indicated that a higher maximum adsorption capacity (775 μg g-1) was achieved by the synthesized MION-MIP. The Langmuir adsorption isotherm model was found to describe well the equilibrium adsorption data. The results from the competitive binding experiment showed that MION-MIP was not only selective toward SDZ but the adsorption of sulfamerazine was also dramatically high. SDZ and sulfamerazine have an almost similar substructure where these two compounds were only differentiated by one methyl group. To explain this result, a computational study was carried out. From a different level of calculation with semiempirical (PM3), Hartree-Fock (HF), and density functional theory (DFT) calculation, SDZ and sulfamerazine showed similar interaction energy and interaction mechanism with the acrylamide monomer. Therefore, both SDZ and sulfamerazine could have the same binding property with the MION-MIP.

Generation of novel hybrid aptamer-molecularly imprinted polymeric nanoparticles

A strategy to exploit aptamers as recognition elements of molecularly imprinted polymeric nanoparticles (AptaMIP NPs) is presented, via modification of the chemical structure of the DNA. It is demonstrated that the introduction of this modified "aptamer monomer" results in an increase of the affinity of the produced MIP NPs, without altering their physical properties such as size, shape, or dispersibility.

Molecularly imprinted polymer-based sensors for atrazine detection by electropolymerization of o-phenylenediamine

A sensitive and selective atrazine (ATZ) electrochemical sensor was developed based on a molecularly imprinted polymer (MIP).