Search

Abstract: Monolithic molecularly imprinted polymers (mMIPs) have been synthesized in a novel way using a trimethylolpropane trimethacrylate core material photo-polymerized in situ in a 100μm I.D. UV-transparent capillary and further photo-grafted to create specific cavities in the grafted layer. This polymerization technique allows the imprints to be directly created on the surface of the material using a minimum amount of template. Three different anaesthetics of similar structures (bupivacaine, mepivacaine and S-ropivacaine) were used as model target molecules to synthesize sample enrichment media. Hence, various mMIPs have been prepared and evaluated on a micro-system against each analyte in order to test the retention properties and cross-selectivities of the materials. The retention factors were determined and compared with the non-imprinted reference column (mNIP), yielding high imprinting factors together with good selectivity factors between the three analytes. A study with a pure enantiomeric target was carried out to assess the degree of stereo-specific imprinting for injection of racemic mixtures. Finally, one column was imprinted with an equimolar mixture of all three anaesthetics to provide further comprehension of the retention mechanism and accredit the possibility of using the material as a sample enrichment entity. Scanning electron microscopy (SEM), nitrogen absorption/desorption (BET) and mercury intrusion porosimetry were used to characterize the monolith and the mMIPs properties. Nuclear magnetic resonance (NMR) has been used to assess the similarities between the mMIP and mNIP. [Copyright &y& Elsevier]

Bulk and magnetic core-shell Molecularly Imprinted Polymers (MMIPs) have been introduced and compared to extract and determine amiodarone from a complex matrix, i.e., plasma, due to the importance of Therapeutic Drug Monitoring (TDM). Polymer synthesis was confirmed by FTIR, AFM, TGA, DLS, VSM, TEM, and the adsorption studies such as capacity, isothermal models, selectivity, and regeneration were performed to evaluate and compare polymer efficiency in extraction and separation of amiodarone from sample solutions and human plasma. Both nano-sized and bulk polymers successfully extracted the target molecule at the low therapeutic ranges and the overdose concentrations (recoveries of 98.38%–102.70%). The maximum adsorption capacity of the MMIPs was 42.5 μg/mg compared with 2.6 μg/mg for bulk polymers. The imprinting factors of the polymers were 15.12 and 6.84 for MMIPs and bulk, respectively. MMIPs and bulk polymers presented 4.68 and 1.66 selectivity factors, respectively, towards amiodarone compared with lidocaine. LOD, LOQ, and enrichment factor in human plasma were 0.09, 0.28 μg mL−1, and 10 respectively. Recoveries of therapeutic concentration from plasma were 91.38 and 97.33% for bulk and MMIPs, respectively. MMIPs as an adsorbent in amiodarone extraction from plasma offered reduced necessary sample amount, less adsorbent consumption, reduced pretreatment time, and reduced elution solvent waste while yielding higher extraction recovery and more specificity for the target compared with the bulk polymer. Bulk polymers have a more straightforward synthesis procedure due to fewer synthesis steps and fewer variables, and Molecularly Imprinted Polymer Solid-phase Extraction (MIP-SPE) has already been introduced commercially. MMIPs prevail on a small scale, and in the context of a simple extraction, separation, or concentration in large-scale bioanalysis, efforts towards optimization and development of MMIPs can unearth tremendous opportunities for green chemistry principles. [Display omitted] • Bulk and magnetic core-shell MIPs (MMIPs) of Amiodarone were synthesized. • Magnetic solid phase extraction combined with HPLC was compared with MIP-SPE. • MIP-SPE and magnetic SPE were applied in amiodarone extraction from human plasma. • MMIPs showed higher capacity, imprinting factor, selectivity, and homogeneity. • MIP-SPE and MMIPs achieved acceptable recoveries in amiodarone extraction. [ABSTRACT FROM AUTHOR]

Abstract: Suspended-state high resolution/magic angle spinning nuclear magnetic resonance spectroscopy and solid-state cross-polarization/magic angle spinning nuclear magnetic resonance spectroscopy were employed to study the interactions between 9-ethyladenine and a 9-ethyladenine molecularly imprinted polymer, and a non-imprinted polymer, respectively, both are copolymers of methacrylic acid and ethyleneglycol dimethacrylate. Template-related structural differences between the materials were revealed by contact time measurements and solid-state nuclear magnetic resonance. Rebinding of the template to the imprinted polymer resulted in shorter contact times for nuclei believed to be involved in the binding site interactions whereas the non-imprinted polymer did not exhibit such effects. This indicates that binding site reoccupation has a stiffening effect lowering the mobility of nearby nuclei. More detailed information was obtained from suspended-state saturation transfer difference high resolution/magic angle spinning nuclear magnetic resonance experiments. These revealed molecular level details concerning the interactions of the adenine guests with the polymer binding sites. Thus, a relatively larger transfer of magnetization was observed in the solute when bound to the molecularly imprinted polymer at a position where multiple hydrogen bonds between the analyte and the template can be expected to take place in the molecularly imprinted polymer only. [Copyright &y& Elsevier]