Synthesis of molecularly imprinted polymers using an amidine-functionalized initiator for carboxylic acid recognition

In traditional molecular imprinting reactions, the initial radicals generated by thermo- or photo-decomposition are randomly distributed in the reaction mixture. Because a noticeable portion of the initial radicals is able to cause self-polymerization of the crosslinking monomer, a significant part of the polymer product does not contain successfully imprinted molecular recognition sites. To solve this problem, we designed a molecular imprinting method using functionalized radical initiator to replace the conventional combination of initiator and functional monomer. Since the active radicals in the reaction mixture carry a template-binding moiety, the actual radical polymerization becomes more likely to take place nearby the molecular template. As a result, the efficiency of molecular imprinting can be improved. In this work, we report the use of amidine-functionalized initiator to synthesize molecularly imprinted polymers (MIPs) for selective recognition of methotrexate, a cytostatic drug used for cancer therapy. As glutamic acid represents a substructure of methotrexate, we select to use N-terminal protected glutamic acid as template to synthesize the MIPs. An initiator, 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) is used to provide strong interaction with the molecular template. Two MIPs synthesized using glutamic acid derivatives as templates display specific binding to the fluorescent amino acid derivative Fmoc-Glu. When the molecular binding is tested against methotrexate, the MIP particles also exhibit specific binding for the cytostatic drug. Using cationic functional initiator to target carboxyl epitope of molecular target, this work provides an additional example of molecular imprinting based on functionalized radical initiators

Liposomes as selenium nanocarriers for foliar application to wheat plants : A biofortification strategy

Altres ajuts: acords transformatius de la UABAltres ajuts: The XAS experiment has been founded by ALBA synchrotron thought granted proposal (grant reference: 2022097174)In the present work, liposomes have been used as nanocarriers in the biofortification of wheat plants with selenium (Se) through foliar application. Liposomal formulations were prepared using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and Phospholipon®90H (P90H) (average size <100 nm), loaded with different concentrations of inorganic Se (selenite and selenate) and applied twice to the plants in the stage of vegetative growth. Liposomes enhanced Se uptake by wheat plants compared to direct application. The highest Se enrichment was achieved using the phospholipid DPPC and a concentration of 1000 μmol·L−1 of Se without affecting the biomass, chlorophylls, carotenoids, and the concentration of mineral nutrients of the plants. The chemical speciation of Se in the plants was further investigated by X-ray absorption spectroscopy (XAS). The results from XAS spectra revealed that most of the inorganic Se was transformed to organic Se and that the use of liposomes influenced the proportion of C-Se-C over C-Se-Se-C species

3,3-Disubstituted 1-acylthioureas as ionophores for Pb(II)-ion selective electrodes: physical and chemical characterization of the sensing membranes

Solid-state Pb(II) ion selective electrodes were developed, which are based on 3,3-disubstituted 1-acylthioureas as ionophores and use PVC membranes. 1-Benzoyl, 1-(2-furoyl), 3,3-diethyl and 3,3-diphenyl were the substituent groups on the thioureide core. The analytical parameters for the constructed electrodes were studied. The electrodes based on 3,3-diethyl substituted thiourea derivatives showed better analytical response to Pb(II) ions with suitable sensitivity and an average lifetime of more than 30 days. Cu(II), Hg(II) and Ag(I) ions were interfering species during Pb(II) detection. Scanning electron microscopy and atomic force microscopy micrographs of the activated sensing membranes revealed morphological changes, which have been associated with the performance of the sensors. The studies have suggested that the detection of few large size particles or aggregates at the membrane surface are responsible for inadequate functioning of the prepared electrodes. This pattern was mainly observed for the sensing membranes based on 3,3-diphenyl groups as substituents and is related to unfavorable steric and electronic factors. Furthermore, X-ray photoelectron spectroscopy profiles S2p and Pb4f supported chemically the analytical response displayed for the four membrane systems. The X-ray photoelectron spectroscopy results combined with scanning electron microscopy and atomic force microscopy studies shed light on the working mechanism of the studied electrodes.</p