Molecularly imprinted materials (MIMs) : synthesis, characterization and evaluation

Orientadores: Adriana Vitorino Rossi, Regina BuffonTese (doutorado) - Universidade Estadual de Campinas, Instituto de QuímicaResumo: Este trabalho envolveu um estudo elaborado da técnica de impressão molecular para síntese, caracterização e avaliação de materiais impressos molecularmente (MIMs) para fluconazol (FLU), cafeína (CAF) e antocianinas (ACYs). O polímero de impressão molecular para FLU (FLUMIP) foi sintetizado utilizando-se ácido metacrílico (monômero funcional), etilenoglicoldimetacrilato (EGDMA) (agente reticulador) e acetonitrila em polimerização térmica. O FLUMIP foi caracterizado e aplicado como sorvente em cartuchos de extração em fase sólida (SPE). Sua capacidade de interação seletiva com o analito foi avaliada, obtendo-se alta afinidade para FLU, em comparação com análogos estruturais, com limite de detecção menor que 1,63X10 mmol/L com cromatografia de ultra alta eficiência acoplada com espectrometria de massas. Este MIP foi usado em cartuchos de SPE para extrair o analito de medicamento em cápsula, com recuperação de 91±10 % (n=9). Outro MIM obtido foi uma sílica organicamente modificada (ORMOSIL) para extração de CAF, a partir da reação de metacrilato de 3- (trimetoxisilil) propila e acetato de vinila, seguindo-se condensação e hidrólise com tetraetilortosilicato usando CAF como molécula modelo. Este ORMOLSIL foi caracterizado e testado quanto à sua eficácia de extrair CAF de amostras de café, com recuperação de 88±5 % (n=9); ele atuou como grupo seletivo com alta porcentagem de recuperação para teofilina (77 %) e teobromina (82 %). Limites de detecção e quantificação 5,14x10 e 1,71x10 mmol/L respectivamente foram obtidos com cromatografia líquida de alta eficiência. Também foi sintetizado um MIP usando rutina molécula modelo (RUTMIP), acrilamida (monômero funcional), EGDMA (agente reticulador) e tetraidrofurano por polimerização em bulk. Embora tenha sido alcançada impressão bem sucedida de rutina, confirmada pela comparação de afinidade de RUTMIP em aplicação de SPE (12 vezes maior que afinidade do polímero não impresso), não se alcançou a seletividade esperada para ACYs utilizando o RUTMIPAbstract: This work involves an elaborative study of molecularly imprinting technique. Keeping in view its robustness and selectivity, this technique was applied for the synthesis of molecularly imprinted materials for the extraction of fluconazole (FLU), caffeine (CAF) and anthocyanins (ACYs). Molecularly imprinted polymer (MIP) for FLU (FLUMIP) was synthesized using methacrylic acid (functional monomer), ethyleneglycoldimethacrylate (crosslinker) and acetonitrile through thermal polymerization. The FLUMIP was characterized and applied as sorbent in solid phase extraction (SPE) cartridges. It was then evaluated for its ability to selectively interact with the analyte and presented an apparent affinity for FLU, which was confirmed by comparing it with structural analogues. The application of ultra high performance liquid chromatography with spectrometer mass detection, allowed a limit of detection 1.63x10 mmol/L. Furthermore, the SPE procedure was applied to extract FLU from medicine samples with recovery of 91±10 % (n=9). An organically modified silica (ORMOSIL) for CAF was also synthesized by reacting vinyl acetate and 3- (trimethoxysilyl) propyl methacrylate, followed by the condensation and hydrolysis with tetraethyl orthosilicate, using CAF as template molecule. The ORMOSIL was characterized and tested for its efficiency to extract the analyte from coffee samples and the percentage recovery of 88±5 % (n=9) was obtained. The cross reactivity studies for theophylline and theobromine showed high recovery (77 % and 82% respectively). The limit of detection and quantification, 5.14x10 and 1.71x10 mmol/L respectively, were achieved using high performance liquid chromatography. Also, a MIP for ACYs (RUTMIP) was synthesized using rutin (template molecule), EGDMA (cross linker) and tetrahydrofuran by the bulk polymerization method. A successful imprinting of rutin was attained. This can be confirmed by the high affinity of rutin for MIP (12 times greater than non imprinted polymer) during SPE procedure; however, the RUTMIP was not efficient enough to selectively extract ACYs from vegetal extractsDoutoradoDoutora em Ciência

A new synthetic route to molecularly imprinted ORMOSIL: characterization and evaluation

CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOA new strategy for synthesis of molecularly imprinted organically modified silica (MIORMOSIL) has been described. The MIORMOSIL was prepared by reacting vinyl acetate and 3-(trimethoxysilyl) propyl methacrylate, followed by condensation and hydrolysis wit536877886CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO190061/2009-

PBPK modelling of ceftriaxone Na-loaded starch-sodium alginate polymeric blend prepared by water-in-oil emulsification for oral delivery

Ceftriaxone is a third-generation cephalosporin antibiotic effective against many bacterial infections. However, owing to its instability in the gastrointestinal tract (GIT), it is administered by injections, which is an unfavourable route of administration. Therefore, the aim of this study was to formulate ceftriaxone into biodegradable and thermally stable polymeric blend microparticles that are suitable for oral delivery. The drug-loaded microparticles were prepared by the water-in-oil (W/O) emulsion method and consisted of starch and sodium alginate (NaAlg) as a polymeric matrix and glutaraldehyde (GA) as a cross-linking agent. Characterization of these particles using scanning electron microscopy (SEM) showed that the particles were spherical in shape with a smooth surface. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) of these particles showed no drug-polymer interactions. The highest percentage yield of particles was obtained at 3% polymer concentration. The particle size increased slightly after drug loading. The drug loading and entrapment efficiency appeared to increase with increasing polymer concentration. In vitro drug release at pH 1.2 and pH 7.4, revealed that drug release was below 20% at the acidic pH, while at pH 7.4, drug release of up to 85% was observed. The release mechanism followed first-order and Fickian diffusion patterns. Plasma concentration-time profiles were simulated for subcontinental Asian populations using commercial PBPK software, and the results suggest that microencapsulation of ceftriaxone sodium in a polymeric blend could represent a promising approach for controlled oral delivery of the drug, with enhanced absorption and bioavailability of the drug

Synergistic effect of reduced graphene oxide layers wrapped in polyaniline sheets to porous blades for boosted oxygen evolution reaction

Electrochemical water splitting is a unique approach for producing renewable energy in hydrogen fuel, though it is limited due to the sluggish kinetics of oxygen evolution reaction (OER). To enhance the efficacy of hydrogen production, it is a need to regulate oxygen evolution reaction. An efficient strategy is to construct a competent electrocatalyst with an immense open, active site, highly stable, porous structure, and large surface area. This study employs an inexpensive, facile, and eco-friendly single-step route to fabricate reduced graphene oxide (rGO) layers wrapped in polyaniline (PANI) sheets to achieve the controlled blades morphology. All the synthesized materials are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), BET to examine their structural, morphological, and textural properties. Interestingly, when all the synthesized materials are employed for electrochemical measurements, rGO/PANI nanocomposite exhibits exceptional performance with a low overpotential of 221 mV to achieve a current density of 10 mA/cm2, lower Tafel slope of 37 mV/dec, and also high stability of 20 h. Overall, this work could lead up to the fabrication of innovative blade structured nanocomposite as an efficient electrocatalyst and make it applicable for multiple applications.- Deanship of Scientific Research at King Khalid University, Saudi Arabia - Research Groups Program [grant number R.G.P. 1/41/42.]. - Bahauddin Zakariya University, Multan

Synthesis of Polyaniline Coated Magnesium and Cobalt Oxide Nanoparticles through Eco-Friendly Approach and Their Application as Antifungal Agents

Plant-mediated synthesis of nanoparticles exhibits great potential to minimize the generation of chemical waste through the utilization of non-toxic precursors. In this research work, we report the synthesis of magnesium oxide (MgO) and cobalt oxide (Co3O4) nanoparticles through a green approach using Manilkara zapota leaves extract, their surface modification by polyaniline (PANI), and antifungal properties against Aspergillus niger. Textural and structural characterization of modified and unmodified metal oxide nanoparticles were evaluated using FT-IR, SEM, and XRD. The optimal conditions for inhibition of Aspergillus niger were achieved by varying nanoparticles’ concentration and time exposure. Results demonstrate that PANI/MgO nanoparticles were superior in function relative to PANI/Co3O4 nanoparticles to control the growth rate of Aspergillus niger at optimal conditions (time exposure of 72 h and nanoparticles concentration of 24 mM). A percentage decrease of 73.2% and 65.1% in fungal growth was observed using PANI/MgO and PANI/Co3O4 nanoparticles, respectively, which was higher than the unmodified metal oxide nanoparticles (67.5% and 63.2%)

Synergistic effect of interfacial phenomenon on enhancing catalytic performance of Pd loaded MnO: X-CeO2-C hetero-nanostructure for hydrogenation and electrochemical reactions

Hetero-nanostructures have proven to be impressive materials due to their multi-functionalities in various catalytic applications. Here, the basic focus has been devoted to interface chemistry among different domains in the field of catalysis to develop an outstanding composite material with exceptional redox and catalytic properties in hydrogenation and as well in electrochemical reactions. The unique nano-hybrid material is synthesized by the loading of Pd nanoparticles onto MnOx-CeO2 mixed oxides. The heterogeneous catalytic ability for hydrogenation reactions were studied such as the reduction of organic pollutant 4-nitrophenol into 4-aminophenol and the hydrogenation of styrene into ethylbenzene. However, for electrochemical reactions, a comprehensive investigation as anode and cathode materials in direct formic acid fuel cells was performed. The strong reducing property of Pd enhanced the catalytic performance of mixed oxides and the synergistic effect of mixed oxides through interfacial phenomenon improved the performance of the hetero-nanostructured catalyst. The as-designed nanocomposite depicts high catalytic efficiency with low-cost economical standards.Scopu

Enhanced Electrocatalytic Performance of Pt3Pd1 Alloys Supported on CeO2/C for Methanol Oxidation and Oxygen Reduction Reactions

Direct methanol fuel cell (DMFC) with noble metals based anode and cathode is a promising energy generator to portable power devices. However, the deterioration of catalyst performance suffered by CO poisoning, crossover of fuel from anode to cathode, and higher economical cost of such devices hinder their commercialization. Herein, all of the above issues have been neutralized and crossed the huge hump of faced challenges. Highly efficient, durable, and surfactant-free catalyst with ultralow Pt3Pd1 loadings supported on CeO2/C was synthesized. The ex-situ and in situ spectroelectrochemical techniques such as, CV, in situ FTIR, and online DEMS studies confirm the highly efficient activity of catalyst toward electro-oxidation of methanol. In addition, the critical and detailed analysis of RDE results prove the superiority of the present material for electro-reduction of oxygen along a cathode side. The as-synthesized catalyst has proven itself as a better substitute for commercial Pt/C catalyst, with enhanced and durable performance as anode and cathode material for DMFCs. The obtained remarkable performance of catalysts can be attributed to the accumulative effects of PtPd bimetallic NPs and the enhanced synergistic factors of CeO2 in a hybrid material. (Graph Presented).- Anhui Government Scholarship programmes. - National Natural Science Foundation of China. - University of Science and Technology of China. - National Key Research and Development Program of China