Cholesterol removal by selected metal-organic frameworks as adsorbents

Preparation of cholesterol-imprinted polymer for selective adsorption of cholesterol from gastrointestinal mimicking solution

The purpose of this study is to synthesize a highly selective adsorbent to remove cholesterol, one of the most important causes of cardiovascular diseases, from the intestinal mimic solution (IMS). For this purpose, cholesterol imprinted polymers were synthesized by suspension polymerization method using the molecular imprinting technique. In the first step, the functional monomer MATyr with hydrophobic character was synthesized. Then, the cholesterol-MATyr monomer precomplex was formed and the polymerization process was carried out by adding cross-linkers with the comonomer HEMA. The synthesized polymer poly(2-hydroxyethyl methacrylate-N-methacryloyl-(L)-tyrosine methylester) poly(HEMA-MATyr) was characterized by FTIR and SEM. The cholesterol adsorbing behavior of the synthesized poly(HEMA-MATyr) microbeads adsorbent was investigated at different initial concentrations, different temperatures, and adsorption times. The maximum adsorption capacity of microbeads was determined as 56.67 mg/g at a concentration of 2.5 mg/L. The amount of cholesterol adsorbed in the IMS was found as 83.07 mg/g polymer, which indicates that 92% of the cholesterol in the medium was adsorbed. The selectivity behavior of the cholesterol imprinted polymer was carried out with the stigmasterol and estradiol molecules, which are similar in structure, molecular weight, and character to the cholesterol molecule. The chol-imprinted polymeric beads were 21.38 and 10.08 fold more selective for cholesterol compared to estradiol and stigmasterol steroids used as competitor agents respectively. Kinetic and isotherm calculations of the synthesized cholesterol imprinted polymer were made and reusability experiments were carried out.

Syntheses and High Proton Conductivities of Two 3D Zr(IV)/Hf(IV)-MOFs from Furandicarboxylic Acid

With the gradual progress of research on proton-conducting metal-organic framework (MOFs), it has become a challenging task to find MOF materials that are easy to prepare and have low toxicity, high stability, and splendid proton conductivity. With the abovementioned objectives in mind, we selected the non-toxic organic ligand 2,5-furandicarboxylic acid and the low toxic quadrivalent metals zirconium(IV) or hafnium(IV) as starting materials and successfully obtained 2 three-dimensional porous MOFs, [M6O4(OH)4(FDC)4(OH)4(H2O)4] [M = ZrIV (1) and HfIV (2)], with ultrahigh water stability using a rapid and green synthesis approach. Their proton conductive ability is remarkable, thanks to the large number of Lewis acidic sites contained in their porous frameworks and the abundant H-bonding network, hydroxyl groups, as well as coordination and crystalline water molecules. The positive correlation of their proton conductivity with relative humidity (RH) and the temperature was observed. Notably, their optimized proton conductivities are 2.80 × 10-3 S·cm-1 of 1 and 3.38 × 10-3 S·cm-1 of 2 under 100 °C/98% RH, which are at the forefront of Zr(IV)/Hf(IV) MOFs with prominent proton conductivity. Logically, their framework features, nitrogen/water adsorption/desorption data, and activation energy values are integrated to deduce their proton conductivity and conducting mechanism differences.

Preparation of Ni-microsphere and Cu-MOF using aspartic acid as coordinating ligand and study of their catalytic properties in Stille and sulfoxidation reactions

In this study, the thermal and catalytic behavior of Ni-microsphere and Cu-MOF were investigated with aspartic acid as the coordinating ligand with different morphologies. The Ni-microsphere and Cu-MOF with aspartic acid, as the coordinating ligand, were prepared via a solvothermal method. The morphology and porosity of the obtained Ni microsphere and Cu-MOF were characterized by XRD, FTIR, TGA, DSC, BET and SEM techniques. The catalytic activity of the Ni-microsphere and Cu-MOF was examined in Stille and sulfoxidation reactions. The Ni microsphere and Cu-MOF were easily isolated from the reaction mixtures by simple filtration and then recycled four times without any reduction of catalytic efficiency.

Metal-organic frameworks for food applications: A review

Metal-organic frameworks (MOFs) are high surface-to-volume ratio crystalline hybrid porous coordination materials composed of metal ions as nodes and organic linkers. The goal of this paper was to provide an updated and comprehensive state-of-the-art review of MOFs for different food applications such as active food contact materials, antimicrobial nanocarriers, controlled release nanosystems for active compounds, nanofillers for food packaging materials, food nanoreactors, food substance nanosensors, stabilizers and immobilizers for active compounds and enzymes, and extractors of food contaminants. Extraction and sensing of several food contaminants have been the main food applications of MOFs. The other applications listed above require further investigation, as they are at an early stage. However, interesting results are being reported for these other fields. Finally, an important limitation of MOFs has been the use of non-renewable feedstocks for their synthesis, but this has recently been solved through the manufacture and use of γ-cyclodextrin-based MOFs.