Three new metal organic frameworks (MOFs) with chemical formulae [(CH3)2NH2] [Sm3(L1)2(HCOO)2(DMF)2(H2O)]·2DMF·18H2O (1), [Cu2(L2)(H2O)2]·2.22DMA (2) and [Zn2(L1)(DMA)]·1.75DMA were synthesized and structurally characterized. 1 and 2 show a classical NbO-like topology and have two types of interconnected cages. 3 exhibits an uncommon zzz topology and has two types of interconnected cages. These MOFs can adsorb large amounts of the drug 5-fluorouracil (5-FU) and release it in a progressive way. 5-FU was incorporated into desolvated 1, 2 and 3 with loadings of 0.40, 0.42, and 0.45 g g(-1), respectively. The drug release rates were 72%, 96% and 79% of the drug after 96 hours in 1, 120 hours in 2 and 96 hours in 3, respectively. Grand Canonical Monte Carlo (GCMC) simulations were performed to investigate the molecular interactions during 5-FU adsorption to the three novel materials. The GCMC simulations reproduced the experimental trend with respect to the drug loading capacity of each material. They also provided a structural description of drug packing within the frameworks, helping to explain the load capacity and controlled release characteristics of the materials. 5-FU binding preferences to 1, 2 and 3 reflect the diversity in pore types, chemistry and sizes. The calculated drug load is more related to the molecular properties of accessible volume Vacc than to the pore size.
The accumulation of antibiotics in wastewater has led to the development and spreading of antibiotic resistance in the environment. Amoxicillin (Amox), a beta-lactamic antibiotic, is one of the most frequently consumed antibiotics in the world. We have applied two metal-organic frameworks (MOFs) containing zinc(II) as platforms to degrade Amox. We have predicted the adsorption of this antibiotic via molecular docking calculations which have been further corroborated by means of Fourier transform infrared and UV-Vis spectroscopies, thermogravimetric analysis, X-ray diffraction and scanning microscopy measurements. We have subsequently performed mass spectrometry analysis of Amox@zeolitic imidazolate framework-8 (ZIF-8) and Amox@Zn(1,4-benzenedicarboxylate) (ZnBDC) to demonstrate the degradation of Amox upon contact with the Zn-containing frameworks. We propose a possible pathway for the degradation of Amox involving the cleavage of the four-membered β-lactam ring. These Zn-containing frameworks provide a biocompatible platform for the degradation in solution of Amox, which should also be suitable to degrade other β-lactam antibiotics.Keywords: β-lactamase activity, gentamicin, β-lactam catalysis, penicilloic and penilloic acids, biocompatible frameworks IntroductionIn the last decade, antibiotics have emerged as novel environmental pollutants. The widespread use of antibiotics in human and veterinary medicine, animal husbandry, plant production and aquaculture has led to high consumption and the gradual accumulation of antibiotics in the environment (e.g., wastewater, landfills, industrial and hospital effluents). [1][2][3][4][5][6] From 100,000 to 200,000 t of antibiotics are consumed per year in hospitals, homes, veterinary use and aquaculture throughout the world. On average, high-income countries generate ca. 0.5 kg of hazardous waste per bed per day whereas low-income countries generate ca. 0.2 kg. Furthermore, low-income countries do not separate hospital waste into hazardous or non-hazardous wastes, making the real quantity of hazardous waste much higher, as reported by the World Health Organization (WHO).Environmental accumulation of antibiotics has raised serious concerns about the induction of antibiotic resistance. [8][9][10] The exposure of bacteria to the subinhibitory antibiotic concentrations found in many natural environments such as sewage water and sludge, rivers, lakes and even drinking water is a crucial aspect of the current antibiotic resistance crisis.11-14 Furthermore, the incomplete absorption or metabolism of antibiotics in target organisms may lead to excretion rates from 5 to 90% of the dose in the form of metabolites or as parent compounds. 15,16 The chemical structure of antibiotics often contains cyclic moieties such as benzene rings, piperazine units, hexahydropyrimidines, sulfonamides, quinolone, and morpholine groups.5 Upon metabolic processing in humans and animals, these meta-stable compounds yield activated metabolites, which are continuously released in Metal Organic Framewor...
New porous composites LnBDC@AC (AC = Activated carbon, Ln = Eu and Gd and BDC = 1,4-benzenedicaboxylate) and CB[6]@AC (CB[6] = Cucurbit[6]uril) were obtained using hydrothermal route. The LnBDC and CB[B] are located inside the pore of the carbon materials as was observed in SEM-EDS, XRPD and FT-IR analysis. Porosimetry analysis showed values typically between AC and LnBDC material, with pore size and surface area, respectively, 29,56 Å and 353.98 m2g-1 for LnBDC@AC and 35,53 Å and 353.98 m2g-1 for CB[6]@AC. Both materials showed good absorptive capacity of metil orange (MO) and methylene blue (MB) with selectivity as a function of pH. For acid pH, both materials present selectivity by MB and alkaline pH for MO, with notable performance for CB[6]@AC. Additionally, europium luminescence was used as structural probe to investigate the coordination environment of Eu3+ ions in the EuBDC@AC composite after adsorption experiment.
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