Amine-functionalized Titanium Metal Organic Framework Research Articles

Melamine foam assisted in-tip packed amine-functionalized titanium metal–organic framework for the selective enrichment of endogenous glycopeptides

Endogenous glycopeptides are significantly important in diverse pathological and physiological systems, but their direct analysis is severely hampered by their low abundance and presence of interfering species in biological fluids. In this study, we synthesized the amine-functionalized titanium metal-organic framework (NH2-MIL-125(Ti)) by a simple hydrothermal method, characterized and used for glycopeptides enrichment. The designed separation media is highly hydrophilic and stable which is suitable for hydrophilic interaction chromatography (HILIC). To make the process smooth, simple, reliable, and robust, NH2-MIL-125(Ti) crystals were packed in pipette-tip using hydrophilic melamine foam, as supporting frit. Free amine groups, present in the structure imparted hydrophilicity and a unique pattern of porosity, contributing to the size exclusion effect that excluded the large-sized proteins up to 1:700 peptide to protein ratio. The prepared MOF particles possessed regular porosity, high surface area, good hydrophilicity, and offered an in-tip flow-based set-up enhanced the enrichment performance for N-linked glycopeptides. The affinity material showed a detection limit of 1 fmol.µL−1 and selectivity up to 1:1000 (HRP digest to BSA digest). Moreover, repeatability and reusability were evaluated up to five rounds of enrichment using the same affinity tip, and scanning electron microscopic images revealed no structural changes in the MOF crystals. Finally, the MOF packed in pipette tip was applied to selectively capture the N-linked endogenous glycopeptides from a healthy saliva sample and 64 unique endogenous glycopeptides were identified. These results demonstrated the excellent potential of NH2-MIL-125(Ti) based affinity tip for glycopeptides which can be used to enrich trace glycopeptide biomarkers from the biological fluids.

Amine-functionalized titanium metal-organic framework (NH2-MIL-125(Ti)): A novel fluorescent sensor for the highly selective sensing of copper ions

Herein, titanium based metal organic framework (MOF) i.e. NH2-MIL-125(Ti) has been successfully fabricated via solvothermal route using titanium isopropoxide and 2-aminoterephthalic acid as starting materials. The characterization and evaluation of structural, morphological and compositional analysis were done using several analytical techniques such as XRD, FTIR, BET surface area, XPS, FE-SEM and HR-TEM. Furthermore, the synthesized MOF's performance was explored as an efficient fluorescent probe for the quantification of transition metal ions. The results revealed that NH2-MIL-125(Ti) was strongly specific and sensitive to Cu(II) ions. Remarkably, the fluorescence intensity of NH2-MIL-125(Ti) decreased proportionally towards the concentration of Cu(II) ions. The sensor provides a useful platform for the detection of Cu(II) ions in the linear range 0–72 μM with a detection limit of 0.72 μM, besides, the value of Stern-Volmer constant was found to be 3.2 × 104 M−1. Moreover, NH2-MIL-125(Ti) as a Cu(II) sensor can be simply recycled affirming its high stability, which reveals NH2-MIL-125(Ti) as a prospective fluorescent probe. The prepared sensor was also applied for the determination of Cu(II) ions in real water samples to test its practical utility.

Graphene oxide enhanced amine-functionalized titanium metal organic framework for visible-light-driven photocatalytic oxidation of gaseous pollutants

Graphene oxide (GO) enhanced amine-functionalized titanium metal organic framework (NH2-MIL-125(Ti)) was fabricated via a facile microwave solvothermal process by using GO, C12H28O4Ti, and 2-aminoterephthalic acid as precursors. Under the microwave irradiation, the surface of GO could act as the microwave antenna for fast absorbing microwave energy with the formation of hot-spots on GO (hot-spots effect). These hot-spots allowed both the well-crystallization of NH2-MIL-125(Ti) crystals with a highly dispersity on the surface of GO and the strong interaction between NH2-MIL-125(Ti) and GO, supported by various characterization such as XRD, Raman, UV–vis and so on. Benefiting from the strong interaction and high electronic conductivity of GO, such GO/ NH2-MIL-125(Ti) hybrid exhibited a greatly enhanced metal organic framework crystallinity, visible-light absorption, photocurrent intensity, electron carrier density and a lower photo-generated electron-hole recombination rate, compared to the pure NH2-MIL-125(Ti). Therefore, the as-obtained hybrid system was proved highly efficient for photocatalytic oxidation of gaseous pollutants, such as nitric oxide (NOx) and acetaldehyde with long durability, under visible light (λ > 420 nm) irradiation.

Water vapor separation from flue gas using MOF incorporated thin film nanocomposite hollow fiber membranes

First time it is proposed that metal organic framework (MOF) incorporated thin film nanocomposite (TFN) membrane drastically enhances the water vapor transport performance from the mixture gas. The incorporation of MOF nanoparticles in a polymer matrix has afforded a new approach for the preparation of membranes with enhanced water vapor permeance, and selectivity. In this work we have synthesized the MOF material and incorporated it in monomer solution to make TFN membrane via interfacial polymerization method. Polysulfone (PSf) hollow fiber membranes have been used as substrate material for the coating of thin nanocomposite layer. The m-phenylene diamine (MPD) and trimesoyl chloride (TMC) were used as the monomer solutions for interfacial polymerization (IP) reaction. The small quantity loading of MOF particles plays a vital role for water vapor transport through the TFN membranes. Synthesized MOF material and prepared membranes were well characterized using different physicochemical analysis techniques including Attenuated total reflectance-Fourier transformed infrared (ATR-FTIR), atomic force microscopy (AFM), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and water contact angle (WCA). The water vapor permeance was increased from 785 GPU, for thin film composite (TFC) membrane, to 2244 GPU (MOF@TFN3) with the selectivity being enhanced from 116 to 542 when the NH2-MIL-125(Ti) MOF (amine-functionalized titanium metal organic framework) nanoparticles content was 0.1 w/w% with respect to monomer solution.

Amine-functionalized titanium metal organic framework for photochemical vapor generation for determination of selenium by inductively coupled plasma optical emission spectrometry

Metal organic framework MIL-125-NH2 was used as a photocatalyst for the photochemical vapor generation to establish an efficient and accurate method for highly sensitive determination of trace selenium by inductively coupled plasma optical emission spectrometry. The mixture of Se (IV) and Se (VI), MIL-125-NH2 nanoparticles and a low molecular weight organic acid was mixed to generate gaseous selenium-containing species which was separated from its liquid phase and transported to inductively coupled plasma optical emission spectrometer for determination. Influencing factors including carrier gas flow rate, type and concentration of catalyst, type and concentration of organic acid, UV irradiation time and power, and sample pH were carefully studied. Under the optimized conditions, a catalytic efficiency of more than 80% was achieved. The limits of detection for Se (IV) and Se (VI) were found to be the same and as low as 0.3ng/mL. The relative standard deviation of Se (IV) and Se (VI) was 2.7% and 2.1% at 20ng/mL (n=11), respectively. The accuracy of the method was evaluated by analysis of natural mineral water and certified reference materials.

A novel humidity sensor based on NH2-MIL-125(Ti) metal organic framework with high responsiveness

A novel porous nanosized humidity-sensing material of amine-functionalized titanium metal organic framework (MOF), NH2-MIL-125(Ti), was investigated. NH2-MIL-125(Ti) nanoparticles with high phase purity and good physicochemical property were synthesized by a simple hydrothermal method. The nanosized MOF was characterized by X-ray diffraction and scanning electron microscope. The average size of the MOF nanoparticles is around 300 nm. Then NH2-MIL-125(Ti) humidity sensor was fabricated by coating the nanosized materials on interdigitated electrodes. The humidity sensor based on NH2-MIL-125(Ti) shows good linearity of RH (11–95 % RH), as well as fast response and recovery time. The RH detecting range is from 11 to 95 % RH at 100 Hz. The response and recovery time are about 45 and 50 s, respectively. Moreover, the sensing mechanism was discussed by complex impedance analysis in detail. These results indicate the potential application of NH2-MIL-125(Ti) in humidity sensors.