Covalent immobilization of human serum albumin on cellulose acetate membrane for scavenging amyloid beta - A stepping extracorporeal strategy for ameliorating Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by interrupted neurocognitive functions and impaired mental development presumably caused by the accumulation of amyloid beta (Aß) in the form of plaques. Targeting Aß has been considered a promising approach for treating AD. In the current study, human serum albumin (HSA), a natural Aß binder, is covalently immobilized onto the surface of a cellulose acetate (CA) membrane to devise an extracorporeal Aß sequester. The immobilization of HSA at 3.06 ± 0.22 µg/mm2 of the CA membrane was found to be active functionally, as evidenced by the esterase-like activity converting p-nitrophenyl acetate into p-nitrophenol. The green fluorescent protein-Aß (GFP-Aß) fusion protein, recombinantly produced as a model ligand, exhibited characteristics of native Aß. These features include the propensity to form aggregates or fibrils and an affinity for HSA with a dissociation constant (KD) of 0.91 µM. The HSA on the CA membrane showed concentration-dependent sequestration of GFP-Aß in the 1-10-µM range. Moreover, it had a greater binding capacity than HSA immobilized on a commercial amine-binding plate. Results suggest that the covalent immobilization of HSA on the CA surface can be used as a potential platform for sequestering Aß to alleviate AD.

CuBTC Metal-Organic Framework Decorated with FeBTC Nanoparticles with Enhance Water Stability for Environmental Remediation Applications.

Metal-organic frameworks (MOFs) based on Cu-benzene tricarboxylate (CuBTC) are widely used for gas storage and removal applications. However, they readily lose their crystal structures under humid conditions, limiting their practical applications. This structural decomposition reduces the specific surface area, gas adsorption capability, and recyclability of CuBTC considerably. In this study, a stable MOF against water exposure was designed based on FeBTC nanoparticle-covered CuBTC (FeCuBTC). A simple one-pot solvothermal process that enables the epitaxial growth of FeBTC on the CuBTC surface was proposed. Structural and morphological analyses after water exposure revealed that the water stability of FeCuBTC was better than that of CuBTC, which completely lost its crystallinity. This observed improvement in the water stability of the synthesized MOF proved to be beneficial for the adsorption of formaldehyde under humid conditions. The proposed strategy herein is simple yet highly effective in the design of hetero-bimetallic MOFs with considerably improved water resistance and extended applicability for environmental remediation processes.

Development and evaluation of bioinspired pH-responsive sericin-chitosan-based hydrogel for controlled colonic delivery of PETase: Harnessing PETase-triggered degradation of microplastics.

The gravity of threats posed by microplastic pollution to the environment cannot be overestimated. Being ubiquitous in the living environment, microplastics reach humans through the food chain causing various hazardous effects. Microplastics can be effectively degraded by PETase enzymes. The current study reports, for the first time, a hydrogel-encapsulated, bioinspired colonic delivery of PETase. A free radical polymerization-assisted hydrogel system was synthesized from sericin, chitosan, and acrylic acid using N,N'-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The hydrogel was characterized with FTIR, PXRD, SEM, and thermal analysis to confirm the development of a stabilized hydrogel system. The hydrogel showed 61 % encapsulation efficiency, maximum swelling, and cumulative PETase release (96 %) at pH 7.4. The mechanism of PETase release exhibited the Higuchi pattern of release with an anomalous transport mechanism. SDS-PAGE analysis confirmed the preservation of the post-release structural integrity of PETase. The released PETase exhibited concentration- and time-dependent degradation of polyethylene terephthalate in vitro. The developed hydrogel system exhibited the intended features of a stimulus-sensitive carrier system that can be efficiently used for the colonic delivery of PETase.

ZIF-8 Membrane Separation Performance Tuning by Vapor Phase Ligand Treatment.

Vapor phase ligand treatment (VPLT) of 2-aminobenzimidazole (2abIm) for 2-methylimidazole (2mIm) in ZIF-8 membranes prepared by two different methods (LIPS: ligand induced permselectivation and RTD: rapid thermal deposition) results in a notable shift of the molecular level cut-off to smaller molecules establishing selectivity improvements from ca. 1.8 to 5 for O2 /N2 ; 2.2 to 32 for CO2 /CH4 ; 2.4 to 24 for CO2 /N2 ; 4.8 to 140 for H2 /CH4 and 5.2 to 126 for H2 /N2 . Stable (based on a one-week test) oxygen-selective air separation performance at ambient temperature, 7 bar(a) feed, and 1 bar(a) sweep-free permeate with a mixture separation factor of 4.5 and oxygen flux of 2.6×10-3  mol m-2 s-1 is established. LIPS and RTD membranes exhibit fast and gradual evolution upon a 2abIm-VPLT, respectively, reflecting differences in their thickness and microstructure. Functional reversibility is demonstrated by showing that the original permeation properties of the VPLT-LIPS membranes can be recovered upon 2mIm-VPLT.

Alkylamine-Integrated Metal-Organic Framework-Based Waveguide Sensors for Efficient Detection of Carbon Dioxide from Humid Gas Streams.

Metal-organic framework (MOF)-based chemical sensors have recently been demonstrated to be highly selective, sensitive, and reversible for CO2 sensing across a range of platforms including optical fiber and surface acoustic wave-based sensors. However, interference of water molecules is a primary issue in CO2 sensing systems based upon MOF layers due to cross-sensitivity, stability of MOF-based materials in humid conditions, and associated baseline drift over the lifetime of sensors. Herein, we develop a simple approach of alleviating the negative effect of water vapor to the optical fiber sensor by using alkylamine (i.e., oleylamine) to form a protective hydrophobic layer on the surface of MOFs for improving water stability. Alkylamine-modification of a MOF-coated optical fiber sensor provides a reversible and stable sensing response to a wide range of CO2 concentrations while also enhancing the CO2 sensitivity of the sensor under wet conditions. The FT-IR and breakthrough studies on the oleylamine-modified MOF confirm that the water vapor does not adversely impact the intrinsic CO2 sorption capacities. Thus, this simple stratrgy for enhancing the CO2/H2O selectivity in the MOF sorbent could also be useful for improving CO2 capture/separation performance in flue gas stream.

High-Flux Zeolitic Imidazolate Framework Membranes for Propylene/Propane Separation by Postsynthetic Linker Exchange.

While zeolitic imidazolate framework, ZIF-8, membranes show impressive propylene/propane separation, their throughput needs to be greatly improved for practical applications. A method is described that drastically reduces the effective thickness of ZIF-8 membranes, thereby substantially improving their propylene permeance (that is, flux). The new strategy is based on a controlled single-crystal to single-crystal linker exchange of 2-methylimidazole in ZIF-8 membrane grains with 2-imidazolecarboxaldehyde (ZIF-90 linker), thereby enlarging the effective aperture size of ZIF-8. The linker-exchanged ZIF-8 membranes showed a drastic increase in propylene permeance by about four times, with a negligible loss in propylene/propane separation factor when compared to as-prepared membranes. The linker-exchange effect depends on the membrane synthesis method.

Defect-induced ripening of zeolitic-imidazolate framework ZIF-8 and its implication to vapor-phase membrane synthesis.

We report for the first time that ZIF-8 crystals undergo an Ostwald-ripening-like process without degradation in the presence of a ligand vapor. The ripening process is dependent on the defect density of the crystals: the more defective the more amenable to the ripening. The process was adapted to synthesize ultra-thin ZIF-8 membranes by vapor-phase secondary growth.

Heteroepitaxially grown zeolitic imidazolate framework membranes with unprecedented propylene/propane separation performances.

Propylene/propane separation is one of the most challenging separations, currently achieved by energy-intensive cryogenic distillation. Despite the great potential for energy-efficient membrane-based separations, no commercial membranes are currently available due to the limitations of current polymeric materials. Zeolitic imidazolate framework, ZIF-8, with the effective aperture size of ∼4.0 Å, has been shown to be very promising for propylene/propane separation. Despite the extensive research on ZIF-8 membranes, only a few reported ZIF-8 membranes have displayed good propylene/propane separation performances presumably due to the challenges of controlling the microstructures of polycrystalline membranes. Here we report the first well-intergrown membranes of ZIF-67 (Co-substituted ZIF-8) by heteroepitaxially growing ZIF-67 on ZIF-8 seed layers. The ZIF-67 membranes exhibited impressively high propylene/propane separation capabilities. Furthermore, when a tertiary growth of ZIF-8 layers was applied to heteroepitaxially grown ZIF-67 membranes, the membranes exhibited unprecedentedly high propylene/propane separation factors of ∼200 possibly due to enhanced grain boundary structure.

Synthesis and characterization of Cu3(BTC)2 membranes by thermal spray seeding and secondary growth.

Crack-free Cu3(BTC)2 membranes were successfully prepared by thermal spray seeding and secondary growth method. Thermal spray seeding method, combining thermal seeding and pressurized spraying, uniformly distributed seed solution on the support, anchoring seed crystals tightly on the support. After secondary growth of the seeded support in the autoclave, continuous crack-free membrane was obtained by controlling cooling and drying steps. The gas permeation test was conducted at various temperatures using H2, CO2, CH4 and N2 gases.

In situ synthesis of thin zeolitic-imidazolate framework ZIF-8 membranes exhibiting exceptionally high propylene/propane separation.

Metal-organic frameworks (MOFs) are a class of hybrid porous crystalline materials comprising of metal centers coordinated to organic linkers. Owing to their well-defined pores and cavities in the scale of molecules combined with abundant surface chemistry, MOFs offer unprecedented opportunities for a wide range of applications including membrane-based gas separations. It is not straightforward (often requiring multiple steps) to prepare membranes of MOFs due to the fact that the heterogeneous nucleation and growth of MOF crystals on porous supports are not generally favored. Furthermore, the performance of polycrystalline MOF membranes strongly depends on the membrane microstructure, in particular, the grain boundary structure. Here we report a simple one step in situ method based on a counter-diffusion concept to prepare well-intergrown ZIF-8 membranes with significantly enhanced microstructure, resulting in exceptionally high separation performance toward propylene over propane.

Highly propylene-selective supported zeolite-imidazolate framework (ZIF-8) membranes synthesized by rapid microwave-assisted seeding and secondary growth.

Here we report a rapid and simple microwave-assisted seeding technique for the synthesis of high-quality ZIF-8 membranes with an average propylene-propane selectivity of about 40. The new seeding method was found to be applicable to other ZIFs including ZIF-7 and SIM-1.

Sol-gel synthesis and characterization of nanostructured TiO2/gamma-Al2O3 composite membranes.

Nanostructured TiO2/gamma-Al2O3 composite membranes with various compositions were prepared by sol-gel method. The structural and textural properties of the composite membranes could be modified by the mixing ratio of boehmite sol and titania sol, and calcination temperature. The existence of alumina in the composite membranes retarded anatase-to-rutile phase transformation, resulting in stabilization of textural properties. Defect-free composite membranes were confirmed by gas permeation test.