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Trace Water Effects on Crystalline 1-Ethyl-3-methylimidazolium Acetate

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Authors: Ashlee Aiello, John R. Hoffman, Anthony P. Kotula, Lucas Q. Flagg, Ruipeng Li, and Jeremiah W. Woodcock

Journal: J. Phys. Chem. B (2023)

 

Abstract

Spontaneous room-temperature crystallization of 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) was observed upon removal of trace water. Sample purity was confirmed using analytical nuclear magnetic resonance spectroscopy to ensure that trace water or other contaminants did not produce this observation. Raman spectroscopy and simultaneous quartz crystal microbalance/infrared spectroscopy measurements were used to study molecular reorganization during crystallization and decrystallization using trace water in the form of atmospheric moisture. These experimental results were supplemented with density functional theory calculations that indicate imidazolium cation ring stacking and side chain clustering with an exclusive arrangement of the acetate anion in the cation ring plane upon water removal. Crystal structure formation was confirmed using two-dimensional wide-angle X-ray scattering. This natural crystallization is attributed to the removal of trace water over extended periods of time and calls attention to the molecular-level role of water in the structure of hygroscopic ionic liquid systems.

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Polyelectrolyte Complexes of Random Copolymers and their Applications in Environmental Remediation

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Author: Jeremy Wang

PhD Thesis: Northwestern University (March 2023)

 

Abstract

As polymer science has advanced as a field, so too have the uses for polymeric materials. We encounter polymers and plastics on a daily basis, and while their presence has greatly improved our quality of life, they have also had a profound and often negative impact on our environment. Plastic waste and pollution are currently problems of great concern, and recent trends in terms of micro– and nanoplastic pollution, and chemical pollution of water continue to exacerbate such worries. In this thesis, we explore how polyelectrolyte complexes of random copolymers can be used to effectively address some of these environmental concerns. The combination of charged interactions and disorder of polymer sequence can provide a novel combination of interactions which are well suited for removing contaminants from water, and even promoting the enzymatic degradation of plastic. The results obtained demonstrate that this research into new polymeric materials not only advances our understanding of fundamental polymer properties but yields relevant applications to the issues we encounter in the present day.

 

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Multispecies biofilms on reverse osmosis membrane dictate the function and characteristics of the bacterial communities rather than their structure

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Authors: Noya Ran, Gil Sorek, Noa Stein, Revital Sharon-Gojman, Moshe Herzberg, and Osnat Gillor

Journal: Environmental Research (2023)

 

Abstract

The main reason for the deterioration of membrane operation during water purification processes is biofouling, which has therefore been extensively studied. Biofouling was shown to reduce membrane performance reflected by permeate flux decline, reduced selectivity, membrane biodegradation, and consequently, an increase in energy consumption. Studies of biofouling focused on the identification of the assembled microbial communities, the excretion of extracellular polymeric substances (EPS), and their combined role in reduced membrane performance and lifetime. However, the link between the structure and function of biofouling communities has not been elucidated to date. Here, we provide a novel insight, suggesting that bacterial functions rather than composition control biofouling traits on reverse osmosis (RO) membranes. We studied the potential activity of RO biofilms at metatranscriptome resolution, accompanied by the morphology and function of the biofouling layer over time, including microscopy and EPS composition, adhesion, and viscoelastic properties. To that end, we cultivated natural multispecies biofilms in RO membranes under treated wastewater flow and extracted RNA to study their taxonomies and gene expression profiles. Concomitantly, the biofilm structure was visualized using both scanning electron microscopy and laser scanning confocal microscopy. We also used quartz crystal microbalance with dissipation to characterize the affinity of EPS to membrane-mimetic sensors and evaluated the viscoelasticity of the Ex-Situ EPS layer formed on the sensor. Our results showed that different active bacterial taxa across five taxonomic classes were assembled on the RO membrane, while the composition shifted between 48 and 96 h. However, regardless of the composition, the maturation of the biofilm resulted in the expression of similar gene families tightly associated with the temporal kinetics of the EPS composition, adhesion, and viscoelasticity. Our findings highlight the temporal selection of specific microbial functions rather than composition, featuring the adhesion kinetics and viscoelastic properties of the RO biofilm.

 

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Modifying last layer in polyelectrolyte multilayer coatings for capillary electrophoresis of proteins

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Authors: Sébastien Roca, Laurent Leclercq, Philippe Gonzalez, Laura Dhellemmes, Laurent Boiteau, Gaulthier Rydzek, and Hervé Cottet

Journal: Journal of Chromatography A (2023)

 

Abstract

Protein adsorption on the inner wall of the fused silica capillary wall is an important concern for capillary electrophoresis (CE) analysis since it is mainly responsible for separation efficiency reduction. Successive Multiple Ionic-polymer Layers (SMIL) are used as capillary coatings to limit protein adsorption, but even low residual adsorption strongly impacts the separation efficiency, especially at high separation voltages. In this work, the influence of the chemical nature and the PEGylation of the polyelectrolyte deposited in the last layer of the SMIL coating was investigated on the separation performances of a mixture of four model intact proteins (myoglobin (Myo), trypsin inhibitor (TI), ribonuclease a (RNAse A) and lysozyme (Lyz)). Poly(allylamine hydrochloride) (PAH), polyethyleneimine (PEI), ε-poly(L-lysine) (εPLL) and α-poly(L-lysine) (αPLL) were compared before and after chemical modification with polyethyleneglycol (PEG) of different chain lengths. The experimental results obtained by performing electrophoretic separations at different separation voltages allowed determining the residual retention factor of the proteins onto the capillary wall via the determination of the plate height at different solute velocities and demonstrated a strong impact of the polycationic last layer on the electroosmotic mobility, the separation efficiency and the overall resolution. Properties of SMIL coatings were also characterized by quartz microbalance and atomic force microscopy, demonstrating a glassy structure of the films.

 

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Effect of Noise on Determining Ultrathin-Film Parameters from QCM-D Data with the Viscoelastic Model

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Authors: Diethelm Johannsmann, Arne Langhoff, Christian Leppin, Ilya Reviakine, and Anna M. C. Maan

Journal: Sensors (2023)

 

Abstract

Quartz crystal microbalance with dissipation monitoring (QCMD) is a well-established technique for studying soft films. It can provide gravimetric as well as nongravimetric information about a film, such as its thickness and mechanical properties. The interpretation of sets of overtone-normalized frequency shifts, Δf/n, and overtone-normalized shifts in half-bandwidth, ΔΓ/n, provided by QCMD relies on a model that, in general, contains five independent parameters that are needed to describe film thickness and frequency-dependent viscoelastic properties. Here, we examine how noise inherent in experimental data affects the determination of these parameters. There are certain conditions where noise prevents the reliable determination of film thickness and the loss tangent. On the other hand, we show that there are conditions where it is possible to determine all five parameters. We relate these conditions to the mathematical properties of the model in terms of simple conceptual diagrams that can help users understand the model’s behavior. Finally, we present new open source software for QCMD data analysis written in Python, PyQTM.

 

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Nanoporous Metal–Organic Framework Thin Films Prepared Directly from Gaseous Precursors by Atomic and Molecular Layer Deposition: Implications for Microelectronics

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Authors: Jenna Multia, Dmitry E. Kravchenko, Víctor Rubio-Giménez, Anish Philip, Rob Ameloot, and Maarit Karppinen

Journal: ACS Appl. Nano Mater. (2023)

 

Abstract

Atomic/molecular layer deposition (ALD/MLD) allows for the direct gas-phase synthesis of crystalline metal–organic framework (MOF) thin films. Here, we show for the first time using krypton and methanol physisorption measurements that ALD/MLD-fabricated copper 1,4-benzenedicarboxylate (Cu-BDC) ultrathin films possess accessible porosity matching that of the corresponding bulk MOF.

 

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Acoustic Array Biochip Combined with Allele-Specific PCR for Multiple Cancer Mutation Analysis in Tissue and Liquid Biopsy

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Authors: Nikoletta Naoumi, Kleita Michaelidou, George Papadakis, Agapi E. Simaiaki, Román Fernández, Maria Calero, Antonio Arnau, Achilleas Tsortos, Sofia Agelaki, and Electra Gizeli

Journal: ACS Sens. (2022)

Abstract

Regular screening of point mutations is of importance to cancer management and treatment selection. Although techniques like next-generation sequencing and digital polymerase chain reaction (PCR) are available, these are lacking in speed, simplicity, and cost-effectiveness. The development of alternative methods that can detect the extremely low concentrations of the target mutation in a fast and cost-effective way presents an analytical and technological challenge. Here, an approach is presented where for the first time an allele-specific PCR (AS-PCR) is combined with a newly developed high fundamental frequency quartz crystal microbalance array as biosensor for the amplification and detection, respectively, of cancer point mutations. Increased sensitivity, compared to fluorescence detection of the AS-PCR amplicons, is achieved through energy dissipation measurement of acoustically “lossy” liposomes binding to surface-anchored dsDNA targets. The method, applied to the screening of BRAF V600E and KRAS G12D mutations in spiked-in samples, was shown to be able to detect 1 mutant copy of genomic DNA in an excess of 104 wild-type molecules, that is, with a mutant allele frequency (MAF) of 0.01%. Moreover, validation of tissue and plasma samples obtained from melanoma, colorectal, and lung cancer patients showed excellent agreement with Sanger sequencing and ddPCR; remarkably, the efficiency of this AS-PCR/acoustic methodology to detect mutations in real samples was demonstrated to be below 1% MAF. The combined high sensitivity and technology-readiness level of the methodology, together with the ability for multiple sample analysis (24 array biochip), cost-effectiveness, and compatibility with routine workflow, make this approach a promising tool for implementation in clinical oncology labs for tissue and liquid biopsy.

 

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Interface Properties of 2D Graphene–Polydopamine Composite Electrodes in Protic Ionic Liquid-Based Electrolytes Explored by Advanced Electrogravimetry

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Authors: Adnane Bouzina, Hubert Perrot, Catherine Debiemme-Chouvy, and Ozlem Sel

Journal: ACS Appl. Energy Mater. (2022)

 

Abstract

A fundamental understanding of the processes occurring at the electrode/electrolyte interfaces is of paramount importance to enhance the performance of energy storage devices. Addressing this issue requires suitable characterization tools, due to the complex nature of such interfaces. By means of electrochemical quartz crystal microbalance (EQCM) and its advanced mode, the so-called ac-electrogravimetry, herein, we report on the interfacial properties of two-dimensional (2D) graphene–polydopamine (ERGO-PDA) composite electrodes in diverse electrolyte compositions including a protic ionic liquid (PIL), pyrrolidinium hydrogen sulfate [Pyr+][HSO4–]. We have performed a comparative study in a [Pyr+][HSO4–]–water binary mixture in the absence and presence of Na2SO4 and compared it with the interfacial behavior of ERGO-PDA in a 0.5 M Na2SO4 (pH = 2) pristine electrolyte. Our EQCM and ac-electrogravimetric analyses reveal that the [Pyr+] ions, due to their chaotropic nature, inhibit the approach of kosmotropic Na+ ions and water molecules to the interface, suppressing the contribution of electrodragged water molecules, substantially observed in the case of pristine aqueous electrolyte. Despite the dissimilarity of the charge compensation process occurring in the presence of [Pyr+][HSO4–], the ERGO-PDA electrode is able to maintain similar cycling stability (99% for 10,000 cycles at 1000 mV·s–1) and specific capacitance values (325 F·cm–3) compared with the pristine aqueous electrolyte, with the advantage of superior energy density (16.3 versus 8.7 mWh·cm–3) due to a noticeably enlarged potential window in [Pyr+][HSO4–]–water binary mixtures.

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V. cholerae MakA is a cholesterol-binding pore-forming toxin that induces non-canonical autophagy

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Authors: Xiaotong Jia, Anastasia Knyazeva, Yu Zhang, Sergio Castro-Gonzalez, Shuhei Nakamura, Lars-Anders Carlson, Tamotsu Yoshimori, Dale P. Corkery, Yao-Wen Wu

Journal: J Cell Biol (2022)

 

Abstract

Pore-forming toxins (PFTs) are important virulence factors produced by many pathogenic bacteria. Here, we show that the Vibrio cholerae toxin MakA is a novel cholesterol-binding PFT that induces non-canonical autophagy in a pH-dependent manner. MakA specifically binds to cholesterol on the membrane at pH < 7. Cholesterol-binding leads to oligomerization of MakA on the membrane and pore formation at pH 5.5. Unlike other cholesterol-dependent cytolysins (CDCs) which bind cholesterol through a conserved cholesterol-binding motif (Thr-Leu pair), MakA contains an Ile-Ile pair that is essential for MakA-cholesterol interaction. Following internalization, endosomal acidification triggers MakA pore-assembly followed by ESCRT-mediated membrane repair and V-ATPase-dependent unconventional LC3 lipidation on the damaged endolysosomal membranes. These findings characterize a new cholesterol-binding toxin that forms pores in a pH-dependent manner and reveals the molecular mechanism of host autophagy manipulation.

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Aerosol Jet Printing of the Ultramicroporous Calcium Squarate Metal–Organic Framework

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Authors: Dmitry E. Kravchenko, Aleksander Matavž, Víctor Rubio-Giménez, Hanne Vanduffel, Margot Verstreken, Rob Ameloot

Journal: Chem. Mater. (2022)

 

Abstract

Efficient methods to deposit thin layers of metal–organic frameworks (MOFs) are needed to integrate these microporous materials into microelectronics, sensing devices, and membranes. Herein, we report for the first time the direct aerosol jet printing of a MOF material. The ultramicroporous MOF [Ca(C4O4) (H2O)] (UTSA-280) was deposited from an aqueous precursor solution. In addition to blanket coatings, aerosol jet printing provides direct access to patterned coatings with a resolution of 100 μm via a digital, maskless approach. Moreover, by enabling spatial control over the layer thickness via the number of passes of the nozzle, this direct-write approach presents a more accessible alternative to advanced patterning techniques such as grayscale lithography.

 

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