Molecular Traps Research Articles

Electrostatic Covalent Organic Frameworks as On-Demand Molecular Traps for High-Energy Li Metal Battery Electrodes

Regulating electrostatic interactions between charged molecules is crucial for enabling advanced batteries with electrochemical reliability. To address this issue, herein, we present a class of electrostatic covalent organic frameworks (COFs) as on-demand molecular traps for high-energy-density Li metal batteries (LMBs). A bipyridine-based COF and its quaternized derivative are synthesized and incorporated into LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes and Li metal protective layers, respectively. These COF molecular traps are effective in chelating transition metal ions dissolved from the cathodes, enhancing Li+ desolvation, suppressing solvent decomposition, and immobilizing anions of electrolytes. The resulting LMB with the COF molecular traps fully utilizes the theoretical specific capacity of NCM811 at cathodes and allows stable Li plating/stripping at anodes. A pouch-type LMB full cell with the COF molecular traps provides high gravimetric/volumetric energy densities (466.7 Wh kgcell–1/1370.1 Wh Lcell–1) under a constrained cell configuration, exceeding those of previously reported Li metal batteries based on porous crystalline frameworks.

Analysis of ATG8 Family Members Using LC3-Interacting Regions (LIR)-Based Molecular Traps.

The ATG8 family of proteins regulates the autophagy process from the autophagosome maturation and cargo recruitment up to degradation. Autophagy dysfunction is involved in the development of multiple diseases. The LC3 interacting region (LIR)-based molecular traps have been designed to isolate endogenous ATG8 proteins and their interactors in order to facilitate the study of selective autophagy events. Here, we summarize protocols describing LC3 traps and sample preparation as well as adaptations for the analysis of ATG8 proteins in different biological models. This protocol was optimized to prepare affinity columns, reduce background, and improve the protein recovery to be analyzed by immunodetection with antibodies recognizing proteins of interest.

BEHAVIOUR OF METHYLCELLULOSE GEL AT HIGHER CONCENTRATIONS FOR CLEANING OF ACRYLIC PAINTED SURFACES

This research demonstrates the application of methylcellulose (MC) as a gelator for cleaning acrylic painted surfaces. Highly thickened methylcellulose gels were predominantly tested to investigate the residue left after cleaning. The function of methylcellulose as a molecular trap was also assessed to minimize the clearance issue. The presence of residue, the efficacy of the methylcellulose as a cleaning agent and its physical impact on the paint surfaces were investigated using a digital microscope in normal, raking, and ultraviolet lights. Scanning electron microscopy (SEM), coupled with energy-dispersive X-ray spectroscopy (EDS) was used to study the compositional and topographical changes on the paint surface. Fourier transform infrared spectroscopy (FTIR) was performed in attenuated total reflectance (ATR) mode to observe the presence of residues after complete removal of the gelling agent. The experimental results indicated a minimum interaction of methylcellulose on the paint surface as the concentration increases in the gel formulation. The super-thickened hydrogels also worked like molecular traps useful for removal of soiling from the painted surfaces.

Interlocked Dithi‐Magnetospheres–Decorated MoS2 Nanosheets as Molecular Sieves and Traps for Heavy Metal Ions

AbstractWater remediation at minimal cost is the need of the day, as freshwater aquifers are declining at an alarming rate. To address this challenge, composite membranes is herein developed using a unique reversible addition–fragmentation chain transfer (RAFT)‐synthesized copolymer as the active surface layer, a commercial reverse osmosis (RO) membrane serving as the support layer, and foamy molybdenum disulfide (MoS2) nanosheets decorated with dithi‐magnetospheres acting as the interlayer. This strategy is adopted because the commercial RO membrane is effective toward desalination but is susceptible to fouling and biofilm. The foamy interlayer MoS2 nanosheets decorated with dithi‐magnetospheres in the composite membranes minimize the additional resistance, both in terms of flow and also facilitate reversible action toward heavy metal removal. Further, the composite membranes exhibit a 7‐log reduction in bacterial colonies for both gram‐positive and gram‐negative strains. A stringent and targeted action is also observed in terms of intracellular reactive oxygen species generation. In addition, excellent reversible antifouling with 98.5% flux retention ratio is observed. The average lead (II) removal at 50 ppm is 95.3% and the average arsenic (III) removal at 50 ppm is observed to be 96%. Thus, these membranes could be the next generation to advance sustainable systems for water remediation.

Capture of organic iodides from nuclear waste by metal-organic framework-based molecular traps

Effective capture of radioactive organic iodides from nuclear waste remains a significant challenge due to the drawbacks of current adsorbents such as low uptake capacity, high cost, and non-recyclability. We report here a general approach to overcome this challenge by creating radioactive organic iodide molecular traps through functionalization of metal-organic framework materials with tertiary amine-binding sites. The molecular trap exhibits a high CH3I saturation uptake capacity of 71 wt% at 150 °C, which is more than 340% higher than the industrial adsorbent Ag0@MOR under identical conditions. These functionalized metal-organic frameworks also serve as good adsorbents at low temperatures. Furthermore, the resulting adsorbent can be recycled multiple times without loss of capacity, making recyclability a reality. In combination with its chemical and thermal stability, high capture efficiency and low cost, the adsorbent demonstrates promise for industrial radioactive organic iodides capture from nuclear waste. The capture mechanism was investigated by experimental and theoretical methods.

Nanoscale Molecular Traps and Dams for Ultrafast Protein Enrichment in High-Conductivity Buffers

We report a new approach, molecular dam, to enhance mass transport for protein enrichment in nanofluidic channels by nanoscale electrodeless dielectrophoresis under physiological buffer conditions. Dielectric nanoconstrictions down to 30 nm embedded in nanofluidic devices serve as field-focusing lenses capable of magnifying the applied field to 10(5)-fold when combined with a micro- to nanofluidic step interface. With this strong field and the associated field gradient at the nanoconstrictions, proteins are enriched by the molecular damming effect faster than the trapping effect, to >10(5)-fold in 20 s, orders of magnitude faster than most reported methods. Our study opens further possibilities of using nanoscale molecular dams in miniaturized sensing platforms for rapid and sensitive protein analysis and biomarker discovery, with potential applications in precipitation studies and protein crystallization and possible extensions to small-molecules enrichment or screening.

Au@pNIPAM Colloids as Molecular Traps for Surface‐Enhanced, Spectroscopic, Ultra‐Sensitive Analysis

Au@pNIPAM Colloids as Molecular Traps for Surface‐Enhanced, Spectroscopic, Ultra‐Sensitive Analysis

Au@pNIPAM Colloids as Molecular Traps for Surface‐Enhanced, Spectroscopic, Ultra‐Sensitive Analysis

Au@pNIPAM Colloids as Molecular Traps for Surface‐Enhanced, Spectroscopic, Ultra‐Sensitive Analysis

Geometrical shape resonances in multicenter systems with icosahedral symmetry: A controllable molecular trap for electrons

Specific shape resonances were studied in systems with the highest point symmetry. The resonances occur in narrow energy intervals and disappear when inner potentials increase. A model system of point scatterers that are placed in the vertexes of an icosahedron and at its center was analyzed. In this system, the geometric resonance lifetime is extremely sensitive to structure changes and may attain 10−10 s, i.e., exceed the rotation period of electrons in atoms by six orders of magnitude. The feasibility of molecular traps that capture elastically scattered electrons and bring them into the resonant state is discussed. The resident time of electrons in these traps can be controlled with external static fields.

Chemistry of the "molecular trap" of protease-catalyzed splicing reaction of complementary segments of alpha-subunit of hemoglobin A.

The complementary fragments of human Hb alpha, alpha1-30, and alpha31-141 are spliced together by V8 protease in the presence of 30% n-propanol to generate the full-length molecule (Hb alpha-semisynthetic reaction). Unlike the other protease-catalyzed protein/peptide splicing reactions of fragment complementing systems, the enzymic condensation of nonassociating segments of Hb alpha is facilitated by the organic cosolvent induced alpha-helical conformation of product acting as the "molecular trap" of the splicing reaction. The segments alpha24-30 and alpha31-40 are the shortest complementary segments that can be spliced by V8 protease. In the present study, the chemistry of the contiguous segment (product) alpha24-40 has been manipulated by engineering the amino acid replacements to the positions alpha27 and alpha31 to delineate the structural basis of the molecular trap. The location of Glu27 and Arg31 residues in the contiguous segment alpha24-40 (as well as in other larger segments) is ideal to generate (i, i + 4) side-chain carboxylate-guanidino interaction in its alpha-helical conformation. The amino acid residue replacement studies have confirmed that the side chains at alpha27 and alpha31 facilitate the semisynthetic reaction. The relative influence of the substitute at these sites on the splicing reaction depends on the chemical nature of the side chain and the location. The gamma-carboxylate guanidino side-chain interaction appears to contribute up to a maximum of 85% of the thermodynamic stability of the molecular trap. The studies also demonstrate that the thermodynamic stability of the molecular trap is determined by two interdependent conformational aspects of the peptide. One is an amino acid-sequence-specific event that facilitates the induction of an alpha-helical conformation to the contiguous segment in the presence of organic cosolvent that imparts some amount of protease resistance to Glu30-Arg31 peptide bond. The second structural aspect is a site-specific event, an i, i + 4 side-chain interaction in the alpha-helical conformation of the peptide which imparts an additional thermodynamic stability to the molecular trap. The results suggest that conformationally driven "molecular traps" of protease-mediated ligation reactions of peptides could be designed into products to facilitate the modular assembly of peptides/proteins.

Enzymatic condensation of nonassociated peptide fragments using a molecular trap.

We have tested the feasibility of achieving protease-catalyzed condensation between nonassociating peptide fragments through mediation of a molecular trap. In this study, two subfragments of bovine pancreatic ribonuclease S-peptide, containing residues 1-10 and 11-15, were rejoined by clostripain catalysis to form the 1-15 peptide. The extent of this stereospecific condensation was enhanced by adding ribonuclease S-protein (residues 21-124), which acts as a trap in binding 1-15 but not 1-10 or 11-15 and which thus shifts the equilibrium to favor 1-15 formation. The resultant (1-15) X (21-124) noncovalent complex, defined as [des-16-20]ribonuclease S, was detected by the enzymatic activity characteristic of the naturally derived ribonuclease S complex. Reaction of 1 mM S-protein and 20 mM fragments leads to 80% of the ribonuclease activity expected from the amount of 21-124 present. This indicates that 4% of the fragments 1-10 and 11-15 were condensed, compared to a maximal condensation of 5% based on the amount of trap. The less than theoretical yield is due largely to slow proteolytic degradation of 21-124 to a form which is no longer able to bind the condensation product 1-15. Yields were increased to 15% by addition of further trap. The successful synthesis of 1-15 emphasizes the usefulness of molecular traps to promote stereospecific fragment condensation between nonassociating peptide fragments for the synthesis and semisynthesis of polypeptides.

Pressure-drop Leak Detector for Gas Chromatographs Equipped with Molecular Sieve Traps

Journal Article Pressure-drop Leak Detector for Gas Chromatographs Equipped with Molecular Sieve Traps Get access Morton Beroza Morton Beroza Entomology Research Division, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Md. Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Chromatographic Science, Volume 2, Issue 4, April 1964, Page 138, https://doi.org/10.1093/chromsci/2.4.138 Published: 01 April 1964