Regulating CRISPR/Cas9 Using Streptavidin‐Biotin Interactions†

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Regulating CRISPR/Cas9 Using Streptavidin-Biotin Interactions†

In this study, a strategy that employs the streptavidin-biotin interaction as a "brake system" for CRISPR/Cas9, effectively allowing for the shutdown of the enzymatic activity of CRISPR/Cas9 is developed.


Comprehensive Summary

Currently, CRISPR/Cas9 technology has found widespread applications across various domains. However, the utility of CRISPR/Cas9 is encumbered by issues pertaining to its reliability and safety, primarily stemming from the uncontrolled activity of the system. Therefore, the design and development of CRISPR/Cas9 systems with controllable activity is of paramount importance. Biotin, characterized by its small molecular weight, and streptavidin, distinguished by its substantial spatial steric hindrance, can be harnessed as an ideal OFF switch (termed a "bioactivity brake") due to their interaction characteristics. In this work, we present a strategy that employs the streptavidin-biotin interaction as a "brake system" for CRISPR/Cas9, effectively allowing for the shutdown of the enzymatic activity of CRISPR/Cas9.

Beyond the Limits of Perbromo‐Substituted Octahedral Pnictogenaboranes: A Spectroscopic and Computational Study

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Beyond the Limits of Perbromo-Substituted Octahedral Pnictogenaboranes: A Spectroscopic and Computational Study

Octahedral closo-1,2-Pn 2B4Br4 (Pn=P, As) react with tetrahydrotoluene (THT) to get conjuncto-3,3’-(1,2-P2B4Br3)2. 4-THT-closo-1,2-P2B4Br3 has also been detected which is isomerized through a pentagonal pyramidal intermediate to the corresponding 3-THT isomer to yield the conjuncto motif. This reaction is due to the presence of σ-holes on Br's. The σ-holes on Pn has enabled ESI-MS to detect various anions.


Abstract

Octahedral closo-1,2-Pn2B4Br4 (Pn=P, As) molecules react with tetrahydrothiophene (THT), regarded as a soft base, much slower than with tetrahydrofuran (THF), considered a hard base. Namely, the reaction begins with only Pn=P at temperatures above 140 °C; 4-Br(CH2)4S-closo-1,2-P2B4Br3 has been detected as the first product resulting from the cleavage and insertion of a thiobutylate group into the B−Br bond. Unlike in the reaction with THF, the addition of a second THT moiety has not been observed. Conversely, also starting from 140 °C, conjuncto-3,3’-(1,2-Pn 2B4Br3)2 has been found as the final product of the reaction, which indicates the presence of 3-Br(CH2)4S-closo-1,2-P2B4Br3 as another intermediate during the conversion. A computational examination has revealed that it occurs through a pentagonal pyramidal stationary point as an additional intermediate, the latter of which serves as the crucial structural assembly for the thermal conversion that produces the conjuncto motif. Computations of the energy balance and 11B and 31P NMR chemical shifts are in agreement with experimental observations. This reaction is made possible by the presence of σ-holes on the bromine atoms. In addition, the presence of the σ-holes on the pnictogens has enabled ESI-MS to detect various anions appearing during earlier and current syntheses.

Enhancing the efficacy of cisplatin against breast cancer cells using carnosine‐functionalized magnetic nanoparticles

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Enhancing the efficacy of cisplatin against breast cancer cells using carnosine-functionalized magnetic nanoparticles

In this study, the feasibility of synthesis and efficiency of superparamagnetic iron oxide nanoparticles (SPIONs) decorated with L-carnosine (CAR) as a safe drug carrier were explored. L-carnosine peptide was linked to the magnetite nanoparticles by terephthalaldehyde as a linker to gain the magnetite nanoparticles rich in carnosine. The cisplatin-loaded carnosine-modified SPIONs were evaluated as the drug delivery system on MCF7 cells.


The majorities of chemotherapy drugs and drug-delivery models have significant health concerns and cause undesirable side effects because they lack specificity and proper targeting systems and are too large. It is crucial to prioritize the rational design and synthesis of chemotherapeutics that specifically target their intended sites. This research work aims to create magnetic nanocarriers conjugated with L-carnosine (CAR) as a cancer-targeting peptide for the development of targeted anticancer drugs. These nanoparticles are designed to reduce toxicity, allow for sustained release, and increase the circulating time of cisplatin. The nanoparticles were made by coating them with silane and an aldehyde linker, which allowed them to be attached to L-carnosine peptide. Cisplatin was then attached to the surface of the nanoparticles via chemical bonds. The prepared nanoparticles were characterized using vibrating sample magnetometer, dynamic light scattering, and scanning electron microscopy and FT-IR spectrophotometry. In vitro studies demonstrated the cytotoxic and inhibitory effects of cisplatin nanoconjugates on breast cancer cells. Significantly, the nanoconjugates showed higher potency compared to free cisplatin. In continuous study, the optimization of synthesized compounds was performed using the DMol3 module in Materials Studio 2017. Energy calculations and molecular docking analysis using the HEX software revealed that the nanoconjugates showed stronger binding to the minor and major grooves of the DNA receptor. These interactions involved eight hydrogen bonds, exceeding those of other compounds.

Hydrogenation of CO2 into Value‐added Chemicals Using Solid‐Supported Catalysts

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Hydrogenation of CO2 into Value-added Chemicals Using Solid-Supported Catalysts

This review discusses the prospect of utilizing earth-abundant CO2 as a feedstock for value-added chemicals via hydrogenation reaction. The recent progress of CO2 mitigation strategies using solid-supported catalysts and its opportunities for converting to numerous value-added chemicals, such as olefin, methanol, and formic acid, are discussed.


Abstract

Reducing CO2 emissions is an urgent global priority. In this context, several mitigation strategies, including CO2 tax and stringent legislation, have been adopted to halt the deterioration of the natural environment. Also, carbon recycling procedures undoubtedly help reduce net emissions into the atmosphere, enhancing sustainability. Utilizing Earth's abundant CO2 to produce high-potential green chemicals and light fuels opens new avenues for the chemical industry. In this context, many attempts have been devoted to converting CO2 as a feedstock into various value-added chemicals, such as CH4, lower methanol, light olefins, gasoline, and higher hydrocarbons, for numerous applications involving various catalytic reactions. Although several CO2-conversion methods have been used, including electrochemical, photochemical, and biological approaches, the hydrogenation method allows the reaction to be tuned to produce the targeted compound without significantly altering infrastructure. This review discusses the numerous hydrogenation routes and their challenges, such as catalyst design, operation, and the combined art of structure-activity relationships for the various product formations.

Redox Reactivity Control Through Electromerism

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Redox Reactivity Control Through Electromerism

The potential of electromerism for the tuning of redox reactivity on a large scale is demonstrated in a systematic study on copper complexes with redox-active diguanidine ligands.


Abstract

In this work, we demonstrate that electromerism could be used to regulate the redox reactivity. Electron self-exchange rates k ex were measured for a series of diamagnetic, monocationic CuI complexes with two redox-active diguanidine ligands and the corresponding paramagnetic, dicationic complexes. The electronic structures of the paramagnetic, dicationic complexes differ. Some complexes are exclusively present as CuII complexes with reduced, neutral diguanidine ligands. In other complexes, an equilibrium is established between the CuII electromer and the CuI electromer with the unpaired electron delocalized on the two partially-oxidized ligands. For these complexes, the k ex values increase with increasing contribution of the CuI electromer. One of the dicationic molecules is exclusively present as CuI complex with radical ligands in dichloromethane at room temperature, and as CuII electromer with neutral ligands at 200 K. Consequently, the electron self-exchange rate k ex is maximal at room temperature, and strongly decreases with decreasing temperature. The temperature effect is much stronger than for similar complexes that remain in the CuII form at all temperatures, demonstrating the use of electromerism to control the redox reactivity on a large scale.

Effect of Ge Incorporation on Lead‐free Cs‐based Triiodide Sn−Ge Co‐alloy Perovskite Thin Films by Spin Coating

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Effect of Ge Incorporation on Lead-free Cs-based Triiodide Sn−Ge Co-alloy Perovskite Thin Films by Spin Coating

The effect of Ge incorporation on spin-coated CsSn1–x Ge x I3 (0≤x≤1) thin films was studied. When the incorporation of Ge increases, CsSn1–x Ge x I3 experiences lattice shrinkage, which is accompanied by the adjustment of the crystallographic phase. The morphology and roughness of the film surface undergo changes as the Ge content increases.


Abstract

A new Sn−Ge co-alloy perovskite that does not contain toxic Pb is attracting attention due to its excellent predicted optoelectronic properties. However, most current research only focuses on compositions with Ge content up to 50 %, resulting in a limited overall understanding on this material system. In this study, CsSn1–x Ge x I3 (0≤x≤1) perovskite thin films were fabricated using spin coating method and characterized in terms of crystallographic, morphological and optical characteristics systematically. The results show that the Ge incorporation causes lattice shrinkage and a change in the crystallographic phase from orthorhombic to trigonal. Additionally, the coverage varies much as Ge increases. The Ge incorporation also results in a blueshift of the photoluminescence peak and a decrease in luminescence intensity as compared to the composition with lower Ge content. Moreover, the carrier dynamics measurement shows that the Ge incorporation increases the carrier nonradiative recombination. This work provides important hints for the development of the Sn−Ge alloy-based perovskite solar cell.

Monocopper model of CuB site of pMMO in N4‐environment oxidizes C−H bonds

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Monocopper model of CuB site of pMMO in N4-environment oxidizes C−H bonds

A tetradentate N-ligand binds CuII in a geometric and electronic environment that resembles the properties of the CuB site of particulate Methane Monooxygenase (pMMO). Its CuI counterpart undergoes ligand oxidation during exposure to air, establishing the flexibility of the tetradentate scaffold that allows O2 activation and subsequent formation of a cupric amidato complex. This reactivity may be relevant for a reevaluation of the active site of pMMO, in which CuB has been relegated due to its “saturated” coordination environment.


Abstract

Discrepancies regarding the coordination environment, donor atoms, nuclearity, and oxidation state of the active site of particulate methane monooxygenase (pMMO), a copper-dependent enzyme capable of activating the strong C−H bond of methane, persist despite numerous structural and spectroscopic studies. To address the proposed mono- (CuII) or bimetallic (2CuI) nature of the so-called CuB site, we report the bis(benzimidazole)-based NMe−N,N’-(1-Me-2-CH2C7H4N2)2C6H4 ligand (N4) and its copper complexes. In the solid state [Cu(N4)(ClO4)]ClO4 features tetragonal geometry defined by the chelating ligand and an axial perchlorate; geometric and EPR parameters are very close to those reported for the CuB site. Attempts to obtain a dicopper(I) analog resulted in [Cu(N4)][CuCl2], based on spectroscopic, electrochemical, and ESI-MS data. Although these results support the assignment of CuB as a monometallic site, air exposure of [Cu(N4)][CuCl2] leads to ligand oxidation in the structurally characterized [Cu(N4=O)Cl], raising the possibility of distorted tetragonal Cu(I) centers activating O2 and oxidizing substrates, in C−H activation chemistry that may take place at CuB.