Electrophilic RNA for Peptidyl‐RNA Synthesis and Site‐Specific Cross‐Linking with tRNA‐Binding Enzymes

RNA functionalization is challenging due to the instability of RNA and the limited range of available enzymatic reactions. We developed a strategy based on solid phase synthesis and post‐functionalization to introduce an electrophilic site at the 3′ end of tRNA analogues. The squarate diester used as an electrophile enabled sequential amidation and provided asymmetric squaramides with high selectivity. The squaramate‐RNAs specifically reacted with the lysine of UDP‐MurNAc‐pentapeptide, a peptidoglycan precursor used by the aminoacyl‐transferase FemX_Wv for synthesis of the bacterial cell wall. The peptidyl‐RNA obtained with squaramate‐RNA and unprotected UDP‐MurNAc‐pentapeptide efficiently inhibited FemX_Wv. The squaramate unit also promoted specific cross‐linking of RNA to the catalytic Lys of FemX_Wv but not to related transferases recognizing different aminoacyl‐tRNAs. Thus, squaramate‐RNAs provide specificity for cross‐linking with defined groups in complex biomolecules due to its unique reactivity.     

The Sedimentation of Colloidal Nanoparticles in Solution and Its Study Using Quantitative Digital Photography

Sedimentation and diffusion are important aspects of the behavior of colloidal nanoparticles in solution, and merit attention during the synthesis, characterization, and application of nanoparticles. Here, the sedimentation of nanoparticles is studied quantitatively using digital photography and a simple model based on the Mason–Weaver equation. Good agreement between experimental time‐lapse photography and numerical solutions of the model is found for a series of gold nanoparticles. The new method is extended to study for the first time the gravitational sedimentation of DNA‐linked gold nanoparticle dimers as a model system of a higher complexity structure. Additionally, simple formulas are derived for estimating suitable parameters for the preparative centrifugation of nanoparticle solutions.     

Facile route for green synthesis of N-benzylideneaniline over bimetallic reduced graphene oxide: chemical reactivity of 2,3,4-substituted derivatives of aniline

Research on Chemical Intermediates - Mn–Co-decorated reduced graphene oxide (Mn–Co–rGO) was prepared by modified condensation method and characterized through XRD, SEM, EDX, FTIR...     

Preparation and characterization of chemically bonded aramid-titania hybrids using isocyanatopropyltrimethoxysilane

Transparent aramid based titania hybrid films have been prepared by the sol–gel process. A mixture of m- and p-phenylenediamines was reacted with terephthaloyl chloride forming aromatic polyamide chains in dimethylacetamide solvent. The titania network was generated insitu in this matrix by the hydrolysis and condensation of the various amounts of tetraethylorthotitanate. Hybrid films with concentrations of titania varying from 2.5 to 12.5 wt% were prepared; the higher percentages of titania in the organic matrix showed a tendency towards phase separation. These films were tested for their thermo-mechanical properties. To achieve a further improvement in properties of the matrix, the aramid chain was functionalized and the inorganic network was chemically bonded using isocyanatopropyltrimethoxysilane. The bonded hybrids showed a narrower distribution of titania particles and these were distributed as a co-continuous phase. The glass transition temperature (Tg) of the hybrid films measured through dynamic mechanical analysis showed a relatively higher increase with inclusion of titania in the covalently bonded hybrids. The maximum value of Tg noted in the chemically bonded composites with 12.5 wt% titania was 361 °C and the storage modulus value was 5.214 GPa at 100 °C, showing an increase of 62 % over the pure polymer. The hybrid films with titania showed an improved UV-stability as compared to the pure polymer.     

One-step synthesis of ultra-small amount of Pd-Alloyed Zinc Nanosheets for efficient electrochemical CO2 reduction to CO

The practicality of the electrochemical CO₂ reduction technique depends on the development of cost-effective, robust, and highly selective catalysts. To achieve this goal, we have engineered self-supported 3D electrodes composed of Pd-Zn nanosheets (NSs) for CO₂ electrochemical reduction to CO with minimal Pd content. This innovative electrode with an increased surface area was created using an electrodeposition method employing a dynamic hydrogen bubble template. By precisely adjusting the Pd content, we improved the thickness, porosity, and surface area of the electrodes, resulting in a CO₂-to-CO selectivity reaching as high as 88.5 %, with an average of at least 80 % sustained over 10 hours. This remarkable improved activity can be attributed to the synergistic effects of an appropriate Pd/Zn atomic ratio as well as to the large surface area of nanosheets structures with rich edge active sites. Furthermore, to get around the limitations of CO₂ mass transfer, reactions were done at high pressures conditions ranging from 3 to 9.5 bar; this strategic approach yielded an outstanding partial current density of −304.6 mA cm⁻² for CO. These noteworthy findings establish concepts for constructing effective and earth-abundant CO-producing electrocatalysts.