We present herein a systematically evaluation of the biosynthesis parameters on the green synthesis of AgNPs by utilizing Cornus officinalis extract under 365 nm UV radiation.

No abstract

Recent times have experienced more than ever the impact of viral infections in humans. Viral infections are known to cause diseases not only in humans but also in plants and animals. Here, we have compiled the literature review of aptamers selected and used for detection and inhibition of viral infections in all three categories: humans, animals, and plants. This review gives an in-depth introduction to aptamers, different types of aptamer selection (SELEX) methodologies, the benefits of using aptamers over commonly used antibody-based strategies, and the structural and functional mechanism of aptasensors for viral detection and therapy. The review is organized based on the different characterization and read-out tools used to detect virus–aptasensor interactions with a detailed index of existing virus-targeting aptamers. Along with addressing recent developments, we also discuss a way forward with aptamers for DNA nanotechnology-based detection and treatment of viral diseases. Overall, this review will serve as a comprehensive resource for aptamer-based strategies in viral diagnostics and treatment.

No abstract

Silyl enol ethers have attracted enormous attention as they could serve as a test bed for the development of novel frustrated Lewis pairs (FLPs) catalytic systems. However, the reaction mechanism of hydrogenation catalysed by metal-free FLPs for these compounds to the corresponding secondary alcohols remains elusive to a large extent in previous studies. We thus performed a thorough investigation on the reaction mechanism by density functional theory (DFT). To illustrate the reaction mechanism of FLPs-catalysed hydrogenation for silyl enol ethers, trimethyl((1-phenylvinyl)oxy)silane (Me-TMS) was chosen as the prototype substrate and toluene as the solvent, where the FLPs were generated by ethylbis(perfluorophenyl)borane (Et-B(C6F5)2) and tri-tert-butylphosphine (t-Bu3P). The M06-2X functional in connection with 6-31＋G(d) basis set was used to optimize the structures of related species including in the Gibbs free energy profiles, and the energies were obtained at M06-2X/6-311＋＋G(d,p) level of theory, where the solvent effect was simulated with the integral equation formalism, polarized continuum mode (IEF-PCM) in both calculations. Our results suggest that the FLPs-catalysed hydrogenation of silyl enol ethers in toluene begins with the formation of B-P-FLPs followed by hydrogen activation, proton transfer and hydride transfer to complete the process. It is obvious from the Gibbs free energy profile that the proton transfer is rate-determining step, the formation of B-P-FLPs and proton transfer are endothermal and the hydride transfer is no barrier. This indicates that the amount of H2 and prototype substrate have significant influence on the FLPs-catalysed hydrogenation of silyl enol ethers. A higher temperature (328.15 K) is disadvantageous to hydrogenation reaction catalysed by FLPs but the reaction could be accelerated under higher pressure (4040 kPa). The Gibbs free energy profile calculations for trimethyl((1-phenylprop-1-en-1-yl)oxy)silane (Et-TMS) and tert-butyldimethyl((1-phenylvinyl)oxy)silane (Me-TBS) reveal that substituent group may inhibit the hydride transfer as the absence of a suitable construction for R-H --transfer, where the hydride does not direct to the C ＋ of silyl enol ethers and the distance between C ＋ and hydride is longer. These results would be helpful to design another novel FLPs-catalysed hydrogenation reaction for silyl enol ethers.

Genetic information and the blueprint of life are stored in the form of nucleic acids. The primary sequence of DNA, read from the canonical double helix, provides the code for RNA and protein synthesis. Yet these already-information-rich molecules have higher-order structures which play critical roles in transcription and translation. Uncovering the sequences, parameters and conditions which govern the formation of these structural motifs has allowed researchers to study them and to utilize them in biotechnological and therapeutic applications in vitro and in vivo.This review covers both DNA and RNA structural motifs found naturally in biological systems including catalytic nucleic acids, non-coding RNA, aptamers, G-quadruplexes, i-motifs, and holliday junctions. For each category, an overview of the structural characteristics, biological prevalence and function will be discussed. The biotechnological and therapeutic

No abstract

A theoretical investigation was performed to disclose the transformation mechanism of 8-oxo-7,8-dihydroguanine radical cation (8-oxoG * + ) to protonated 2-amino-5-hydroxy-7,9-dihydropurine-6,8-dione (5-OH-8-oxoG) in base pair. The energy profiles for three possible pathways of the events were mapped. It is shown that direct loss of H7 from base paired 8-oxoG * + is the only energetically favorable pathway to generate neutral radical, 8-oxoG(-H7) * . Further oxidation of 8-oxoG(-H7) * : C to 8-oxoG(-H7) + : C is exothermic. However, the 8-oxoG(-H7) + : C deprotonation from all possible active sites is infeasible, indicating the inaccessible second proton loss and the lack of essential intermediate 2-amino-7,9-dihydropurine-6,8-dione (8-oxoG OX ). This makes 8-oxoG(-H7) + act as the precursor of hydration leading to the generation of protonated 5-HO-8-oxoG by stepwise fashion in base pair, which would initiate the step down guanidinohydantoin (Gh) pathway. These results clearly specify the structure-dependent transformation for 8-oxoG * + and verify the emergence of protonated 5-HO-8-oxoG in base pair.