Notes

100 Gbps IM/DD links using quad-polarization: Efficiency, complexity, as well as electrical power dissipation.
DNA molecular probes have emerged as a powerful tool for RNA imaging. Hurdles in cell-specific delivery and other issues such as insufficient stability, limited sensitivity, or slow reaction kinetics, however, hinder the further application of DNA molecular probes in vivo. Herein, we report an aptamer-tethered DNA polymer for cell-specific transportation and amplified imaging of RNA in vivo via a DNA cascade reaction. DNA polymers are constructed through an initiator-triggered hybridization chain reaction using two functional DNA monomers. The prepared DNA polymers show low cytotoxicity and good stability against nuclease degradation and enable cell-specific transportation of DNA circuits via aptamer-receptor binding. Moreover, assembling the reactants of hairpins C1 and C2 on the DNA polymers accelerates the response kinetics and improves the sensitivity of the cascade reaction. We also show that the DNA polymers enable efficient imaging of microRNA-21 in live cells and in vivo via intravenous injection. The DNA polymers provide a valuable platform for targeted and amplified RNA imaging in vivo, which holds great implications for early clinical diagnosis and therapy.Kynureninases (KYNases) are enzymes that play a key role in tryptophan catabolism through the degradation of intermediate kynurenine and 3'-hydroxy-kynurenine metabolites (KYN and OH-KYN, respectively). Bacterial KYNases exhibit high catalytic efficiency toward KYN and moderate activity toward OH-KYN, whereas animal KYNases are highly selective for OH-KYN, exhibiting only minimal activity toward the smaller KYN substrate. These differences reflect divergent pathways for KYN and OH-KYN utilization in the respective kingdoms. We examined the Homo sapiens and Pseudomonas fluorescens KYNases (HsKYNase and PfKYNase respectively) using pre-steady-state and hydrogen-deuterium exchange mass spectrometry (HDX-MS) methodologies. We discovered that the activity of HsKYNase critically depends on formation of hydrogen bonds with the hydroxyl group of OH-KYN to stabilize the entire active site and allow productive substrate turnover. With the preferred OH-KYN substrate, stabilization is observed at the substrate-binding site and the region surrounding the PLP cofactor. With the nonpreferred KYN substrate, less stabilization occurs, revealing a direct correlation with activity. This correlation holds true for PfKYNases; however there is only a modest stabilization at the substrate-binding site, suggesting that substrate discrimination is simply achieved by steric hindrance. We speculate that eukaryotic KYNases use dynamic mobility as a mechanism of substrate specificity to commit OH-KYN to nicotinamide synthesis and avoid futile hydrolysis of KYN. These findings have important ramifications for the engineering of HsKynase with high KYN activity as required for clinical applications in cancer immunotherapy. Our study shows how homologous enzymes with conserved active sites can use dynamics to discriminate between two highly similar substrates.The colorimetric gas sensor offers an opportunity for the simple and rapid detection of toxic gaseous substances based on visually discernible changes in the color of the sensing material. In particular, the accurate detection of trace amounts of certain biomarkers in a patient's breath provides substantial clues regarding specific diseases, for example, hydrogen sulfide (H2S) for halitosis and ammonia (NH3) for kidney disorder. However, conventional colorimetric sensors often lack the sensitivity, selectivity, detection limit, and mass-productivity, impeding their commercialization. Herein, we report an inexpensive route for the meter-scale synthesis of a colorimetric sensor based on a composite nanofiber yarn that is chemically functionalized with an ionic liquid as an effective H2S adsorbent and lead acetate as a colorimetric dye. As an eye-readable and weavable sensing platform, the single-strand yarn exhibits enhanced sensitivity supported by its high surface area and well-developed porosity to detect the breath biomarker (1 ppm of H2S). Alternatively, the yarn loaded with lead iodide dyes could reversibly detect NH3 gas molecules in the ppm-level, demonstrating the facile extensibility. Finally, we demonstrated that the freestanding yarns could be sewn into patterned textiles for the fabrication of a wearable toxic gas alarm system with a visual output.β-glucosyltransferase (β-GT) catalyzes the glucosylation of 5-hydroxymethylcytosine (5-hmC) to enable the survival of bacteriophage and parasite in host cells, and it is a critical tool enzyme for 5-hmC assay. However, few methods are available for β-glucosyltransferase assay, and they usually have the drawbacks of radioactive contamination, high background, laborious procedures, and unsatisfactory sensitivity. Herein, we develop a new fluorescent biosensor with zero background signal for sensitive detection of β-GT activity based on 5-hmC glucosylation-triggered helicase-dependent amplification (HDA). The detection probe we designed may act as both a probe for β-GT recognition and a template for HDA amplification. The β-GT-catalyzed 5-hmC glucosylation can protect the detection probes from both the cleavage by MfeI restrictive enzyme and the digestion by exonucleases I and III. The remaining detection probes can subsequently act as the templates for exponential HDA amplification to generate numerous double-stranded DNA products, which can be easily detected by SYBR Green I in a label-free manner. The zero background can be achieved by efficient elimination of primer-dimer nonspecific amplification and complete digestion of nonglucosylated detection probes. This biosensor exhibits high sensitivity and good specificity, and it can be further used to analyze β-GT kinetic parameters and screen the inhibitors, providing a powerful platform for deeper understanding of β-GT biological functions and promoting β-GT-related epigenetic studies. Furthermore, this biosensor can be extended to detect various DNA-modifying enzymes by simply replacing the recognition sequence and restriction enzyme.Taq DNA polymerase, one of the first thermostable DNA polymerases to be discovered, has been typecast as a DNA-dependent DNA polymerase commonly employed for PCR. However, Taq polymerase belongs to the same DNA polymerase superfamily as the Molony murine leukemia virus reverse transcriptase and has in the past been shown to possess reverse transcriptase activity. We report optimized buffer and salt compositions that promote the reverse transcriptase activity of Taq DNA polymerase and thereby allow it to be used as the sole enzyme in TaqMan RT-qPCRs. We demonstrate the utility of Taq-alone RT-qPCRs by executing CDC SARS-CoV-2 N1, N2, and N3 TaqMan RT-qPCR assays that could detect as few as 2 copies/μL of input viral genomic RNA.Presented here are two novel porous supramolecular boron imidazolate frameworks (BIF-106 and BIF-107), which are stabilized through relatively weak interactions between two-dimensional boron imidazolate layers. Moreover, BIF-107 exhibits efficient CO2 photoreduction to CO with a remarkable rate of 1186.0 μmol·g-1·h-1 under visible-light irradiation.Noble-metal nanoframes consisting of interconnected, ultrathin ridges have received considerable attention in the field of heterogeneous catalysis. The enthusiasm arises from the high utilization efficiency of atoms for significantly reducing the material loading while enhancing the catalytic performance. In this review article, we offer a comprehensive assessment of research endeavors in the design and rational synthesis of noble-metal nanoframes for applications in catalysis. We start with a brief introduction to the unique characteristics of nanoframes, followed by a discussion of the synthetic strategies and their controls in terms of structure and composition. We then present case studies to elucidate mechanistic details behind the synthesis of mono-, bi-, and multimetallic nanoframes, as well as heterostructured and hybrid systems. We discuss their performance in electrocatalysis, thermal catalysis, and photocatalysis. Finally, we highlight recent progress in addressing the structural and compositional stability issues of nanoframes for the assurance of robustness in catalytic applications.The high demand for H2 gas sensors is not just limited to industrial process control and leak detection applications but also extends to the food and medical industry to determine the presence of various types of bacteria or underlying medical conditions. For instance, sensing of H2 at low concentrations (93%) toward H2 over other gas species such as CO2, C4H8O, C3H6O, CH3CHO, and NO, which are commonly found to coexist in the environment.Pancreatic cancer is one of the foremost malignant gastrointestinal tumors, with prognosis and postoperative prediction remaining challenging because of the lack of facile, sensitive diagnostic methods and a specific single biomarker. Combined-biomarker analysis which provides a promising strategy to conquer such dilemma still requires developments in methodologies to gain accurate and reliable outcomes with wash-/separation-free scenarios and minimal interferences. Herein, a multiplex single-particle homogeneous immunoassay was proposed by simultaneously evaluating three pancreatic cancer-related biomarkers. Owing to the excellent resolution and multielement detectors without mass spectra overlapping, single-particle ICP-MS simultaneously provided biomarkers (CA125, CEA, and CA199) with three to four order-of-magnitude linear ranges and low-level limits of detection from specific antibody-labeled noble metal nanoparticles (AuNPs, AgNPs, and PtNPs). By scrutinizing both intensity and frequency signals, the proposed method was successfully applied in patients' serological evaluation, with results correlating well with those measured by the clinical routine method. The proposed method provides a potential tool in risk assessment of disease recurrence and survival.Simultaneous incorporation of cellulose nanocrystals (CNCs) and chitin nanofibers (ChNFs) into a polyvinyl alcohol (PVA) matrix opens possibilities for customization of more environmentally friendly composite materials. When used in tricomponent composite hydrogels, the opposite surface charges on CNCs and ChNFs lead to the construction of beneficial nanofiber structures. In this work, composite hydrogels containing CNCs, ChNFs, or their mixtures are produced using cyclic freeze-thaw (FT) treatments. When considering different compositions and FT cycling, tricomponent composite hydrogels containing a specific ratio of CNCs/ChNFs are shown to have promising mechanical performance in comparison to other samples. These results together with results from water absorption, rheological, and light scattering studies suggest that the CNC/ChNF structures produced property improvement by concurrently accessing the stronger interfacial interactions between CNCs and PVA and the longer lengths of the ChNFs for load transfer. Overall, these results provide insight into using electrostatically driven nanofiber structures in nanocomposites.Amid our understanding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the mechanisms involved in the causation of acute-phase coronavirus disease (COVID-19), we have come across clinical cases that have been shown to run a protracted course of COVID-19 with complex clinical findings related to organ systems in general and the CNS in particular that deserve to be addressed in the COVID long-haulers, for which the more clinically-related term chronic COVID syndrome (CCS) has been coined recently. An in-depth understanding of the mechanism that forms the basis of CCS and neurological deficits in CCS is needed as this can help in determining the management of cases of neuro-COVID, which is emerging as a less lethal but more disabling disease state. find more This Viewpoint highlights this syndrome, the possible pathogenetic pathways involved, and the treatment approaches that can be taken to help manage COVID long-haulers in CCS.
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