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In this work, amine-functionalized ZIF8 (i.e., ZIF8-A) was dispersed in n-heptanol (ZIF8-A/n-heptanol) to remove SO2. The effects of ZIF8-A proportion, SO2 concentration, and absorption and desorpt...

Life science is often focused on the microscopic level. Single-molecule technology has been used to observe components at the micro- or nanoscale. Single-molecule imaging provides unprecedented information about the behavior of individual molecules in contrast to the information from ensemble methods that average the information of many molecules in various states. A typical feature of living systems is motion. The lack of synchronicity of motion biomachines in living systems makes it challenging to image the motion process with high resolution. Thus, single-molecule technology is especially useful for real-time study on motion mechanism of biomachines, such as viral DNA packaging motor, or other ATPases. The most common optical instrumentations in single-molecule studies are optical tweezers and single molecule total internal refection fluorescence microscopy (smTIRF). Optical tweezers are the force-based technique. The analysis of RNA using optical tweezer has led to the discovery of the rubbery or amoeba property of RNA nanoparticles for compelling vessel extravasation to enhance tumor targeting and fast renal excretion. The rubbery property of RNA lends mechanistic evidence for RNAs use as an ideal reagent in cancer treatment with undetectable toxicity. Single molecule photobleaching allows for the direct counting of biomolecules. This technique was invented for single molecule counting of RNA in the phi29 DNA packaging motor to resolve the debate between five and six copies of RNA in the motor. The technology has subsequently extended to counting components in biological machines composed of protein, DNA, and other macromolecules. In combination with statistical analysis, it reveals biomolecular mechanisms in detail and leads to the development of ultra-sensitive sensors in diagnosis and forensics. This review focuses on the applications of optical tweezers and fluorescence-based techniques as single-molecule technologies to resolve mechanistic questions related to RNA and DNA nanostructures.

Alternaria blight in mustard cause heavy damage to the foliar parts resulting into poor growth and development of plants and thereby reduces seed yield. Inorder to manage Alternaria infestation in mustard seed for yield maximization, an experiment was conducted in the plant protection laboratory in Nepal Polytechnic Institute, Bharatpur, Chitwan in 2018, using Completely Randomized Design (CRD) with four replicates. Five treatments i.e.Uthane M-45 (2g/kg), Neem powder (3 g/kg), Bojho powder (4g/kg), Trichoderma harzianum, (107 Conidia/mL) and control (without treatment) were used for seed treatment of local variety of Mustard. Four hundred seeds for each treatment (25 seeds in each petriplate) were plated using triple layers of moistened blotter paper in petriplate and incubated at (27±20C) for 2 days and followed deep freezing for 24 hrs. Data of disease incidence and seed germination were recorded in 3, 7 and 10 days after incubation (DAI). Seedling vigor and seedling weight were also recorded at 5 DAI. The percentage of Alternaria spp incidence on seeds at different DAI showed highly significant with respect to different treatments. Application of Uthane M-45 and T. harzianum significantly reduced the seed-borne infection of Alternaria spp. as compared to control. At 3 DAI Uthane M-45 completely checked the pathogen however, only 4% and 5% disease incidence was observed in 7 DAI and 10 DAI respectively. Bio control agent Trichoderma harzianum was found next best alternative after Uthane M-45 to control disease. Plant extract Bojho powder and Neem powder were found better than control to check the disease. Furthermore, highest germination (76%) was observed in Trichoderma treatment whereas, lowest germination was found in control.

Mechanical anisotropy is an essential property for biomolecules to assume structural and functional roles in mechanobiology. However, there is insufficient information on the mechanical anisotropy of ligand-biomokcule complexes. Herein, we investigated the mechanical property of individual human telomeric G-quadruplexes bound with a telomestatin ligand by optical tweezers. Stacking of the ligand to the G-tetradplanes changes the conformation of the G-quadruplex, which resembles a balloon squeezed at certain directions. Such a squeezed balloon effect strengthens the G-tetrad planes whereas dislocates and weakens the loops in the G-quadruplex upon ligand binding. These dynamic interactions indicate that the binding between the ligand and G-quadruplex follows the induced-fit model. We anticipate that the altered mechanical anisotropy of the ligand-G-quadruplex complex can add additional level of regulations on the motor enzymes that process DNA or RNA molecules.

Rubber is a fascinating material in both industry and daily life. The development of elastomeric material in nanotechnology is imperative due to its economic and technological potential. By virtue of their distinctive physicochemical properties, nucleic acids have been extensively explored in material science. The Phi29 DNA packaging motor contains a 3WJ with three angles of 97°, 125°, and 138°. Here, the rubber-like property of RNA architectures was investigated using optical tweezers and in vivo imaging technologies. The 3WJ 97° interior angle was contracted or stretched to 60°, 90°, and 108° at will to build elegant RNA triangles, squares, pentagons, cubes, tetrahedrons, dendrimers, and prisms. RNA nanoarchitecture was stretchable and shrinkable by optical tweezer with multiple extension and relaxation repeats like a rubber. Comparing to gold and iron nanoparticles with the same size, RNA nanoparticles display stronger cancer-targeting outcomes, while less accumulation in healthy organs. Generally, the upper limit of renal excretion is 5.5 nm; however, the 5, 10, and 20 nm RNA nanoparticles passed the renal filtration and resumed their original structure identified in urine. These findings solve two previous mysteries: (1) Why RNA nanoparticles have an unusually high tumor targeting efficiency since their rubber or amoeba-like deformation property enables them to squeeze out of the leaky vasculature to improve the EPR effect; and (2) why RNA nanoparticles remain non-toxic since they can be rapidly cleared from the body via renal excretion into urine with little accumulation in the body. Considering its controllable shape and size plus its rubber-like property, RNA holds great promises for industrial and biomedical applications especially in cancer therapeutics delivery.

Vitex negundo (VN) is a widely used plant in folk medicine, namely for the treatment of jaundice, wounds, body ache, toothache, asthma, eye pain, and migraine. These effects have been increasingly attributed to its chemical composition. Here, we assessed the VN chemical and nutritional composition and biological activity, with particular emphasis on antioxidant and antimicrobial effects. VN methanol and hexane extracts revealed the presence of important phytochemical, such as terpenoids, polyphenol, steroids, saponins, phenolic compound and flavonoids. Total phenolic content of VN methanol extract from bark was 1082.473 mg/g GAE and that of leaves was 1382.984 mg/g GAE. The total flavonoids content in VN methanol extract from VN bark was 127.744 mg/g QE and that of leaves was 123.776 mg/g QE. VN methanol extract from bark exhibited high antioxidant effects (IC50=38.47 ppm). The content (%) of ash, moisture, crude fiber, crude protein and fat in VN leaves was, respectively, 7.86%, 18.35%, 6.52%, 9.687% and 6.19%. VN leaves methanol extract revealed antimicrobial activity against Bacillus subtilis and Staphylococcus aureus, with inhibition halos being, respectively, 13 mm and 14 mm, and the MBC values were found to be 1.562 mg/mL and 6.25 mg/mL, respectively. Similarly, VN bark methanol extract led to inhibition halos of 18 mm and 15 mm for B. subtilis and S. aureus, respectively, and the MBC values were found to be 2.372 mg/mL and 0.245 mg/mL. GC-MS analysis of the VN bark methanol extract revealed that monoolein was the major compounds, with an area of 0.57%. Thus, our results encourage the potential use of VN as a medicinal product, with high protein contents, and prominent antioxidant and anti-bacterial effects.

Single-crystal iron oxide nanorings have been proposed as a promising candidate for magnetic hyperthermia application because of their unique shape-induced vortex-domain structure, which supports good colloidal stability and enhanced magnetic properties. However, the synthesis of single crystalline iron oxide has proven to be challenging. In this article, we showed that chemically synthesized multigrain magnetite nanorings disfavor a shape-induced magnetic vortex-domain structure. Our results indicate that the multigrain Fe3O4 nanorings with an average outer diameter of ~110 nm and an inner to outer diameter ratio of ~0.5 do not show a shape-induced vortex-domain structure, which was observed in the single-crystal Fe3O4 nanorings of similar dimensions. At 300 Ks, multigrain magnetite nanorings showed an effective anisotropy field of 440 Oe, which can be attributed to its high surface area and intraparticle interaction. Both calorimetric and AC loop measurements showed a moderate inductive heating efficiency of multigrain magnetite nanorings of ~300 W/g at 800 Oe. Our results shed light on the magnetic ground states of chemically synthesized multigrain Fe3O4 nanorings.

G-Quadruplex and i-motif are tetraplex structures that may form in opposite strands at the same location of a duplex DNA. Recent discoveries have indicated that the two tetraplex structures can have conflicting biological activities, which poses a challenge for cells to coordinate. Here, by performing innovative population analysis on mechanical unfolding profiles of tetraplex structures in double-stranded DNA, we found that formations of G-quadruplex and i-motif in the two complementary strands are mutually exclusive in a variety of DNA templates, which include human telomere and promoter fragments of hINS and hTERT genes. To explain this behavior, we placed G-quadruplex- and i-motif-hosting sequences in an offset fashion in the two complementary telomeric DNA strands. We found simultaneous formation of the G-quadruplex and i-motif in opposite strands, suggesting that mutual exclusivity between the two tetraplexes is controlled by steric hindrance. This conclusion was corroborated in the BCL-2 promoter sequence, in which simultaneous formation of two tetraplexes was observed due to possible offset arrangements between G-quadruplex and i-motif in opposite strands. The mutual exclusivity revealed here sets a molecular basis for cells to efficiently coordinate opposite biological activities of G-quadruplex and i-motif at the same dsDNA location.

The 3' human telomeric overhang provides ample opportunities for the formation and interaction of G-quadruplexes, which have shown impacts on many biological functions including telomerase activities in the telomere region. However, in the few investigations on DNA constructs that approach to the full length of the human telomeric overhang, the presence of higher-order quadruplex-quadruplex interactions is still a subject of debate. Herein, we employed dynamic splint ligation (DSL) to prepare a DNA construct, 5'-(TTAGGG)24 or 24G, which has the length comparable to the full stretch of 3' human telomeric overhang. Using mechanical unfolding assays in laser tweezers, we observed a minor population (∼5%) of higher-order interactions between G-quadruplexes, while the majority of the quadruplexes follow the bead-on-a-string model. Analyses on the noninteracting G-quadruplexes in the 24G construct showed features similar to those of the stand-alone G-quadruplexes in the 5'-(TTAGGG)4 (4G) construct. As each 24G construct contains as many as six G-quadruplexes, this method offers increased throughput for the time-consuming mechanical unfolding experiments of non-B DNA structures.

Miscued communication often leads to misfolding and aggregation of the proteins involved in many diseases. Owing to the ensemble average property of conventional techniques, detailed communication diagrams are difficult to obtain. Mechanical unfolding affords an unprecedented perspective on cooperative transitions by observing a protein along a trajectory defined by two mutated cysteine residues. Nevertheless, this approach requires tedious sample preparation at the risk of altering native protein conformations. To address these issues, we applied click chemistry to tether a protein to the two dsDNA handles through primary amines in lysine residues as well as at the N terminus. As a proof of concept, we used laser tweezers to mechanically unfold and refold calmodulin along 36 trajectories, maximally allowed by this strategy in a single batch of protein preparation. Without a priori knowledge of the particular residues to which the double-stranded DNA handles attach, we used hierarchical cluster analysis to identify 20 major trajectories, according to the size and the pattern of unfolding transitions. We dissected the cooperativity into all-or-none and partially cooperative events, which represent strong and weak high-order interactions in proteins, respectively. Although the overall cooperativity is higher within the N or C lobe than that between the lobes, the all-or-none cooperativity is anisotropic among different the unfolding trajectories and becomes relatively more predominant when the size of the protein segments increases. The average cooperativity for all-or-none transitions falls within the expected range observed by ensemble techniques, which supports the hypothesis that unfolding of a free protein can be reconstituted from individual trajectories.

In investigating the binding interactions between the human telomeric RNA (TERRA) G-quadruplex (GQ) and its ligands, it was found that the small molecule carboxypyridostatin (cPDS) and the GQ-selective antibody BG4 simultaneously bind the TERRA GQ. We previously showed that the overall binding affinity of BG4 for RNA GQs is not significantly affected in the presence of cPDS. However, single-molecule mechanical unfolding experiments revealed a population (48 %) with substantially increased mechanical and thermodynamic stability. Force-jump kinetic investigations suggested competitive binding of cPDS and BG4 to the TERRA GQ. Following this, the two bound ligands slowly rearrange, thereby leading to the minor population with increased stability. Given the relevance of G-quadruplexes in the regulation of biological processes, we anticipate that the unprecedented conformational rearrangement observed in the TERRA-GQ-ligand complex may inspire new strategies for the selective stabilization of G-quadruplexes in cells.

A new approach to the synthesis and 1,3-dipolar cycloadditions of nitrones has been described from 2,3-dihydro-4H-pyran and various hydroxylamines, with electron-deficient alkynes for the synthesis of isoxazoline derivatives. Significant rate acceleration and improved yields of exclusively exo isoxazolines in 1-butyl-3-methylimidazolium based ionic liquids have been observed. Novel isoxazolines may be used as a precursor for the synthesis of variety of peptides.

Recent experiments provided controversial observations that either parallel or non-parallel G-quadruplex exists in molecularly crowded buffers that mimic cellular environment. Here, we used laser tweezers to mechanically unfold structures in a human telomeric DNA fragment, 5′-(TTAGGG)4TTA, along three different trajectories. After the end-to-end distance of each unfolding geometry was measured, it was compared with PDB structures to identify the best-matching G-quadruplex conformation. This method is well-suited to identify biomolecular structures in complex settings not amenable to conventional approaches, such as in a solution with mixed species or at physiologically significant concentrations. With this approach, we found that parallel G-quadruplex coexists with non-parallel species (1:1 ratio) in crowded buffers with dehydrating cosolutes [40% w/v dimethyl sulfoxide (DMSO) or acetonitrile (ACN)]. In crowded solutions with steric cosolutes [40% w/v bovine serum albumin (BSA)], the parallel G-quadruplex constitutes only 10% of the population. This difference unequivocally supports the notion that dehydration promotes the formation of parallel G-quadruplexes. Compared with DNA hairpins that have decreased unfolding forces in crowded (9 pN) versus diluted (15 pN) buffers, those of G-quadruplexes remain the same (20 pN). Such a result implies that in a cellular environment, DNA G-quadruplexes, instead of hairpins, can stop DNA/RNA polymerases with stall forces often

Microwave-induced 1,3-dipolar cycloaddition reactions of dihydropyran derived nitrone with various activated alkenes have been studied in situ and found to afford new isoxazolidine derivatives with moderate selectivity.

The separate arrangement of target recognition and signal transduction in conventional biosensors often compromises the real-time response and can introduce additional noise. To address these issues, we combined analyte recognition and signal reporting by mechanochemical coupling in a single-molecule DNA template. We incorporated a DNA hairpin as a mechanophore in the template, which, under a specific force, undergoes stochastic transitions between folded and unfolded hairpin structures (mechanoescence). Reminiscent of a tuning fork that vibrates at a fixed frequency, the device was classified as a molecular tuning fork (MTF). By monitoring the lifetime of the folded and unfolded hairpins with equal populations, we were able to differentiate between the mono- and bivalent binding modes during individual antibody-antigen binding events. We anticipate these mechanospectroscopic concepts and methods will be instrumental for the development of novel bioanalyses.

The well-demonstrated biological functions of DNA G-quadruplex inside cells call for small molecules that can modulate these activities by interacting with G-quadruplexes. However, the paucity of the understanding of the G-quadruplex stability contributed from submolecular elements, such as loops and tetraguanine (G) planes (or G-quartets), has hindered the development of small-molecule binders. Assisted by click chemistry, herein, we attached pulling handles via two modified guanines in each of the three G-quartets in human telomeric G-quadruplex. Mechanical unfolding using these handles revealed that the loop interaction contributed more to the G-quadruplex stability than the stacking of G-quartets. This result was further confirmed by the binding of stacking ligands, such as telomestatin derivatives, which led to similar mechanical stability for all three G-quartets by significant reduction of loop interactions for the top and bottom G-quartets. The direct comparison of loop interaction and G-quartet stacking in G-quadruplex provides unprecedented insights for the design of more efficient G-quadruplex-interacting molecules. Compared to traditional experiments, in which mutations are employed to elucidate the roles of specific residues in a biological molecule, our submolecular dissection offers a complementary approach to evaluate individual domains inside a molecule with fewer disturbances to the native structure.

Nitrones (III) generated in situ from dihydropyran (I) and hydroxylamines (II) undergo further cycloaddition with alkynes (III) or methacrolein (VI) to give title compounds (V) or (VII).

As an intracellular organelle, phospholipid-coated lipid droplets have shown increasing importance due to their expanding biological functions other than the lipid storage. The growing biological significance necessitates a close scrutiny on lipid droplets, which have been proposed to mature in a cell through processes such as fusion. Unlike phospholipid vesicles that are well-known to fuse through docking and hemifusion steps, little is known on the fusion of lipid droplets. Herein, we used laser tweezers to capture two micrometer-sized 1,2,3-trioleoylglycerol (triolein) droplets coated with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) that closely resemble intracellular lipid droplets. We started the fusion processes by a well-controlled collision between the two lipid droplets in phosphate buffer at pH 7.4. By monitoring the change in the pathway of a trapping laser that captures the collided lipid droplets, docking and physical fusion events were clearly distinguished for the first time and their lifetimes were determined with a resolution of 10 μs after postsynchronization analysis. Our method revealed that the rate-limiting docking process is affected by anions according to a Hofmeister series, which sheds light on the important role of interfacial water shedding during the process. During the physical fusion, the kinetics between bare triolein droplets is faster than lipid droplets, suggesting that breaking of phospholipid coating is involved in the process. This scenario was further supported by direct observation of a short-lived hemifusion state with ∼46 ms lifetime in POPC-coated lipid droplets, but not in bare triolein droplets.

Starting from the known dihydropyran-derived nitrone (I), a series of isoxazolines are prepared via regioselective cycloaddition reaction with electron-deficient alkynes.

This study presents effects of intravenous laser blood irradiation (ILBI) in a transient immunodeficiency patient with juvenile idiopathic arthritis (JIA) treated with an interleukin-6 receptor inhibitor (Tocilizumab). Biological agents induce JIA remission, but some patients do not respond favorably to this final therapeutic line of defense. ILBI was performed in a 16-year-old male patient, with JIA and transient immunodeficiency. When ILBI was introduced, the patient was receiving disease-modifying drugs, steroids, tocilizumab, and physical therapy. Because the disease was not well controlled, ILBI was applied in addition to other ongoing therapies. The patient underwent 1 session daily, and 10 successive sessions per month, repeated every 3 months, for 7 months. Patient evaluation was performed before ILBI was started and at 3, 6, 9, and 12 months after ILBI initiation, using the ACR Pediatric response. The outcome was evaluated using Pediatric 50, 70, and 90 responses and compared to initial status, after 3, 6, 9, and 12 months. At the end of study, the titre of IgA and IgG levels returned to normal. Synergistic anti-inflammatory effect of ILBI was evident, if applied additionally in combination with tocilizumab, in a patient with a therapy-resistant severe form of JIA and related subacute transient immunodeficiency.

Single-stranded guanine (G)-rich sequences at the 3' end of human telomeres provide ample opportunities for physiologically relevant structures, such as G-quadruplexes, to form and interconvert. Population equilibrium in this long sequence is expected to be intricate and beyond the resolution of ensemble-average techniques, such as circular dichroism, NMR, or X-ray crystallography. By combining a force-jump method at the single-molecular level and a statistical population deconvolution at the sub-nanometer resolution, we reveal a complex population network with unprecedented transition dynamics in human telomeric sequences that contain four to eight TTAGGG repeats. Our kinetic data firmly establish that G-triplexes are intermediates to G-quadruplexes while long-loop G-quadruplexes are misfolded population minorities whose formation and disassembly are faster than G-triplexes or regular G-quadruplexes. The existence of misfolded DNA supports the emerging view that structural and kinetic complexities of DNA can rival those of RNA or proteins. While G-quadruplexes are the most prevalent species in all the sequences studied, the abundance of a misfolded G-quadruplex in a particular telomeric sequence decreases with an increase in the loop length or the number of long-loops in the structure. These population patterns support the prediction that in the full-length 3' overhang of human telomeres, G-quadruplexes with shortest TTA loops would be the most dominant species, which justifies the modeling role of regular G-quadruplexes in the investigation of telomeric structures.

Microwave-induced 1,3-dipolar cycloaddition reactions of nitrone (III) with activated alkenes such as (IV) and (VIII) provides access to new isoxazolidine derivatives.

On analyse les spectres electroniques d'absorption (EAS) et les spectrese electroniques de diffusion (EDS) de quelques pyridazinuium ylures. En solution, le caractere dipolaires des molecules fait apparaitre des interactions d'orientation induction. Dans les solvents protiques des interactions specifiques accentuent le deplacement hypsochrome de la bande d'absorption a caractere de transfert de charge situee dans la visible

Potassium superoxide mixed with potassium hydroxide is an effective oxidizing flux for rock and ore samples. Sodium is not added to the sample and potassium may be removed by precipitation with perchloric acid. Traces of cations with various charges, i.e., Ca2+, Eu3+, and Th4+, are not significantly carried down but silver(I) is partially lost to the precipitate.

The following methods of determining lanthanides in geological samples are reviewed, together with the separation techniques necessarily associated with them: neutron-activation analysis, atomic-absorption and flame-emission spectrometry, plasma-source emission spectrometry, mass spectrometry, X-ray fluorescence spectrometry, and spectrophotometry.

The cation-exchange behaviour of micro and trace quantities of thorium on Dowex 50-X8 in the presence of carbonate and phosphate has been studied. Carbonate causes loss of thorium to the column effluent at pH 10.In the presence of phosphate, thorium is incompletely sorbed in the pH range 2-4.5, the loss being maximum at pH 3.8. Outside this range, thorium is quantitatively sorbed and recovered. A method that does not employ ion-exchange has been developed for the microdetermination of thorium in phosphate solution. The phosphate is precipitated as bismuth phosphate and thorium is leached from the precipitate with ammonium carbonate solution and determined with Arsenazo III. Uranium, molybdenum and vanadium are removed with Alamine 336. The results obtained for a standard ore are in excellent agreement with the certified value.