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Angiogenin is a potent angiogenic factor that is known to play an important role in tumor angiogenesis. In this paper, we investigate the cellular internalization of angiogenin conjugated with its highly specific aptamer. By using fluorophore-labeled aptamer and confocal laser scanning microscopy, we have developed a novel and simple method by which to visualize the real-time process of angiogenin internalization. Specifically, when aptamer--angiogenin conjugates were added into cell cultures, conjugates could be selectively bound to HUVE cells (human umbilical vein endothelial cells) and MCF-7 cells (human breast cancer cells). Nuclear staining and Z-axis scanning studies demonstrated that the aptamer--angiogenin conjugates were internalized to intracellular organelles, and dynamic confocal imaging studies indicated that the conjugates were quickly internalized. These results provide the first evidence that a fluorophore-labeled aptamer can be used as a fluorescent probe to visualize the spatiotemporal process of protein internalization in real time.

A facile and general strategy has been employed to fabricate a "nanoreactor" consisting of a hollow Pt nanocage-encapsulated mesoporous SiO2 shell. The hollow composite, which contained highly dispersed catalytic Pt nanoparticles inside the cavity enclosed by the mesoporous SiO2 shell, was considered an ideal framework structure for a nanoreactor that efficiently catalyzes substrate molecules with enhanced activity. The designed SiO2 shell can not only maintain active Pt nanoparticle resistance to harsh environments but also isolate the molecular recognition sites from the surface of Pt nanoparticles, thus retaining their catalytic activity. In addition, the certain space confinement effect aroused by the hollow structure led to a higher catalytic activity. Based on their catalytic activity, these nanoreactors have been demonstrated to function as biosensors for highly sensitive detection of measles-specific IgM antibodies in capture enzyme-linked immunosorbent assays. The detection limit of the prepared biosensor was as low as 1 ng/mL, 3 orders of magnitude lower than that of the conventional immunoassay. The specific catalytic properties of this nanoreactor could have great potential applications that include catalysis, biological labeling, and bioassays. [ABSTRACT FROM AUTHOR]

A new value for the proton affinity of C3H6 is offered. The calculation was obtained by pulsed field ionization-photoelectron photoion coincidence spectroscopy.

Polanyi et al. designed effective rules to foresee the significance of reactant vibration and collision energy in driving reactions over barriers for triatomic systems. A direct dynamics trajectory study of the vibrational effects is presented and the origins of these vibrational effects are explored.

The reaction of acetaldehyde cations with ethane is examined as a function of collision energy and acetaldehyde vibrational phase. It is observed that over a wide range of collision and vibrational energy, CH3CHO(super +) vibrational stimulation improves the charge transfer.

The vacuum ultraviolet pulsed field ionization-photoelectron (PFI-PE) spectra for CS2 are measured in full energy range of 12.6-13.5 eV, revealing complex vibronic band structures for the CS2(super +)[A~(super 2)pi(sub u)] state. Three dimensional potential energy functions for CS2 (super +1)[A~(super 2)pi(sub u)] are also generated theoretically.

Wereport an in-depth study on the gas-phase reactions of singletO2[a1Δg] with methionine (Met)at different ionization and hydration states (including deprotonated[Met – H]−, hydrated deprotonated [Met –H]−(H2O)1,2, and hydratedprotonated MetH+(H2O)1,2), usingguided-ion-beam scattering mass spectrometry. The measurements includethe effects of collision energy (Ecol)on reaction cross sections over a center-of-mass Ecolrange from 0.05 to 1.0 eV. The aim of this study isto probe the influences of Met ionization and hydration on its oxidationmechanism and dynamics. Density functional theory calculations, Rice-Ramsperger-Kassel-Marcusmodeling, and quasi-classical, direct dynamics trajectory simulationswere performed to examine the properties of various complexes andtransition states that might be important along reaction coordinates,probe reaction potential energy surfaces, and to establish the atomic-levelmechanism for the Met oxidation process. No oxidation products wereobserved for the reaction of [Met – H]−with 1O2due to the high-energy barriers located in theproduct channels for this system. However, this nonreactive propertywas altered by the microsolvation of [Met – H]−; as a result, hydroperoxides were captured as the oxidation productsfor [Met – H]−(H2O)1,2+ 1O2. For the reaction of MetH+(H2O)1,2+ 1O2, besidesformation of hydroperoxides, an H2O2eliminationchannel was observed. The latter channel is similar to what was foundin the reaction of dehydrated MetH+with 1O2(J. Phys. Chem. B2011, 115, 2671). The reactions of hydrated protonated and deprotonatedMet are all inhibited by Ecol, becomingnegligible at Ecol≥ 0.5 eV. Thekinetic and dynamical consequences of microsolvation on Met oxidationand their biological implications are discussed. [ABSTRACT FROM AUTHOR]

Quasi-classical, direct dynamicstrajectories were calculated atthe B3LYP/6-31G* level of theory, in an attempt to understand decompositionmechanisms of 1-ethyl-3-methylimidazolium dicyanamide (EMIM+DCA–) and 1-ethyl-2,3-dimethylimidazolium dicyanamide(EMMIM+DCA–). The trajectories showedmany dissociation paths for these two ionic liquids. Using trajectoryresults as a guide, structures of transition states and products thatmight be important for decomposition of these two compounds were determinedusing density functional theory calculations. Rice–Ramsperger–Kassel–Marcus(RRKM) theory was then utilized to examine properties of energizedionic liquids and to determine unimolecular rates for crossing varioustransition states. On the basis of RRKM modeling, initial decompositionpaths for energized EMIM+DCA–correspondto formation of an N-heterocyclic carbene and acidpair via transfer of the C2 proton of EMIM+to DCA–, and evolution of methylimidazole and ethylimidazolevia SN2 alkyl abstraction by DCA–. Similardecomposition paths were identified for energized EMMIM+DCA–, except that the reactivity of C2 of the imidazoliumcation is significantly reduced upon substitution of a methyl groupfor a hydrogen atom at this position. The present work demonstratesthat dynamics simulations, in conjunction with statistical modeling,are able to provide insight into decomposition mechanisms, kinetics,and dynamics for alkylimidazolium-based ionic liquids and to predictproduct branching ratios and how they vary with decomposition temperatures. [ABSTRACT FROM AUTHOR]

A CH3COCl-promoted allylic trifluoromethylthiolation of allylsilanes with trifluoromethanesulfanamide has been described. The method allows for an efficient synthesis of a wide range of allylic trifluoromethylthiolated compounds under mild conditions. [ABSTRACT FROM AUTHOR]

We report the formation and characterization of multiply negatively charged sodium bis(2-ethylhexyl) sulfosuccinate (NaAOT) aggregates in the gas phase, by electrospray ionization of methanol/water solution of NaAOT followed by detection using a guided-ion-beam tandem mass spectrometer. Singly and doubly charged aggregates dominate the mass spectra with the compositions of [NaAOT] ( n = 1-18 and z = 1-2). Solvation by water was detected only for small aggregates [NaAOTHO] of n = 3-9. Incorporation of glycine and tryptophan into [NaAOT] aggregates was achieved, aimed at identifying effects of guest molecule hydrophobicity on micellar solubilization. Only one glycine molecule could be incorporated into each [NaAOT] of n ≥ 7, and at most two glycine molecules could be hosted in that of n ≥ 13. In contrast to glycine, up to four tryptophan molecules could be accommodated within single aggregates of n ≥ 6. However, deprotonation of tryptophan significantly decrease its affinity towards aggregates. Collision-induced dissociation (CID) was carried out for mass-selected aggregate ions, including measurements of product ion mass spectra for both empty and amino acid-containing aggregates. CID results provide a probe for aggregate structures, surfactant-solute interactions, and incorporation sites of amino acids. The present data was compared with mass spectrometry results of positively charged [NaAOT] aggregates. Contrary to their positive analogues, which form reverse micelles, negatively charged aggregates may adopt a direct micelle-like structure with AOT polar heads exposed and amino acids being adsorbed near the micellar outer surface. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

We report a reaction apparatus developed to monitor singlet oxygen (O) reactions in solution using on-line ESI mass spectrometry and spectroscopy measurements. O was generated in the gas phase by the reaction of HO with Cl, detected by its emission at 1270 nm, and bubbled into aqueous solution continuously. O concentrations in solution were linearly related to the emission intensities of airborne O, and their absolute scales were established based on a calibration using 9,10-anthracene dipropionate dianion as an O trapping agent. Products from O oxidation were monitored by UV-Vis absorption and positive/negative ESI mass spectra, and product structures were elucidated using collision-induced dissociation-tandem mass spectrometry. To suppress electrical discharge in negative ESI of aqueous solution, methanol was added to electrospray via in-spray solution mixing using theta-glass ESI emitters. Capitalizing on this apparatus, the reaction of O with methionine was investigated. We have identified methionine oxidation intermediates and products at different pH, and measured reaction rate constants. O oxidation of methionine is mediated by persulfoxide in both acidic and basic solutions. Persulfoxide continues to react with another methionine, yielding methionine sulfoxide as end-product albeit with a much lower reaction rate in basic solution. Density functional theory was used to explore reaction potential energy surfaces and establish kinetic models, with solvation effects simulated using the polarized continuum model. Combined with our previous study of gas-phase methionine ions with O, evolution of methionine oxidation pathways at different ionization states and in different media is described. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Accelerating the migration of interfacial carriers in heterojunctions is crucial for achieving highly sensitive photoelectrochemical (PEC) sensing. In this study, we developed three-dimensional (3D)/two-dimensional (2D) CuInS 2 /red phosphorus nanosheet (CuInS 2 /RP NS) n-n heterojunction functional materials with enhanced interfacial charge transfer capabilities for PEC sensing. The 3D CuInS 2 serves as a conductive layer, providing excellent electronic conductivity and superior electron absorption and transport properties. In contrast, the ultrathin RP NS acts as a transport layer that enhances carrier mobility. The 3D/2D heterojunction ensures a large interface contact surface, shortening the carrier transport distance. A well-aligned band position generates a substantial built-in electric field, providing a significant driving force for efficient carrier separation and migration, thereby improving response sensitivity. A PEC aptamer sensor was constructed based on the synthesized heterostructure for ciprofloxacin detection. The detection limit of the CuInS 2 /RP NS aptamer sensor for ciprofloxacin is 2.03 × 10 -15 mg·mL -1 , with a linear range from 1.0 × 10 -14 to 1.0 × 10 -5 mg·mL -1 . This work presents a strategy for enhancing the photoelectric response by modulating the interface structure of heterojunctions, thereby opening new prospects for the application of highly sensitive PEC sensors in antibiotic detection.

The benchmark advanced oxidation technology (AOT) that uses UV/H 2 O 2 integrated with hypochlorous species exhibits great potential in removing micropollutants and enhancing wastewater treatability for reclamation purposes. Although efforts have been made to study the reactions of H 2 O 2 with hypochlorous species, there exist great discrepancies in the order of reaction kinetics, the rate constants, and the molecule-level mechanisms. This results in an excessive use of hypochlorous reagents and system underperformance during treatment processes. Herein, the titled reaction was investigated systematically through complementary experimental and theoretical approaches. Stopped-flow spectroscopic measurements revealed a combination of bi- and trimolecular reaction kinetics. The bimolecular pathway dominates at low H 2 O 2 concentrations, while the trimolecular pathway dominates at high H 2 O 2 concentrations. Both reactions were simulated using direct dynamics trajectories, and the pathways identified in the trajectories were further validated by high-level quantum chemistry calculations. The theoretical results not only supported the spectroscopic data but also elucidated the molecule-level mechanisms and helped to address the origin of the discrepancies. In addition, the impact of the environmental matrix was evaluated by using two waters with discrete characteristics, namely municipal wastewater and ammonium-rich wastewater. Municipal wastewater had a negligible matrix effect on the reaction kinetics of H 2 O 2 and the hypochlorous species, making it a highly suitable candidate for this integration technique. The obtained in-depth reaction mechanistic insights will enable the development of a viable and economical technology for safe water reuse.

Triple-negative breast cancer is one of the most prevalent malignant cancers worldwide. Disrupting the MTDH-SND1 protein-protein interaction has recently been shown to be a promising strategy for breast cancer therapy. In this work, a novel potent stabilized peptide with a stronger binding affinity was obtained through rational structure-based optimization. Furthermore, a sulfonium-based peptide delivery system was established to improve the cell penetration and antitumor effects of stabilized peptides in metastatic breast cancer. Our study further broadens the in vivo applications of the stabilized peptides for blocking MTDH-SND1 interaction and provides promising opportunities for breast cancer therapy., Competing Interests: The authors declare the following competing financial interest(s): Y.K. is a founder and equity holder of Firebrand Thera-peutics, Inc, which is developing inhibitors against MTDH/SND1. All other authors declare they have no competing interests., (© 2023 The Authors. Published by American Chemical Society.)

We report the one-pot synthesis of N -CF 3 heteroaryl amides (NTFMHA) from heteroaryl carboxylic acids and sterically hindered isothiocyanates, including various amino acid analogues, in the presence of AgF. The key to this reaction is the utilization of free heteroaryl acyl chlorides, rather than their corresponding hydrochloride salts. This method represents a complementary method of our previous work and enables modification to a variety of previously inaccessible structures, including α-tertiary amines and N -CF 3 -modified pharmaceuticals.

In DNA, guanine is the most susceptible to oxidative damage by exogenously and endogenously produced electronically excited singlet oxygen ( 1 O 2 ). The reaction mechanism and the product outcome strongly depend on the nucleobase ionization state and structural context. Previously, exposure of a monomeric 9-methylguanine radical cation (9MG •+ , a model guanosine compound) to 1 O 2 was found to result in the formation of an 8-peroxide as the initial product. The present work explores the 1 O 2 oxidation of 9MG •+ and its dehydrogenated neutral form [9MG - H] • within a Watson-Crick base pair consisting of one-electron-oxidized 9-methylguanine-1-methylcytosine [9MG·1MC] •+ . Emphasis is placed on entangling the base pair structural context and intra-base pair proton transfer with and consequences thereof on the singlet oxygenation of guanine radical species. Electrospray ionization coupled with guided-ion beam tandem mass spectrometry was used to study the formation and reaction of guanine radical species in the gas phase. The 1 O 2 oxidation of both 9MG •+ and [9MG - H] • is exothermic and proceeds barrierlessly either in an isolated monomer or within a base pair. Single- and multi-referential theories were tested for treating spin contaminations and multi-configurations occurring in radical- 1 O 2 interactions, and reaction potential energy surfaces were mapped out to support experimental findings. The work provides a comprehensive profile for the singlet oxygenation of guanine radicals in different charge states and in the absence and the presence of base pairing. All results point to an 8-peroxide as the major oxidation product in the experiment, and the oxidation becomes slightly more favorable in a neutral radical form. On the basis of a variety of reaction pathways and product profiles observed in the present and previous studies, the interplay between guanine structure, base pairing, and singlet oxygenation and its biological implications are discussed.

8-Bromoguanosine is generated in vivo as a biomarker for early inflammation. Its formation and secondary reactions lead to a variety of biological sequelae at inflammation sites, most of which are mutagenic and linked to cancer. Herein, we report the formation of radical cations of 8-bromoguanine (8BrG •+ ) and 8-bromoguanosine (8BrGuo •+ ) and their reactions toward the lowest excited singlet molecular oxygen ( 1 O 2 )─a common reactive oxygen species generated in biological systems. This work aims to investigate synergistic, oxidatively generated damage of 8-brominated guanine and guanosine that may occur upon ionizing radiation, one-electron oxidation, and 1 O 2 oxidation. Capitalizing on measurements of reaction product ions and cross sections of 8BrG •+ and 8BrGuo •+ with 1 O 2 using guided-ion beam tandem mass spectrometry and augmented by computational modeling of the prototype reaction system, 8BrG •+ + 1 O 2 , using the approximately spin-projected ωB97XD/6-31+G(d,p) density functional theory, the coupled cluster DLPNO-CCSD(T)/aug-cc-pVTZ and the multireference CASPT2(21,15)/6-31G**, probable reaction products, and potential energy surfaces (PESs) were mapped out. 8BrG •+ and 8BrGuo •+ present similar exothermic oxidation products, and their reaction efficiencies with 1 O 2 increase with decreasing collision energy. Both single- and multireference theories predicted that the two most energetically favorable reaction pathways correspond to 1 O 2 -addition to the C8 and C5-positions of 8BrG •+ , respectively. The CASPT2-calculated PES represents the best quantitative agreement with the experimental benchmark, in that the oxidation exothermicity is close to the water hydration energy of product ions and, thus, is able to eliminate a water ligand in the product ions.

Coronavirus disease 2019 (COVID-19) pandemic, a global health threat, was caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The SARS-CoV-2 papain-like cysteine protease (PLpro) was recognized as a promising drug target because of multiple functions in virus maturation and antiviral immune responses. Inhibitor GRL0617 occupied the interferon-stimulated gene 15 (ISG15) C-terminus-binding pocket and showed an effective antiviral inhibition. Here, we described a novel peptide-drug conjugate (PDC), in which GRL0617 was linked to a sulfonium-tethered peptide derived from PLpro-specific substrate LRGG. The EM-C and EC-M PDCs showed a promising in vitro IC50 of 7.40 ± 0.37 and 8.63 ± 0.55 μM, respectively. EC-M could covalently label PLpro active site C111 and display anti-ISGylation activities in cellular assays. The results represent the first attempt to design PDCs composed of stabilized peptide inhibitors and GRL0617 to inhibit PLpro. These novel PDCs provide promising opportunities for antiviral drug design.

Chiral growth and chirality transfer associated with plasmonic nanostructures have rejuvenated the field of chirality. As the precise regioselective growth of inorganic crystals into chiral shapes at the nanoscale is extremely challenging, "bottom-up" synthesis of intrinsically chiral nanoparticles with structural stability is obviously attractive and important. With the thiolated bimolecular cosurfactants, we demonstrated a chemical strategy for the synthesis of intrinsically helical plasmonic nanorods (HPNRs) with strong and tailorable plasmonic circular dichroism (PCD) responses, deriving from the zwitterionic interactions between the -NH 3 + and -COO - groups of the cysteine molecules (Cys). The influence of structural parameters of HPNRs on PCD responses was analyzed systematically by theoretical simulations. Among the different structural parameters, the pitch depth was found to have the greatest impact on the PCD signals, in agreement with the experimental results. Moreover, the obtained HPNRs with the strong, tunable, and stable chiroptical properties were found to be able to induce circularly polarized luminescence of achiral luminophores. Due to the generality of this effect, this chiral plasmonic nanostructure may have great potential for use in the fields of chiral sensors, chiral catalysis, and displays.

Hot solvent-assisted gravity drainage (HS-AGD) is an effective way to exploit oil sands and heavy oil both economically and environmentally. The visualized microscopic seepage experiments and two-dimensional (2-D) macroscopic simulation experiments of HS-AGD are carried out, and the results are compared with that of steam-assisted gravity drainage (SAGD) in detail for the first time in order to compare their development effects of the oil sand reservoir. MacKay River oil sand bitumen is taken as an oil sample in the experiments, with n -hexane as the solvent. Micro seepage characteristics of the hot solvent and steam and the remaining oil distribution of the solvent and steam drive are investigated through microseepage experiments. The expanding process of the solvent/steam chamber and production performance of HS-SAGD and SAGD are investigated through macrosimulation experiments. The study found that the sweep efficiency of hot solvent is higher than that of steam at the same temperature due to the small interfacial tension between the condensed solvent and heated bitumen. Due to the severe gravity segregation, the steam accumulated at the top of the model during the 2-D physical simulation experiment, which results in the huge heat loss at the top of the model. The temperature of the steam chamber is significantly lower than that of the solvent chamber. The oil recovery of 200 °C hot solvent vapor is twice as much as that of 300 °C steam owing to the different drainage mechanisms of the HS-AGD and SAGD. In SAGD, only heat transfer reduces the viscosity of oil sand bitumen. The components of oil produced in SAGD have little difference compared with that of the original bitumen. In HS-AGD, both mass transfer and the sensible heat transfer reduce the viscosity of oil sand bitumen. The in situ asphaltene precipitation induced by heated-solvent extraction also upgrades the bitumen. The results of component analysis show that in HS-AGD, the content of heavy components in the oil sand bitumen is obviously reduced. This paper aims to reveal the oil drainage mechanism of HS-AGD and SAGD from the macroscopic and microscopic view and to provide theoretical guidance for the field application of this technology., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Increasing the local concentration of DNA-based probes is a convenient way to improve the sensitivity of biosensors. Instead of using organic solvents or ionic liquids that phase-separate with water based on hydrophobic interactions, we herein studied a classic aqueous two-phase system (ATPS) comprising polyethylene glycol (PEG) and dextran. Polymers of higher molecular weights and higher concentrations favored phase separation. DNA oligonucleotides are selectively enriched in the dextran-rich phase unless the pH was increased to 12. A higher volume ratio of PEG-to-dextran and a higher concentration of PEG also enrich more DNA probes in the dextran-rich phase. The partition efficiency of the T 15 DNA was enriched around seven times in the dextran phase when the volume ratio of dextran and PEG reached 1:10. The detection of limit improved by 3.6-fold in a molecular beacon-based DNA detection system with the ATPS. The ATPS also increased the sensitivity for the detection of Hg 2+ and adenosine triphosphate, although these target molecules alone distributed equally in the two phases. This work demonstrates a simple method using water soluble polymers to improve biosensors.