Constituent Molecules Research Articles

Multiscale calculation of carrier mobility in organic solids through the fine-tuned kinetic Monte Carlo simulation

A multiscale approach is proposed to calculate carrier mobility (μ) in organic solids, bridging the molecular-level simulations and the kinetic Monte Carlo (kMC) method. The amorphous molecular supercell was prepared by the molecular dynamic simulation, then the density functional calculations were performed to obtain the relevant parameters for Marcus charge transfer between the constituent molecules. The on-lattice type kMC simulation implementing the Marcus transfer is systematically tuned to best mimic the profile of carrier transport in the simulated molecular supercell. The calculated μ readily reproduced the Pool-Frenkel field dependency, indicating that the present work well represents the typical behavior of carrier transport in organic systems. It is also shown that the calculation results of 4 anthracene-derivatives and 6 hole-transporting molecules agree well with the time-of-flight measurements from literature, while requiring the modest calculation cost in comparison with the similar calculations introduced elsewhere.

Spatial inhomogeneity and molecular aggregation behavior in aqueous binary liquid mixtures

The component molecules in aqueous mixtures tend to aggregate with increasing concentration, and it has been conclusively reported that their spatial distribution is no longer uniform. Here, we attempt to measure the spatial inhomogeneity of constituent molecules in the cosolvent-water mixture by calculating the h value wherein the time-varying molecular configurations are obtained from molecular dynamics (MD) simulations conducted at various concentrations and temperatures. The results reveal that the miscible methanol solutions have a small h value, indicating the homogeneous distribution of components, while the immiscible dichloromethane-water mixtures have a relatively large h value, representing the localization of components due to the formation of two separated liquid phases. In the butanol-water mixture, the h value decreases significantly with increasing temperature, which reflects a temperature-dependent phase change from two liquid phases to a single phase, resulting in uniform distribution of molecular components at high temperatures. Meanwhile, in the graph theoretical analysis of cosolvent aggregates and water H-bond network, two prominent types of aggregation behavior are shown in the investigated binary liquid system, i.e., self-associated or spatially extended aggregates. The growth of self-associated cosolvent aggregates facilitates the liquid-liquid phase separation, resulting in a heterogeneous distribution of components with high h values. The development of a spatially extended network enables fully mixing with water H-bond network, bringing about the homogeneous distribution of constituent molecules and thus resulting in low h values. The concept of spatial inhomogeneity and bifurcating hypothesis on aggregation behavior is anticipated to contribute significantly to understanding the underlying issues, such as miscibility and liquid-liquid phase separation in aqueous mixtures.

A 1:1 solvate structure of succinonitrile and lithium thiocyanate

A 1:1 solvate structure of succinonitrile and lithium thiocyanate, namely, catena-poly[lithium-di-μ-thiocyanato-lithium-di-μ-butanedinitrile], [Li(NCS)(C4H4N2)] n or LiSCN·NC(CH2)2CN, was isolated and its structure was solved. Lithium ions are tetrahedrally coordinated by two nitrile groups from separate succinonitrile molecules, as well as S and N atoms of separate SCN− anions. The succinonitrile molecules and Li+ ions form double-chain one-dimensional coordination polymers that are bridged by Li2(SCN)2 dimers. The coordination network extends along [\overline{1}01]. Weak hydrogen-bonding interactions are also noted among the constituent molecules.

Revealed Properties of Various Self-Assemblies in Two Catanionic Surfactant Systems in Relation to Their Polarity and Molecular Packing State.

A catanionic surfactant system is an aqueous solution or dispersion of cationic and anionic surfactants that spontaneously self-assemble into structures such as micelles, vesicles, and coacervates. Their structural diversity varies depending on the ratios of cationic and anionic surfactants (compositions), the chemical structure of the constituent molecules, etc. Herein, two types of catanionic surfactant systems were systematically characterized: (i) cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS), both typical ionic surfactants; and (ii) dodecylmethylimidazolium ammonium bromide ([C12mim]Br) and SDS, where the former is an ionic liquid. By observing the sample appearance, turbidity, and particle size, the phase state of each system was analyzed according to the total concentration of surfactants and the molar ratio of cationic surfactants to the total concentration. Especially, for specific compositions of catanionic surfactant vesicles (cataniosome), the closed structure of the vesicles was confirmed through calcein entrapment and release detected with a fluorescence assay. The polarities of the interface of the prepared self-assemblies were evaluated using a fluorescence probe, Laurdan. The packing state of the molecules in the formed self-assembly structure was estimated using Raman spectroscopy. The results clearly indicate consistent phase-transition behavior for the CTAB-SDS (i) and [C12mim]Br-SDS (ii) systems, depending on the total surfactant concentration and composition, while the membrane properties of the two systems differed. The cataniosome formed in the CTAB-SDS system was in a tightly packed membrane state and more hydrophobic than that formed in the [C12mim]Br-SDS system owing to the difference in the structure of the constituting molecule: [C12mim]Br has a larger head group and shorter acyl chain than CTAB. The self-assembly properties evaluated in this study were compared with those of typical lipid membranes, liposomes (lipid vesicles), to determine a possible application of the catanionic systems with various self-assembly formulations.

Analysis of Small-Molecule Mixtures by Super-Resolved 1H NMR Spectroscopy.

Analysis of small molecules is essential to metabolomics, natural products, drug discovery, food technology, and many other areas of interest. Current barriers preclude from identifying the constituent molecules in a mixture as overlapping clusters of NMR lines pose a major challenge in resolving signature frequencies for individual molecules. While homonuclear decoupling techniques produce much simplified pure shift spectra, they often affect sensitivity. Conversion of typical NMR spectra to pure shift spectra by signal processing without a priori knowledge about the coupling patterns is essential for accurate analysis. We developed a super-resolved wavelet packet transform based 1H NMR spectroscopy that can be used in high-throughput studies to reliably decouple individual constituents of small molecule mixtures. We demonstrate the efficacy of the method on the model mixtures of saccharides and amino acids in the presence of significant noise.

Димеризация фталоцианина алюминия в органической и водно-органической средах

Aluminum phthalocyanine chloride (AlClPc) is a photoactive macroheterocyclic compound, which, in its monomeric form, is used as a photosensitizer (PS) in photodynamic therapy and diagnostics. In this paper, its physicochemical properties were studied in organic (N, N-dimethylformamide, DMF) and aqua-organic (DMF-aqua) media. It has been shown that the hydrophobic properties of AlClPc prevent its widespread use in various pharmacological compositions due to its tendency to aggregate in aqueous solutions, which leads to the formation of non-fluorescent aggregates and a decrease in its photodynamic activity. The geometry and electronic structure of AlClPc in the monomeric and dimerized (H- and 
 J-aggregates) states were studied using quantum-chemical calculations with the help of the electron density functional theory (DFT) method. Different types of orientation during the dimerization of AlClPc molecules are presented: “back to back”, “head to head”, “head to back”, as well as mixed-oriented types. It has been proven that both in DMF and DMF-aqua media, the preferred orientation is “back to back”, without sacrificing the monomeric geometry of the constituent molecules in the dimer. It is shown that in an aqueous organic solvent the AlClPc molecule is easily hydrated with the formation of a coordination bond between the Al atom of the AlClPc molecule and the O atom of the aqua molecule. The bond length is 2.23 Å, and the hydration energy is 16.84 kcal/mol. Hydration promotes the formation of dimers, in which two aqua molecules play the role of "bridges" between two AlClPc molecules. In such dimer, each aqua molecule has two bonds: one coordination bond between its O atom and the Al atom of one of the AlClPc molecules and one hydrogen bond between its H atom and the N atom of another AlClPc molecule. Based on the calculated data obtained, the AlClPc dimers in the DMF medium were assigned to H-aggregates, and in the DMF-water medium, to J-aggregates, respectively.

Prediction of refractive indices and molecular radii of binary mixtures of Polyethylene glycol (PEG-200,400) and cyclic ethers: Insight into molecular interactions

Using five refractive index mixing rules: Lorentz–Lorenz, Gladstone–Dale, Weiner, Heller, and Arago –Biot; refractive indices of six binary polymer mixtures have been determined at 303.15 K, under atmospheric pressure. The binary mixtures investigated here are PEG-200 + 1,3-Dioxolane, PEG-200 + Oxolane, PEG-200 + Oxane, PEG-400 + 1,3-Dioxolane, PEG-400 + Oxolane, and PEG-400 + Oxane. A good agreement has been observed between the obtained results and respective literature data for all these mixtures. The relative merit of refractive index mixing rules is assessed. Deviation in refractive index and reduced free volume values are also calculated using the refractive index data taken from the literature. Furthermore, the molecular radius of these binary polymer mixtures is computed with the help of the refractive index and molar volume data. In addition, an ideal mixing method is also employed to calculate the molecular radius of these systems.The molecular radius of these binary mixtures is found to be additive with respect to the mole fraction of the pure components. Finally, the results are discussed in terms of the intermolecular interactions among the constituent molecules.

Unsupervised segmentation of biomedical hyperspectral image data: tackling high dimensionality with convolutional autoencoders.

Information about the structure and composition of biopsy specimens can assist in disease monitoring and diagnosis. In principle, this can be acquired from Raman and infrared (IR) hyperspectral images (HSIs) that encode information about how a sample's constituent molecules are arranged in space. Each tissue section/component is defined by a unique combination of spatial and spectral features, but given the high dimensionality of HSI datasets, extracting and utilising them to segment images is non-trivial. Here, we show how networks based on deep convolutional autoencoders (CAEs) can perform this task in an end-to-end fashion by first detecting and compressing relevant features from patches of the HSI into low-dimensional latent vectors, and then performing a clustering step that groups patches containing similar spatio-spectral features together. We showcase the advantages of using this end-to-end spatio-spectral segmentation approach compared to i) the same spatio-spectral technique not trained in an end-to-end manner, and ii) a method that only utilises spectral features (spectral k-means) using simulated HSIs of porcine tissue as test examples. Secondly, we describe the potential advantages/limitations of using three different CAE architectures: a generic 2D CAE, a generic 3D CAE, and a 2D convolutional encoder-decoder architecture inspired by the recently proposed UwU-net that is specialised for extracting features from HSI data. We assess their performance on IR HSIs of real colon samples. We find that all architectures are capable of producing segmentations that show good correspondence with HE stained adjacent tissue slices used as approximate ground truths, indicating the robustness of the CAE-driven spatio-spectral clustering approach for segmenting biomedical HSI data. Additionally, we stress the need for more accurate ground truth information to enable a precise comparison of the advantages offered by each architecture.

Infrared Spectroscopy of Li+ Solvation in EmimBF4 and in Propylene Carbonate: Ab Initio Molecular Dynamics and Experiment.

Infrared (IR) spectra of solutions of the lithium salt LiBF4 in the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EmimBF4) and in the organic solvent propylene carbonate (PC) are studied via infrared spectroscopy and ab initio molecular dynamics (AIMD) simulations. The measurements show that the major effects of LiBF4 in both solutions, compared to their neat counterparts, are the appearance of a new broad band in the 300-450 cm-1 frequency region and a broadening of the IR structure in the 900-1200 cm-1 region with the development of a new peak at 980 cm-1. Computational analysis indicates that hindered translational motions of Li+ in its solvation cage are mainly responsible for the former, while the latter is due to Li+-induced structural changes and accompanying vibrational frequency shifts of constituent ions and molecules of the solutions. In addition, molecular motions in these and lower-frequency regions are generally correlated, disclosing the collective nature of the vibrational dynamics, which involve multiple ions/molecules. Herein, a detailed analysis of these features via AIMD simulations of the spectrum and its components arising from auto- and cross-correlations of motions of constituent molecular species, combined with generalized normal modes of the solutions and normal modes of small Li+-containing clusters, is presented. Other minor spectral changes caused by the lithium salt as well as the interaction-induced effect on IR spectra are also discussed.

Metasurface-Enhanced Infrared Spectroscopy: An Abundance of Materials and Functionalities.

Infrared spectroscopy provides unique information on the composition and dynamics of biochemical systems by resolving the characteristic absorption fingerprints of their constituent molecules. Based on this inherent chemical specificity and the capability for label-free, noninvasive, and real-time detection, infrared spectroscopy approaches have unlocked a plethora of breakthrough applicationsfor fields ranging from environmental monitoring and defense to chemical analysis and medical diagnostics. Nanophotonics has played a crucial role for pushing the sensitivity limits of traditional far-field spectroscopy by using resonant nanostructures to focus the incident light into nanoscale hot-spots of the electromagnetic field, greatly enhancing light-matter interaction. Metasurfaces composed of regular arrangements of such resonators further increase the design space for tailoring this nanoscale light control both spectrally and spatially, which has established them as an invaluable toolkit for surface-enhanced spectroscopy. Starting from the fundamental concepts of metasurface-enhanced infrared spectroscopy, a broad palette of resonator geometries, materials, and arrangements for realizing highly sensitive metadevices is showcased, with a special focus on emerging systems such as phononic and 2Dvan der Waals materials, and integration with waveguides for lab-on-a-chip devices. Furthermore, advanced sensor functionalities of metasurface-based infrared spectroscopy, including multiresonance, tunability, dielectrophoresis, live cell sensing, and machine-learning-aided analysis are highlighted.

Combinatorial microRNA Loading into Extracellular Vesicles for Increased Anti-Inflammatory Efficacy.

Extracellular vesicles (EVs) have emerged as promising therapeutic entities in part due to their potential to regulate multiple signaling pathways in target cells. This potential is derived from the broad array of constituent and/or cargo molecules associated with EVs. Among these, microRNAs (miRNAs) are commonly implicated as important and have been associated with a wide variety of EV-induced biological phenomena. While controlled loading of single miRNAs is a well-documented approach for enhancing EV bioactivity, loading of multiple miRNAs has not been fully leveraged to maximize the potential of EV-based therapies. Here, an established approach to extrinsic nucleic acid loading of EVs, sonication, was utilized to load multiple miRNAs in HEK293T EVs. Combinations of miRNAs were compared to single miRNAs with respect to anti-inflammatory outcomes in assays of increasing stringency, with the combination of miR-146a, miR-155, and miR-223 found to have the most potential amongst the tested groups.

Symmetry Breaking Charge Transfer in DNA-Templated Perylene Dimer Aggregates.

Molecular aggregates are of interest to a broad range of fields including light harvesting, organic optoelectronics, and nanoscale computing. In molecular aggregates, nonradiative decay pathways may emerge that were not present in the constituent molecules. Such nonradiative decay pathways may include singlet fission, excimer relaxation, and symmetry-breaking charge transfer. Singlet fission, sometimes referred to as excitation multiplication, is of great interest to the fields of energy conversion and quantum information. For example, endothermic singlet fission, which avoids energy loss, has been observed in covalently bound, linear perylene trimers and tetramers. In this work, the electronic structure and excited-state dynamics of dimers of a perylene derivative templated using DNA were investigated. Specifically, DNA Holliday junctions were used to template the aggregation of two perylene molecules covalently linked to a modified uracil nucleobase through an ethynyl group. The perylenes were templated in the form of monomer, transverse dimer, and adjacent dimer configurations. The electronic structure of the perylene monomers and dimers were characterized via steady-state absorption and fluorescence spectroscopy. Initial insights into their excited-state dynamics were gleaned from relative fluorescence intensity measurements, which indicated that a new nonradiative decay pathway emerges in the dimers. Femtosecond visible transient absorption spectroscopy was subsequently used to elucidate the excited-state dynamics. A new excited-state absorption feature grows in on the tens of picosecond timescale in the dimers, which is attributed to the formation of perylene anions and cations resulting from symmetry-breaking charge transfer. Given the close proximity required for symmetry-breaking charge transfer, the results shed promising light on the prospect of singlet fission in DNA-templated molecular aggregates.

Crystal Prediction via Genetic Algorithms in a Model Chiral System.

Chiral crystals and their constituent molecules play a prominent role in theories about the origin of biological homochirality and in drug discovery, design, and stability. Although the prediction and identification of stable chiral crystal structures is crucial for numerous technologies, including separation processes and polymorph selection and control, predictive ability is often complicated by a combination of many-body interactions and molecular complexity and handedness. In this work, we address these challenges by applying genetic algorithms to predict the ground-state crystal lattices formed by a chiral tetramer molecular model, which we have previously shown to exhibit complex fluid-phase behavior. Using this approach, we explore the relative stability and structures of the model's conglomerate and racemic crystals, and present a structural phase diagram for the stable Bravais crystal types in the zero-temperature limit.

Methanolic Moringa oleifera leaf extract protects against epithelial barrier damage and enteric bacterial translocation in intestinal I/R: Possible role of caspase 3.

Background: Activation of caspase 3 has been implicated in the pathogenesis of I/R injury in various organs, but there is a paucity of data on its role in IIRI. Also, no reports were found on the beneficial role of methanolic Moringa oleifera leaf extract (MMOLE) in IIRI. This study investigated the involvement of caspase 3 in IIRI, and the impact of MMOLE in IIRI. Methods: Male Wistar rats were randomized into five groups; the sham-operated group that was sham-operated and received 0.5 ml of distilled water for 7 days prior to sham surgery, and the IIRI, febuxostat (FEB) +IIRI, low dose MMOLE (LDMO)+IIRI, and high dose MMOLE (HDMO)+IIRI groups that underwent I/R and also received 0.5 ml of distilled water, 10 mg/kg of febuxostat, 200 mg/kg of MMOLE, and 400 mg/kg of MMOLE respectively for 7 days prior to I/R. Markers of hepatic function, oxidative stress, and inflammation as well as enteric bacterial translocation and histoarchitecture integrity of intestinal and hepatic tissues were evaluated. The bioactive components of MMOLE were also determined by GC-MS. Results: As revealed by GC-MS, the active bioactive components of MMOLE were thiosemicarbazone, hydrazine, 1,3-dioxolane, octanoic acid, 1,3-benzenediamine, 9-octadecenoic acid, oleic acid, nonadecanoic acid, 3-undecanone, phosphonic acid, and cyclopentanecarboxylic acid. MMOLE alleviated IIRI-induced rise in intestinal and hepatic injury markers, malondialdehyde, TNF-α, IL-6, and myeloperoxidase activities. MMOLE improved IIRI-induced suppression of reduced glutathione, thiol and non-thiol proteins, and superoxide dismutase, catalase and glutathione peroxidase activities. These were associated with suppression of IIRI-induced caspase 3 activity and bacterial translocation. Histopathological evaluation revealed that MMOLE attenuated IIRI-induced alterations in intestinal and hepatic histoarchitecture integrity. MMOLE also militated against increased absolute and relative intestinal and hepatic weight, intestinal and hepatic injuries, epithelial mucosal barrier dysfunction, and enteric bacterial translocation associated with IIRI by downregulating oxidative stress-mediated activation of caspase 3. Conclusion: IIRI is associated with a rise in caspase 3 activity. Also, MMOLE confers protection against IIRI, possibly due to its constituent bioactive molecules, especially hydrazine, 9-octadecenoic acid, 1,3-dioxolane, oleic acid, and nonadecanoic acid.

Intrinsically chiral ferronematic liquid crystals: An inversion of the helical twist sense at the chiral nematic – Chiral ferronematic phase transition

The ferroelectric nematic phase is a unique example of a polar phase without positional order of the constituent molecules. The properties of the ferronematic phase formed by intrinsically chiral molecules are discussed. Chirality makes the phase structure helical with the similar pitch length in the N* and N F * phases, but with opposite sense. The materials show strong non-linear optical properties. • Intrinsically chiral mesogens forming ferroelectric fluidic nematic, N F *, phase were obtained and studied. • In both, paraelectric and ferroelectric nematic phases, molecular chirality leads to helical structure. • Inversion of helix twist sense was observed at the N*-N F *phase transition. • Giant dielectric permittivity, above 10 4 , was determined in ferroelectric nematic phase. • Strong nonlinear optical properties were confirmed for ferronematic phase. Strongly dipolar mesogenic compounds with a chiral center located in a lateral alkyl chain were synthesized, and shown to form the ferroelectric nematic phase. The presence of molecular chirality induced a helical structure in both the N* and N F * phases, but with opposite helix sense in the two phases. The relaxation frequency of the polar fluctuations is only weakly affected by helical structure, it was found to be slightly lower for the chiral N F * phase than for its achiral, non-branched counterpart with the same lateral chain length.

Sample-shape dependent energy levels in organic semiconductors

Energy levels in an organic semiconductor are mainly determined by the molecular orbital energies of the constituent molecules. Recent studies, however, have revealed that the energy levels can be altered as much as 1 eV by the molecular orientation in the film or the molecular mixing ratio in the binary film, owing to the intermolecular electrostatic interaction. Because of the long-range nature of Coulomb interaction, theory predicts that the electrostatic energy should depend on the sample shape. In this article, we examine the coverage-dependent energy levels of zinc phthalocyanine and per-fluorinated zinc phthalocyanine in the submonolayer region with ultraviolet photoelectron spectroscopy (UPS) and low-energy inverse photoelectron spectroscopy (LEIPS). Using the procedure we reported previously, we separately evaluated the electronic polarization energy and electrostatic energy as a function of coverage. Unlike the electronic polarization, which contributes only as much as 10 meV, the electrostatic energy contributes as much as 120 meV to the coverage-dependent energy shift. We conclude that the shift in energy levels by changing the coverage is attributed to the sample shape-dependent energy level, owing to the long-range nature of the charge--permanent quadrupole interaction.

Restoration of Hepatic and Intestinal Integrity by Phyllanthus amarus Is Dependent on Bax/Caspase 3 Modulation in Intestinal Ischemia-/Reperfusion-Induced Injury.

Ethnopharmacological relevance: Oxidative stress is a key player in intestinal ischemia/reperfusion (I/R) injury (IIRI) with a tendency to trigger systemic inflammatory response, resulting in progressive distal organ injury. To date, the role of Bax/caspase 3 signaling in IIRI has not been reported. Furthermore, the discovery of a safe and effective drug remains pertinent in improving the outcome of IIRI. Therefore, this study investigated the role of Bax/caspase 3 signaling in intestinal I/R-induced intestinal and hepatic injury. In addition, the protective effect and possible associated mechanism of action of methanolic Phyllanthus amarus leaf extract (PA) against intestinal I/R-induced intestinal and hepatic injury were evaluated. Materials and methods: Fifty male Wistar rats were randomized into five groups (n = 10). The sham-operated group was received 0.5 mL of distilled water for seven days prior to the sham surgery, while the IIRI, febuxostat (FEB) + IIRI, low-dose PA (LDPA) + IIRI, and high-dose PA (HDPA) + IIRI groups underwent the I/R procedure. In addition to the procedure, IIRI, FEB + IIRI, LDPA + IIRI, and HDPA + IIRI received 0.5 mL of distilled water, 10 mg/kg of febuxostat, 200 mg/kg of PA, and 400 mg/kg of PA, respectively, for seven days prior to the I/R procedure. Results: Administration of methanolic Phyllanthus amarus leaf extracts attenuated the intestinal I/R-induced rise in intestinal and hepatic injury markers, malondialdehyde, nitric oxide, TNF-α, IL-6, and myeloperoxidase activities. In addition, Phyllanthus amarus ameliorated I/R-induced suppression of reduced glutathione, thiol and non-thiol proteins, and superoxide dismutase, catalase, and glutathione peroxidase activities in intestinal and hepatic tissues. These were coupled with the suppression of I/R-induced bacterial translocation, downregulation of I/R-induced activation of Bax/caspase 3 signaling, and improvement of I/R-induced distortion of intestinal and hepatic histoarchitecture by Phyllanthus amarus. Conclusion: Methanolic Phyllanthus amarus leaf extract protects against intestinal and hepatic injuries associated with intestinal I/R by suppressing oxidative-stress-mediated activation of Bax/caspase 3 signaling. The beneficial effects of Phyllanthus amarus may be ascribed to its constituent bioactive molecules, especially tannins, anthocyanin, alkaloids, and phenolics.

A comparative photophysical study of molecular association of structurally similar phenothiazine dyes in aqueous solutions of caffeine

This paper comparatively reports the role of a molecular additive (caffeine) on the absorption and emission spectral characteristics and molecular association of a series of phenothiazine dyes in aqueous solutions. The studied dyes were five phenothiazine dyes (thionine, azure A, azure B, toluidine blue O, and methylene blue) with strong close molecular structures. The spectral data of the water-caffeine-dye systems were systematically analyzed and discussed based on the chemical structure of the constituent molecules. The aggregate structure and the dimer characteristics were analysed based on the exciton model. The additive was to act as strong water structure-breaker over the range of studied concentration. The main driving force for breaking the dye aggregation is water-caffeine or dye-caffeine interactions at low and moderate caffeine contain. At the high additive concentrations, the caffeine-caffeine, dye-dimer caffeine, and caffeine-water-caffeine might have crucial role in the spectral and aggregation behavior of the dyes. Caffeine induces markedly fluorescence quenching in emission spectra of the studied dyes.

Exploring cell and tissue mechanics with optical tweezers.

Cellular and tissue biosystems emerge from the assembly of their constituent molecules and obtain a set of specific material properties. To measure these properties and understand how they influence cellular function is a central goal of mechanobiology. From a bottoms-up, physics or engineering point-of-view, such systems are a composition of basic mechanical elements. However, the sheer number and dynamic complexity of them, including active molecular machines and their emergent properties, makes it currently intractable to calculate how biosystems respond to forces. Because many diseases result from an aberrant mechanotransduction, it is thus essential to measure this response. Recent advances in the technology of optical tweezers have broadened their scope from single-molecule applications to measurements inside complex cellular environments, even within tissues and animals. Here, we summarize the basic optical trapping principles, implementations and calibration procedures that enable force measurements using optical tweezers directly inside cells of living animals, in combination with complementary techniques. We review their versatility to manipulate subcellular organelles and measure cellular frequency-dependent mechanics in the piconewton force range from microseconds to hours. As an outlook, we address future challenges to fully unlock the potential of optical tweezers for mechanobiology.

The Hypoglycemic Effect of JinQi Jiangtang Tablets Is Partially Dependent on the Palmatine-Induced Activation of the Fibroblast Growth Factor Receptor 1 Signaling Pathway.

JinQi Jiangtang tablet (JQJTT) is a Chinese patent medicine that has been shown to be beneficial for patients with diabetes both preclinically and clinically; however, the molecular mechanism underlying the effects of JQJTT remains unclear. In this study, surface plasmon resonance fishing was employed to identify JQJTT constituent molecules that can specifically bind to fibroblast growth factor receptor 1 (FGFR1), leading to the retrieval of palmatine (PAL), a key active ingredient of JQJTT. In vivo and in vitro experiments demonstrated that PAL can significantly stimulate FGFR1 phosphorylation and upregulate glucose transporter type 1 (GLUT-1) expression, thereby facilitating glucose uptake in insulin resistance (IR) HepG2 cells as well as alleviating hyperglycemia in diabetic mice. Our results revealed that PAL functions as an FGFR1 activator and that the hypoglycemic effect of JQJTT is partially dependent on the PAL-induced activation of the FGFR1 pathway. In addition, this study contributed to the understanding the pharmacodynamic basis and mechanism of action of JQJTT and provided a novel concept for future research on PAL.