Upconversion Emission Enhancement in Yb³⁺/Er³⁺-Codoped Y₂O₃ Nanocrystals by Tridoping with Li⁺ Ions

We demonstrate that tridoping with Li+ ions enhances the visible green and red upconversion (UC) emissions in Er3+/Yb3+-codoped Y2O3 nanocrystals by up to half of the bulk counterpart, i.e., about 2 orders of magnitude higher than previous results. X-ray diffraction and decay time investigations give evidence that tridoping with Li+ ions can tailor the local crystal field of the Y2O3 host lattice. Theoretical calculations illustrate well that a significant UC intensity enhancement arises from the synthesized tailoring effect induced by the Li+ ions, which increase lifetimes in the intermediate 4I11/2 (Er) and 2F5/2 (Yb) states, increase optically active sites in the Y2O3 host lattice, and dissociate the Yb3+ and Er3+ ion clusters in the nanocrytals. The general theoretical description of the visible UC radiations shows that the Yb3+ ion sensitization and the tailoring effect induced by the Li+ ions are two independent enhancement mechanisms, which is expected to lead to an increasing number of photonic and biomedical applications in the future

Postoperative hypodynamia of lower limbs due to lumbar disc herniation in the presence of a tethered cord

Postoperative hypodynamia of lower limbs due to lumbar disc herniation in the presence of a tethered cor

Photoisomerization of Heptamethine Cyanine Dyes Results in Red-Emissive Species: Implications for Near-IR, Single-Molecule, and Super-Resolution Fluorescence Spectroscopy and Imaging

Photoisomerization kinetics of the near-infrared (NIR) fluorophore Sulfo-Cyanine7 (SCy7) was studied by a combination of fluorescence correlation spectroscopy (FCS) and transient state (TRAST) excitation modulation spectroscopy. A photoisomerized state with redshifted emission was identified, with kinetics consistent with a three-state photoisomerization model. Combining TRAST excitation modulation with spectrofluorimetry (spectral-TRAST) further confirmed an excitation-induced redshift in the emission spectrum of SCy7. We show how this red-emissive photoisomerized state contributes to the blinking kinetics in different emission bands of NIR cyanine dyes, and how it can influence single-molecule, super-resolution, as well as Förster resonance energy transfer (FRET) and multicolor readouts. Since this state can also be populated at moderate excitation intensities, it can also more broadly influence fluorescence readouts, also readouts not relying on high excitation conditions. However, this additional red-emissive state and its photodynamics, as identified and characterized in this work, can also be used as a strategy to push the emission of NIR cyanine dyes further into the NIR and to enhance photosensitization of nanoparticles with absorption spectra further into the NIR. Finally, we show that the photoisomerization kinetics of SCy7 and the formation of its redshifted photoisomer depend strongly on local environmental conditions, such as viscosity, polarity, and steric constraints, which suggests the use of SCy7 and other NIR cyanine dyes as environmental sensors. Such environmental information can be monitored by TRAST, in the NIR, with low autofluorescence and scattering conditions and on a broad range of samples and experimental conditions

Fluorescence Bar-Coding and Flowmetry Based on Dark State Transitions in Fluorescence Emitters

Reversible dark state transitions in fluorophores represent a limiting factor in fluorescence-based ultrasensitive spectroscopy, are a necessary basis for fluorescence-based super-resolution imaging, but may also offer additional, largely orthogonal fluorescence-based readout parameters. In this work, we analyzed the blinking kinetics of Cyanine5 (Cy5) as a bar-coding feature distinguishing Cy5 from rhodamine fluorophores having largely overlapping emission spectra. First, fluorescence correlation spectroscopy (FCS) solution measurements on mixtures of free fluorophores and fluorophore-labeled small unilamellar vesicles (SUVs) showed that Cy5 could be readily distinguished from the rhodamines by its reversible, largely excitation-driven trans–cis isomerization. This was next confirmed by transient state (TRAST) spectroscopy measurements, determining the fluorophore dark state kinetics in a more robust manner, from how the time-averaged fluorescence intensity varies upon modulation of the applied excitation light. TRAST was then combined with wide-field imaging of live cells, whereby Cy5 and rhodamine fluorophores could be distinguished on a whole cell level as well as in spatially resolved, multiplexed images of the cells. Finally, we established a microfluidic TRAST concept and showed how different mixtures of free Cy5 and rhodamine fluorophores and corresponding fluorophore-labeled SUVs could be distinguished on-the-fly when passing through a microfluidic channel. In contrast to FCS, TRAST does not rely on single-molecule detection conditions or a high time resolution and is thus broadly applicable to different biological samples. Therefore, we expect that the bar-coding concept presented in this work can offer an additional useful strategy for fluorescence-based multiplexing that can be implemented on a broad range of both stationary and moving samples

Excitation Pulse Duration Response of Upconversion Nanoparticles and Its Applications

Lanthanide-doped upconversion nanoparticles (UCNPs) have rich photophysics exhibiting complex luminescence kinetics. In this work, we thoroughly investigated the luminescence response of UCNPs to excitation pulse durations. Analyzing this response opens new opportunities in optical encoding/decoding and the assignment of transitions to emission peaks and provides advantages in applications of UCNPs, e.g., for better optical sectioning and improved luminescence nanothermometry. Our work shows that monitoring the UCNP luminescence response to excitation pulse durations (while keeping the duty cycle constant) by recording the average luminescence intensity using a low-time resolution detector such as a spectrometer offers a powerful approach for significantly extending the utility of UCNPs

Some Insights into the Stereochemistry of Inhibition of Macrophage Migration Inhibitory Factor with 2-Fluoro-<i>p</i>-hydroxycinnamate and Its Analogues from Molecular Dynamics Simulations

Macrophage migration inhibitory factor (MIF) exhibits tautomerase activity on phenylpyruvate and has E-stereochemistry preference. To investigate the binding modes of its competitive inhibitors and evaluate their binding affinities, molecular dynamics simulations together with MM-PBSA (molecular mechanics Poisson−Boltzmann surface area) analysis were performed on MIF complexed with (E)-2-fluoro-p-hydroxycinnamate and five analogues. Pro-1 was discovered to form a bifurcated hydrogen bond between its protonated nitrogen and carboxylate oxygens of E-ligands and Tyr-36. No hydrogen bonds were found between Pro-1 and Z-ligands. This distinct binding characteristic of E- and Z-ligands with Pro-1 may be the main factor for the large difference in their binding affinities, which is consistent with the previous report that Pro-1 is essential for the catalytic activity of MIF. MM-PBSA analysis revealed that energy components including van der Waals, electrostatic, and hydrophobic interactions are in favor of binding, among which electrostatic interactions are predominant to the binding affinity difference

Data_Sheet_1_Prognostic Impact of Blood Pressure Change Patterns on Patients With Aortic Dissection After Admission.pdf

ObjectivesHypertension is a predominant risk factor for aortic dissection (AD), and blood pressure (BP) control plays a vital role in the management of AD. However, the correlation between BP change and the prognosis for AD remains unclear. This study aims to demonstrate the impact of BP change patterns on AD prognosis.MethodsThis retrospective study included AD patients at two institutions (Shanghai Ninth People's Hospital Affiliated with Shanghai Jiao Tong University School of Medicine and the Vascular Department of the First Affiliated Hospital of Anhui Medical University) between 2004 and 2018. The systolic BP (SBP) change patterns of these patients were analyzed by functional data analysis (FDA). The relationship between BP change patterns and the risk of adverse events (AEs) was assessed using survival analysis.ResultsA total of 458 patients with AD were eligible for analysis. The logistic regression analysis indicated that compared with that in patients with low SBP variation (SBPV), the incidence of AEs in patients with high SBPV was significantly higher (35.84 vs. 20.35%, OR 2.19, P ConclusionsThis study classified AD patients into four groups according to the SBP change patterns the first 30 min following admission, of which those with accelerating rises in SBP are at the highest risk of AEs, while those with decelerating drops have the best prognosis in the first 24 h after admission. Clinical practitioners may benefit from analyzing patterns of in-hospital SBP.</p

Epigenetic target identification strategy based on multi-feature learning

The identification of potential epigenetic targets for a known bioactive compound is essential and promising as more and more epigenetic drugs are used in cancer clinical treatment and the availability of chemogenomic data related to epigenetics increases. In this study, we introduce a novel epigenetic target identification strategy (ETI-Strategy) that integrates a multi-task graph convolutional neural network prior model and a protein-ligand interaction classification discriminating model using large-scale bioactivity data for a panel of 55 epigenetic targets. Our approach utilizes machine learning techniques to achieve an AUC value of 0.934 for the prior model and 0.830 for the discriminating model, outperforming inverse docking in predicting protein-ligand interactions. When comparing with other open-source target identification tools, it was found that only our tool was able to accurately predict all the targets corresponding to each compound. This further demonstrates the ability of our strategy to take full advantage of molecular-level information as well as protein-level information in molecular activity prediction. Our work highlights the contribution of machine learning in the identification of potential epigenetic targets and offers a novel approach for epigenetic drug discovery and development. Communicated by Ramaswamy H. Sarma</p

Frequency-Domain Method for Characterization of Upconversion Luminescence Kinetics

The frequency-domain (FD) method provides an alternative to the commonly used time-domain (TD) approach in characterizing the luminescence kinetics of luminophores, with its own strengths, e.g., the capability to decouple multiple lifetime components with higher reliability and accuracy. While extensively explored for characterizing luminophores with down-shifted emission, this method has not been investigated for studying nonlinear luminescent materials such as lanthanide-doped upconversion nanoparticles (UCNPs), featuring more complicated kinetics. In this work, employing a simplified rate-equation model representing a standard two-photon energy-transfer upconversion process, we thoroughly analyzed the response of the luminescence of UCNPs in the FD method. We found that the FD method can potentially obtain from a single experiment the effective decay rates of three critical energy states of the sensitizer/activator ions involved in the upconversion process. The validity of the FD method is demonstrated by experimental data, agreeing reasonably well with the results obtained by TD methods