Sterically Hindered Tetradentate [Pt(O

Described here are sterically hindered tetradentate [Pt(O^N^C^N)] emitters (Pt-1, Pt-2, and Pt-3) developed for stable and high-performance green phosphorescent organic light-emitting diodes (OLEDs). These Pt(II) emitters exhibit strong saturated green phosphorescence (λmax = 517-531 nm) in toluene and mCP thin films with emission quantum yields as high as 0.97, radiative rate constants (kr) as high as 4.4-5.3 × 105 s-1 and reduced excimer emission, and with a preferential horizontally oriented transition dipole ratio of up to 84%. Theoretical calculations show that p-(hetero)arene substituents at the periphery of the ligand scaffolds in Pt-1, Pt-2, and Pt-3 can i) enhance the spin-orbit coupling (SOC) between the lower singlet excited states and the T1 state, and S0→Sn (n = 1 or 2) transition dipole moment, and ii) introducing additional SOC activity and the bright 1ILCT[π(carbazole)→π*(N^C^N)] excited state (Pt-2 and Pt-3), which are the main contributors to the increased kr values. Utilizing these tetradentate Pt(II) emitters, green phosphorescent OLEDs are fabricated with narrow-band electroluminescence (FWHM down to 36 nm), high external quantum efficiency, current efficiency up to 27.6% and 98.7 cd A-1, and an unprecedented device lifetime (LT95) of up to 9270 h at 1000 cd m-2 under laboratory conditions.

Self-feedback loop-containing synthetic mRNA switches for controlled microRNA sensing.

Synthetic mRNA switches are powerful cell fate manipulation tools that sense cellular input molecules to directly control protein expression at the translational level. The lack of available switch designs that can mimic the natural sophisticated protein regulation is a fundamental issue that limits the application of synthetic mRNA switches. Here we report a new set of synthetic mRNA switches by incorporating self-feedback loop machineries to dynamically control protein expression levels upon sensing cellular microRNAs. We redesigned the coding region of the switch to express output protein along with mRNA regulatory proteins. RNA-binding proteins (RBPs) and RBP-binding RNA motifs (aptamers) guide the regulatory proteins to act on their own mRNAs, enhancing or flattening the effect of microRNA sensing. Importantly, we demonstrated that the switches with the positive feedback feature can enlarge a high-or-low microRNA effect into a nearly all-or-none pattern, substantially boosting the use of synthetic mRNA switches as high-performance microRNA sensors or binary cell regulation tools. We believe these novel mRNA switch designs provide new strategies to construct complex mRNA-based genetic circuits for future molecular sensing and cell engineering.

Reproducibility of Foveal Avascular Zone and Superficial Macular Retinal Vasculature Measurements in Healthy Eyes Determined by Two Different Scanning Protocols of Optical Coherence Tomography Angiography.

PURPOSE: To assess the reproducibility of quantitative measurements of the foveal avascular zone (FAZ) and retinal vasculature determined by different scanning protocols of optical coherence tomography angiography (OCTA) in healthy volunteers. METHOD: All participants were scanned by two trained operators using an AngioPlex OCTA. Both angiography protocols (6 × 6 mm and 3 × 3 mm) were performed three times on the same eye by operator A and one additional time by operator B. The FAZ area and perimeter, retinal vessel length density (VLD) and perfusion density (PD) of different regions were analysed. RESULTS: Fifty-two eyes from 52 subjects were recruited for this study. The repeated measurements of FAZ, VLD, and PD parameters obtained by the same operator, as well as by different operators, were not significantly different when the same protocol was used (p > 0.05). The intra- and inter-operator intraclass correlation coefficients (ICCs) of the FAZ and central VLD and PD parameters (range, 0.99-0.95) were better than the intra- and inter-operator ICCs of VLD and PD in the inner and outer rings (range, 0.86-0.90). The FAZ area, perimeter, and VLDs obtained by the 3 × 3 mm protocol were larger than those obtained by the 6 × 6 mm protocol (p < 0.01), but the PDs obtained by the 3 × 3 mm protocol were smaller than those obtained by the 6 × 6 mm protocol (p < 0.001). All of the corresponding parameters obtained by the two protocols were positively correlated (r = 0.64-0.99, p < 0.001). CONCLUSION: Both the 6 × 6 and 3 × 3 mm protocols of the AngioPlex OCTA provide good reproducibility for assessing the FAZ and superficial retinal vasculature. However, the values obtained by these different protocols cannot be compared directly.

VPg-based bidirectional synthetic mRNA circuits enable orthogonal protein regulation for high-resolution cell separation.

Synthetic mRNA circuits commonly sense input to produce binary output signals for cell separation. Based on virus-origin cap-independent translation initiation machinery and RBP-aptamer interaction, we designed smart synthetic mRNA-based circuits that sense single input molecules to bidirectionally tune output signals in an orthogonal manner, enabling high-resolution separation of cell populations.

Color-Tunable Organic Light-Emitting Diodes with Single Pt (O

Color-tunable organic light-emitting diodes (CT-OLEDs) have a large color-tuning range, high efficiency and operational stability at practical luminance, making them ideal for human-machine interactive terminals of wearable biomedical devices. However, the device operational lifetime of CT-OLEDs is currently far from reaching practical requirements. To address this problem, a tetradentate Pt(II) complex named tetra-Pt-dbf, which can emit efficiently in both monomer and aggregation states, is designed. This emitter has high Td of 508 °C and large intermolecular bonding energy of -52.0 kcal mol⁻1, which improve its thermal/chemical stability. This unique single-emitter CT-OLED essentially avoids the "color-aging issue" and achieves a large color-tuning span (red to yellowish green) and a high external quantum efficiency （EQE） of ≈30% at 1000 cd m-2 as well as an EQE of above 25% at 10000 cd m-2. A superior LT90 operational lifetime of 520,536 h at a functional luminance of 100 cd m-2, which is over 20 times longer than the state-of-the-art CT-OLEDs, is estimated. To demonstrate the potential application of such OLEDs in wearable biomedical devices, a simple electromyography (EMG)-visualization system is fabricated using the CT-OLEDs.

Catalytic formation of ketones from unactivated esters through rhodium chelation-assisted C-O bond activation.

A new method for building aryl aryl ketones containing heterocyclic rings through chelation-assisted C-O bond activation catalyzed by a rhodium complex has been developed. In this reaction, methyl quinoline-8-carboxylate, methyl quinoxaline-5-carboxylate, and their derivatives were reacted with an excess amount of a substituted phenyl boronic acid in the presence of a rhodium(I) complex to give substituted phenyl(quinolin-8-yl)methanone, phenylquinoxalin-5-ylmethanone, and their derivatives in medium to high yields. The current method offers a highly favorable synthetic pathway to efficiently build related drugs with an 8-benzoylquinoline core structure. This method may prove especially valuable for medicinal chemists for the late-stage introduction of versatile ketone moieties into complex scaffolds for diversity-oriented synthetic strategies.

Dual Input-Controlled Synthetic mRNA Circuit for Bidirectional Protein Expression Regulation.

Synthetic mRNA circuits manipulate cell fate by controlling output protein expression via cell-specific input molecule detection. Most current circuits either repress or enhance output production upon input binding. Such binary input-output mechanisms restrict the fine-tuning of protein expression to control complex cellular events. Here we designed mRNA circuits using enhancer/repressor modules that were independently controlled by different input molecules, resulting in bidirectional output regulation; the maximal enhancement over maximal repression was 57 fold. The circuit either enhances or represses protein production in different cells based on the difference in the expression of two microRNAs. This study examined novel bidirectional circuit designs capable of fine-tuning protein production by sensing multiple input molecules. It also broadened the scope of cell manipulation by synthetic mRNA circuits, facilitating the development of mRNA circuits for precise cell manipulation and providing cell-based solutions to biomedical problems.

Higher contrast thresholds for vanishing optotype recognition in macular visual fields among glaucoma patients: a structure-function analysis.

BACKGROUND/AIMS: We aimed to explore the impact of glaucomatous macular damage, specifically retinal ganglion cell (RGC) loss, on macular pattern vision measured by the vanishing optotype (VO) recognition contrast threshold. METHODS: Seventy-two patients (mean age, 33.51±7.05 years) with primary open-angle glaucoma and 36 healthy controls (mean age, 30.25±6.70 years) were enrolled. VO recognition contrast thresholds of each participant were measured at the 16 preset test locations covering the central 5° visual field (VF). Macular sensitivity (MS) was tested by macular threshold test of Humphrey Field Analyzer. Macular RGC plus inner plexiform layer (GCIPL) thickness was also measured by spectral domain optical coherence tomography. RESULTS: The VO contrast threshold demonstrated weak-to-moderate correlations (rho=-0.275 to -0.653) with MS (p<0.001). There was a significantly higher VO contrast threshold in glaucoma group (p<0.0001). At similar levels of MS, patients with glaucoma with GCIPL damage showed remarkably higher VO contrast thresholds than those with preserved GCIPL (p=0.0079). The structure-function relationships between VO contrast threshold and GCIPL thickness (rho=-0.725 to -0.802) were remarkably stronger than those between MS and GCIPL thickness (rho=0.210 to 0.448). VO contrast threshold showed stronger correlation with average GCIPL thickness (rho=-0.362 to -0.778) than MS (rho=0.238 to 0.398) at multiple test locations in glaucoma group. CONCLUSIONS: Glaucomatous eyes have higher contrast thresholds for VO recognition in fovea-around VF. Stronger structure-function relationships indicate that VO contrast threshold is more vulnerable to RGC damage.