Red Dots Research Articles

π-Pimer, π-Dimer, π-Trimer, and 1D π-Stacks in a Series of Benzene Triimide Radical Anions: Substituent-Modulated π Interactions and Physical Properties in Crystalline State

π-Pimer, π-Dimer, π-Trimer, and 1D π-Stacks in a Series of Benzene Triimide Radical Anions: Substituent-Modulated π Interactions and Physical Properties in Crystalline State

Quantum Dot-Based White Organic Light-Emitting Diodes Excited by a Blue OLED

In this study, white organic light-emitting diodes (OLEDs) consisting of red quantum dots (RQD) and green quantum dots (GQD) were investigated. These are the most exciting new lighting technologies that have grown rapidly in recent years. The white OLED development processes used consisted of the following methods: (a) fabrication of a blue single-emitting layer OLED, (b) nanoimprinting into QD photoresists, and (c) green and red QD photoresists as color conversion layers (CCL) excited by blue OLEDs. To fabricate the blue OLED, the HATCN/TAPC pair was selected for the hole injection/transport layer on ITO and TPBi for the electron transport layer. For blue-emitting material, we used a novel polycyclic framework of thermally activated delayed fluorescence (TADF) material, ν-DABNA, which does not utilize any heavy metals and has a sharp and narrow (FWHM 28 nm) electroluminescence spectrum. The device structure was ITO/HATCN (20 nm)/TAPC (30 nm)/MADN: ν-DABNA (40 nm)/TPBi (30 nm)/LiF (0.8 nm)/Al (150 nm) with an emitting area of 1 cm × 1 cm. The current density, luminance, and efficiency of blue OLEDs at 8 V are 87.68 mA/cm2, 963.9 cd/m2, and 1.10 cd/A, respectively. Next, the bottom emission side of the blue OLED was attached to nanoimprinted RQD and GQD photoresists, which were excited by the blue OLED in order to generate an orange and a green color, respectively, and combined with blue light to achieve a nearly white light. In this study, two different excitation architectures were tested: BOLED→GQD→RQD and BOLED→RQD→GQD. The EL spectra showed that the BOLED→GQD→RQD architecture had stronger green emissions than BOLED→RQD→GQD because the blue OLED excited the GQD PR first then RQD PR. Due to the energy gap architectures in BOLED-GQD-RQD, the green QD absorbed part of the blue light emitted from the BOLED, and the remaining blue light penetrated the GQD to reach the RQD. These excited spectra were very close to the white light, which resulted in three peaks emitting at 460, 530, and 620 nm. The original blue CIE coordinates were (0.15, 0.07). After the excitation combination, the CIE coordinates were (0.42, 0.33), which was close to the white light position.

Red Dot Commenting System in CGH – Past, Present and Future

Red Dot Commenting System in CGH – Past, Present and Future

Solid-Phase Synthesis of Red Fluorescent Carbon Dots for the Dual-Mode Detection of Hexavalent Chromium and Cell Imaging.

The excellent optical properties and biocompatibility of red fluorescence carbon dots (R-CDs) provide a new approach for the effective analysis of hexavalent chromium Cr(VI) in environmental and biological samples. However, the application of R-CDs is still limited by low yield and unfriendly synthesis route. In this study, we developed a new type of R-CDs based on a simple and green solid-phase preparation strategy. The synthesized R-CDs can emit bright red fluorescence with an emission wavelength of 625 nm and also have an obvious visible light absorption capacity. Furthermore, the absorption and fluorescence signals of the R-CDs aqueous solution are sensitive to Cr(VI), which is reflected in color change and fluorescence quenching. Based on that, a scanometric and fluorescent dual-mode analysis system for the rapid and accurate detection of Cr(VI) was established well within the limit of detection at 80 nM and 9.1 nM, respectively. The proposed methods also possess high specificity and were applied for the detection of Cr(VI) in real water samples. More importantly, the synthesized R-CDs with good biocompatibility were further successfully applied for visualizing intracellular Cr(VI) in Hela cells.

A design of red emission CDs-based aptasensor for sensitive detection of insulin via fluorescence resonance energy transfer

We successfully designed an aptasensor based on the red emission carbon dots (R-CDs) and effectively detected insulin (INS) via fluorescence resonance energy transfer (FRET). In the process, the aptamer (apt) labeled with R-CDs (R-CDs@apt) was used as fluorescence donor and graphene oxide (GO) was used as fluorescence receptor. The successful detection due to the aptamer sequence has a certain affinity for Go and INS, while the affinity for INS is stronger than that of GO. When INS is not added to the detection system, the aptamer is adsorbed onto the surface of GO, shortening the distance between R-CDs@apt and GO, resulting in FRET and the quenching of fluorescence of R-CDs@apt. When INS was added to the detection system, the aptamer selectively bound INS and separated from the adsorption of GO, FRET gradually disappeared and the fluorescence of R-CDs@apt/GO/INS system was restored. By comparing the changes of fluorescence intensity before and after adding INS, the detection of INS was implemented. The aptasensor has a good linear curve with the detection limit of as low as 1.1 nM when the concentration of INS reached 1.3–150 nM. This method has excellent selectivity and anti-interference. Therefore, it is a potential method for detecting substances in biological fluids.

Small Molecule NIR‐II Dyes for Switchable Photoluminescence via Host –Guest Complexation and Supramolecular Assembly with Carbon Dots

Small molecular NIR‐II dyes are highly desirable for various biomedical applications. However, NIR‐II probes are still limited due to the complex synthetic processes and inadequate availability of fluorescent core. Herein, the design and synthesis of three small molecular NIR‐II dyes are reported. These dyes can be excited at 850–915 nm and emitted at 1280–1290 nm with a large stokes shift (≈375 nm). Experimental and computational results indicate a 2:1 preferable host–guest assembly between the cucurbit[8]uril (CB) and dye molecules. Interestingly, the dyes when self‐assembled in presence of CB leads to the formation of nanocubes (≈200 nm) and exhibits marked enhancement in fluorescence emission intensity (Switch‐On). However, the addition of red carbon dots (rCDots, ≈10 nm) quenches the fluorescence of these host–guest complexes (Switch‐Off) providing flexibility in the user‐defined tuning of photoluminescence. The turn‐ON complex found to have comparable quantum yield to the commercially available near‐infrared fluorophore, IR‐26. The aqueous dispersibility, cellular and blood compatibility, and NIR‐II bioimaging capability of the inclusion complexes is also explored. Thus, a switchable fluorescence behavior, driven by host–guest complexation and supramolecular self‐assembly, is demonstrated here for three new NIR‐II dyes.

Red emissive N–S co-doped carbon dots for live imaging of tumor spheroid in the microfluidic device

Here, we present a one-pot, water-based synthesis of red emissive biocompatible carbon dots (R-CDs) for live bioimaging of U87 microglia tumor spheroids produced in a microwell-based microfluidic device. R-CDs were synthesized by the hydrothermal method, using thiourea and para-phenylenediamine as the starting precursors. The mold of the microfluidic platform was produced by a lab-made high-resolution optical 3D printer and CNC micro-milling. The optical and physical properties of synthesized R-CDs were validated by different analytical methods such as fluorescent and absorption spectroscopy, FT-IR, DLS, and TEM. The prepared R-CDs emit red light with a maximum fluorescent wavelength of 584 nm. The prepared R-CD has low cytotoxicity and has been successfully applied for staining the glioblastoma spheroid without any fixation step. Therefore, it is a promising fluorescent probe in live 3D cell imaging.

Pressure-Induced Bifurcation in the Photoluminescence of Red Carbon Quantum Dots: Coexistence of Emissions from Surface Groups and Nitrogen-Doped Cores.

Carbon quantum dots (CDs) with favorable fluorescent properties have stimulated considerable effort to modulate their photoluminescence (PL) for bioimaging and sensing. However, the fluorescent mechanisms are still only partially understood due to the diverse physicochemical properties of CDs prepared by various synthesis methods and postpreparation processes. In this report, pressure-induced bifurcation of PL is reported in red carbon quantum dots (R-CDs) for the first time. The splitting of PL into an irreversible blue-shifted peak and a reversible red-shifted peak under pressure suggests the coexistence of multiple fluorescent mechanisms in R-CDs, i.e., emissions from surface groups and nitrogen-doped cores. The concentration and excitation laser energy dependencies of pressure-induced bifurcation, as well as the time-resolved PL, further support the coexistence of multiple emitters. Our results provide a method for distinguishing between the different fluorescent mechanisms related to surface groups and carbon cores in CDs.

Analysis of Mn2+ and Zn2+ Ions in Macroalgae with Heteroelement-Doped Carbon-Based Fluorescent Probe.

Kelp and laver are large economic macroalgae in China, which are rich in nutrients, especially Mn and Zn. Excessive intake of Mn and Zn can be harmful to the human body. Therefore, it is necessary to develop a convenient and efficient method to detect the contents of Mn and Zn in macroalgae. In this experiment, red carbon dots (R-CDs) doped with N and S elements were prepared by the thermal solvent method. The obtained R-CDs displayed excitation wavelength-independent fluorescent emission in the red spectral region. The R-CDs were used to construct a fluorescent probe for specific recognition of Mn2+ and Zn2+, achieving high-sensitivity detection of Mn2+ and Zn2+. The detection results showed a good linear relationship between fluorescence intensity and Mn2+ concentration, and the calculated detection limit was 0.23 nmol/L. For the detection of Zn2+, the detection limit was estimated as 19.1 nmol/L. At the same time, the content distribution of Mn and Zn elements in macroalgae produced in Fujian was investigated by the constructed fluorescence probe. It was found that kelp, laver, and their products are rich in Mn and Zn elements, and the content of Mn and Zn elements in laver is higher than that in kelp, which can be used as the optimal food supplement for Mn and Zn elements.

Broadband nonlinear optical properties of red fluorescent carbon dots

Carbon dots (CDs) provide ideal platforms for applications in bioimaging, sensing, and photocatalysis. Herein, a new type of red fluorescent carbon dot (RCD) is successfully synthesized, and its broadband nonlinear optical (NLO) properties are systematically characterized. The nonlinear absorption coefficient (αNL) values of the RCDs at 580, 630, 650, 1064 nm are − 0.65, −3.09, −4.02, and 0.14 cm/GW, respectively. The nonlinear absorption transforms from saturable absorption to two-photon absorption in the near-infrared domain. We demonstrate the application of the RCDs for imaging Hela cells. Our results indicate that the synthesized RCDs with a broadband NLO response exhibit potential applications in saturable absorbers and deep-tissue imaging.

TCNQ-based organic cocrystal integrated red emission and n-type charge transport

Simultaneously realizing the optical and electrical properties of organic materials is always challenging. Herein, a convenient and promising strategy for designing organic materials with integrated optoelectronic properties based on cocrystal engineering has been put forward. By selecting the fluorene (Flu) and the 7,7′,8,8′-tetracyanoquinodimethane (TCNQ) as functional constituents, the Flu-TCNQ cocrystal prepared shows deep red emission at 702 nm, which is comparable to the commercialized red quantum dot. The highest electron mobility of organic field-effect transistor (OFET) based on Flu-TCNQ is 0.32 cm2 V−1 s−1. Spectroscopic analysis indicates that the intermolecular driving force contributing to the co-assembly of Flu-TCNQ is mainly charge transfer (CT) interaction, which leads to its different optoelectronic properties from constituents.Graphical

Examination of Subungual Hematomas and Subungual Melanocytic Lesions by Using Optical Coherence Tomography and Dermoscopy

Introduction: Examination of subungual pigmented lesions is sometimes a diagnostic challenge for clinicians. Objectives: The study was aimed to investigate characteristic patterns in optical coherence tomography (OCT) of subungual hematomas and determine distinctive features that can differentiate them from subungual melanocytic lesions. Methods: VivoSight® (Michelson Diagnostics, Maidstone, UK) was used to examine 71 subungual hematomas and 11 subungual melanocytic lesions in 69 patients (18 female and 51 male patients). Results: On OCT, bleeding was related to sharply defined black sickle-shaped (p < 0.001) or globular regions (not significant [ns]) with a hyperreflective margin (0.002), a grey center (0.013), hyperreflective lines in the area (ns) or periphery (p = 0.031), peripheral fading (p = 0.029), and red dots in the area (p = 0.001). In the 1 case of melanoma in situ examined, we found curved vessels with irregular sizes and distribution on the dermis of the nailbed, while subungual hematomas and subungual benign nevi presented as clustered red dots and/or regularly distributed curved vessels. Conclusion: Our findings indicate that the use of OCT in addition to dermoscopy provides high-resolution optical imaging information for the diagnosis of subungual hematoma and facilitates the differential diagnosis of subungual hematomas and subungual melanocytic lesions.

FC 114: Monoclonal Gammopathy in Kidney Transplanted Patients: Novel Insights into Long-Term Outcomes

Abstract BACKGROUND AND AIMS As in the general population the prevalence of monoclonal gammopathies (MG) in kidney transplant (KT) candidates increases with age. Little is known about the epidemiology and long-term consequences of MG on overall survival, graft outcomes and infectious and neoplastic complications in patients undergoing KT. METHOD We retrospectively identified patients with MG at the time of transplant (KTMG) or appearing de novo after the KT (DNMG) in 3059 patients who underwent a KT from January 2007 to June 2019 at Necker Hospital Paris (N = 1978) and from January 1998 to December 2017 at CHU Poitiers, France (N = 1081). Using a propensity score, we established a control cohort of KTMG from Necker Hospital, matched on the main covariates influencing post KT outcomes. RESULTS We identified 70 (2.3%) KTMG and 114 (3.7%) DNMG patients, presenting with identical demographic characteristics except for an older age in KTMG (62 versus 57 years; P = 0.03). MG isotypes among the 184 KT recipients with MGUS were IgG (n = 117, 64%), IgA (n = 16, 9%) or IgM (n = 16, 9%). Interestingly, DNMG patients presented more frequently with bi- or triclonal MG than KTMG patients (n = 28, 25% versus n = 7, 10%, respectively; P = 0.02). At the time of KT, among 62 patients with available sFLC measurement in KTMG, 11 (17%) had an abnormal kappa/lambda ratio. Because of systematic evaluation of SPEP during follow-up, we observed that MG disappeared during follow up more frequently in DNMG compared to KTMG (n = 51, 45% versus n = 17, 24%, respectively; P = 0.007). Figure 1 represents the results of SPEP during follow-up. FIGURE 1: Monoclonal gammopathy timescale. Serum protein electrophoresis follow-up from KT;each patient is represented by one line. Blueand green lines represent negative SPEP, performed before and after the detection of MG, and red lines represent positive SPEP with MG identification. Clinical last follow-up is represented by dots: red dot for death, blue dot for graft loss and green dot for last follow-up alive with functional graft. Overall survival was poorer in KTMG than in DNMG (87 versus 176 months; P &amp;lt; 0.001). Cox model including age, sex, rank of transplantation and KTMG or DNMG revealed that age, rank of transplantation and KTMG were independent risk factors for death. Graft survival, occurrence of rejection and haematological complications were comparable between the two groups. To better evaluate the effect of MGUS at the time of KT, KTMG patients from Necker Hospital were compared with matched KT recipients. There was no difference between KTMG and controls regarding the main baseline predictors of post-KT outcomes except for lower level of residual gammaglobulins [7.5 g/L (IQR 6–9.9)] in KTMG versus 10.7 g/l (IQR 8.9–13.1) in controls (P &amp;lt; 0.0001). KTMG patients developed more frequently solid cancers (15% versus 5%; P = 0.04) and bacterial infections (63% versus 48%; P = 0.08). There was no significant difference regarding survival, frequency of rejection or haematological complications. However, KTMG patients with an abnormal kappa/lambda ratio at the time of KT tended to have poorer overall survival than those with normal kappa/lambda ratio and controls (respective medians 72, 87 and 103 months; P = 0.08) (Figure 2). CONCLUSION We report here the largest cohort of KT recipients who underwent systematic SPEP screening at the time of KT and yearly during post-transplant follow-up. We observed that MGUS prevalence in KT candidates is close to that reported in the general population. We confirm that outcomes of patients harboring MGUS at the time of KT are similar to those of matched controls without MGUS, supporting that MGUS should not be a contraindication for KT. Nevertheless, we observed that KTMG patients developed more frequently and earlier solid cancers and infections, suggesting that MGUS is associated with a relative immunodeficiency in these patients. We also showed that patients with abnormal sFLC kappa/lambda ratio experienced poor outcomes, claiming for systematic measurement of sFLC in the pre-KT workup. Clinical last follow-up is represented by dots: red dot for death, blue dot for graft loss and green dot for last follow-up alive with functional graft.

Cadmium‐Doped Zinc Sulfide Shell as a Hole Injection Springboard for Red, Green, and Blue Quantum Dot Light‐Emitting Diodes (Adv. Sci. 15/2022)

Cadmium-Doped Zinc Sulfide Shell as a Hole Injection Springboard In article number 2104488, Zhao Chen, Shuming Chen, Wai-Yeung Wong, and co-workers design an outermost cadmium-doped zinc sulfide shell, which can be used as a hole injection springboard and makes the hole to be easily injected into quantum dot emissive layers step-by-step. It sounds like a pianist (hole) who walks up a staircase of piano key (cadmium-doped zinc sulfide shell) and plays a beautiful piano music (efficient red, green, and blue emissions).

Pure-colored red, green, and blue quantum dot light-emitting diodes using emitting layers composed of cadmium-free quantum dots and organic electron-transporting materials

This study focuses on the use of highly saturated and efficient red, green, and blue (RGB) cadmium (Cd)-free quantum dot light-emitting diodes (QD-LEDs). RGB QD-LEDs were fabricated using emitting layers (EMLs) comprising Cd-free QDs (red and green InP-based QDs and blue Zn–SeTe QDs) and organic electron-transporting materials (ETMs). The green QD-LED with high color purity was realized by adjusting the QD concentration in the EMLs and suppressing the defect-associated emission in the QD-LEDs. Narrow emissions of the full-width at half-maximum of 40, 34, and 23 nm were realized in the RGB QD-LEDs, respectively. Wide-area coverage of 80% of the available color reproduction area specified in Recommendation ITU-R BT.2020 was achieved using the developed RGB QD-LEDs without applying any color filter and cavity structure. Furthermore, the addition of organic ETMs into the EMLs improved the efficiency of all RGB QD-LEDs.

Despite Challenges, QD Vision Laid the Foundation for Quantum‐Dot Displays

Despite Challenges, QD Vision Laid the Foundation for Quantum‐Dot Displays

Chronic fibrosing esophagitis with diffuse esophageal intramural pseudo-diverticulosis.

Diffuse esophageal intramural pseudo‐diverticulosis (DEIPD) is a chronic fibrosing inflammation of the esophagus of unknown origin. Its name derives from the characteristic pseudo‐diverticula formed by dilated ducts of submucosal glands. With an assumed prevalence of approximately 5–50/100 000, DEIPD is more frequent than previously estimated. It preferentially affects men between 50 and 70 years of age with a history of alcohol and tobacco abuse. Key symptoms are chronic dysphagia and food impactions. Typical endoscopic findings are multiple small, longitudinally aligned pseudo‐diverticle openings and trachealization of the esophagus. Additionally, the usually gray mucosa may show a fine‐grained pattern of very small red dots that merge into a pink tint, called “faux uni pattern.” Once established, clinical symptoms and endoscopic changes persist throughout life. Although there is no known causal therapy, complications like bolus impactions, candida infections, or reflux can and should be treated.

Highly Efficient Red Quantum Dot Light-Emitting Diodes by Balancing Charge Injection and Transport.

Quantum dot light-emitting diodes (QLEDs) have promising commercial value and application prospects in the fields of displays and lighting. However, a charge-transfer imbalance always exists in the devices. In this work, the high-efficiency red QLEDs were obtained via employing the mixtures of poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-butylphenyl) (TFB) and 4,4'-bis(carbazole-9-yl)-1,1'-biphenyl (CBP) as hole-transport layers (HTLs) by solution processing. The optimized mixing concentration of CBP is 20 wt %. The corresponding red QLED exhibited a maximum luminance of 963 433 cd m-2, a maximum current efficiency of 38.7 cd A-1, an external quantum efficiency of 30.0%, a central wavelength of 628 nm with a narrow full width at half-maximum (fwhm) of 24 nm, and a 5-fold T50 lifetime enhancement at an extremely high luminance of 200 000 cd m-2. The characteristics of carrier-only devices with QD emissive layers (QD EMLs) and impedance characteristics of QLEDs demonstrate that these advances are chiefly ascribed to the more balanced charge transport and efficient hole-electron recombination in EML. We anticipate that our results could offer a low-cost and simple solution-processed method for preparing high-performance QLEDs.

Hydrothermal Synthesis of High-Yield Red Fluorescent Carbon Dots with Ultra-Narrow Emission by Controlled O/N Elements.

Red fluorescent carbon dots (r-CDs) with narrow dual emissions (600nm and 658-683nm, full width at half-maximums (FWHMs) of 20nm and 30nm), fluorescence quantum yield of 41.0%, and yield of 83.3% are prepared by hydrothermal method using o-phenylenediamine as precursor and inorganic oxidant as yield enhancer, and they have graphite nitrate-like structures. The long-wavelength side emission is aggregation-induced emission (AIE). A logarithmic relationship between the AIE wavelength (y) and the concentration (x) (y=8.853ln(x)+688.53, R=0.998) is found. This regularity and the high monochromaticity of AIE are related to the existence of highly ordered structures proved by X-ray diffraction. Its intrinsic emission (FWHM: 20nm) is the narrowest among the r-CDs prepared by hydrothermal method. The reason is that the decrease of oxygen content makes the FWHMs become narrow, and the decrease of the pyridine nitrogen content and the increase of pyrrole nitrogen content make them narrower further. The Fourier-transform infrared spectra and control experiment prove that oxidative polymerization is a necessary preparation step. The linear relationship between the amount of the oxidant and the CDs yield indicates that the yield can be increased only by increasing the conversion rate of the polymerization process.

One step synthesis of efficient red emissive carbon dots and their bovine serum albumin composites with enhanced multi-photon fluorescence for in vivo bioimaging

Efficient red emissive carbon dots (CDs) in aqueous solutions are very scarce for high performance bioimaging applications. In this work, we report a one-step solvothermal treatment to synthesize pure red emissive CDs (FA-CDs) from citric acid and urea in formic acid without complicated purification procedures. Photoluminescence quantum yield (PLQY) of 43.4% was observed in their dimethyl sulfoxide solutions. High PLQY up to 21.9% in aqueous solutions was achieved in their bovine serum albumin (BSA) composites (FA-CDs@BSA) with significantly enhanced multi-photon fluorescence. The strong surface electron-withdrawing structure of FA-CDs caused by the high content of C = O groups contributes for their pure red emission. Owing to the significantly enhanced single and multi-photon red fluorescence and enlarged particle sizes after composing with BSA, in vivo tumor imaging and two-photon fluorescence imaging of blood vessels in mouse ear have been realized via intravenous injection of FA-CDs@BSA aqueous solutions.