Effects of various cross-linked collagen scaffolds on wound healing in rats model by deep-learning CNN.

Scar tissue is connective tissue formed on the wound during the wound-healing process. The most significant distinction between scar tissue and normal tissue is the appearance of covalent cross-linking and the amount of collagen fibers in the tissue. This study investigates the efficacy of four types of collagen scaffolds in promoting wound healing and regeneration in a Sprague-Dawley murine model-the histomorphology analysis of collagen scaffolds and developing a deep learning model for accurate tissue classification. Four female rats (n = 24) groups received collagen scaffolds prepared through physical and chemical crosslinking. Wound healing progress was evaluated by monitoring granulation tissue formation, collagen matrix organization, and collagen fiber deposition, with histological scoring for quantification-the EDC and HA groups demonstrated enhanced tissue regeneration. The EDC and HA groups observed significant differences in wound regeneration outcomes. Deep-learning CNN models with data augmentation techniques were used for image analysis to enhance objectivity. The CNN architecture featured pre-trained VGG16 layers and global average pooling (GAP) layers. Feature visualization using Grad-CAM heatmaps provided insights into the neural network's focus on specific wound features. The model's AUC score of 0.982 attests to its precision. In summary, collagen scaffolds can promote wound healing in mice, and the deep learning image analysis method we proposed may be a new method for wound healing assessment.

Acetylated tau exacerbates learning and memory impairment by disturbing with mitochondrial homeostasis.

Increased tau acetylation at K274 and K281 has been observed in the brains of Alzheimer's disease (AD) patients and animal models, and mitochondrial dysfunction are noticeable and early features of AD. However, the effect of acetylated tau on mitochondria has been unclear until now. Here, we constructed three type of tau forms, acetylated tau mutant by mutating its K274/K281 into Glutamine (TauKQ) to mimic disease-associated lysine acetylation, the non-acetylation tau mutant by mutating its K274/K281 into Arginine (TauKR) and the wild-type human full-length tau (TauWT). By overexpression of these tau forms in vivo and in vitro, we found that, TauKQ induced more severe cognitive deficits with neuronal loss, dendritic plasticity damage and mitochondrial dysfunctions than TauWT. Unlike TauWT induced mitochondria fusion, TauKQ not only induced mitochondria fission by decreasing mitofusion proteins, but also inhibited mitochondrial biogenesis via reduction of PGC-1a/Nrf1/Tfam levels. TauKR had no significant difference in the cognitive and mitochondrial abnormalities compared with TauWT. Treatment with BGP-15 rescued impaired learning and memory by attenuation of mitochondrial dysfunction, neuronal loss and dendritic complexity damage, which caused by TauKQ. Our data suggested that, acetylation at K274/281 was an important post translational modification site for tau neurotoxicity, and BGP-15 is a potential therapeutic drug for AD.

The clinical application effects of artificial dermis scaffold and autologous split-thickness skin composite grafts combined with vacuum-assisted closure in refractory wounds.

To investigate the clinical application effects of artificial dermis scaffold and autologous split-thickness skin composite grafts combined with vacuum-assisted closure (V.A.C) in refractory wounds. A retrospective analysis was performed on 70 patients with refractory wounds admitted to the First Affiliated Hospital of Soochow University from June 2019 to December 2021 (44 males and 25 females, with an average age of 49.3 ± 21.4 years). There were 26 patients with chronic ulcers; 3 patients with cancerous wounds; 16 patients with hot crush injuries; and 25 patients with traumatic wounds, including 21 cases of hands, 33 cases of feet, 6 cases of upper limbs, and 10 cases of lower limbs. The patients were divided into an artificial dermis scaffold group (35 patients, including 21 males and 14 females, aged 49.5 ± 21.3 years) and a skin graft group (35 patients, including 23 males and 11 females, aged 49.1 ± 21.5 years). In the artificial dermis scaffold group, after debridement, the artificial dermis scaffold was transplanted for approximately 2 weeks until the wound surface was well vascularized, after which the autologous split-thick skin graft was transplanted. Negative pressure wound therapy was performed throughout the treatment. In the skin grafting group, after debridement, the autologous split-thickness skin graft (aSTSG) was transplanted, and negative pressure wound therapy was performed continuously. The wound healing rate; skin graft survival rate; postoperative wound infection; exudative fluid volume; subcutaneous haematoma; hospitalisation time; hospitalisation cost; Vancouver Scar Scale (VSS) score, used to evaluate the scar of the recipient area at 6 months after the operation; and the sensory disorder grading method, used to evaluate the sensory recovery of the recipient area, were compared between the two groups. All 70 refractory wounds healed. In the artificial dermis scaffold group, the skin graft survival rate was 90% (86%-95%), the hospitalisation time was 38 (29-45) days, the hospitalisation cost was 148 102 (118242-192327) yuan, and the VSS score was 1.9 ± 1.3. There were significant differences in skin graft survival rate (70% [60%-80%]), length of hospital stay (21 [14-28] days), hospitalisation cost (76 201 [39228-135 919] yuan) and VSS score [6.1 ± 3.6] between the skin graft group and the artificial dermis scaffold group (P < .05). The skin graft survival rate, scar hyperplasia and sensory recovery of the recipient area in the artificial dermis scaffold group were better than those in the skin graft group, but the hospitalisation time was relatively longer, and the hospitalisation cost was relatively higher. Wound healing rate, postoperative wound infection, exudate volume, and subcutaneous haematoma of patients in the two groups were similar, and there were no significant differences (P > .05). The artificial dermis scaffold and composite transplantation of autologous aSTSG with V.A.C can promote painless wound healing and improve the skin survival rate, skin colour and lustre, and flexible smooth texture and is conducive to less scar hyperplasia and postoperative functional exercise and recovery. This method provides a reasonable and effective scheme for the treatment of clinical refractory wounds.

Th1/Th2 cytokine levels: A potential diagnostic tool for patients with necrotizing fasciitis.

INTRODUCTION: Necrotizing fasciitis (NF) has emerged as rare but rapidly progressive, life-threatening severe skin and soft tissue infection. We conducted a study to investigate whether Th1/Th2 cytokines could serve as biomarkers to distinguish NF from class III skin and soft tissue infections (SSTIs). METHODS: A retrospective review was performed for 155 patients suffering from serious skin and soft tissue infections from October 2020 to February 2022. Th1/Th2 cytokines were obtained from peripheral blood and wound drainage fluid samples. Data on demographic characteristics, causative microbiological organisms, Th1/Th2 cytokines, c-reactive protein, procalcitonin and white blood cell (WBC) were extracted for analysis. Factors with statistical difference(p < 0.1) were included in the multivariate logistic regression model. The clinical differential diagnostic values of interleukin-2(IL-2), IL-6, IL-10, tumor necrosis factor-α (TNF-α) and interferon-r (IFN-r) were analyzed by receiver operating characteristic (ROC) curve. RESULTS: Among the 155 patients, 66(43%) patients were diagnosed as NF. We found no significant difference for sex, age, location of infection, coexisting condition, predisposition, duration of symptoms before admission and micro-organisms, WBC, procalcitonin and c-reactive protein in NF and class III SSTIs group. NF had higher levels of IL-6 in serum (50.46 [24.89, 108.89] vs. 11.87 [5.20, 25.32] pg/ml; p＜0.01), IL-10 in serum (3.45 [2.03, 5.12] vs. 2.51 [1.79, 3.29] pg/ml; p＜0.01), IL-2 in wound drainage fluid (0.89 [0.49, 1.33] vs. 0.63 [0.14, 1.14] pg/ml; p = 0.02), IL-6 in wound drainage fluid (5000.84 [1392.30, 13287.19] vs. 1927.82 (336.65, 6759.27) pg/ml; p＜0.01), TNF-a in wound drainage fluid (5.20 [1.49, 22.97] vs. 0.96 [0.12, 3.21] pg/ml; p＜0.01) and IFN-r in wound drainage fluid (1.32 [0.47, 4.62] vs. 0.68 [0.10, 1.88] pg/ml; p = 0.02) as compared to the class III SSTIs. Multivariate logistic regression analyses showed that IL-6 in serum, IL-10 in serum and TNF-a in wound drainage fluid exhibited independently significant associations with diagnosis of NF(p＜0.05). In ROC curve analysis of IL-2, IL-6, IL-10, TNF-a and IFN-r for diagnosis of NF, the area under the curve (AUC) of IL-6 in serum could reach to 0.80 (p＜0.001). Using 27.62 pg/ml as the cut off value, the sensitivity was 74% and the specificity was 79% in IL-6 in serum. CONCLUSIONS: Th1/Th2 cytokines, IL-6 in serum in particular, are potential biomarkers for the diagnosis of NF in the early stage. However, larger patient populations with multiple centers and prospective studies are necessary to ensure the prognostic role of Th1/Th2 cytokines.

Identification of aberrantly methylated differentially expressed genes and pro-tumorigenic role of KIF2C in melanoma.

Background: Skin Cutaneous Melanoma (SKCM) is known as an aggressive malignant cancer, which could be directly derived from melanocytic nevi. However, the molecular mechanisms underlying the malignant transformation of melanocytes and melanoma tumor progression still remain unclear. Increasing research showed significant roles of epigenetic modifications, especially DNA methylation, in melanoma. This study focused on the identification and analysis of methylation-regulated differentially expressed genes (MeDEGs) between melanocytic nevus and malignant melanoma in genome-wide profiles. Methods: The gene expression profiling datasets (GSE3189 and GSE114445) and gene methylation profiling datasets (GSE86355 and GSE120878) were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) and differentially methylated genes (DMGs) were identified via GEO2R. MeDEGs were obtained by integrating the DEGs and DMGs. Then, a functional enrichment analysis of MeDEGs was performed. STRING and Cytoscape were used to describe the protein-protein interaction (PPI) network. Furthermore, survival analysis was implemented to select the prognostic hub genes. Next, we conducted gene set enrichment analysis (GSEA) of hub genes. To validate, SKCM cell culture and lentivirus infection was performed to reveal the expression and behavior pattern of KIF2C. Patients and specimens were collected and then immunohistochemistry (IHC) staining was conducted. Results: We identified 237 hypomethylated, upregulated genes and 182 hypermethylated, downregulated genes. Hypomethylation-upregulated genes were enriched in biological processes of the oxidation-reduction process, cell proliferation, cell division, phosphorylation, extracellular matrix disassembly and protein sumoylation. Pathway enrichment showed selenocompound metabolism, small cell lung cancer and lysosome. Hypermethylation-downregulated genes were enriched in biological processes of positive regulation of transcription from RNA polymerase II promoter, cell adhesion, cell proliferation, positive regulation of transcription, DNA-templated and angiogenesis. The most significantly enriched pathways involved the transcriptional misregulation in cancer, circadian rhythm, tight junction, protein digestion and absorption and Hippo signaling pathway. After PPI establishment and survival analysis, seven prognostic hub genes were CKS2, DTL, KIF2C, KPNA2, MYBL2, TPX2, and FBL. Moreover, the most involved hallmarks obtained by GSEA were E2F targets, G2M checkpoint and mitotic spindle. Importantly, among the 7 hub genes, we found that down-regulated level of KIF2C expression significantly inhibited the proliferative ability of SKCM cells and suppressed the metastasis capacity of SKCM cells. Conclusions: Our study identified potential aberrantly methylated-differentially expressed genes participating in the process of malignant transformation from nevus to melanoma tissues based on comprehensive genomic profiles. Transcription profiles of CKS2, DTL, KIF2C, KPNA2, MYBL2, TPX2, and FBL provided clues of aberrantly methylation-based biomarkers, which might improve the development of precision medicine. KIF2C plays a pro-tumorigenic role and potentially inhibited the proliferative ability in SKCM.

Preparation, in vitro and in vivo Evaluation of Thermosensitive in situ Gel Loaded with Ibuprofen-Solid Lipid Nanoparticles for Rectal Delivery.

Background: Ibuprofen (IBU), a nonsteroidal anti-inflammatory drug, shows poor gastrointestinal absorption due to its low solubility, which limits its clinical application. Objective: In the present study, we aimed to develop thermosensitive gel-mediated ibuprofen-solid lipid nanoparticles (IBU-SLN-ISG) to improve the dissolution and bioavailability of IBU after rectal delivery. Methods: IBU-loaded SLNs (IBU-SLNs) were developed and optimized applying Box-Behnken design. The optimized IBU-SLNs were characterized by physicochemical parameters and morphology. Then, the optimized IBU-SLNs was incorporated into the gel and characterized for gel properties and rheology and investigated its release in vitro, pharmacokinetics in vivo, rectal irritation and rectal retention time. Results: The optimized SLNs had an EE of 90.74 ± 1.40%, DL of 11.36 ± 1.20%, MPS of 166.77 ± 2.26 nm, PDI of 0.27 ± 0.08, and ZP of -21.00 ± 0.59 mV. The FTIR spectra confirmed successful encapsulation of the drug inside the nanoparticle as only peaks responsible for the lipid could be identified. This corroborated well with XRD spectra, which showed a completely amorphous state of the IBU-SLNs as compared to the crystalline nature of the pure drug. The gelation temperature of the prepared IBU-SLN-ISG was 33.30 ± 0.78°C, the gelation time was 14.67 ± 2.52 s, the gel strength was 54.00 ± 1.41 s, and the mucoadhesion was (11.54±0.37) × 102dyne/cm2. The in vitro results of IBU-SLNs and IBU-SLN-ISG showed a biphasic release pattern with initial burst release followed by sustained release. More importantly, IBU-SLN-ISG produced much better absorption of IBU and improved bioavailability in rats. In addition, IBU-SLN-ISG caused no irritation or damage to rectal tissues, and could be retained in the rectum for a long time. Conclusion: Thermosensitive in situ gel loaded with IBU-solid lipid nanoparticles might be further developed as a more convenient and effective rectal dosage form.

Differential development and electrophysiological activity in cultured cortical neurons from the mouse and cynomolgus monkey.

In vitro cultures of primary cortical neurons are widely used to investigate neuronal function. However, it has yet to be fully investigated whether there are significant differences in development and function between cultured rodent and primate cortical neurons, and whether these differences influence the utilization of cultured cortical neurons to model pathological conditions. Using in vitro culture techniques combined with immunofluorescence and electrophysiological methods, our study found that the development and maturation of primary cerebral cortical neurons from cynomolgus monkeys were slower than those from mice. We used a microelectrode array technique to compare the electrophysiological differences in cortical neurons, and found that primary cortical neurons from the mouse brain began to show electrical activity earlier than those from the cynomolgus monkey. Although cultured monkey cortical neurons developed slowly in vitro, they exhibited typical pathological features-revealed by immunofluorescent staining-when infected with adeno-associated viral vectors expressing mutant huntingtin (HTT), the Huntington's disease protein. A quantitative analysis of the cultured monkey cortical neurons also confirmed that mutant HTT significantly reduced the length of neurites. Therefore, compared with the primary cortical neurons of mice, cultured monkey cortical neurons have longer developmental and survival times and greater sustained physiological activity, such as electrophysiological activity. Our findings also suggest that primary cynomolgus monkey neurons cultured in vitro can simulate a cell model of human neurodegenerative disease, and may be useful for investigating time-dependent neuronal death as well as treatment via neuronal regeneration. All mouse experiments and protocols were approved by the Animal Care and Use Committee of Jinan University of China (IACUC Approval No. 20200512-04) on May 12, 2020. All monkey experiments were approved by the IACUC protocol (IACUC Approval No. LDACU 20190820-01) on August 23, 2019 for animal management and use.

Identification and expression profiling analysis of ascorbate peroxidase gene family in Actinidia chinensis (Hongyang).

Ascorbate peroxidase (APX) is one of the important antioxidant enzymes in the active oxygen metabolism pathway of plants and animals, especially it is the key enzyme to clear H2O2 in chloroplast and the main enzyme of vitamin C metabolism. However, knowledge about APX gene family members and their evolutionary and functional characteristics in kiwifruit is limited. In this study, we identified 13 members of the APX gene family in the kiwifruit (cultivar: Hongyang) genome according the APX proteins conserved domain of Arabidopsis thaliana. Phylogenetic analysis by maximum likelihood split these 13 genes into four groups. The APX gene family members were distributed on nine chromosomes (Nos. 4, 5, 11, 13, 20, 21, 23, 25, 28). Most of the encoded hydrophilic and lipid-soluble enzymes were predicted to be located in the cytoplasm, nucleus and chloroplast. Among them, AcAPX4, AcAPX5, AcAPX8, AcAPX12 were transmembrane proteins, and AcAPX8 and AcAPX12 had the same transmembrane domain. The gene structure analysis showed that AcAPXs were composed of 4-22 introns, except that AcAPX10 was intron-free. Multiple expectation maximization for motif elicitation program (MEME) analyzed 13 APX protein sequences of Actinidia chinensis and identified 10 conserved motifs ranging in length from 15 to 50 amino acid residues. Additionally, the predicted secondary structures of the main motifs consisted of α-helix and random coils. The gene expression of fruits in different growth stages and bagging treatment were determined by qRT-PCR. The results showed that 8 AcAPXs had the highest expression levels during the color turning period and only the gene expression of AcAPX3 was consistent with the ascorbic acid content; five AcAPXs were consistent with the ascorbic acid content after bagging. Our data provided evolutionary and functional information of AcAPX gene family members and revealed the gene expression of different members in different growth stages and bagging treatments These results may be useful for future studies of the structures and functions of AcAPX family members.

Effects of nonlinear phase in cascaded mode-locked Nd:YVO4 laser.

A diode-pumped mode-locked Nd:YVO4 laser via positive cascaded second-order Kerr lens using periodically poled MgO:LN at 1064 nm was reported. Mode-locking performances including output power, bandwidth, pulse duration, and time-bandwidth product were studied under different phase-mismatched conditions. The induced nonlinear phase combined with soft aperture effect yield a stable mode-locked operation in a wide phase-mismatched range (-8π < ∆kL < -π). Additionally, the mode-locking bandwidth was broadened by self-phase modulation and the time-bandwidth product was increased to be more than twice the ideal product for a sech2 pulse shape. Under 11 W diode pump power, the measured average power, pulse repetition rate and pulse duration are 1.3 W, 186 MHz and 2.8 ps, respectively.

Repairing Facial Soft Tissue Defects by Swelling Anesthesia after Tumor Resection with Narrow Pedicle Flaps.

AIMS: To investigate the role of swelling anesthesia in repairing facial soft tissue defects after tumor resection and temporal superficial artery frontal branch of narrow pedicle flap. MATERIALS AND METHODS: From January 2008 to June 2008, 16 patients from Department of Ophthalmology with eye or eyelid tumors after eyeball removal of eye and part resection of surrounding soft tissue, undergoing postoperative swelling anesthesia with superficial temporal artery flap repair to prevent facial soft tissue defect formation and bone exposure, were recruited. RESULTS: In all 16 patients facial soft tissue defect repair had good effects, with limited bleeding, and short operation times. Seven days after surgery, all flaps were in good repair. On postoperative follow-up after 3 months, flaps showed a similar appearance as with facial tissue. CONCLUSIONS: Swelling anesthesia for superficial temporoparietal artery frontal branch of narrow pedicle flap to repair soft tissue defect after facial tumor resection is feasible, and is linked with good analgesic effects, high postoperative survival of skin flaps, and good cosmetic effects.

Longitudinal plasmon modes of Ag nanorod coupled with a pair of quantum dots.

The longitudinal plasmon modes of an elongated Ag nanorod induced by an obliquely incident plane wave were analyzed theoretically. Our results show that the proximities at the two apexes of the nanorod are the hotspots at the dipole (m = 1), quadrupole (m = 2), sextupole (m = 3), octupole (m = 4), decapole (m = 5) and duodecapole (m = 6) modes. This phenomenon implies that a pair of quantum dots (QDs) located at these hotspots might be excited simultaneously through these plasmon modes. Consequently, the coherent spontaneous emission of the paired QDs could be induced through these modes. Furthermore, the coherent emission of the pair of excited QDs was studied, where these QDs were modeled as two electric dipoles (bi-dipole) oscillating with anti-symmetric or symmetric configurations. The radiative and nonradiative powers show that the maximum Purcell factors occur at these modes; the odd modes enhance the emission of the anti-symmetric configuration, and the even modes the symmetric one. However, only those bi-dipoles emitting at the lower-order (e.g., dipole, quadrupole and sextupole) modes of Ag nanorod are with high apparent quantum yields. In addition, the correlation of these plasmon modes of Ag nanorod with the dispersion relation of Ag nanowire was discussed.

Subwavelength Fabry-Perot resonator: a pair of quantum dots incorporated with gold nanorod.

The two apexes of an elongated gold nanorod (GNR) irradiated by a plane wave are shown to be the hotspots at the longitudinal plasmon modes. This phenomenon implies that a pair of quantum dots (QDs) located at these apexes might be excited simultaneously if the excitation band of QDs coincides with one of these modes. Consequently, a coherent emission of the two emitters could happen subsequently. In the following coherent emission, these two-level emitters are simulated as two oscillating dipoles (bi-dipole) with some possible phase differences. Our results show that the maximum radiative and nonradiative powers of the bi-dipole occur at the longitudinal plasmon dipole, quadrupole, sextupole, and octupole modes of GNR. Moreover, the strongest emissions are induced by the in-phase bi-dipole coupled to the odd modes and the 180° out-of-phase one to the even modes, respectively. The excitation and emission behaviors of a pair of QDs incorporated with GNR demonstrate the possibility of using this structure as a subwavelength resonator of Fabry-Perot type. In addition, the correlation between these modes of the GNR and the dispersion relation of gold nanowire is also discussed.

Dual molecular light switches for pH and DNA based on a novel Ru(II) complex. A non-intercalating Ru(II) complex for DNA molecular light switch.

A new Ru(II) complex of [Ru(phen)(2)(Hcdpq)](ClO(4))(2) {phen = 1,10-phenanthroline, Hcdpq = 2-carboxyldipyrido[3,2-f:2',3'-h]quinoxaline} was synthesized and characterized. The spectrophotometric pH and calf thymus DNA (ct-DNA) titrations showed that the complex acted as a dual molecular light switch for pH and ct-DNA with emission enhancement factors of 17 and 26, respectively. It was shown to be capable of distinguishing ct-DNA from yeast RNA with this binding selectivity being superior to two well-known DNA molecular light switches of [Ru(bpy)(2)(dppz)](2+) {bpy =2,2'-bipyridine, and dppz = dipyrido-[3,2-a:2',3'-c]phenazine}and ethidium bromide. The complex bond to ct-DNA probably in groove mode with a binding constant of (4.67 ± 0.06) × 10(3) M(-1) in 5 mM Tris-HCl, 50 mM NaCl (pH = 7.10) buffer solution, as evidenced by UV-visible absorption and luminescence titrations, the dependence of DNA binding constants on NaCl concentrations, DNA competitive binding with ethidium bromide, and emission lifetime and viscosity measurements. To get insight into the light-switch mechanism, theoretical calculations were also performed by applying density functional theory (DFT) and time-dependent DFT.

Functional IrIII complexes and their applications.

Iridium complexes are drawing great interest because they exhibit high phosphorescence quantum efficiency. Extensive efforts have been devoted to the molecular design of ligands to achieve phosphorescent emission over a wide range of wavelengths that is compatible with many applications. In this research news article, we focus on materials design to improve the performance of phosphorescent Ir(III) complexes for organic light-emitting diodes (OLEDs), luminescence sensitizers, and biological imaging.

Synthesis, characterization, and in vivo targeted imaging of amine-functionalized rare-earth up-converting nanophosphors.

Rare-earth up-converting nanophosphors (UCNPs) have great potential to become a new generation of biological luminescent labels, but their use has been limited by difficulties in obtaining water-soluble UCNPs bearing appropriate functional groups. To address this problem, we report herein a simple and efficient procedure for the preparation of amine-functionalized UCNPs by a modified hydrothermal microemulsion route assisted with 6-aminohexanoic acid. The amine content of the resultant UCNPs has been determined to be (9.5+/-0.8) x 10(-5) mol/g, which not only confers excellent dispersibility in aqueous solution, but also allows further conjugation with targeted molecules such as folic acid (FA) as a ligand. By means of the laser scanning up-conversion luminescence microscopy (LSUCLM) and the in vivo up-conversion luminescence (UCL) imaging under excitation at the CW infrared laser at 980 nm, FA-coupled UCNPs have been demonstrated to be effective in targeting folate-receptor overexpressing HeLa cells in vitro and HeLa tumor in vivo and ex vivo. These results indicated that our UCNPs could be used as whole-body targeted UCL imaging agents.

Highly efficient sensitized red emission from europium (III) in Ir-Eu bimetallic complexes by 3MLCT energy transfer.

Two novel iridium-europium bimetallic complexes, {[(dfppy)2Ir(mu-phen5f)]3EuCl}Cl2 and (dfppy)2Ir(mu-phen5f)Eu(TFAcA)3 [dfppy represents 2-(4',6'-difluorophenyl)-pyridinato-N,C(2'), phen5f stands for 4,4,5,5,5-pentafluoro-1-(1',10'-phenanthrolin-2'-yl)-pentane-1,3-dionate and TFAcA represents trifluoroacetylacetonate], were successfully synthesized. The novel ligand Hphen5f with four coordination sites was designed as a bridge to link the Ir (III) center and the Eu (III) center. The X-ray diffraction data shows that the nonbonding distances for Eu...Ir are 6.028, 5.907, and 6.100 A in the bimetallic complex {[(dfppy)2Ir(mu-phen5f)]3EuCl}Cl2. Photophysical studies implied that the high efficient red luminescence from the Eu (III) ion was sensitized by the (3)MLCT (metal-to-ligand charge transfer) energy based on an Ir (III) complex-ligand in a d-f bimetallic assembly. The excitation window for the new bimetallic complex {[(dfppy)2Ir(mu-phen5f)]3EuCl}Cl2 extends up to 530 nm (1 x 10(-3) M in EtOH), indicating that this bimetallic complex can emit red light under the irradiation of sunlight.

Studies of Langmuir-Blodgett films of an ion pair metal complex containing Eu(III)-Ru(II) dual chromophores.

A surfactant ion-pair complex, [Ru(bpy)(2)L][Eu(NTA)(4)](2) (in which L = 1-docosyl-2-(2- pyridyl)benzimidazole, bpy = 2,2'-bipyridine, and NTA = 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedionato) has been synthesized. The surface pressure-area isotherm measurements show that the complex forms a stable Langmuir film at the air-water interface without adding any electrolytes into the subphase. The monolayers formed at the surface pressures of 5 mN m(-1) and 20 mN m(-1), have been successfully transferred onto glass and quartz substrates with the transfer ratios close to unity. The Langmuir-Blodgett films were studied by UV-visible, infrared, and emission spectroscopies, atomic force microscopy, and cyclic voltammetry. The optical, redox, and morphology properties of the LB films were found to be significantly affected by the target surface pressures used for the film depositions.

pi-Conjugated chelating polymers with charged iridium complexes in the backbones: synthesis, characterization, energy transfer, and electrochemical properties.

A series of pi-conjugated chelating polymers with charged iridium (Ir) complexes in the backbones were synthesized by a Suzuki polycondensation reaction, leading to homogeneous polymeric materials that phosphoresce red light. The fluorene and bipyridine (bpy) segments were used as polymer backbones. 5,5'-Dibromobipyridine served as a ligand to form a charged iridium complex monomer with 1-(9'9-dioctylfluorene-2-yl)isoquinoline (Fiq) as the cyclometalated ligand. Chemical and photophysical characterization confirmed that Ir complexes were incorporated into the backbones as one of the repeat units by means of the 5,5'-dibromobipyridine ligand. Chelating polymers showed almost complete energy transfer from the host fluorene segments to the guest Ir complexes in the solid state when the feed ratio was 2 mol %. In the films of the corresponding blend system, however, energy transfer was not complete even when the content of Ir complexes was as high as 16 mol %. Both intra- and intermolecular energy-transfer processes existed in this host-guest system, and the intramolecular energy transfer was a more efficient process. All chelating polymers displayed good thermal stability, redox reversibility, and film formation. These chelating polymers also showed more efficient energy transfer than the corresponding blended system and the mechanism of incorporation of the charged Ir complexes into the pi-conjugated polymer backbones efficiently avoided the intrinsic problems associated with the blend system, thus offering promise in optoelectronic applications.

Effective tuning of HOMO and LUMO energy levels by p-n diblock and triblock oligomer approaches.

A novel series of oligomers consisting of thiophene as a p-type unit and oxadiazole as an n-type unit were separately synthesized. On the basis of the characterization of photophysical and electrochemical properties, the structure-property relationships of the oligomers were investigated. Cyclic voltammogram studies showed that changing the number of thiophene and oxadiazole units could effectively modulate the electronic properties of the p-n diblock and triblock oligomers. The effect of molecular regiochemistry on electronic properties is also investigated. The observed electronic properties were consistent with theoretical calculations. These systems serve as excellent examples, demonstrating the band gap control principle in the p-n heterostructure oligomers.

Highly selective two-photon chemosensors for fluoride derived from organic boranes.

[reaction: see text] Three organoboron compounds are shown to be two-photon fluorescent sensors for fluoride anion with high sensitivity and selectivity. The recognition mechanism is attributed to the unique steric structure of the bulky dimesitylboryl group and the Lewis acid-base interaction between trivalent boron atom and fluoride anion.