AIE-ESIPT Photoluminescent Probe Based on 3-(3-Hydroxypyridin-2-yl)isoquinolin-4-ol for the Detection of Intracellular Hydrogen Peroxide.

Excited-state intramolecular proton transfer (ESIPT) molecules, which feature large Stokes shifts to avoid self-absorption, play an essential role in photoluminescent bioimaging probes. Herein, we report the development of an ESIPT molecule 3-(3-hydroxypyridin-2-yl)isoquinolin-4-ol (PiQ). PiQ not only undergoes a distinct ESIPT process unlike the symmetrical 2,2'-bipyridyl-3,3'-diol but also exhibits aggregation-induced emission (AIE) characteristics. PiQ self-assembles into aggregates with an average size of 241.0 ± 51.9 nm in aqueous solutions, leading to significantly enhanced photoluminescence. On the basis of the ESIPT and AIE characteristics of PiQ, the latter is functionalized with a hydrogen peroxide-responsive 4-pinacoratoborylbenzyl group (B) and a carboxylesterase-responsive acetyl group (A) to produce a photoluminescent probe B-PiQ-A. The potential of PiQ for applications in bioimaging and chemical sensing is underscored by its efficient detection of both endogenous and exogenous hydrogen peroxide in living cells.

MMP-2-Activatable Photoacoustic Tumor Imaging Probes Based on Al- and Si-Naphthalocyanines.

Enzyme-activatable photoacoustic probes are powerful contrast agents to visualize diseases in which a specific enzyme is overexpressed. In this study, aluminum and silicon naphthalocyanines (AlNc and SiNc, respectively) conjugated with matrix metalloprotease-2 (MMP-2)-responsive PLGLAG peptide sequence and poly(ethylene glycol) (PEG) as an axial ligand were designed and synthesized. AlNc-peptide-PEG conjugates AlNc-pep-PEG formed dimeric species interacting with each other through face-to-face H-aggregation in water, while SiNc-based conjugates SiNc-pep-PEG hardly interacted with each other because of the two bulky hydrophilic axial ligands. Both conjugates formed spherical nanometer-sized self-assemblies in water, generating photoacoustic waves under near-infrared photoirradiation. The treatment of MNc-peptide-PEG conjugates (M = Al, Si) with MMP-2 smoothly induced the cleavage of the PLGLAG sequence to release the hydrophilic PEG moiety, resulting in the aggregation of MNcs. By comparing the PA signal intensity changes at 680 and 760 nm, the photoacoustic signal intensity ratios were shown to be enhanced by 3-5 times after incubation with MMP-2. We demonstrated that MNc-peptide-PEG conjugates (M = Al, Si) could work as activatable photoacoustic probes in the in vitro experiment of MMP-2-overexpressed cell line HT-1080 as well as the in vivo photoacoustic imaging of HT-1080-bearing mice.

Association of periodontal disease with atherosclerosis in 70-year-old Japanese older adults.

Periodontal disease and arteriosclerotic disease are greatly affected by aging. In this study, the association of conventional risk factors and periodontal disease with atherosclerosis was longitudinally examined in Japanese older adults. Subjects in this study were 490 community-dwelling septuagenarians (69-71 years) randomly recruited from the Basic Resident Registry of urban or rural areas in Japan. At the baseline examination, all subjects underwent socioeconomic and medical interviews; medical examinations, including examinations for carotid atherosclerosis, hypertension, diabetes mellitus, and dyslipidemia; and conventional dental examinations, including a tooth count and measurement of probing pocket depth (PPD). After 3 years, 182 septuagenarians who had no atherosclerosis at the baseline examination were registered and received the same examination as at the baseline. In the re-examination conducted 3 years after the baseline survey, 131 (72.0%) of the 182 participants who had no atherosclerosis at the baseline examination were diagnosed with carotid atherosclerosis. Adjusting and analyzing the mutual relationships of the conventional risk factors for atherosclerosis by multiple logistic regression analysis for the 171 septuagenarians with a full set of data, the proportion of teeth with PPD ≥ 4 mm was independently related to the prevalence of atherosclerosis (odds ratio: 1.029, P < 0.022). This longitudinal study of Japanese older adults suggests that periodontal disease is associated with the onset/progression of atherosclerosis. Maintaining a healthy periodontal condition may be an important factor in preventing the development and progression of atherosclerosis.

Bis-Metal Complexes of Doubly N-Confused Dioxohexaphyrins as Potential Near-Infrared-II Photoacoustic Dyes.

We investigated the detailed photophysical properties of a series of bis-metal (Zn and Cu) dioxohexaphyrin complexes as potential second near-infrared (NIR-II)-light responsive dyes. A cisoid-configured 28π-electron-conjugated dioxohexaphyrin analogue (c-3a) containing two peculiar "confused pyrrole" moieties in the framework is identified as a reduced isomer derivative of a transoid 26π-dioxohexaphyrin (t-2a). The symmetry-altered structure of c-3a affords a heteroleptic inner environment within the NNNN/NNOO donor core, which imparts its highly flexible electronic features and nonplanar geometry. The macrocycle c-3a can be transformed into the corresponding 26π-electron congener (c-2a) having a coplanar rectangular structure by unique solvent-mediated redox reactivity. Furthermore, upon metal complexation, saddle-distorted bis-metal complexes (c-M2-2a) were formed as the 26π-conjugated structural isomer of the trans-dioxohexaphyrin species (i.e., t-M2-2a). These isoelectronic dioxohexaphyrins demonstrate precise geometry-dependent photophysical properties. Broad tailing NIR-II absorption, weak emissive character, and rapid-decay of the S1 state are observed for c-Zn2-2a. In contrast, the coplanar t-M2-2a exhibits efficient photoacoustic response upon laser excitation with NIR-II light (λ > 1000 nm). To the best of our knowledge, this is the first example of an expanded porphyrin-based photoacoustic contrast agent responsive to NIR-II light.

π-Conjugated Macrocycles Bearing Angle-Strained Alkynes.

Angle-strained alkyne-containing π-conjugated macrocycles are attractive compounds both in functional materials chemistry and biochemistry. Their interesting reactivity as well as photophysical and supramolecular properties have been revealed in the past three decades. This review highlights the recent advances in angle-strained alkyne-containing π-conjugated macrocycles, especially their synthetic methods, the bond angles of alkynes (∠sp at C≡C-C), and their functions. The theoretical and experimental research on cyclo[n]carbons and para-cyclophynes consisting of ethynylenes and para-phenylenes are mainly summarized. Related macrocycles bearing other linkers, such as ortho-phenylenes, meta-phenylenes, heteroaromatics, biphenyls, extended aromatics, are also overviewed. Bond angles of strained alkynes in π-conjugated macrocycles, which are generable, detectable, and isolable, are summarized at the end of this review.

An enzyme-triggered turn-on fluorescent probe based on carboxylate-induced detachment of a fluorescence quencher.

We developed a new class of turn-on fluorescent probes for an esterase. After the esterase-mediated hydrolysis produced carboxylate (as a fluorescence activator), the fluorescence intensity was markedly increased through the detachment of a quencher moiety from the quenched Cy5 fluorophore. Because the probes based on this new activator-induced quencher-detachment (AiQd) adopt a non-immolative linker between the cleavable site and the fluorophore, the rate of the enzymatic reaction is greatly improved, without the generation of any by-products.

Near-Infrared Circularly Polarized Luminescence through Intramolecular Excimer Formation of Oligo(p-phenyleneethynylene)-Based Double Helicates.

Carbon-based double helicates consisting of two anthracene-containing oligo(p-phenyleneethynylene) units and two flexible chiral 1,1'-binaphthyl units or two rigid chiral 9,9'-spirobifluorene units were developed. The curved oligo(p-phenyleneethynylene) fragments in the double helicates were successfully constructed by tin-mediated reductive aromatization. Helical oligo(p-phenyleneethynylene) double strands fixed by two rigid spirobifluorene units showed little structural change under photoirradiation, thereby emitting circularly polarized luminescence (CPL) in the visible region with a high quantum yield (ΦPL =0.93). In contrast, flexible binaphthyl units induced dynamic structural change of the oligo(p-phenyleneethynylene) luminophores under photoirradiation, leading to strong CPL (|glum |=1.1×10-2 ) in the near-infrared (NIR) region. UV/Vis, circular dichroism (CD), CPL and NMR spectroscopic analyses of the binaphthyl-hinged double helicate suggested excimer formation between two π-conjugated strands in the excited state. Theoretical calculations highlight the importance of the tightly interlocked excimer structure of the carbon-based double helicate in controlling the angle between the electric and magnetic transition dipole moments for strong NIR CPL generation.

Unique Tube-Ring Interactions: Complexation of Single-Walled Carbon Nanotubes with Cycloparaphenyleneacetylenes.

Carbon nanotubes (CNTs) interlocked by cyclic compounds through supramolecular interaction are promising rotaxane-like materials applicable as 2D and 3D networks of nanowires and disease-specific theranostic agents having multifunctionalities. Supramolecular complexation of CNTs with cyclic compounds in a "ring toss'' manner is a straightforward method to prepare interlocked CNTs; however, to date, this has not been reported on. Here, the "ring toss" method to prepare interlocked CNTs by using π-conjugated carbon nanorings: [8]-, [9]-, and [10]cycloparaphenyleneacetylene (CPPA) is reported. CPPAs efficiently interact with CNTs to form CNT@CPPA complexes, while uncomplexed CPPAs can be recovered without decomposition. CNTs, which tightly fit in the cavities of CPPAs through convex-concave interaction, efficiently afford "tube-in-ring"-type CNT@CPPA complexes. "Tube-in-ring"-type and "ring-on-tube"-type complexation modes are successfully distinguished by spectroscopic, thermogravimetric, and microscopic analyses.

Polymeric Self-Assemblies with Boron-Containing Near-Infrared Dye Dimers for Photoacoustic Imaging Probes.

Polymers containing pyrrolopyrrole aza-BODIPY (PPAB) and thiophene-bridged BODIPY dimers (TBD) having poly(ethylene glycol) (PEG) or PEGylated hyaluronic acid (HA) were prepared by facile conjugation approaches. Self-assemblies consisting of TBD-conjugated polymers more efficiently generated photoacoustic (PA) signals than PPAB-PEG conjugate upon irradiation with near-infrared pulsed laser light. Among dye-conjugated polymers examined, TBD-HA-PEG conjugates efficiently generated photoacoustic signals, 1.49-1.83 times stronger than that of commercially available indocyanine green (ICG). We found that the following two factors are essential to enhance PA signals from self-assemblies: (1) the formation of strongly interacting TBD aggregates and (2) enhancement of the elastic modulus of self-assemblies by conjugating TBDs with HA. TBD-conjugated HA derivatives circulated in blood vessels for a longer time (15.6 ± 4.9% injected dose (ID) in blood 24 h after injection) and more specifically accumulated in tumor tissues (17.8 ± 3.5% ID/g in tumor 24 h after injection) than ICG-conjugated HA derivatives, visualizing a tumor site more clearly. The cell uptake experiment of dye-HA conjugates indicates that ICG-conjugated polymers internalized into cells or merged with cell walls to emit strong fluorescence, while TBD-conjugated polymers were not internalized into cells. Because the disassembly of the TBD-conjugated HA derivatives is suppressed, aggregated TBDs emit weak fluorescence but efficiently generate strong PA signals in tumor tissues.

FGF-2 promotes initial osseointegration and enhances stability of implants with low primary stability.

OBJECTIVES: The aim of this study was to examine the effect of basic fibroblast growth factor (FGF-2) on osseointegration of dental implants with low primary stability in a beagle dog model. MATERIALS AND METHODS: Customized titanium implants that were designed to have low contact with the existing bone were installed into the edentulous mandible of beagle dogs. To degrade the primary stability of the implants, the diameters of the bone sockets exceeded the implant diameters. FGF-2 (0.3%) plus vehicle (hydroxypropyl cellulose) or vehicle alone was topically applied to the sockets in the FGF-2 and control groups, respectively. In Study 1, the new bone area and length of new bone-to-implant contact (BIC) were evaluated at 4, 8, and 12 weeks after installation using histomorphometry and scanning electron microscopy. In Study 2, the implant stability quotient (ISQ) values were sequentially measured for 16 weeks using an Osstell system. RESULTS: The histomorphometric analysis revealed that the new bone area and length of BIC in the FGF-2 group were significantly larger than those in the control group at 4 weeks. Electron microscopic observation showed intimate contact between the mature lamellar bone and the implant surfaces, osseointegration, in both groups. The ISQ values in the FGF-2 group were significantly increased from 6 to 16 weeks compared with those in the control group. CONCLUSIONS: Taken together, our study demonstrates that FGF-2 promoted new bone formation around the dental implants and subsequent osseointegration, resulting in promotion of stability of implants with low primary stability.

Near-infrared dye-conjugated amphiphilic hyaluronic acid derivatives as a dual contrast agent for in vivo optical and photoacoustic tumor imaging.

Amphiphilic hyaluronic acid (HA) derivatives bearing hydrophobic indocyanine green dye derivatives and hydrophilic poly(ethylene glycol) were synthesized through the use of condensation and copper-catalyzed click cyclization reactions. The amphiphilic HA derivatives dissolved in water and formed self-assemblies in which the near-infrared dyes were tightly packed and arranged to form dimers or H-aggregates. By irradiating an aqueous solution of HA derivatives with near-infrared light, photoacoustic signals were detected along with fluorescence emission. Self-assemblies consisting of HA derivatives could smoothly accumulate in tumor tissues by passive tumor targeting. By utilizing HA derivatives as a contrast agent, tumor sites were clearly visualized by optical imaging as well as by photoacoustic tomography.

Sonication-induced formation of size-controlled self-assemblies of amphiphilic Janus-type polymers as optical tumor-imaging agents.

In this study, amphiphilic Janus-type polymers were synthesized via ring-opening metathesis polymerization (ROMP), multiple vicinal diol formation, and grafting of poly(ethylene glycol) monomethyl ether (mPEG). These amphiphilic polymers formed self-assemblies, which were a mixture of micelles and multimicellar aggregates, in water. By choosing suitable Janus-type polymers and irradiating an aqueous solution of polymers using a sonicator, either small micelles or large multimicellar aggregates were obtained selectively. Hydrophobic substituents controlled the aggregation-disaggregation behavior, leading to the formation of metastable self-assemblies by sonication. The formation of self-assemblies with a uniform size was affected by ultrasonic frequency, rather than power. In vivo optical tumor imaging revealed that the large-size multimicellar aggregates persisting for a long time in blood circulation slowly accumulated in tumor tissues. In contrast, the tumor site was rapidly, clearly visualized using the small-size micelles.

Calcitonin gene-related peptide regulates periodontal tissue regeneration.

Calcitonin gene-related peptide (CGRP), a neuropeptide composed of 37 amino acids secreted from the sensory nerve endings, reportedly possesses various physiological effects, such as vasodilation and neurotransmission. Recently, there have been increasing reports of the involvement of CGRP in bone metabolism; however, its specific role in the pathogenesis of periodontitis, particularly in the repair and healing processes, remains to be elucidated. Therefore, this study aimed to investigate dynamic expression patterns of CGRP during the destruction and regeneration processes of periodontal tissues in a mouse model of experimental periodontitis. We also explored the effects of CGRP on periodontal ligament cells, which can differentiate to hard tissue-forming cells (cementoblasts or osteoblasts). Our findings demonstrated that CGRP stimulation promotes the differentiation of periodontal ligament cells into hard tissue-forming cells. Experimental results using a ligature-induced periodontitis mouse model also suggested fluctuations in CGRP expression during periodontal tissue healing, underscoring the vital role of CGRP signaling in alveolar bone recovery. The study results highlight the important role of nerves in the periodontal ligament not only in sensory reception in the periphery, as previously known, but also in periodontal tissue homeostasis and tissue repair processes.

A reductively convertible nickel phthalocyanine precursor as a biological thiol-responsive turn-on photoacoustic contrast agent.

A nickel phthalocyanine precursor bearing poly(ethylene glycol) as a turn-on contrast agent for photoacoustic imaging was prepared. The water-soluble polymeric chains were smoothly eliminated through thiol-mediated reductive aromatization in cancer cells, enabling the detection of endogenous biological thiols in vitro and in vivo.

Dual-responsive near-infrared turn-on fluorescent probe for cancer stem cell-specific visualization.

Aldehyde dehydrogenase 1A1 (ALDH1A1) stands out as one of the most reliable intracellular biomarkers for stem cells because it is expressed in both cancer stem cells (CSCs) and normal somatic stem cells (NSCs). Although several turn-on fluorescent probes for ALDH1A1 have been developed to visualize CSCs in cancer cells, the discrimination of CSCs from NSCs is difficult. We here report an AND-type dual-responsive fluorescent probe, CHO_ßgal, the near-infrared fluorescence of which can be turned on after responding to both ALDH1A1 and ß-galactosidase. The AND-type dual responsiveness enables CSCs to be clearly visualized, whereas NSCs are non-emissive in microscopy. CSC-positive metastasis model lungs were successfully discriminated from normal lungs in ex vivo staining experiments using CHO_ßgal, whereas the single-input ALDH1A1-responsive probe failed to achieve this discrimination owing to pronounced false-positive fluorescence output from lung NSCs. In tissue slice staining experiments, even in the presence of adjacent normal tissues, the peripheral region-specific localization of CSCs was clear. The versatility of CHO_ßgal holds promise not only as a fundamental in vitro research tool for visualizing CSCs but also as a valuable asset in practical tissue staining diagnosis, significantly contributing to the assessment of cancer malignancy.

Light-controllable cell-membrane disturbance for intracellular delivery.

Highly polar and charged molecules, such as oligonucleotides, face significant barriers in crossing the cell membrane to access the cytoplasm. To address this problem, we developed a light-triggered twistable tetraphenylethene (TPE) derivative, TPE-C-N, to facilitate the intracellular delivery of charged molecules through an endocytosis-independent pathway. The central double bond of TPE in TPE-C-N is planar in the ground state but becomes twisted in the excited state. Under light irradiation, this planar-to-twisted structural change induces continuous cell membrane disturbances. Such disturbance does not lead to permanent damage to the cell membrane. TPE-C-N significantly enhanced the intracellular delivery of negatively charged molecules under light irradiation when endocytosis was inhibited through low-temperature treatment, confirming the endocytosis-independent nature of this delivery method. We have successfully demonstrated that the TPE-C-N-mediated light-controllable method can efficiently promote the intracellular delivery of charged molecules, such as peptides and oligonucleotides, with molecular weights ranging from 1000 to 5000 Da.

Lectin histochemistry of posterior lingual glands of developing rats.

The posterior lingual glands are classified as Weber and von Ebner glands. Glycans play an important role in salivary glands. Although the distribution of glycans can explain functional diversity and variation, there are many unknowns in the developing rat posterior lingual glands. The purpose of this study was to elucidate the relationship between the development and function of the posterior lingual gland in rats by histochemical analysis using lectins that bind to sugar residues. In adult rats, Arachis hypogaea (PNA), Glycine maximus (SBA), and Triticum vulgaris (WGA) were associated with serous cells and Dolichos biflorus (DBA) with mucous cells. In both Weber's and von Ebner's glands, all 4 lectins were bound to serous cells in early development, but as development progressed, DBA disappeared in serous cells and only the DBA remained in mucous cells. These results suggest that Galß (1,3) > Galß(1,4) > Gal, αGalNAc > αGal > ßGalNAc, NeuAc > (GalNAc)2-3>>>GlcNAc, and GalNAcα(1,3) are present in the early stage of development, but that GalNAcα(1,3) disappear in serous cells and only GalNAcα(1,3) are localized in mucous cells after maturation. These results indicate that Weber glands function as serous glands in the early postnatal stage when von Ebner glands have not matured.

A case of neuroendocrine tumor at the external urethral meatus after total cystectomy.

Introduction: The histological types of urethral cancer are mainly squamous cell or transitional cell carcinoma. Neuroendocrine tumor is extremely a rare type of urethral cancer. Case presentation: A 72-year-old man visited with an erythema at the external urethral meatus. After 3 months, a 1-cm reddish solid tumor was found on the external urethral meatus. He had a history of bladder cancer (pTa with carcinoma in situ), including the prostatic urethra, and underwent radical cystectomy with urethrectomy and ileal conduit construction 11 years ago. After 3 months, a 1-cm reddish solid tumor was found on the external urethral meatus. The pathological diagnosis was a neuroendocrine tumor. Partial penectomy was performed. Conclusion: Small cell neuroendocrine tumor could occur on urethral remnant after radical cystectomy with urethrectomy for urothelial cancer. Inspection of the penis and urethral meatus is important during regular follow-up of patients after radical cystectomy.

Periodontal Tissue Regeneration by Transplantation of Autologous Adipose Tissue-Derived Multi-Lineage Progenitor Cells With Carbonate Apatite.

We have developed an autologous transplantation method using adipose tissue-derived multi-lineage progenitor cells (ADMPCs) as a method of periodontal tissue regeneration that can be adapted to severe periodontal disease. Our previous clinical study confirmed the safety of autologous transplantation of ADMPCs and demonstrated its usefulness in the treatment of severe periodontal disease. However, in the same clinical study, we found that the fibrin gel used as the scaffold material might have caused gingival recession and impaired tissue regeneration in some patients. Carbonate apatite has a high space-making capacity and has been approved in Japan for periodontal tissue regeneration. In this study, we selected carbonate apatite as a candidate scaffold material for ADMPCs and conducted an in vitro examination of its effect on the cellular function of ADMPCs. We further performed autologous ADMPC transplantation with carbonate apatite as the scaffold material in a model of one-wall bone defects in beagles and then analyzed the effect on periodontal tissue regeneration. The findings showed that carbonate apatite did not affect the cell morphology of ADMPCs and that it promoted proliferation. Moreover, no effect on secretor factor transcription was found. The results of the in vivo analysis confirmed the space-making capacity of carbonate apatite, and the acquisition of significant new attachment was observed in the group involving ADMPC transplantation with carbonate apatite compared with the group involving carbonate apatite application alone. Our results demonstrate the usefulness of carbonate apatite as a scaffold material for ADMPC transplantation.

Immunomodulation of dendritic cells differentiated in the presence of nicotine with lipopolysaccharide from Porphyromonas gingivalis.

Tobacco smoking is a significant risk factor for periodontal diseases. Nicotine, one of the most studied constituents in cigarette smoke, is thought to modify immune responses. Dendritic cells (DCs), which are key mediators between innate and adaptive immunity, stimulate naive T cells to differentiate to effector T-cell subsets that may be actively involved in the immunopathogenesis of periodontal diseases. In this study, we evaluated the effects of nicotine and lipopolysaccharide (LPS) from Porphyromonas gingivalis, alone and in combination, on the functions of human monocyte-derived DCs to elucidate the mechanism of tissue destruction of smoking-associated periodontal diseases. P. gingivalis LPS-stimulated DCs differentiated with nicotine (NiDCs) induced lower T-cell proliferation and human leukocyte antigen (HLA)-DR expression, but elevated expression of programmed cell death ligand 1. Additionally, NiDCs impaired interferon-γ production but maintained interleukin (IL)-5 and IL-10 production in co-cultured T cells. Furthermore, NiDCs produced lower levels of proinflammatory cytokines compared with DCs differentiated in the absence of nicotine. Interestingly, NiDCs preferentially produced the T helper 2 (Th2)-type chemokines macrophage chemotactic protein-1 and macrophage-derived chemokine. These results suggest that the presence of nicotine during differentiation of DCs modulates the immunoregulatory functions of P. gingivalis LPS-stimulated DCs.