Pyridinium-Yne Click Polymerization: A Facile Strategy toward Functional Poly(Vinylpyridinium Salt)s with Multidrug-Resistant Bacteria Killing Ability.

Polymeric materials with antibacterial properties hold great promise for combating multidrug-resistant bacteria, which pose a significant threat to public health. However, the synthesis of most antibacterial polymers typically involves complicated and time-consuming procedures. In this study, we demonstrate a simple and efficient strategy for synthesizing functional poly(vinylpyridinium salt)s via pyridinium-yne click polymerization. This click polymerization could proceed with high atom economy under mild conditions without any external catalyst, yielding soluble and thermally stable poly(vinylpyridinium salt)s with satisfactory molecular weights and well-defined structures in excellent yields. Additionally, the incorporation of luminescent units such as fluorene, tetraphenylethylene, and triphenylamine into the polymer backbone confers excellent aggregation-enhanced emission properties upon the resulting polymers, rendering them suitable for bacterial staining. Moreover, the existence of pyridinium salt imparts intrinsic antibacterial activity against multidrug-resistant bacteria to the polymers, enabling them to effectively inhibit wound bacterial infection and significantly expedite the healing process. This work not only provides an efficient method to prepare antibacterial polymers, but also opens up the possibility of various applications of polymers in healthcare and other antibacterial fields.

IL-7-Treated Periodontal Ligament Cells Regulate Local Immune Homeostasis by Modulating Treg/Th17 Cell Polarization.

Both interleukin (IL)-7 and human periodontal ligament cells (hPDLCs) have immunomodulatory properties. However, their combined effect on CD4+T cells has never been studied. In this study, we aimed to investigate the effect of conditioned medium of hPDLCs treated with rhIL-7 on the differentiation of CD4+T cells into regulatory T cells/T helper 17 cells (Treg/Th17 cells) and observe the effect of IL-7 on the immunomodulatory properties of PDLCs. After hPDLCs were treated with different concentrations of rhIL-7 for 24 h, the collected supernatants were used to incubate CD4+T cells for 3 days. A gamma-secretase inhibitor (DAPT) was used to suppress the activation of the Notch1 signaling pathway. Cell proliferation, apoptosis, and necrosis were determined using the cell counting kit-8 (CCK-8) and flow cytometry (FCM). The expressions of forkhead box P3 (Foxp3) in CD4+T cells and transforming growth factor (TGF-ß) and IL-6 in the supernatants were determined by ELISA. Reverse transcription-quantitative PCR (RT-qPCR), and the Western blot (WB) determined the mRNA levels and protein expression of various target factors. FCM was used to detect the mean fluorescence intensity of PD-L1 in hPDLCs and to analyze the differentiation of Treg/Th17 cells. Our results showed that IL-7 promoted proliferation and inhibited apoptosis in hPDLCs, promoted the expression of TGF-ß, PD-L1, Notch1, Jagged1, and Hes1, and inhibited the levels of hypoxia-inducible factor (HIF)-1α and TCF7, whereas the addition of DAPT effectively reversed these effects. Importantly, we found that the conditioned medium of hPDLCs treated with rhIL-7 promoted the polarization of CD4+T cells into Treg cells but had no significant effect on the differentiation of Th17 cells. Our study indicated that treatment of PDLCs with IL-7 can promote the polarization of CD4+T cells into Treg cells by modulating the expression of inflammatory factors and signaling molecules through activating the Notch1 signaling pathway, thus participating in the regulation of immune homeostasis in the periodontal microenvironment.

Periodontal ligament cells under mechanical force regulate local immune homeostasis by modulating Th17/Treg cell differentiation.

OBJECTIVES: Improper orthodontic force often causes root resorption or destructive bone resorption. There is evidence that T helper 17 (Th17) cells and regulatory T (Treg) cells may be actively involved in bone remodeling during tooth movement. In a combination of in vitro and in vivo studies, we investigated the effect of human periodontal ligament cells (hPDLCs) on Th17/Treg cells under different orthodontic forces and corticotomy. MATERIAL AND METHODS: hPDLCs were cultured in vitro and subjected to different mechanical forces. The expression of interleukin (IL)-6 and transforming growth factor (TGF)-ß in the supernatant and the mRNA levels of hypoxia inducible factor (HIF)-1α, Notch1, and TGF-ß in hPDLCs were investigated. Supernatants were collected and co-cultured with activated CD4+T cells, and the differentiation of Th17/Treg cells was analyzed by flow cytometry. We also established an animal model of tooth movement with or without corticotomy. The tooth movement distance, alveolar bone height, and root resorption were analyzed using micro-computed tomography. Expression of interleukin (IL)-17A, forkhead Box P3 (Foxp3), and IL-6 were analyzed using immunohistochemistry, while osteoclasts were evaluated by tartrate-resistant acid phosphatase (TRAP) staining. The mRNA levels of IL-17A, IL-6, Foxp3, IL-10, HIF-1α, notch1, and C-X-C motif chemokine ligand 12 (CXCL12) in alveolar bone and gingiva were investigated. RESULTS: Heavy force repressed cell viability and increased the mortality rate of hPDLCs; it also improved the expression of IL-6, declined the expression of TGF-ß, and promoted the mRNA expression level of HIF-1α. The expression of TGF-ß and Notch1 mRNA decreased and then increased. The supernatant of hPDLCs under heavy force promotes the polarization of Th17 cells. The heavy force caused root resorption and decreased alveolar bone height and increased the positive area of IL-17A immunohistochemical staining and the expression of IL-17A, IL-6, HIF-1α, and Notch1 mRNA. Corticotomy accelerated tooth movement, increased the proportion of Foxp3-positive cells, and up-regulated the expression of Foxp3, IL-10, and CXCL12 mRNA. CONCLUSIONS: During orthodontic tooth movement, the heavy force causes root resorption and inflammatory bone destruction, which could be associated with increased expression of Th17 cells and IL-6. Corticotomy can accelerate tooth movement without causing root resorption and periodontal bone loss, which may be related to the increased expression of Treg cells. CLINICAL RELEVANCE: Altogether, this report provides a new perspective on the prevention of inflammatory injury via the regulation of Th17/Treg cells in orthodontics.

Novel Quinolizine AIE System: Visualization of Molecular Motion and Elaborate Tailoring for Biological Application.

Molecular motions are ubiquitous in nature and they immutably play intrinsic roles in all actions. However, exploring appropriate models to decipher molecular motions is an extremely important but very challenging task for researchers. Considering aggregation-induced emission (AIE) luminogens possess their unique merits to visualize molecular motions, it is particularly fascinating to construct new AIE systems as models to study molecular motion. Herein, a novel quinolizine (QLZ) AIE system was constructed based on the restriction intramolecular vibration (RIV) mechanism. It was demonstrated that QLZ could act as an ideal model to visualize single-molecule motion and macroscopic molecular motion via fluorescence change. Additionally, further elaborate tailoring of this impressive core achieved highly efficient reactive oxygen species production and realized fluorescence imaging-guided photodynamic therapy applications, which confirms the great application potential of this new AIE-active QLZ core. Therefore, this work not only provides an ideal model to visualize molecular motion but also opens a new way for the application of AIEgens.

One-for-all phototheranostics: Single component AIE dots as multi-modality theranostic agent for fluorescence-photoacoustic imaging-guided synergistic cancer therapy.

Construction of single component theranostic agent with one-for-all features to concurrently afford both multi-modality imaging and therapy is an appealing yet significantly challenging task. Herein, a type of luminogens with aggregation-induced emission (AIE) characteristics are tactfully designed and facilely synthesized. These AIE luminogens (AIEgens) exhibit long emission wavelengths, good photostability, remarkable biocompatibility, good reactive oxygen species (ROS) generation performance and excellent photothermal conversion efficiency, which allow them to be powerfully utilized for in vitro and in vivo cancer phototheranostics. The results show that one of the AIEgens is capable of precisely diagnosing solid tumors of mice by means of combined near-infrared-I/II (NIR-I/II) fluorescence-photoacoustic imaging, meanwhile this AIEgen can activate photodynamic and photothermal synergistic therapy (PDT-PTT) upon laser irradiation, resulting in excellent tumor elimination efficacy with only once injection and irradiation. This study thus provides a versatile platform for practical cancer theranostics.

Hypoxia-activated probe for NIR fluorescence and photoacoustic dual-mode tumor imaging.

Construction of tumor microenvironment responsive probe with more than one imaging modality, in particular toward hypoxia of solid tumors, is an appealing yet significantly challenging task. In this work, we designed a hypoxia-activated probe TBTO (Triphenylamine-Benzothiadiazole-Triphenylamine derivative featuring four diethylamino N-Oxide groups) for in vivo imaging. TBTO could undergo bioreduction in a hypoxic microenvironment to yield compound TBT sharing both near-infrared (NIR) aggregation-induced emission and strong twisted intramolecular charge transfer features, which endows the probe with excellent performance in NIR fluorescence and photoacoustic dual-mode tumor imaging. This study offers useful insights into designing a new generation agent for clinical cancer diagnosis.

Aggregation-Induced Emission Luminogens Married to 2D Black Phosphorus Nanosheets for Highly Efficient Multimodal Theranostics.

Inspired by the respective advantages of aggregation-induced emission (AIE)-active photosensitizers and black phosphorus nanomaterials in cancer treatment, the facile construction of novel AIE photosensitizers married to 2D black phosphorus nanosheets and their application for multimodal theranostics are demonstrated. The developed nanomaterial simultaneously possesses distinctive properties and multiple functions including excellent stability, good biocompatibility, intensive fluorescence emission in the NIR region, high-performance reactive oxygen species generation, good photothermal conversion efficiency, outstanding cellular uptake, and effective accumulation at the tumor site. Both in vitro and in vivo evaluation show that the presented nanotheranostic system is an excellent candidate for NIR fluorescence-photothermal dual imaging-guided synergistic photodynamic-photothermal therapies. This study thus not only extends the applications scope of AIE and black phosphorus materials, but also offers useful insights into designing a new generation of cancer theranostic protocol for potential clinical applications.

Doping AIE Photothermal Molecule into All-Fiber Aerogel with Self-Pumping Water Function for Efficiency Solar Steam Generation.

Utilizing solar energy to generate clean water by interface solar steam generation is considered to be a promising strategy to address the challenge of global water shortage. However, it is challenge to design an idealized structure with all of the required characters such as high photothermal conversion efficiency, large surface to volume, and porous and continuous water pumping. Herein, we demonstrate a three-dimensional all-fiber aerogel (3D AFA) that can float on the water surface and continuously self-pump water. More notably, an aggregation-induced emission (AIE) photothermal molecule is doped into the 3D AFA, which is endowed with the superior capacity of transferring solar energy into heat. Combining these distinctive benefits, the presented 3D AFA exhibits a high evaporation rate (1.43 kg m-2 h-1) and solar-to-vapor conversion efficiency (86.5%) under irradiation of 1 sun, as well as a high evaporation rate (10.9 kg m-2 d-1) under natural sunlight. Besides, the designed 3D AFA possesses sustainable stability and a self-cleaning function to restrain salt deposition, and there is no significant change in the evaporation performance after many cycles in the case of seawater treatment. With a highly efficient evaporation rate and long-term sustainable solar steam generation, such 3D AFA can offer a new strategy for desalination.

Thermosensitive and photocrosslinkable hydroxypropyl chitin-based hydrogels for biomedical applications.

In situ forming injectable hydrogels based on thermosensitive polymers are being investigated for tissue engineering applications. However, the major limitations of this kind of hydrogels are low gel stability and weak mechanical properties under physiological conditions. Here, thermosensitive hydroxypropyl chitin (HPCH) was synthesized homogenously and subsequently functionalized with photocrosslinkable methacrylate groups via glycidyl methacrylate to generate glycidyl methacrylate-modified HPCH (GM-HPCH). The obtained new GM-HPCH polymers exhibited similar reversible thermosensitive sol-gel transition behaviors at a low concentration (2 wt% in PBS). The physical thermogelation GM-HPCH hydrogels were able to be photocrosslinked by UV irradiation under physiological conditions to form enhanced stable and mechanically strong hydrogels. The mechanical property, swelling and degradation behavior of the hydrogels could be tuned by controlling the degree of substitution of methacrylate groups and UV exposure time. Cytotoxicity test displayed that the photocrosslinked thermogels were non-cytotoxic. The photocrosslinkable GM-HPCH thermogels hold great potential for biomedical applications.

Injectable and Degradable pH-Responsive Hydrogels via Spontaneous Amino-Yne Click Reaction.

Injectable hydrogels have attracted increasing attention in tissue regeneration and local drug delivery applications. Current click reactions for preparing injectable hydrogels often require a photoinitiator or catalyst, which may be toxic and may involve complex synthesis of precursors. Here, we report a facile and inexpensive method to prepare injectable and degradable hydrogels via spontaneous amino-yne click reaction without using any initiator or catalyst under physiological conditions based on telechelic electron-deficient dipropiolate ester of polyethylene glycol and water-soluble commercially available carboxymethyl chitosan (CMC). The gelation time, mechanical property, and degradation rate of the hydrogels could be adjusted by varying CMC concentrations and stoichiometric ratios. The reversible pH-induced sol-gel transitions of the hydrogel are presented and the pH-controlled drug release behaviors are demonstrated, of which the mechanism is discussed. In vitro cytotoxicity assays and in vivo in situ injection study of the CMC-based hydrogels showed favorable gel formation, nontoxicity, and good tissue biocompatibility. Therefore, these biodegradable and injectable hydrogels prepared by spontaneous amino-yne click reaction hold potential for tissue engineering and other biomedical applications.

Peach gum polysaccharide polyelectrolyte: preparation, properties and application in layer-by-layer self-assembly.

The hydrolyzed peach gum polysaccharide (HPGP) prepared at acidic condition is investigated as an anionic polyelectrolyte for the first time. A hydrolysis mechanism is proposed by monitoring the hydrolysis efficiency and morphological change of crude peach gum, and the intrinsic viscosity of resulted HPGP as a function of hydrolysis time. Fourier transform infrared (FTIR) spectroscopy and ζ-potential measurements reveal that HPGP with multiple carboxylic groups is negatively charged in water in the pH range 3-11. The HPGP exhibits remarkable pH and ionic strength responsiveness, as proven by dynamic light scattering (DLS) and atomic force microscopy (AFM) measurements. Moreover, the layer-by-layer (LbL) self-assembly experiments further confirmed that the HPGP can be utilized as an anionic polyelectrolyte. Considering the facile availability, favorable compatibility and intriguing functionality of HPGP, this study opens up enormous opportunities for the large-scale utilization of peach gum resource.

Multihydroxy dendritic upconversion nanoparticles with enhanced water dispersibility and surface functionality for bioimaging.

Upconversion nanoparticle (UCNP) as a new class of imaging agent is gaining prominence because of its unique optical properties. An ideal UCNP for bioimaging should simultaneously possess fine water dispersibility and favorable functional groups. In this paper, we present a simple but effective method to the synthesis of a UCNP-based nanohybrid bearing a multihydroxy hyperbranched polyglycerol (HPG) shell by the combination of a "grafting from" strategy with a ring-opening polymerization technique. The structure and morphology of the resulting UCNP-g-HPG nanohybrid were characterized in detail by Fourier transform infrared, (1)H NMR, thermogravimetric analysis, and transmission electron microscopy measurements. The results reveal that the amount of grafted HPG associated with the thickness of the HPG shell can be well tuned. UCNP-g-HPG shows high water dispersibility and strong and stable upconversion luminescence. On the basis of its numerous surface hydroxyl groups, UCNP-g-HPG can be tailored by a representative fluorescent dye rhodamine B to afford a UCNP-g-HPG-RB nanohybrid that simultaneously presents upconversion and downconversion luminescence. Preliminary biological studies demonstrate that UCNP-g-HPG shows low cytotoxicity, high luminescent contrast, and deep light penetration depth, posing promising potential for bioimaging applications.

Peach gum for efficient removal of methylene blue and methyl violet dyes from aqueous solution.

This study investigated the potential use of natural peach gum (PG) as alternative adsorbent for the removal of dyes from aqueous solutions. The PG showed high adsorption capacities and selectivity for cationic dyes (e.g., methylene blue (MB) and methyl violet (MV)) in the pH range 6-10. 98% of MB and MV could be adsorbed within 5 min, and both of the adsorptions reached equilibrium within 30 min. The dye uptake process followed the pseudo-second-order kinetic model. The intraparticle diffusion was not the sole rate controlling step. Equilibrium adsorption isotherm data indicated a good fit to the Langmuir isotherm model. Regeneration study revealed that PG could be well regenerated in acid solution. The recovered PG still exhibited high adsorption capacity even after five cycles of desorption-adsorption. On the basis of its excellent adsorption performance and facile availability, PG can be employed as an efficient low cost adsorbent for environmental cleanup.

Amphibious fluorescent carbon dots: one-step green synthesis and application for light-emitting polymer nanocomposites.

A facile and green approach for the synthesis of amphibious fluorescent carbon dots (CDs) from natural polysaccharide is reported. Light-emitting polymer nanocomposites with excellent optical performance can be easily prepared by incorporation of the amphibious CDs into the polymer matrix.

One-step synthesis of robust amine- and vinyl-capped magnetic iron oxide nanoparticles for polymer grafting, dye adsorption, and catalysis.

Magnetic iron oxide nanoparticles (MIONs) bearing amine and vinyl groups are fabricated straightforwardly using vinyl-based tertiary amine molecules as both alkaline source and ligands based on the coprecipitation of iron ions in aqueous solution. The as-prepared MIONs present amphiphilic performance that can be well-dispersed both in aqueous solution and common organic solvents (e.g., ethanol, dichloromethane and tetrahydrofuran). Transmission electron microscopy (TEM), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM) measurements reveal that the MIONs are superparamagnetic Fe3O4 nanoparticles with a mean diameter below 10 nm. The presence of ligands on the surface of MIONs was confirmed by thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) characterizations. Benefiting from the surface vinyl groups, the MIONs are able to graft polyvinyl-based polymers by in situ polymerization of the corresponding vinyl monomers as confirmed by grafting poly(methyl methacrylate) (PMMA) in this paper. On the basis of their surface amine groups, the MIONs show high adsorption capacity (ca. 0.42 mmol/g) for congo red dye and excellent performance for in situ growth of Pt nanocatalyst. Moreover, the MIONs possess high stability and can be reused several times without obvious decrease of their adsorption capacity and catalytic efficiency. Considering the facile fabrication process and versatile performance of the obtained MIONs, this work may open up new opportunities for the large-scale applications of MIONs.