Unraveling Dynamic Helicity Inversion and Chirality Transfer through the Synthesis of Discrete Azobenzene Oligomers by an Iterative Exponential Growth Strategy.

Unraveling the chirality transfer mechanism of polymer assemblies and controlling their handedness is beneficial for exploring the origin of hierarchical chirality and developing smart materials with desired chiroptical activities. However, polydisperse polymers often lead to an ambiguous or statistical evaluation of the structure-property relationship, and it remains unclear how the iterative number of repeating units function in the helicity inversion of polymer assemblies. Herein, we report the macroscopic helicity and dynamic manipulation of the chiroptical activity of supramolecular assemblies from discrete azobenzene-containing oligomers (azooligomers), together with the helicity inversion and morphological transition achieved solely by changing the iterative chain lengths. The corresponding assemblies also differ from their polydisperse counterparts in terms of thermodynamic properties, chiroptical activities, and morphological control.

Association between gut microbiota and endometriosis: a two-sample Mendelian randomization study.

Background: Recent studies have shown that an imbalance in gut microbiota (GM) may not always be associated with endometriosis (EMS). To investigate this further, we conducted a two-sample Mendelian randomization study. Methods: MR analysis was performed on genome-wide association study (GWAS) summary statistics of GM and EMS. Specifically, the MiBioGen microbiota GWAS (N = 18,340) was used as exposure. The FinnGen study GWAS (8,288 EMS cases and 68,969 controls) was used as outcome. We primarily used the inverse variance weighted (IVW) method to analyze the correlation and conducted a sensitivity analysis to verify its reliability. Results: (1) MR analysis: The results of the IVW method confirmed that a total of 8 GM taxa were related to the risk of EMS. Class-Melainabacteria (p = 0.036), family-Ruminococcaceae (p = 0.037), and genus-Eubacteriumruminantium (p = 0.015) had a protective effect on EMS, whereas order-Bacillales (p = 0.046), family-Prevotellaceae (p = 0.027), genus-Anaerotruncus (p = 0.025), genus-Olsenella (p = 0.036) and genus-RuminococcaceaeUCG002 (p = 0.035) could increase the risk of EMS. (2) Sensitivity analysis: Cochrane's Q test (p > 0.05), MR-Egger intercept method (p > 0.05), and leave-one-out method confirmed the robustness of MR results. Conclusion: This study performed a MR analysis on two large national databases and identified the association between 8 GM taxa and EMS. These taxa could potentially be utilized for indirectly diagnosing EMS and could lead to novel perspectives in research regarding the pathogenesis, diagnosis, and treatment of EMS.

Sequence effect on the self-assembly of discrete amphiphilic co-oligomers with fluorene-azobenzene semirigid backbones.

Sequences can have a dramatic impact on the unique properties and self-assembly in natural macromolecules, which has received increasing interest. Herein, we report a series of discrete amphiphilic co-oligomers with the same composition but different building blocks in a semirigid backbone. These sequence-defined oligomers possess two primary amine groups on the side chain of the azobenzene building block, and hence, they become amphipathic due to quaternization of the amine groups when protonated in acidic aqueous solution. These oligomer isomers assembled into different nanoparticles, including nanofibers, hollow vesicles and spherical micellar complexes, in a THF/water/HCl mixture under the same conditions. UV-vis absorption spectra, differential scanning calorimetry (DSC) and X-ray scattering (XRD) experiments combined with theoretical calculations reveal that the sequence-controlled co-oligomers induce different molecular packing conformations and arrangement modes of building blocks in self-assembly. Furthermore, these self-assembled nanoparticles demonstrate photoresponsive morphological transformation and fluorescence emission under UV light irradiation due to trans-to-cis photoisomerization of azobenzene. This work demonstrates that customizing functional nanoparticles can be achieved by controlling the sequence structure in synthetic co-oligomers.

IL-6 secretion of CD4+ T cells stimulated by LC3-positive extracellular vesicles in human epithelial ovarian cancer.

BACKGROUND: Ovarian cancer (OC) as the most fatal gynecological malignancy worldwide, with epithelial ovarian cancer (EOC) being the predominant and most lethal form, poses a serious threat to human health. LC3-positive extracellular vesicles (LC3+ EVs) promote tumorigenesis by educating CD4+ T cells in a murine melanoma model. However, regulation of LC3+ EVs in human EOC remains largely unknown.  METHODS: Differential analysis of Rab8a, Hsp90α and Il6 expression was performed using GEPIA2. The number of LC3+ EVs and the frequency of Heat shock protein 90α+ LC3+ EVs (HSP90α+ LC3+ EVs) in the ascites of EOC patients were tested by flow cytometry. IL-6, IL-10, IFN-γ, IL-4 and TGF-ß were measured by ELISA. CD4+ T cells were isolated from peripheral blood of healthy human donors using MACS magnetic bead technology.  RESULTS: Higher Rab8a, Hsp90a and Il6 expression of cancer tissues compared with normal adjacent tissues in OC were found. The level of IL-6 was positively correlated with LC3+ EVs number, HSP90α+ LC3+ EVs percentage in the ascites, and ROMA index of the patient. In addition, elevated IL-6 production by CD4+ T cells induced by LC3+ EVs was observed, which was suppressed by anti-HSP90α or anti-TLR2.  CONCLUSIONS: LC3+ EVs level and HSP90α+ LC3+ EVs percentage were associated with elevated IL-6 in the ascites of EOC patients. HSP90α on LC3+ EVs from human EOC could stimulate CD4+ T cell production of IL-6 via TLR2.

Polymerization-Induced Helicity Inversion Driven by Stacking Modes and Self-Assembly Pathway Differentiation.

Regulating the mutual stacking arrangements is of great interest for understanding the origin of chirality at different hierarchical levels in nature. Different from molecular level chirality, the control and manipulation of hierarchical chirality in polymer systems is limited to the use of external factors as the energetically demanding switching stimulus. Herein, the first self-assembly strategy of polymerization-induced helicity inversion (PIHI), in which the controlled packing and dynamic stereomutation of azobenzene (Azo) building blocks are realized by in situ polymerization without any external stimulus, is reported. A multiple helicity inversion and intriguing helix-helix transition of polymeric supramolecular nanofibers occurs during polymerization, which is collectively confirmed to be mediated by the transition between functionality-oriented π-π stacking, H-, and J-aggregation. The studies further reveal that helicity inversion proceeds through a delicate interplay of the thermodynamically and kinetically controlled, pathway-dependent interconversion process, which should provide new insight into the origin and handedness control of helical nanostructures with desired chirality.

Controlling the Multiple Chiroptical Inversion in Biphasic Liquid-Crystalline Polymers.

While controlling the chirality and modulating the helicity is a challenging task, it attracts great research interest for gaining a better understanding of the origin of chirality in nature. Herein, structurally similar azobenzene (Azo) vinyl monomers were designed in which the alkyl chains comprised the chiral stereocenter with different achiral tail lengths. Combining the synchronous polymerization, supramolecular stacking and self-assembly, the multiple chiroptical inversion of the Azo-polymer supramolecular assemblies can be modulated by the tail length and DP of Azo blocks during in situ polymerization. The DP-, UV light-, temperature-, aging time-dependent chiroptical properties and liquid-crystalline (LC) characterization indicated that the amorphous-to-LC phase transition and biphasic LC interconversion allow the transcription of intra-chain π-π stacking, inter-chain H- and J-aggregation, thereby controlling the dynamic multiple reversal of supramolecular chirality.

Transfer, Amplification, Storage, and Complete Self-Recovery of Supramolecular Chirality in an Achiral Polymer System.

Supramolecular chirality and its complete self-recovery ability are highly mystical in nature and biological systems, which remains a major challenge today. Herein, we demonstrate that partially cross-linked azobenzene (Azo) units can be employed as the potential chiral trigger to fully heal the destroyed helical superstructure in achiral nematic polymer system. Combining the self-assembly of Azo units and terminal hydroxyl groups in polymer side chains allows the vapor-induced chiral nematic phase and covalent fixation of the superstructure via acetal reaction. The induced helical structure of Azo units can be stored by inter-chain cross-linking, even after removal of the chiral source. Most interestingly, the stored chiral information can trigger perfect chiral self-recovery (CSR) behavior after being destroyed by UV light, heat, and solvents. The results pave a new way for producing novel chiroptical materials with reversible chirality from achiral sources.

An On-Demand Dissoluble Chitosan Hydrogel Containing Dynamic Diselenide Bond.

A new kind of on-demand dissolution hydrogel is successfully synthesized by modification of chitosan using γ-selenobutyrolactone. The chitosan hydrogel with different selenium contents is formed by ring opening of γ-selenobutyrolactone with the amines of D-glucosamine units on the chitosan backbone. The structure of the hydrogel was confirmed by 1H NMR, XRD and XPS. Its physical and biological properties were evaluated by rheology characterization, degradation tests and cytotoxicity test. The hydrogel showed excellent biocompatibility and good degradation properties under oxidation or reduction conditions. All the evidence demonstrated that this type of material has good prospects for dressing applications.

Smart supramolecular nanofibers and nanoribbons from uniform amphiphilic azobenzene oligomers.

A series of self-assembled 1D nanostructures, including straight and helix nanofibers, nanoribbons, and nanobelts, were fabricated from uniform amphiphilic azobenzene oligomers with tunable molecular weight and side chain functionality, promoted by multiple and cooperative supramolecular interactions. Additionally, the morphological transformation of the nanofibers was achieved during the photoisomerization process.

Controllable Radical Polymerization of Selenide Functionalized Vinyl Monomers and Its Application in Redox Responsive Photonic Crystals.

Selenium-containing monomer (p-phenylseleno) styrene (p-PhSeSt) is polymerized by reversible addition-fragmentation chain transfer polymerization. Polymer, (P(p-PhSeSt)), with controlled molecular weight and narrow molecular weight is obtained. The selenide moiety in obtained P(p-PhSeSt) can be selectively oxidized to selenoxide or selenone groups by H2 O2 or NaClO, respectively. These oxidized groups can be further reduced to selenide by Na2 S2 O4 . The structure changing of polymers during such redox cycle is characterized by nuclear magnetic resonance, X-ray photoelectron spectroscopy, and size exclusion chromatography. Properties, such as thermal performance, glass transition temperature, water contact angles, and refractive indices, of the resulting polymers are systematically investigated before and after oxidation. In addition, SiO2 inverse opal photonic crystal (IOPC) is fabricated by sacrificial polymer colloidal template method. Owing to changes of the RIs of P(p-PhSeSt) after selective oxidation, the predictable change of PC bandgap as a redox-responsive PC sensor is successfully realized, which provides new perspectives for modulating photonic crystals.

2,5-Dimethylfuran/Acrylonitrile as Latent Monomer for Sequence-Controlled Copolymer and Sequence-Dependent Thermo-Responsivity.

Sequence control has attracted increasing attention for its ability of regulating polymer property and performance. Herein, the sequence-controlled polymer containing acrylonitrile (AN) is achieved by using 2,5-dimethylfuran/acrylonitrile adduct as a latent monomer. The temperature-dependent retro Diels-Alder reaction is engaged in controlling the release of AN during RAFT polymerization, that is, regulating the instant AN concentration via a non-invasive and in situ manner. Such control over the instant AN concentration and particularly the molar ratio of comonomer pair leads to the simultaneous change of monomer units in "living" polymeric chain, thus resulting in the sequence-controlled polymeric structures. By delicately manipulating the polymerization temperature, diverse sequence-on-demand structures of AN-containing copolymers, such as poly(AN/methyl methacrylate), poly(AN/styrene), poly(AN/butyl acrylate), poly(AN/N,N-dimethylacrylamide), and poly(AN/N-isopropylacrylamide) are created. Meanwhile, this study presents an initial attempt in tuning the thermal responsivity of poly(AN/N-isopropylacrylamide), which is closely correlated to the sequence of polymer structure. More importantly, the polymer with averagely distributed AN units results in the higher thermal sensitivity. Therefore, the synthetic strategy proposed in this work offers a promising platform for accessing the sequence-controlled copolymers containing AN structures, thus expanding the investigation on the relationship between the polymer structures and correlated properties.

Visual Ozone Sensor: Structural Color Change of Pendant Selenium-Containing Maleimide Polymers via Oxidation.

Pendant selenium-containing maleimide polymers with different selenium contents are synthesized via a radical copolymerization of styrene and N-butylmaleimide phenyl selenide. The polymer structures are characterized by nuclear magnetic resonance, gel permeation chromatography, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and scanning electron microscopy with an energy-dispersive spectrometer, which results in the desired structures and selenium contents. The refractive indices of the polymers, which change as a function of different contents of selenium and oxidative stimuli by H2 O2 or O3 , are investigated. Finally, a photonic crystal (PC) is prepared based on the selenium-containing polymer. The visible color changes of the PC are investigated as a function of different concentrations and contact times of O3 .

Supramolecular Chirality in Azobenzene-Containing Polymer System: Traditional Postpolymerization Self-Assembly Versus In Situ Supramolecular Self-Assembly Strategy.

Recently, the design of novel supramolecular chiral materials has received a great deal of attention due to rapid developments in the fields of supramolecular chemistry and molecular self-assembly. Supramolecular chirality has been widely introduced to polymers containing photoresponsive azobenzene groups. On the one hand, supramolecular chiral structures of azobenzene-containing polymers (Azo-polymers) can be produced by nonsymmetric arrangement of Azo units through noncovalent interactions. On the other hand, the reversibility of the photoisomerization also allows for the control of the supramolecular organization of the Azo moieties within polymer structures. The construction of supramolecular chirality in Azo-polymeric self-assembled system is highly important for further developments in this field from both academic and practical points of view. The postpolymerization self-assembly strategy is one of the traditional strategies for mainly constructing supramolecular chirality in Azo-polymers. The in situ supramolecular self-assembly mediated by polymerization-induced self-assembly (PISA) is a facile one-pot approach for the construction of well-defined supramolecular chirality during polymerization process. In this review, we focus on a discussion of supramolecular chirality of Azo-polymer systems constructed by traditional postpolymerization self-assembly and PISA-mediated in situ supramolecular self-assembly. Furthermore, we will also summarize the basic concepts, seminal studies, recent trends, and perspectives in the constructions and applications of supramolecular chirality based on Azo-polymers with the hope to advance the development of supramolecular chirality in chemistry.

A Novel Synthesis of Poly(Ester-Alt-Selenide)s by Ring-Opening Copolymerization of γ-Selenobutyrolactone and Epoxy Monomer.

Ring-opening copolymerization (ROCOP) is an effective means to prepare functionalized polyester. In this work, a type of selenide-containing polyesters with controllable structure, molecular weight, and molecular weight distribution was successfully prepared by ROCOP of γ-selenobutyrolactone and epoxy compounds. The influence of the catalyst, solvent, and reaction temperature on the reaction efficiency was examined. Then, kinetic study was investigated under an optimized condition. The structure of the copolymers was carefully characterized by nuclear magnetic resonance (NMR), 1H NMR, 13C NMR, and 77Se NMR, Matrix-assisted laser-desorption-ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and size exclusion chromatography (SEC). The resulting polymers showed a linear structure with a sequence regulated backbone repeating unit of ester-selenide. On this basis, some typical epoxides were investigated to verify the scope of the polymerization system. Due to the "living"/controlled characteristics of this ROCOP, multiblock, amphiphilic, and stereotactic copolymers could be prepared with a pre-designed structure. As expected, the selenide-containing amphiphilic copolymer could self-assemble to micelles and showed an oxidative response.

Smart azobenzene-containing tubular polymersomes: fabrication and multiple morphological tuning.

A fundamental challenge in nanomaterial science is to facilely fabricate nonspherical polymersomes. Here, several kinds of novel tubular polymersomes were fabricated via self-assembly of amphiphilic azobenzene-containing block copolymers. Besides, their shape could be tuned by multiple approaches including changes in the chemical structure, self-assembly conditions and external stimuli.

In Situ Controlled Construction of a Hierarchical Supramolecular Chiral Liquid-Crystalline Polymer Assembly.

Hierarchical supramolecular chiral liquid-crystalline (LC) polymer assemblies are challenging to construct in situ in a controlled manner. Now, polymerization-induced chiral self-assembly (PICSA) is reported. Hierarchical supramolecular chiral azobenzene-containing block copolymer (Azo-BCP) assemblies were constructed with π-π stacking interactions occurring in the layered structure of Azo smectic phases. The evolution of chirality from terminal alkyl chain to Azo mesogen building blocks and further induction of supramolecular chirality in LC BCP assemblies during PICSA is achieved. Morphologies such as spheres, worms, helical fibers, lamellae, and vesicles were observed. The morphological transition had a crucial effect on the chiral expression of Azo-BCP assemblies. The supramolecular chirality of Azo-BCP assemblies destroyed by 365 nm UV irradiation can be recovered by heating-cooling treatment; this dynamic reversible achiral-chiral switching can be repeated at least five times.

Novel AIEgen-Functionalized Diselenide-Crosslinked Polymer Gels as Fluorescent Probes and Drug Release Carriers.

Stimuli-responsive functional gels have shown significant potential for application in biosensing and drug release systems. In this study, aggregation-induced emission luminogen (AIEgen)-functionalized, diselenide-crosslinked polymer gels were synthesized via free radical copolymerization. A series of polymer gels with different crosslink densities or tetraphenylethylene (TPE) contents were synthesized. The diselenide crosslinker in the gels could be fragmented in the presence of H2O2 or dithiothreitol (DTT) due to its redox-responsive property. Thus, the TPE-containing polymer chains were released into the aqueous solution. As a result, the aqueous solution exhibited enhanced fluorescence emission due to the strong hydrophobicity of TPE. The degradation of polymer gels and fluorescence enhancement in an aqueous solution under different H2O2 or DTT concentrations were studied. Furthermore, the polymer gels could be used as drug carriers, suggesting a visual drug release process under the action of external redox agents. The AIEgen-functionalized, diselenide-crosslinked polymer gels hold great potential in the biomedical area for biosensing and controlled drug delivery.

Facile Fabrication of Semiconducting Single-Walled Carbon Nanotubes Patterns on Flexible Substrate Based on a Photoimmobilization Technique.

Single-walled carbon nanotubes (SWCNTs) have attracted significant attention due to their outstanding properties. For their wide applications in electronics and optoelectronics, pure semiconducting SWCNTs (s-SWCNTs) and their precise placement are preconditions. Recent advances have focused on developing effective strategies to separate s-SWCNTs from raw SWCNTs, a mixture of metallic and semiconducting nanotubes, and deposit s-SWCNTs on target substrates. Herein, a polyfluorene-based alternative copolymer (PFBP) containing the benzophenone group was employed. PFBP achieved higher yield for s-SWCNTs than the well-studied poly(9,9-dioctylfluorene) through solution process. Subsequently, the dispersed s-SWCNTs were immobilized on a flexible polyethylene terephthalate in a facile manner by the photoreactive benzophenone group upon exposure to UV irradiation, and chemically robust patterns were fabricated from micro to macro scales through photomasks. Our method accomplished by utilizing photoimmobilization is a simple cleaning procedure and an important step forward in pitch scaling for further applications of conjugated polymer wrapped s-SWCNTs.

One-Step Photocontrolled Polymerization-Induced Self-Assembly (Photo-PISA) by Using In Situ Bromine-Iodine Transformation Reversible-Deactivation Radical Polymerization.

Polymerization-induced self-assembly (PISA) has become an effective strategy to synthesize high solid content polymeric nanoparticles with various morphologies in situ. In this work, one-step PISA was achieved by in situ photocontrolled bromine-iodine transformation reversible-deactivation radical polymerization (hereinafter referred to as Photo-BIT-RDRP). The water-soluble macroinitiator precursor α-bromophenylacetate polyethylene glycol monomethyl ether ester (mPEG1k-BPA) was synthesized in advance, and then the polymer nanomicelles (mPEG1k-b-PBnMA and mPEG1k-b-PHPMA, where BnMA means benzyl methacrylate and HPMA is hydroxypropyl methacrylate) were successfully formed from a PISA process of hydrophobic monomer of BnMA or HPMA under irradiation with blue LED light at room temperature. In addition, the typical living features of the photocontrolled PISA process were confirmed by the linear increase of molecular weights of the resultant amphiphilic block copolymers with monomer conversions and narrow molecular weight distributions (Mw/Mn < 1.20). Importantly, the photocontrolled PISA process is realized by only one-step method by using in situ photo-BIT-RDRP, which avoids the use of transition metal catalysts in the traditional ATRP system, and simplifies the synthesis steps of nanomicelles. This strategy provides a promising pathway to solve the problem of active chain end (C-I) functionality loss in two-step polymerization of BIT-RDRP.

Near-Infrared, Light-Induced Cationic and Radical RAFT Polymerization Catalyzed by Iron Complex.

A near-infrared (NIR) light induced controlled cationic polymerization is presented here. The halide abstraction reaction between the cyclopentadienyl iron dicarbonyl dimer (Fe2(Cp)2(CO)4) and an organic halide is utilized to generate initial radicals or cations under mild conditions, which can be further combined with both radical and cationic reversible addition-fragmentation chain transfer (RAFT) polymerization. Well-defined poly(vinyl ether)s and polyacrylates are prepared successfully under NIR light by this method. The excellent penetration ability of NIR light through thick barriers has been verified by polymerization in the presence of an A4 paper. In addition, iron-based radical polymerization has been used for three-dimensional (3D) printing to fabricate materials with different thicknesses.