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From plastic to functional elastomer by constructing Cu–S dynamic reversible bonds in CO2-based polycarbonate.

A strategy for upcycling poly(ethylene terephthalate) into a high-value UV-curable polyurethane acrylate coating using bio-based cardanol diol as a glycolysis agent.

Although molecular design strategies for highly bright near-infrared II (NIR-II) fluorophores were proposed, the lack of solid structural identification (single crystal) hinders the further development of this field. This thorny issue is addressed by performing the structure-function relationship of NIR-II dyes, as confirmed by molecular single crystal engineering. Single crystal structure analysis confirms that twisted architectures (large dihedral angles ∼70°) and loose packing patterns (intermolecular distance of ∼3.4-4.5 Å) are key elements to enhance the absolute quantum yield (QY) in the solid state. Through regulating donor-acceptor distance and donor-acceptor interactions, the resultant well-defined TBP

Aldehyde end-capped CO2-based polycarbonates were prepared to serve as a green platform for the construction of diverse functional polymers.

Site-specific functional polymers are generally synthesized from functionalized chain transfer agents (CTA) in the presence of catalysts. However, the poor solubility or chemical inertness of CTAs may lead to polymerizations uncontrollable. Now, this issue is addressed by proposing a strategy of designing chain-transfer-catalyst (CTC) that combines catalyst and CTA into one. The occurrence of catalytic effect naturally triggers the chain transfer process to give catalyst-labeled polymers with well-defined structures. As a proof-of-concept, cobalt(III) porphyrin catalysts with one, two and four hydroxyl groups act as efficient CTCs, giving the corresponding site-specific functional poly(propylene carbonate)s (PPC), diversifying the topology of polymers. Furthermore, porphyrin-capped PPCs with controllable Mn in the range of 1,000–16,800 g mol−1 were obtained by using monofunctional CTC (CTCOH). Moreover, different from traditional “catalyst+CTA” systems, a novel dynamic network transfer mechanism of CTCOH was proposed. This study provides a CTC strategy for the synthesis of site-specific functional polymers.

Sleep disturbances exacerbate the progression of Alzheimer's disease (AD), but disturbances of non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep may have different effects. Neurofilament light chain (NfL), an axon-specific protein, is an indicator of the severity of neuronal apoptosis. To investigate whether or not NREM or REM sleep is crucial to neuronal survival, we examined the effects of induced NREM or REM sleep loss on NfL levels in APP/PS1 mice, a model of AD, and their wild-type (WT) C57BL/6 J littermates.At 6 months of age, WT mice and AD mice were equally divided into six groups, namely, the WT-normal sleep (S), WT-total sleep deprivation (TSD), WT-REM deprivation (RD), AD-S, AD-TSD and AD-RD groups, according to the type of sleep intervention applied. All mice underwent 6 days of sleep intervention. Cerebrospinal fluid (CSF) and plasma NfL levels were measured at baseline and on days 2, 4 and 6, and spatial memory was assessed in the Morris water maze (MWM) test.Among the 18 WT and 18 AD mice, CSF and plasma NfL levels were higher in AD-TSD mice than in AD-S or AD-RD mice, while no significant difference was observed between the latter two groups. In AD-TSD mice, CSF and plasma NfL levels increased with the duration of sleep deprivation. A similar pattern of results was observed for the WT groups.NREM sleep loss may increase CSF and plasma NfL levels in both WT and AD mice.

Iatrogenic extrahepatic bile duct injury remains a dreaded complication while performing cholecystectomy. Although X-ray based cholangiography could reduce the incidence of biliary tract injuries, the deficiencies including radiation damage and expertise dependence hamper its further clinical application. The effective strategy for intraoperative cholangiography is still urgently required. Herein, a fluorescence-based imaging approach for cholangiography in the near-infrared IIb window (1500-1700 nm) using TT3-oCB, a bright aggregation-induced emission luminogen with large π-conjugated planar unit, is reported. In phantom studies, TT3-oCB nanoparticles exhibit high near-infrared IIb emission and show better image clarity at varying penetrating depths. When intrabiliary injected into the gallbladder or the common bile duct of the rabbit, TT3-oCB nanoparticles enable the real-time imaging of the biliary structure with deep penetrating capability and high signal-to-background ratio. Moreover, the tiny iatrogenic biliary injuries and the gallstones in established disease models could be precisely diagnosed by TT3-oCB nanoparticle assisted near-infrared IIb imaging. In summary, we reported a feasible application for aggregation-induced emission dots as biliary contrast agent and realized high-quality cholangiography in the near-infrared IIb window with precise diagnostic ability and nonradioactive damage, which could possibly be applied for intraoperative diagnosis.

A facile alkyne-based multicomponent polymerization route was developed for the construction of solution-processable fluoropolymers with multiple functionalities. The palladium-catalyzed one-pot po...

The brightness of organic fluorescence materials determines their resolution and sensitivity in fluorescence display and detection. However, strategies to effectively enhance the brightness are still scarce. Conventional planar π-conjugated molecules display excellent photophysical properties as isolated species but suffer from aggregation-caused quenching effect when aggregated owing to the cofacial π-π interactions. In contrast, twisted molecules show high photoluminescence quantum yield (ΦPL) in aggregate while at the cost of absorption due to the breakage in conjugation. Therefore, it is challenging to integrate the strong absorption and high solid-state ΦPL, which are two main indicators of brightness, into one molecule. Herein, we propose a molecular design strategy to boost the brightness through the incorporation of planar blocks into twisted skeletons. As a proof-of-concept, twisted small-molecule TT3-oCB with larger π-conjugated dithieno[3,2-b:2',3'-d]thiophene unit displays superb brightness at the NIR-IIb (1500-1700 nm) than that of TT1-oCB and TT2-oCB with smaller thiophene and thienothiophene unit, respectively. Whole-body angiography using TT3-oCB nanoparticles presents an apparent vessel width of 0.29 mm. Improved NIR-IIb image resolution is achieved for femoral vessels with an apparent width of only 0.04 mm. High-magnification through-skull microscopic NIR-IIb imaging of cerebral vasculature gives an apparent width of ∼3.3 μm. Moreover, the deeply located internal organ such as bladder is identified with high clarity. The present molecular design philosophy embodies a platform for further development of in vivo bioimaging.

Conjugated polyelectrolytes prepared from carbon–carbon coupling polymerization have difficulties in controlling the precision molecular weight (Mn), so that the effect of Mn on their performance r...

The traditional design strategies for highly bright solid-state luminescent materials rely on weakening the intermolecular π-π interactions, which may limit diversity when developing new materials. Herein, we propose a strategy of tuning the molecular packing mode by regioisomerization to regulate the solid-state fluorescence. TBP-e-TPA with a molecular rotor in the end position of a planar core adopts a long-range cofacial packing mode, which in the solid state is almost non-emissive. By shifting molecular rotors to the bay position, the resultant TBP-b-TPA possesses a discrete cross packing mode, giving a quantum yield of 15.6±0.2 %. These results demonstrate the relationship between the solid-state fluorescence efficiency and the molecule's packing mode. Thanks to the good photophysical properties, TBP-b-TPA nanoparticles were used for two-photon deep brain imaging. This molecular design philosophy provides a new way of designing highly bright solid-state fluorophores.

Objective Spontaneous K-complexes (SKCs), a hallmark of stage 2 sleep, have been reported to decrease in density in Alzheimer's disease (AD) patients. However, few former studies have explored the alterations in SKC characteristics in the pre-clinical phase of AD—amnestic mild cognitive impairment (aMCI). The aim of our prospective cohort study was to investigate the changing trend in SKC characteristics during the progression of aMCI. Methods SKC density, amplitude and duration were measured in aMCI subjects and normal controls (NC) at two-year follow-up assessments by polysomnography (PSG). In sum, 22 NCs, 25 stable aMCI (sMCI) subjects and 20 progressive aMCI (pMCI) subjects finished the four follow-up PSG assessments, and their data were used for analysis. Results SKC density and amplitude, but not duration, decreased during the follow-up assessments in both NCs and aMCI subjects, but the rate of decrease of these parameters was greater in aMCI subjects. With the progression of aMCI, significant differences in SKC density and amplitude among the three groups were observed, whereas SKC density showed no difference at the early stage of aMCI. The receiver operating characteristic (ROC) curve results demonstrated that SKC density and amplitude could distinguish aMCI subjects from NCs with high specificity and sensitivity. Conclusion Our results suggest that SKCs decrease with ageing and the progression of aMCI, and SKC characteristics may be potential biomarkers for diagnosing aMCI.

Iatrogenic ureteral injury is a dreaded complication of abdominal and pelvic surgeries, and thus, intraoperative identification of ureters is of paramount importance but lacks efficient methods and probes. Herein, we used near-infrared II (NIR-II, 1000-1700 nm) fluorescence imaging with advantages of higher spatial resolution, deeper tissue penetration, lower light scattering, and less tissue autofluorescence to identify ureters by aggregation-induced emission luminogen dots (AIE dots). The intraoperative ureteral injuries and common ureteral diseases can be visualized timely and precisely. Due to the longer emission wavelength and higher quantum yield of the AIE dots, it largely outperforms the commercial indocyanine green dye in brightness and penetration depth. It was the first time to realize the intraoperative identification of ureters in vivo using NIR-II imaging. Thus, our work provides a new platform for intraoperative monitoring during clinical operation.

π-Conjugated chromophores have been investigated for many years and successful theoretical models have been developed to explain their photophysical properties. However, materials have appeared sporadically that do not fit within these existing models. Some of these materials possess entirely nonconjugated structures based on saturated C–C, C–O or C–N bonds, but their aggregates or solid-state forms show bright visible emission. This phenomenon is termed as clusterization-triggered emission (CTE) and the materials possessing the property are labeled clusteroluminogens. In this review, we provide a brief summary of the recent development of clusteroluminogens. The materials are classified into three categories: polymers (natural and synthetic polymers), small molecules (with and without aromatic rings) and metal clusters. Possible luminescence mechanisms underpinning the different categories of clusteroluminogens are analyzed individually. Finally, we put forward a comprehensive theory of the through-space conjugation (TSC) for these chromophores. Based on the CTE effect and TSC theory, various applications have been envisioned, for example in the areas of process monitoring, structural visualization, sensors, and probes. It is anticipated that this new research direction will bring many breakthroughs, not only in the theoretical areas, but also in these advanced applications of light-emitting materials.

The direct ring-opening polymerization (ROP) of propylene carbonate (PC) only affords oligomers with substantial unidentified by-products, which hinders the efficient utilization of PC. Through detailed studies, for the first time, a careful mechanism involving the in situ release of propylene oxide (PO) from PC decarboxylation is proposed. Further, we report a novel strategy of copolymerization of PC/cyclic anhydrides via in situ capture of the formed intermediates. Results show that PC is successfully transformed into polyesters. Especially for the ring-opening alternating copolymerization (ROAC) of PC/phthalic anhydride (PA), a variety of advantages are manifold: i) slow-release of PO ensuring a perfectly alternating structure; ii) quantitative and fast transformation of PC; iii) visualization of polymerization process by a CO

Aggregation-induced emission (AIE) is a cutting-edge fluorescence technology, giving highly-efficient solid-state photoluminescence. Particularly, AIE luminogens (AIEgens) with emission in the range of second near-infrared window (NIR-II, 1000–1700 nm) have displayed salient advantages for biomedical imaging and therapy. However, the molecular design strategy and underlying mechanism for regulating the balance between fluorescence (radiative pathway) and photothermal effect (non-radiative pathway) in these narrow bandgap materials remain obscure. In this review, we outline the latest achievements in the molecular guidelines and photophysical process control for developing highly efficient NIR-II emitters or photothermal agents with aggregation-induced emission (AIE) attributes. We provide insights to optimize fluorescence efficiency by regulating multi-hierarchical structures from single molecules (flexibilization) to molecular aggregates (rigidification). We also discuss the crucial role of intramolecular motions in molecular aggregates for balancing the functions of fluorescence imaging and photothermal therapy. The superiority of the NIR-II region is demonstrated by fluorescence/photoacoustic imaging of blood vessels and the brain as well as photothermal ablation of the tumor. Finally, a summary of the challenges and perspectives of NIR-II AIEgens for in vivo theranostics is given., Structural and process controls of NIR-II AIEgens realize manipulating of radiative (R) and nonradiative (NR) decay for precise theranostics.

Alpha 1-antichymotrypsin (ACT), an acute-phase protein, has been reported to be increased in the brain and blood of Alzheimer's disease (AD) patients. However, few previous studies have focused on amnestic mild cognitive impairment (aMCI) patients. The aim of our study was to investigate the changing trend in ACT concentrations during the progression of aMCI. Hence, we measured the cerebrospinal fluid (CSF) and serum levels of ACT in aMCI subjects and normal controls (NC) at 2-year follow-up assessments using ELISA and Western blot. Forty-four NCs, 28 stable aMCI (sMCI) patients, and 20 progressive aMCI (pMCI) patients finished the follow-up assessments, and their data were used for analysis. We found that CSF and serum ACT levels of both sMCI and pMCI patients increased over time, while those of NCs remained stable; CSF and serum ACT levels were significantly higher in both sMCI and pMCI patients than in NCs, except for baseline serum ACT. In pMCI patients prior to developing AD, CSF and serum ACT levels were already significantly higher than those in sMCI patients. The ROC curve results demonstrated that combining CSF and serum ACT levels can distinguish aMCI patients from NCs with high specificity and sensitivity. Our data suggest that ACT may be a biomarker for diagnosing aMCI.

All matter is in motion, and such behavior has been well studied in the gas and liquid states. However, the study of solid-state molecular motion is still in its infancy, mainly, because of the abs...

The mechanism of autolysis ofVolvariella volvacea(V. volvacea) at low temperature has not been fully explained. As mannitol is among the most important osmotic adjustment substances in fungal resistance, this study sampled mycelia of strains V23 and VH3 treated at 0°C for 0, 2, 4, 8, and 10 h to analyze changes in intracellular mannitol content by high-performance anion chromatography with pulsed amperometric detection (HAPEC-PAD). Reverse transcription quantitative PCR (RT-qPCR) analysis was applied to assess differences in the transcript levels of genes associated with mannitol metabolism under low-temperature stress. A mannitol solution was added to cultures ofV. volvaceafruiting bodies, and effects on the hypothermic resistance of these organs were explored by evaluating variations in sensory properties during cryogenic storage after harvest. The results suggested that in the initial stage of low-temperature treatment, intracellular mannitol was largely catabolized as an energy storage material and the expression of genes encoding enzymes involved in synthetic reactions was inhibited. However, low-temperature resistance was induced with further treatment, with activation of mannitol synthesis and inhibition of degradation; the cells accumulated mannitol, leading to osmoregulation. No significant elongation ofV. volvaceafruiting bodies during storage at 4°C was observed, and these organs tended to shrink and collapse. The sensory quality of mannitol-treated fruiting bodies was much better than that of control fruiting bodies. Application of a mannitol solution at the cultivation stage ofV. volvaceasomewhat improved the low-temperature resistance of the fruiting bodies, verifying the correlation between mannitol and resistance to this stress inV. volvacea. The results of this study lay a foundation for a deeper understanding of the autolysis mechanism ofV. volvacea, providing technical support for increasing the cryopreservation time of this species and extending the postharvest shelf life of its fruiting bodies. In addition, the mechanism underlying the low-temperature tolerance of the VH3 strain should be further explained at the molecular level.

Planar donor and acceptor (D-A) conjugated structures are generally believed to be the standard for architecting highly efficient photothermal theranostic agents, in order to restrict intramolecular motions in aggregates (nanoparticles). However, other channels of extra nonradiative decay may be blocked. Now this challenge is addressed by proposing an "abnormal" strategy based on molecular motion in aggregates. Molecular rotors and bulky alkyl chains are grafted to the central D-A core to lower intermolecular interaction. The enhanced molecular motion favors the formation of a dark twisted intramolecular charge transfer state, whose nonradiative decay enhances the photothermal properties. Result shows that small-molecule NIRb14 with long alkyl chains branched at the second carbon exhibits enhanced photothermal properties compared with NIRb6, with short branched chains, and much higher than NIR6, with short linear chains, and the commercial gold nanorods. Both in vitro and in vivo experiments demonstrate that NIRb14 nanoparticles can be used as nanoagents for photoacoustic imaging-guided photothermal therapy. Moreover, charge reversal poly(β-amino ester) makes NIRb14 specifically accumulate at tumor sites. This study thus provides an excited molecular motion approach toward efficient phototheranostic agents.

Biological and synthetic polymers play important roles in human life and modern society. Understanding their properties and dynamic processes are thus particularly crucial. However, modern instruments suffer from ex situ, tedious sample preparation, and even show “blindness” to the testing process. Fortunately, fluorescent technology based on aggregation-induced emission (AIE) luminogens is cutting-edge and holds great potential to address this challenge. Owing to their twisted flexible structures, the emission of AIE luminogens (AIEgens) is sensitive to the surrounding microenvironmental changes, enabling them to function as sensitive fluorescent probes based on the mechanism of restriction of intramolecular motion (RIM). AIEgens can even detect subtle polarity variation when imparting them with donor–acceptor structures to trigger the twisted intramolecular charge transfer effect. In this short review, we have briefly described the recent applications of AIEgens in polymer-related fields for monitoring protein conformation, fibrillation, and enzyme activity, DNA synthesis, sequence and G-quadruplexes, analyzing a polymerization reaction, glass transition, and phase separation, and detecting humidity, and heat, etc. The outlook on the further applications of AIE technology in the polymer field is also discussed.

Controlling molecular assembled structures of a single luminogen through external manipulation is a general and powerful concept for designing emission-tunable materials. However, these reported powder-like compounds generally show limited emission color, high serendipitous-discovery dependence and poor mechanical properties. To overcome these limitations, we describe a simple yet powerful strategy that is adapted from methods used to control bulk commodity polymers, to modulate the molecular assembled architecture of dopant. We use luminogens with aggregation-induced emission characteristics and intrinsic blue and yellow emissions at their crystalline and amorphous states as demonstrations. When incorporating such luminogens (AIEgens) in the desired polymer matrix with tailored microstructure, white light and white circularly polarized light are generated, which are inaccessible from single and achiral AIEgen alone. The introduced strategy for realizing diverse light emission is an innovative way of developing luminogens and provides useful continuous emissive materials in the forms of macroscopic films and fibers for developing flexible devices and wearable systems.