Facilitating safe and sustained submucosal lift through an endoscopically injectable shear-thinning carboxymethyl starch sodium hydrogel.

Traditional submucosal filling materials frequently show insufficient lifting height and duration during clinical procedures. Here, the anionic polysaccharide polymer sodium carboxymethyl starch and cationic Laponite to prepare a hydrogel with excellent shear-thinning ability through physical cross-linking, so that it can achieve continuous improvement of the mucosal cushion through endoscopic injection. The results showed that the hydrogel (56.54 kPa) had a lower injection pressure compared to MucoUp (68.56 kPa). The height of submucosal lifting height produced by hydrogel was higher than MucoUp, and the height maintenance ability after 2 h was 3.20 times that of MucoUp. At the same time, the hydrogel also showed satisfactory degradability and biosafety, completely degrading within 200 h. The hemolysis rate is as low as 0.76 %, and the cell survival rate > 80 %. Subcutaneous implantation experiments confirmed that the hydrogel showed no obvious systemic toxicity. Animal experiments clearly demonstrated the in vivo feasibility of using hydrogels for submucosal uplift. Furthermore, successful endoscopic submucosal dissection was executed on a live pig stomach, affirming the capacity of hydrogel to safely and effectively facilitate submucosal dissection and mitigate adverse events, such as bleeding. These results indicate that shear-thinning hydrogels have a wide range applications as submucosal injection materials.

Versatile Injectable Carboxymethyl Chitosan Hydrogel for Immediate Hemostasis, Robust Tissue Adhesion Barrier, and Antibacterial Applications.

Iatrogenic ulcers resulting from endoscopic submucosal dissection surgery remain a significant clinical concern due to the risk of uncontrolled bleeding. Herein, we have developed an injectable shear-thinning hydrogel cross-linked through electrostatic interactions and hydrogen bonding. The hydrogel underwent comprehensive characterization, focusing on rheological behavior, injectability, microstructure, film-forming capability, adhesion, swelling behavior, degradation kinetics, antibacterial efficacy, hemostatic performance, and biocompatibility. The incorporation of poly(vinyl alcohol) notably enhanced the internal structural stability and injection pressure, while the Laponite content influenced self-healing ability, modulus, and viscosity. Additionally, the hydrogel exhibited pH sensitivity, appropriate degradation, and swelling rates and displayed favorable film-forming and adhesion properties. Notably, it demonstrated excellent resistance against Escherichia coli and Staphylococcus aureus, highlighting its potential to create an optimal wound environment. In vivo studies further confirmed the hydrogel's exceptional hemostatic performance, positioning it as an optimal material for endoscopic submucosal dissection (ESD) surgery. Moreover, cell experiments and hemolysis tests revealed high biocompatibility, supporting their potential to facilitate the healing of iatrogenic ulcers post-ESD surgery. In conclusion, our hydrogels hold great promise as endoscopic treatment materials for ESD-induced ulcers given their outstanding properties.

Conductive Hydrogel Patches with High Elasticity and Fatigue Resistance for Cardiac Microenvironment Remodeling.

Remodeling the conductive zone to assist normal myocardial contraction and relaxation during myocardial fibrosis has become the primary concern of myocardial infarction (MI) regeneration. Herein, we report an unbreakable and self-recoverable hyaluronic acid conductive cardiac patch for MI treatment, which can maintain structural integrity under mechanical load and integrate mechanical and electrical conduction and biological cues to restore cardiac electrical conduction and diastolic contraction function. Using the free carboxyl groups and aldehyde groups in the hydrogel system, excellent adhesion properties are achieved in the interface between the myocardial patch and the tissue, which can be closely integrated with the rabbit myocardial tissue, reducing the need for suture. Interestingly, the hydrogel patch exhibits sensitive conductivity (ΔR/R0 ≈ 2.5) for 100 cycles and mechanical stability for 500 continuous loading cycles without collapse, which allows the patch to withstand mechanical damage caused by sustained contraction and relaxation of the myocardial tissue. Moreover, considering the oxidative stress state caused by excessive ROS in the MI area, we incorporated Rg1 into the hydrogel to improve the abnormal myocardial microenvironment, which achieved more than 80% free radicalscavenging efficiency in the local infarcted region and promoted myocardial reconstruction. Overall, these Rg1-loaded conductive hydrogels with highly elastic fatigue resistance have great potential in restoring the abnormal electrical conduction pathway and promoting the myocardial microenvironment, thereby repairing the heart and improving the cardiac function.

Enzyme-regulated NO programmed to release from hydrogel-forming microneedles with endogenous/photodynamic synergistic antibacterial for diabetic wound healing.

The infection-prone wound pathology microenvironment leads to ulceration and difficult healing of diabetic wounds, which seriously affects the quality of survival of patients. In this study, natural polymer materials gelatin and polylysine were used as substrates. By introducing iron/tannic acid (FeIIITA) composite nanoparticles with excellent photothermal properties into the system, the glutamine residues of gelatin were crosslinked with the primary ammonia of polylysine by glutamine aminotransferase. A nanocomposite hydrogel with excellent antibacterial ability and NO production was constructed it was used to improve the clinical problems of diabetes wounds that were difficult to vascularize and easy to be infected. Under the premise of maintaining its structural stability, the hydrogel can be customized to meet the needs of different mechanical strengths by adjusting the ratios to match different diabetic wounds. Meanwhile, the photothermal effect of FeIIITA nanoparticles can synergize with the endogenous antibacterial ability of polylysine to improve the antibacterial efficacy of hydrogels. The potential of hydrogel to promote intracellular NO production was confirmed by fluorescent staining. Microneedle patches prepared from hydrogel can be applied to diabetic wounds, which can achieve NO deep release. Its anti-inflammatory and angiogenic abilities are also useful in achieving effective healing of diabetic wounds.

Injectable shear-thinning sodium alginate hydrogels with sustained submucosal lift for endoscopic submucosal dissection.

Endoscopic submucosal dissection (ESD) is one of the most effective approaches for the minimally invasive treatment of early gastrointestinal cancers. Submucosal injections help safely and successfully remove lesions during ESD by elevating the mucosa and separating the submucosal muscle layer. Herein, we report dynamic injectable sodium alginate hydrogels (ISAHs) with shear-thinning for ESD surgery, which were easily fabricated by the sulfhydryl group of GSH-modified sodium alginate (SA-GSH) reacting with the aldehyde group of oxidized sodium alginate (OSA) at room temperature. ISAHs have advantageous self-healing abilities and antioxidant activity. Additionally, according to an in vitro test on porcine colorectal submucosal lifting, the submucosal elevation heights created by ISAHs were 13 % -18 % greater than those created by commercial ESD solutions (0.4 w/v% sodium hyaluronate). These properties and biocompatibility were confirmed in vitro and in vivo experiments. ISAHs will hopefully become a novel submucosal injectable hydrogel to assist ESD surgery.

Adaptive injectable carboxymethyl cellulose/poly (γ-glutamic acid) hydrogels promote wound healing.

The clinical acceleration of skin autogenous healing remains a great challenge, especially in the early stage after injury. In this work, a novel directly injectable hydrogel with high self-adaptability is designed as a provisional matrix to close the apposition of wound edges, using carboxymethyl cellulose and poly (γ-glutamic acid) through Schiff-base reaction. Benefiting from the dynamic covalent cross-linking structure, the functional biodegradable hydrogels are easy to prepare (gel time 5-180 s), demonstrating adequate mechanical strength (40-120 kPa), anti-fatigue abilities, and rapid self-healing (5-10 min at skin defect). Furthermore, the hydrogels exhibit biocompatibility and proliferation-promoting activity with murine fibroblasts. In the full-thickness dermal animal models, it significantly promoted collagen deposition, skin-function restoration, and VEGF expression. This hydrogel shows potential as a dressing available for skin regeneration during the healing of dermal injuries.

Bio-fabricated nanocomposite hydrogel with ROS scavenging and local oxygenation accelerates diabetic wound healing.

Chronic wounds, especially diabetic wounds, involve abnormally long inflammatory periods due to their pathological microenvironment of high reactive oxygen species (ROS) levels and lack of blood vessels. Here, via a mild, simple and feasible fabrication approach, a sustained oxygenation system is proposed, consisting of MnO2 nanosheets and a dual-network hydrogel fabricated from natural biomaterials including silk fibroin (SF) and carboxymethyl cellulose (CMC). Compared with the initial value (61.09 kPa), the compression modulus of the dual-network hydrogel increased by 116.2% through the coordination of strong covalent bonds and sacrificial coordination bonds constructed by enzymatic crosslinking and UV-irradiation crosslinking; the intrinsic shear-thinning effect endows the dual-network hydrogel with satisfactory injectable properties to be customized as a predetermined shape to accommodate the irregular wounds of diabetes. The encapsulated MnO2 nanosheets can catalyze the excessive ROS into necessary O2in situ and, after co-incubating with the SF/CMC@MnO2 hydrogels, cells in oxidative stress show significantly lower ROS (3 times) and higher O2 (17 times) levels that are conductive to relieving oxidative stress, promoting angiogenesis and reducing inflammation in vivo. Meanwhile, these SF-based hydrogels can offset the overexpression of matrix metalloproteinases (MMPs) in diabetic wounds (more than 80%) and promote remodeling of the extracellular matrix. Eventually, wound healing rates >76% in 7 days and 100% in 14 days were achieved by the bio-fabricated nanocomposite hydrogel and are remarkably faster than the commercial dressing healing rates (<30% in 7 days and <80% in 14 days). These results indicate that this bio-fabricated hydrogel system with multiple and customizable functions has great promise in the personalized clinical care of chronic wounds.

A One-Pot Strategy to Synthesize Block Copolyesters from Monomer Mixtures Using a Hydroxy-Functionized Ionic Liquid.

One-pot transformation of monomer mixtures into block copolymers remains a key challenge. Herein, a metal-free route to prepare block copolymers from monomer mixtures by a hydroxyl functionalized ionic liquid of 3-(2-hydroxyl-ethyl)-1-methylimidazolium bromide (HEMIMB) is described. HEMIMB can bridge two catalytic cycles including ring-opening alternating copolymerization (ROAC) of phthalic anhydride (PA) with epoxides and ring-opening polymerization (ROP) of L-lactide (LA), and enable a selective copolymerization from PA, LA, and epoxides. The selective copolymerization depends on the presence of PA in mixed feedstocks, exhibits the first ROAC of PA with epoxides and then ROP of LA to the formation of block polyesters in one-pot strategy. This work is beneficial to the development of metal-free catalysts for sequence-controlled polymerization that enable block architectures from mixtures of monomers.

Antithermal Quenching of Luminescence in Zero-Dimensional Hybrid Metal Halide Solids.

Zero-dimensional (0D) hybrid metal halides have emerged as a new generation of luminescent phosphors owing to their high radiative recombination rates, which, akin to their three-dimensional cousins, commonly demonstrate thermal quenching of luminescence. Here, we report on the finding of antithermal quenching of luminescence in 0D hybrid metal halides. Using (C9NH20)2SnBr4 single crystals as an example system, we show that 0D metal halides can demonstrate antithermal quenching of luminescence. A combination of experimental characterizations and first-principles calculations suggests that antithermal quenching of luminescence is associated with trap states introduced by structural defects in (C9NH20)2SnBr4. Importantly, we find that antithermal quenching of luminescence is not only limited to (C9NH20)2SnBr4 but also exists in other 0D metal halides. Our work highlights the important role of defects in impacting photophysical properties of hybrid metal halides and may stimulate new efforts to explore metal halides exhibiting antithermal quenching of luminescence at higher temperatures.

General Mild Reaction Creates Highly Luminescent Organic-Ligand-Lacking Halide Perovskite Nanocrystals for Efficient Light-Emitting Diodes.

The presence of labile bulky insulating hydrocarbon ligands in halide perovskite nanocrystals (NCs) passivates surface traps but concurrently makes charge transport difficult in optoelectronic devices. Early efforts routinely rely on the replacement of long-chain ligands with short-chain cousins, leading to notable changes in NC's sizes and photophysical properties and thus making it hard to obtain devices with nearly designed emissions. Here we report a general solution-phase ligand-exchange strategy to produce organic-ligand-lacking halide perovskite NCs with high photoluminescence (PL) quantum yields and good stability in ambient air. We demonstrate that the ligand exchange can be achieved by a well-controlled mild reaction of thionyl halide with the carboxylic and amine groups on the NC's surface, resulting in nearly dry NCs with well-passivated surfaces and almost unaltered emission characteristics. Consequently, we achieve exceptionally high-performance blue perovskite NC light-emitting diodes (LEDs) with an external quantum efficiency of up to 1.35% and an extremely narrow full width at half-maximum of 14.6 nm. Our work provides a systematic framework for preparing high-quality organic-ligand-lacking perovskite NC inks that can be directly cast as films featuring effective charge transport, thereby providing the foundation for further development of a wide range of efficient perovskite optoelectronic devices.

Defective [Bi2 O2 ]2+ Layers Exhibiting Ultrabroad Near-Infrared Luminescence.

Aurivillius phases have been routinely known as excellent ferroelectrics and have rarely been deemed as materials that luminesce in the near-infrared (NIR) region. Herein, it is shown that the Aurivillius phases can demonstrate broadband NIR luminescence that covers telecommunication and biological optical windows. Experimental characterization of the model system Bi2.14 Sr0.75 Ta2 O9-x , combined with theoretical calculations, help to establish that the NIR luminescence originates from defective [Bi2 O2 ]2+ layers. Importantly, the generality of this finding is validated based on observations of a rich bank of NIR luminescence characteristics in other Aurivillius phases. This work highlights that incorporating defects into infinitely repeating [Bi2 O2 ]2+ layers can be used as a powerful tool to space-selectively impart unusual luminescence emitters to Aurivillius-phase ferroelectrics, which not only offers an optical probe for the examination of defect states in ferroelectrics, but also provides possibilities for coupling of the ferroelectric property with NIR luminescence.

X-ray-activated long persistent phosphors featuring strong UVC afterglow emissions.

Phosphors emitting visible and near-infrared persistent luminescence have been explored extensively owing to their unusual properties and commercial interest in their applications such as glow-in-the-dark paints, optical information storage, and in vivo bioimaging. However, no persistent phosphor that features emissions in the ultraviolet C range (200-280 nm) has been known to exist so far. Here, we demonstrate a strategy for creating a new generation of persistent phosphor that exhibits strong ultraviolet C emission with an initial power density over 10 milliwatts per square meter and an afterglow of more than 2 h. Experimental characterizations coupled with first-principles calculations have revealed that structural defects associated with oxygen introduction-induced anion vacancies in fluoride elpasolite can function as electron traps, which capture and store a large number of electrons triggered by X-ray irradiation. Notably, we show that the ultraviolet C afterglow intensity of the yielded phosphor is sufficiently strong for sterilization. Our discovery of this ultraviolet C afterglow opens up new avenues for research on persistent phosphors, and it offers new perspectives on their applications in terms of sterilization, disinfection, drug release, cancer treatment, anti-counterfeiting, and beyond.

Doping-Enhanced Short-Range Order of Perovskite Nanocrystals for Near-Unity Violet Luminescence Quantum Yield.

All-inorganic perovskite nanocrystals (NCs) have emerged as a new generation of low-cost semiconducting luminescent system for optoelectronic applications. The room-temperature photoluminescence quantum yields (PLQYs) of these NCs in the green and red spectral range approach unity. However, their PLQYs in the violet are much lower, and an insightful understanding of such poor performance remains missing. We report a general strategy for the synthesis of all-inorganic violet-emitting perovskite NCs with near-unity PLQYs through engineering local order of the lattice by nickel ion doping. A broad range of experimental characterizations, including steady-state and time-resolved luminescence spectroscopy, X-ray absorption spectra, and magic angle spinning nuclear magnetic resonance spectra, reveal that the low PLQY in undoped NCs is associated with short-range disorder of the lattice induced by intrinsic defects such as halide vacancies and that Ni doping can substantially eliminate these defects and result in increased short-range order of the lattice. Density functional theory calculations reveal that Ni doping of perovskites causes an increase of defect formation energy and does not introduce deep trap states in the band gap, which is suggested to be the main reason for the improved local structural order and near-unity PLQY. Our ability to obtain violet-emitting perovskite NCs with near-perfect properties opens the door for a range of applications in violet-emitting perovskite-based devices such as light-emitting diodes, single-photon sources, lasers, and beyond.

Cs4PbBr6/CsPbBr3 Perovskite Composites with Near-Unity Luminescence Quantum Yield: Large-Scale Synthesis, Luminescence and Formation Mechanism, and White Light-Emitting Diode Application.

All-inorganic perovskites have emerged as a new class of phosphor materials owing to their outstanding optical properties. Zero-dimensional inorganic perovskites, in particular the Cs4PbBr6-related systems, are inspiring intensive research owing to the high photoluminescence quantum yield (PLQY) and good stability. However, synthesizing such perovskites with high PLQYs through an environment-friendly, cost-effective, scalable, and high-yield approach remains challenging, and their luminescence mechanisms has been elusive. Here, we report a simple, scalable, room-temperature self-assembly strategy for the synthesis of Cs4PbBr6/CsPbBr3 perovskite composites with near-unity PLQY (95%), high product yield (71%), and good stability using low-cost, low-toxicity chemicals as precursors. A broad range of experimental and theoretical characterizations suggest that the high-efficiency PL originates from CsPbBr3 nanocrystals well passivated by the zero-dimensional Cs4PbBr6 matrix that forms based on a dissolution-crystallization process. These findings underscore the importance in accurately identifying the phase purity of zero-dimensional perovskites by synchrotron X-ray technique to gain deep insights into the structure-property relationship. Additionally, we demonstrate that green-emitting Cs4PbBr6/CsPbBr3, combined with red-emitting K2SiF6:Mn4+, can be used for the construction of WLEDs. Our work may pave the way for the use of such composite perovskites as highly luminescent emitters in various applications such as lighting, displays, and other optoelectronic and photonic devices.

Transformation of Perovskite BaBiO3 into Layered BaBiO2.5 Crystals Featuring Unusual Chemical Bonding and Luminescence.

Engineering oxygen coordination environments of cations in oxides has received intense interest thanks to the opportunities for the discovery of novel oxides with unusual properties. Herein, the synthesis of stoichiometric layered BaBiO2.5 by a nontopotactic phase transformation of perovskite BaBiO3 is presented. By analyzing the synchrotron X-ray diffraction data by the maximum-entropy method/Rietveld technique, it was found that Bi is involved in an unusual chemical bonding situation with four oxygen atoms featuring one ionic bond and three covalent bonds, which results in an asymmetric coordination geometry. Photophysical characterization revealed that this peculiar structure shows near-infrared luminescence differing from that of conventional Bi-containing compounds. Experimental and theoretical results led to the proposal of an excitonic nature of the luminescence. This work highlights that synthesizing materials with uncommon Bi-O bonding and Bi coordination geometry provides a pathway to the discovery of systems with new functionalities. This could inspire interest in the exploration of a range of materials containing heavier p-block elements with prospects for finding systems with unusual properties.

Ion-Exchangeable Microporous Polyoxometalate Compounds with Off-Center Dopants Exhibiting Unconventional Luminescence.

The synthesis of luminescent polyoxometalates (POMs) typically relies on the assembly of POM ligands with rare earth or transition metals, placing significant constraints on the composition, structure, and hence the luminescence properties of the resultant systems. Herein, we show that the ion-exchange strategy can be used for the synthesis of novel POM-based luminescent materials. We demonstrate that introducing bismuth ions into an ion-exchangeable, microporous POM compound yields an unconventional system luminescing in the near-infrared region. Experimental characterization, coupled with quantum chemical calculations, confirms that bismuth ions site-specifically occupy an off-center site in the lattice, and have an asymmetric coordination geometry unattainable by other means, thus giving rise to peculiar emission. Our findings offer an effective strategy for the synthesis of POM-based luminescent materials, and the design concept may potentially be adapted to the creation of POM-based systems with other functionalities.

Controlling Crystallization of All-Inorganic Perovskite Films for Ultralow-Threshold Amplification Spontaneous Emission.

All-inorganic lead halide perovskites have gained considerable interest owing to their potential applications in an array of high-performance optoelectronic devices. However, producing highly luminescent, nearly pinhole-free, all-inorganic perovskite films through a simple solution process remains challenging. Here, we provide a detailed investigation of the crystallization control of inorganic perovskite films fabricated by a one-step spin-coating process. Our results reveal that the coating temperature in the fabrication process is of paramount importance in influencing perovskite crystallization and that lowering the coating temperature and fine stoichiometry modification of the precursors favor the suppression of trap states in CsPbBr3 perovskite films. A broad range of experimental characterizations help us identify that nonsynergistic assembly of solutes, resulting from poor diffusion capability of inorganic salts, is the dominant cause for the inhomogeneous element distribution, low luminescence yield, and poor surface coverage of the resulting films. Importantly, we find that polyethylene glycol can also be used for tailoring the crystallization process, which enables the attainment of high-quality CsPbBr3 films with a maximum luminescence yield of ∼30%. Finally, we demonstrate that amplification spontaneous emission with an ultralow threshold can be readily accomplished by using the developed film as an emissive component. Our findings provide deep insights into the crystallization control of CsPbBr3 perovskite films and establish a systematic route to high-quality all-inorganic perovskite films, paving the way for widespread optoelectronic applications.