Overcoming Electrostatic Interaction via Pulsed Electroreduction for Boosting the Electrocatalytic Urea Synthesis.

Electrocatalytic urea synthesis under ambient conditions offers a promising alternative strategy to the traditional energy-intensive urea industry protocol. Limited by the electrostatic interaction, the reduction reaction of anions at the cathode in the electrocatalytic system is not easily achievable. Here, we propose a novel strategy to overcome electrostatic interaction via pulsed electroreduction. We found that the reconstruction-resistant CuSiOx nanotube, with abundant atomic Cu-O-Si interfacial sites, exhibits ultrastability in the electrosynthesis of urea from nitrate and CO2. Under a pulsed potential approach with optimal operating conditions, the Cu-O-Si interfaces achieve a superior urea production rate (1606.1 µg h-1 mgcat. -1) with high selectivity (79.01 %) and stability (the Faradaic efficiency is retained at 80 % even after 80 h of testing), outperforming most reported electrocatalytic synthesis urea catalysts. We believe our strategy will incite further investigation into pulsed electroreduction increasing substrate transport, which may guide the design of ambient urea electrosynthesis and other energy conversion systems.

Macrophage-mediated extracellular matrix remodeling after fat grafting in nude mice.

Clinical unpredictability and variability following fat grafting remain non-negligible problems due to the unknown mechanism of grafted fat retention. The role of the extracellular matrix (ECM), which renders cells with structural and biochemical support, has been ignored. This study aimed to clarify the ECM remodeling process, related cellular events, and the spatiotemporal relationship between ECM remodeling and adipocyte survival and adipogenesis after fat grafting. Labeled Coleman fat by the matrix-tracing technique was grafted in nude mice. The ECM remodeling process and cellular events were assessed in vivo. The related cytokines were evaluated by qRT-PCR. An in vitro cell migration assay was performed to verify the chemotactic effect of M2-like macrophages on fibroblasts. The results demonstrated that in the periphery, most of the adipocytes of the graft survived or regenerated, and the graft-derived ECM was gradually replaced by the newly-formed ECM. In the central parts, most adipocytes in the grafts died shortly after, and a small part of the graft-derived and newly-formed ECM was expressed with irregular morphology. Adipose ECM remodeling is associated with increased infiltration of macrophages and fibroblasts, as well as up-regulated expression of cytokines in the adipose tissue. To sum up, our results describe the various preservation mode of fat grafts after transplantation and underscore the importance of macrophage-mediated ECM remodeling in graft preservation after fat grafting. The appreciation and manipulation of underlying mechanisms that are operant in this setting stand to explore new therapeutic approaches and improve clinical outcomes of fat grafting.

A Homochiral Fulgide Organic Ferroelectric Crystal with Photoinduced Molecular Orbital Breaking.

Thermally triggered spatial symmetry breaking in traditional ferroelectrics has been extensively studied for manipulation of the ferroelectricity. However, photoinduced molecular orbital breaking, which is promising for optical control of ferroelectric polarization, has been rarely explored. Herein, for the first time, we synthesized a homochiral fulgide organic ferroelectric crystal (E)-(R)-3-methyl-3-cyclohexylidene-4-(diphenylmethylene)dihydro-2,5-furandione (1), which exhibits both ferroelectricity and photoisomerization. Significantly, 1 shows a photoinduced reversible change in its molecular orbitals from the 3 π molecular orbitals in the open-ring isomer to 2 π and 1 σ molecular orbitals in the closed-ring isomer, which enables reversible ferroelectric domain switching by optical manipulation. To our knowledge, this is the first report revealing the manipulation of ferroelectric polarization in homochiral ferroelectric crystal by photoinduced breaking of molecular orbitals. This finding sheds light on the exploration of molecular orbital breaking in ferroelectrics for optical manipulation of ferroelectricity.

Efficient Removal of Pb2+ from Water by Bamboo-Derived Thin-Walled Hollow Ellipsoidal Carbon-Based Adsorbent.

Lead ion (Pb2+) is one of the most common water pollutants. Herein, with bamboo as the raw material, we fabricate a thin-walled hollow ellipsoidal carbon-based adsorbent (CPCs900) containing abundant O-containing groups and carbon defects and having a specific surface area as large as 730.87 m2 g-1. CPCs900 shows a capacity of 37.26 mg g-1 for adsorbing Pb2+ in water and an efficiency of 98.13% for removing Pb2+ from water. This is much better than the activated carbon commonly used for removing Pb2+ from water (12.19 mg g-1, 30.48%). The bond interaction of Pb2+ with the O-containing groups on CPCs900 and the electrostatic interaction of Pb2+ with the electron-rich carbon defects on CPCs900 could be the main forces to drive Pb2+ adsorption on CPCs900. The outstanding adsorption performance of CPCs900 could be due to the abundant O-containing groups and carbon defects as well as the large specific surface area of CPCs900. Bamboo has a large reserve and a low price. The present work successfully converts bamboo into adsorbents with outstanding performances in removing Pb2+ from water. This is of great significance for meeting the huge industrial demand on highly efficient adsorbents for removing toxic metal ions from water.

Metabolic installation of macrophage-recruiting glycan ligand on tumor cell surface for in vivo tumor suppression.

Synthetic probes that could direct immune cells against tumors are potential immunotherapeutics. We herein report in vivo tumor suppression via an intravenously injected abiotic sialic acid (TCCSia) that could be metabolically incorporated into tumor cell surface to yield of a high affinity ligand (TCCSiaα2,3-Gal) of Siglec-1 specifically expressed on macrophages. We observed marked suppression of pulmonary metastasis and subcutaneous tumor growth of B16F10 melanoma cells in mice with TCCSia, suggesting the utility of abiotic sialic acid to modulate tumor immunity via recruiting Siglec+ immune cells.

Adipose Collagen Fragment: A Novel Adipose-Derived Extracellular Matrix Concentrate for Skin Filling.

BACKGROUND: Skin filler is an option for treating skin aging and wrinkles; however, currently used fillers are limited by poor biocompatibility, rapid degradation, and possible hypersensitivity reactions. Autologous adipose tissue-derived products have been recognized as promising options for skin rejuvenation. OBJECTIVES: This study aimed to develop a novel adipose-derived product for skin filling. METHODS: Adipose collagen fragment (ACF) was prepared through pulverization, filtration, and centrifugation. The macrography, structure, types of collagen, and cell viability of ACF were evaluated by immunostaining, western blotting, and cell culture assays. ACF, nanofat, and phosphate-buffered saline (9 spots/side, 0.01 mL/spot) were intradermally injected in the dorsal skin of 36 female BALB/c nude mice; the skin filling capacity and the collagen remodeling process were then investigated. Twenty-one female patients with fine rhytides in the infraorbital areas were enrolled and received clinical applications of ACF treatment. Therapeutic effects and patients' satisfaction scores were recorded. RESULTS: The mean [standard deviation] yield of ACF from 50 mL of Coleman fat was 4.91 [0.25] mL. ACF contained nonviable cells and high levels of collagen I, collagen IV, and laminin. Fibroblasts and procollagen significantly increased in ACF and ACF-treated dermis (P < 0.05). Overall, 85.7% of patients were satisfied with the therapy results, and no infections, injection site nodules, or other unwanted side effects were observed. CONCLUSIONS: ACF significantly improved dermal thickness and collagen synthesis and may serve as a potential autologous skin filler.

Adipose Collagen Fragment: A Novel Adipose-Derived Extracellular Matrix Concentrate for Skin Filling.

BACKGROUND: Skin filler is an option for treating skin aging and wrinkles; however, currently used fillers are limited by poor biocompatibility, rapid degradation, and possible hypersensitivity reactions. Autologous adipose tissue-derived products have been recognized as promising options for skin rejuvenation. OBJECTIVES: This study aimed to develop a novel adipose-derived product for skin filling. METHODS: Adipose collagen fragment (ACF) was prepared through pulverization, filtration, and centrifugation. The macrography, structure, types of collagen, and cell viability of ACF were evaluated by immunostaining, western blotting, and cell culture assays. ACF, nanofat, and phosphate-buffered saline (9 spots/side, 0.01 mL/spot) were intradermally injected in the dorsal skin of 36 female BALB/c nude mice; the skin filling capacity and the collagen remodeling process were then investigated. Twenty-one female patients with fine rhytides in the infraorbital areas were enrolled and received clinical applications of ACF treatment. Therapeutic effects and patients' satisfaction scores were recorded. RESULTS: The mean [standard deviation] yield of ACF from 50 mL of Coleman fat was 4.91 [0.25] mL. ACF contained nonviable cells and high levels of collagen I, collagen IV, and laminin. Fibroblasts and procollagen significantly increased in ACF and ACF-treated dermis (P < 0.05). Overall, 85.7% of patients were satisfied with the therapy results, and no infections, injection site nodules, or other unwanted side effects were observed. CONCLUSIONS: ACF significantly improved dermal thickness and collagen synthesis and may serve as a potential autologous skin filler.

Enhanced CO2 Photoreduction through Spontaneous Charge Separation in End-Capping Assembly of Heterostructured Covalent-Organic Frameworks.

It is well known that charge separation is crucial for efficient photocatalytic solar conversion. Although some covalent-organic frameworks (COFs) exhibit visible-light harvest, the large exciton binding energies reduce their photocatalytic efficiencies. Herein, we developed a novel method to post-treat the olefin-linked COFs with end-capping polycyclic aromatic hydrocarbons (PAHs) for spontaneous charge separation. Interestingly, a type-II heterostructure is constructed in our perylene-modified COFs which displays drastically enhanced performance for photocatalytic CO2 reduction, with an efficiency of 8-fold higher than that of unmodified COF. A combination of electrochemical, steady-state, and time-resolved spectroscopic measurements indicates that such drastically enhanced performance should be attributed to photoinduced spontaneous charge separation in the heterostructure. These results illustrate the feasibility of engineering the charge-separation properties of crystalline porous frameworks at a molecular level for artificial photosynthesis.

The First High-Temperature Supramolecular Radical Ferroics.

Organic radical ferroics such as TEMPO have attracted widespread interest. However, the relatively low Curie temperature of 287 K and melting point of 311 K severely hinder its application potential. Despite extensive interest, high-temperature radical ferroics have not yet been found. Here, taking advantage of chemical design and supramolecular radical chemistry, we designed two high-temperature organic supramolecular radical ferroics [(NH3 -TEMPO)([18]crown-6)](ReO4 ) (1) and [(NH3 -TEMPO)([18]crown-6)](ClO4 ) (2), which can retain ferroelectricity up to 413 K and 450 K, respectively. To our knowledge, they are both the first supramolecular radical ferroics and unprecedented high-temperature radical ferroics, where the supramolecular component is vital for the stabilization of the radical and extending the working temperature window. Both also have paramagnetism, non-interacting spin moments, and excellent piezoelectric and electrostrictive behaviors comparable to that of LiNbO3 .

The susceptible-unidentified infected-confirmed (SUC) epidemic model for estimating unidentified infected population for COVID-19.

In this article, we propose the Susceptible-Unidentified infected-Confirmed (SUC) epidemic model for estimating the unidentified infected population for coronavirus disease 2019 (COVID-19) in China. The unidentified infected population means the infected but not identified people. They are not yet hospitalized and still can spread the disease to the susceptible. To estimate the unidentified infected population, we find the optimal model parameters which best fit the confirmed case data in the least-squares sense. Here, we use the time series data of the confirmed cases in China reported by World Health Organization. In addition, we perform the practical identifiability analysis of the proposed model using the Monte Carlo simulation. The proposed model is simple but potentially useful in estimating the unidentified infected population to monitor the effectiveness of interventions and to prepare the quantity of protective masks or COVID-19 diagnostic kit to supply, hospital beds, medical staffs, and so on. Therefore, to control the spread of the infectious disease, it is essential to estimate the number of the unidentified infected population. The proposed SUC model can be used as a basic building block mathematical equation for estimating unidentified infected population.

On-Surface Crystallization Behaviors of H-Bond Donor-Acceptor Complexes at Liquid/Solid Interfaces.

Two-dimensional (2D) crystallization behaviors of A-TPC n ( n = 4, 6, 10), T3C4, and hydrogen-bonded complexes T3C4@TPC n ( n = 4, 6, 10) are investigated by means of scanning tunneling microscope (STM) observations and density functional theory (DFT) calculations. The STM observations reveal that A-TPC4, A-TPC10, and T3C4 self-organize into dumbbell-shaped structures, well-ordered bright arrays, and zigzag structures, respectively. Interestingly, T3C4@TPC10 fails to form the cage-ball structure, whereas T3C4@TPC4 and T3C4@TPC6 co-assemble into cage-ball structures with the same lattice parameters. The filling rates of the balls of these two kinds of cage-ball structures depend heavily on the deposition sequence. As a result, the filling rates of the cages in T3C4/A-TPC n ( n = 4, 6) with deposition of T3C4 anterior to A-TPC n are higher than those in A-TPC n/T3C4 ( n = 4, 6) with the opposite deposition sequence. Furthermore, lattice defects formed by T3C4 coexist with the cage-ball structures. Moreover, the similar energy per unit area of lattice defects (-0.101 kcal mol-1 Å-2) and the two cage-ball networks (-0.194 and -0.208 kcal mol-1 Å-2, respectively), illustrating the similar stabilities of lattice defects and cage-ball networks, demonstrates the rationality of lattice defects. Combining STM investigations and DFT calculations, this work could provide a useful approach to investigate the 2D crystallization mechanisms of supramolecular liquid crystals on surfaces.

The shielding effect of metal complexes on the binding affinities of ligands to metalloproteins.

Metal ions are important regulatory cofactors in a wide variety of proteins. Conventional wisdom suggests that stronger metal-ligand interactions have a larger effect on the ligand binding affinity. However, some experimental data do not support this conventional wisdom. In this study, we used a theoretical derivation approach to explore the effect of metal-ligand interactions on ligand binding affinities. Both theoretical derivation and experimental data indicate that metal-ligand interactions weaken the original interactions of the metal ions, which reduce the contributions of the metal-ligand interactions to the ligand binding affinities. The shielding effect is so large that some strong metal-ligand interactions contribute little to the ligand binding affinities. The binding free energies contributed by metal-ligand interactions have a limited relationship with the strengths of the interactions. Considering that the shielding effect of metal complexes is essential for accurately modelling metal-ligand interactions, our findings challenge the conventional wisdom and represent a significant advance for the design of drugs targeted for metalloproteins and for exploring the enormous catalytic power of metalloproteins.

Effective lead optimization targeting the displacement of bridging receptor-ligand water molecules.

Enhancing the binding affinities of ligands by means of lead modifications that displace bridging water molecules at protein-ligand interfaces is an important and widely studied lead optimization strategy. However, it is still challenging to ensure the success of this lead optimization strategy. Here we use theoretical derivations, which are then validated using reported experimental data, to identify the major determining factors in lead optimization designed to displace bridging water molecules. Our findings demonstrate that the nature of hydrogen-bond pairing between the ligand and protein polar atom(s) is the principal factor displacing interface water molecules, and not the binding strength of the water molecule. Our results also indicate that all interfacing bridging water molecules can potentially be targeted for displacement using this new approach. In summary, we show that strong-strong/weak-weak hydrogen-bond pairings of ligand atoms with protein atoms may provide useful guidance in lead modifications by designing modified ligands with higher binding affinities than their lead molecules. This study can help to increase the efficiency of rational drug design.

Water-induced formation of a chiral phenylalanine derivative supramolecule.

In biological systems, chiral self-assemblies are formed in water. To understand the role of water in the formation of supramolecular chirality, an amino acid derivative, N,N-diphenylalanine-3,4,9,10-perylenetetracarboxylicdiimide (PBI-Phe), was synthesized from perylene-3,4,9,10-tetracarboxylic dianhydride and phenylalanine. PBI-Phe self-assembled into a spherical structure in pure DMSO, but into a helical fiber structure in a solution of DMSO mixed with water. Furthermore, increasing the relative amount of water included in the solution led to an increase the supramolecular chirality.

Hierarchical self-assembly of amino acid derivatives into stimuli-responsive luminescent gels.

In this study, unique luminescent gels have been obtained from two components between amino acid functionalized perylene derivatives and 4,4'-bipyridyl units via hierarchical self-assembly. The luminescent gels have been investigated by means of ultraviolet spectra (UV), fluorescence spectra, Scanning Electron Microscopy (SEM) and Laser Scanning Confocal Microscopy (LSCM), which illustrate the strong fluorescence intensity of the gels. In order to further reveal the self-assembly driving forces, the two-dimensional (2D) self-assembly behaviours have been studied by scanning tunneling microscopy (STM) on a highly oriented pyrolytic graphite (HOPG) substrate at the solid-liquid interface, which indicates that the driving forces are attributed to the intermolecular hydrogen bonding and π-π stacking interactions. According to the interaction mode, these organogelators are found to rapidly transform from gels to solutions by adding triethylamine.

Flexible, transparent, and sustainable cellulose-based films for organic solar cell substrates.

Cellulose, often considered a highly promising substitute for petroleum-based plastics, offers several compelling advantages, including abundant availability, cost-effectiveness, environmental friendliness, and biodegradability. However, its inherent highly crystalline structure and extensive hydrogen-bonded network pose challenges for processing and recycling. In this study, we introduce the concept of cellulose vitrimers (CVs), wherein dynamic bonds are incorporated to reconfigure the hydrogen-bonded network, resulting in a mechanically robust, highly transparent material. CVs exhibit exceptional malleability, thermal stability, and noteworthy resistance to water and solvents. Due to the dynamic bond disassociation, CVs can be effectively chemically recycled using a well-established "dissolution-and-reforming" process. Moreover, CVs have proven successful as flexible substrate materials for organic solar cells, outperforming traditional petroleum-based polyethylene naphthalate (PEN). Given these advantages, CVs have the potential to replace conventional petroleum-based materials as recyclable and environmentally friendly alternatives, particularly within the realm of electronic devices and displays.

Combined Use of Autologous Sustained-Release Scaffold of Adipokines and Acellular Adipose Matrix to Construct Vascularized Adipose Tissue.

BACKGROUND: Adipose tissue engineering plays a key role in the reconstruction of soft-tissue defects. The acellular adipose matrix (AAM) is a promising biomaterial for the construction of engineered adipose tissue. However, AAM lacks sufficient adipoinduction potency because of the abundant loss of matrix-bound adipokines during decellularization. METHODS: An adipose-derived extracellular matrix collagen scaffold, "adipose collagen fragment" (ACF), was prepared using a novel mechanical method that provides sustained release of adipokines. Here, the authors used label-free proteomics methods to detect the protein components in AAM and ACF. In vivo, ACF was incorporated into AAM or acellular dermal matrix and implanted into nude mice to evaluate adipogenesis. Neoadipocytes, neovessels, and corresponding gene expression were evaluated. The effects of ACF on adipogenic differentiation of human adipose-derived stem cells and tube formation by human umbilical vein endothelial cells were tested in vitro. RESULTS: Proteomics analysis showed that ACF contains diverse adipogenic and angiogenic proteins. ACF can release diverse adipokines and induce highly vascularized, mature adipose tissue in AAM, and even in nonadipogenic acellular dermal matrix. Higher expression of adipogenic markers peroxisome proliferator-activated receptor gamma and CCAAT/enhancer-binding protein alpha and greater numbers of tubule structures were observed in ACF-treated groups in vitro. CONCLUSION: The combination of ACF and AAM could serve as a novel and promising strategy to construct mature, vascularized adipose tissue for soft-tissue reconstruction. CLINICAL RELEVANCE STATEMENT: The combined use of AAM and ACF has been proven to induce a highly vascularized, mature, engineered adipose tissue in the nude mouse model, which may serve as a promising strategy for soft-tissue reconstruction.

Efficient fabrication of anisotropic regenerated cellulose films from bamboo via a facile wet extrusion strategy.

Bamboo, featuring fast growth rate and high cellulose content, is considered to be one of the most attractive feedstocks for degradable bio-materials as a substitute for plastics. However, those was limited to the fields of bamboo structural materials mainly by physical processes. Herein, we report a facile continuous wet extrusion strategy for scalable manufacturing of anisotropic regenerated cellulose films in alkali/urea aqueous solution for the first time. The bamboo cellulose solution was regenerated in H2SO4/Na2SO4/ZnSO4 aqueous solution to facilitate the construction of dense fibrils networks. Moreover, under the synergistic effect of shear orientations and stretching processes in wet extrusion molding, the cellulose networks promoted further orientated assembly into aligned fibrils. Therefore, these anisotropic cellulose hydrogels exhibited good mechanical properties, and the tensile strength was increased from 1.67 MPa of anisotropic cellulose hydrogel with 1.0 of stretching ration (ACH-1.0) to 2.13 MPa of ACH-1.4 with increasing stretching ratio from 1.0 to 1.4, which was about 1.34 times higher than that of the isotropic hydrogel fabricated by tape-casting. Moreover, ACH-1.4 exhibited commendable thermal stability and air barrier properties. This work demonstrated a simple and continuous bottom-up approach for fabrication of anisotropic bamboo-based cellulose hydrogels and films with excellent mechanical properties.

Synthesis of fluorescent derivatives of praziquantel: cell-imaging and interaction with Schistosoma japonicum cercariae.

Schistosomiasis is one of the most burdensome of the neglected tropical diseases. Praziquantel is a recommended drug for treatment against all forms of schistosomiasis. To investigate the interaction between praziquantel and Schistosoma japonicum cercariae, two praziquantel derivatives (PZQ-2 and PZQ-3) and one praziquantel fluorescent derivative (PZQ-5) have been synthesized and characterized using nuclear magnetic resonance spectroscopy (NMR) and MS spectra. The cytotoxicity of PZQ-2, PZQ-3 and PZQ-5 was measured by performing the methyl thiazolyl tetrazolium (MTT) assay. The cell viability for them shows that the three compounds exhibit low cytotoxicity to HeLa cells. Cell imaging experiments demonstrate that PZQ-5 is biocompatible and cell-permeable, which indicates that PZQ-5 is suitable for studying their interaction. Confocal fluorescence microscopy revealed that PZQ-5 is mainly located at the cercarial tegument, which leads to the death of cercariae with the increase in time.

Temperature-controlled self-assembling structure with selective guest-recognition at the liquid-solid interface.

We investigate the influence of temperature on the self-assembly of 2,6,11-tricarboxydecyloxy-3,7,10-triundecyloxy triphenylene (asym-TTT) adsorbed on HOPG using scanning tunneling microscopy (STM) at the liquid/solid interface. We show that the packing structures of 2D self-assembled asym-TTT can be precisely tuned by adjusting the substrate temperature. The temperature change from 20 °C to 35 °C induces two phase transitions and increment in the packing density from 0.161 to 0.179 molecules per nm(2). The density-functional theory (DFT) calculations reveal that their interaction energies are similar. In particular, the experimental findings further illustrate the preferential adsorption of guest molecules, such as phthalocyanine, only in the domain of more close packing structures.