Charge Transfer Complexes (CTCs) with Pyridinium Salts: Toward Efficient Dual Photochemical/Thermal Initiators and 3D Printing Applications.

In both organic and polymer synthesis, photochemistry of charge transfer complexes (CTCs) is considered as a powerful approach to expand visible-light-driven radical chemistry reaction. One reports herein on the development of a class of useful CTCs using pyridinium salts as efficient electron acceptors (combined with N, N, 3,5-tetramethylaniline, TMA) to achieve a multiwavelength (375-560 nm) metal-free LED photopolymerization process under mild conditions (open to air, without monomer purification and inhibitor removal). The UV-vis absorption spectra and molecular modeling simultaneously verify its potential blue-green absorbing wavelength range. Also, their good thermal initiation behavior at relatively low temperatures makes it easier to achieve thick samples and/or polymerization in the shadow region in practice. More importantly, with excellent photoinitiating capability, the formulation is successfully applied to direct laser write (DLW) and high-resolution 3D printing, yielding a series of objects with well-defined structures, such as letters, ring, solid squares, and chess pieces. These new pyridinium salt acceptors further extend the applicability to visible photopolymerizable resins and additive-containing formulations for efficient surface and deep curing.

A Guanidinium-Rich Polymer for Efficient Cytosolic Delivery of Native Proteins.

Cytosolic protein delivery is critical for the development of protein-based therapeutics. However, an efficient and robust carrier that can deliver native proteins without biological or chemical modifications into cells is highly desired. Here, we developed a guanidinium-rich polymer consisting of a cationic polymer scaffold modified with both phenyl and biguanide moieties. The polymer showed much higher protein binding affinity and endocytosis and reduced cytotoxicity compared to a control polymer by replacing the biguanide with monoguanide moieties. The guanidinium-rich polymer is capable of transporting proteins with various molecular weights and charge properties into the cytosol of living cells efficiently, while maintaining their bioactivities. This study permits the development of cationic polymers modified with phenylbiguanide moieties for efficient intracellular protein delivery.

Polyethylene microplastic modulates lettuce root exudates and induces oxidative damage under prolonged hydroponic exposure.

Root exudates are pivotal in plant stress responses, however, the impact of microplastics (MPs) on their release and characteristics remains poorly understood. This study delves into the effects of 0.05 % and 0.1 % (w/w) additions of polyethylene (PE) MPs on the growth and physiological properties of lettuce (Lactuca sativa L.) following 28 days of exposure. The release characteristics of root exudates were assessed using UV-vis and 3D-EEM. The results indicated that PE increased leaf number but did not significantly affect other agronomic traits or pigment contents. Notably, 0.05 % PE increased the total root length and surface area compared to the 0.1 % addition, while a non-significant trend towards decreased root activity was observed with PE MPs. PE MPs with 0.1 % addition notably reduced the DOC concentration in root exudates by 37.5 %, while 0.05 % PE had no impact on DOC and DON concentrations. PE addition increased the SUVA254, SUVA260, and SUVA280 values of root exudates, with the most pronounced effect seen in the 0.05 % PE treatment. This suggests an increase of aromaticity and hydrophobic components induced by PE addition. Fluorescence Regional Integration (FRI) analysis of 3D-EEM revealed that aromatic proteins (region I and II) were dominant in root exudates, with a slight increase in fulvic acid-like substances (region III) under 0.1 % PE addition. Moreover, prolonged PE exposure induced ROS damage in lettuce leaves, evidenced by a significant increase in content and production rate of O2·-. The decrease in CAT and POD activities may account for the lettuce's response to environmental stress, potentially surpassing its tolerance threshold or undergoing adaptive regulation. These findings underscore the potential risk of prolonged exposure to PE MPs on lettuce growth.

Macro- and microplastic leachates show a slightly toxic effect on seed germination of cotton.

Utilizing degradable mulching film effectively decreases the accumulation of plastic residuals in agriculture fields and their impacts on plant growth. However, the chemical risks to plants raised by leached substances from different microplastics are still unknown. This work determined the characteristics of macro- and microplastic leachates from different degradation (PE, PO, and Bio) and size (1 × 1 cm, 450-600 µm and <355 µm), as well as their impact on the germination of two varieties of cotton seeds. Our study revealed that degradable characteristics of macro-plastic significantly affect its leachates. Leachates of Bio gained higher dissolved organic carbon (DOC) concentration, aromatic, and values of slope ratios (SR) compared with PO and PE. The particle size of Bio macro- and microplastics also influences indicators such as SR, E250/E365, E253/E203, and Fmax value; however, fluctuations of those indicators were significantly lower than that induced by different degradable traits. Leachates of PE, PO, and Bio seem to have little impact on the germination of two varieties of cotton seeds, only mean germination time (MGT) and shoot height were slightly different among each treatment. A slight fluctuation of enzyme activities also indicates that plastic leachate did not generate excessive oxidative stress in cotton during germination. Leachates of macro- and microplastic under the tested concentration exhibited a slight toxic impact on cotton, which has high-stress tolerance. Thus, further studies should concentrate on the effects of plastic leachate on sensitive plants.

Immobilization of poly-L-lysine brush via surface initiated polymerization for the development of long-term antibacterial coating for silicone catheter.

Bacterial colonization of indwelling catheter remains a major threat in healthcare units worldwide. Developing approaches to prevent catheter-associated infections (CAIs) is, therefore, in great demand. Herein, to endow silicone catheter with long-term antibacterial properties, antimicrobial poly-L-lysine (PLL) brush was developed on the surface of catheter via surface initiated ring open polymerization. Surface characterizations confirmed the successful immobilization of PLL. The PLL-tethered catheter showed potent antibacterial activities against catheter-associated urinary tract infections (CAUTIs) related pathogens. Moreover, after immersing in simulated body fluid for 28 days or incubating at 60 °C for 65 days, the bactericidal properties of PLL-tethered catheter were still retained. Furthermore, the PLL-tethered catheter exhibited good anti-infection activity and biocompatibility in vivo. The PLL-tethered surfaces hold great potential in the development of antibacterial silicone catheter to combat CAIs in clinical applications.

Ultralight, highly flexible in situ thermally crosslinked polyimide aerogels with superior mechanical and thermal protection properties via nanofiber reinforcement.

HYPOTHESIS: Advanced thermal-insulation materials for human use in high-temperature and ultra-low-temperature environments have received extensive attention. However, facile synthesis of aerogels with excellent mechanical and thermal properties via freeze-drying or electrospinning alone is still challenging. We hypothesized that a polyimide aerogel with high mechanical strength and good thermal-insulation performance and suitability for various applications at high and low temperatures could be prepared facilely using a simple and novel preparation strategy that combines electrospinning, freeze-drying, and in situ thermal crosslinking. EXPERIMENTS: Polyamideimide (PAI) nanofibers loaded with bismaleimide (BMI) were electrospun and dispersed into a polyamic acid aqueous solution. PAI/BMI-nanofiber-reinforced polyimide (IBNR-PI) aerogels with an interpenetrating network structure were prepared by freeze-drying and heat treatment. FINDINGS: The IBNR-PI aerogels possessed extremely low volume density (26 mg cm-3) and high porosity (94.92%). Most importantly, they showed high tensile strength and good compressive fatigue resistance with plastic deformation of only 7% after 1000 compression cycles. The aerogels also showed a significantly low thermal conductivity (30.06 mW m-1 K-1) and excellent thermal insulation over a wide temperature range. Thus, the IBNR-PI aerogels are excellent candidates for thermal-insulation materials at high and low temperatures.

Directional and integrated conversion of whole components in biomass for levulinates and phenolics with biphasic system.

Integrated conversion and stepwise extraction of whole components in biomass with biphasic system are introduced for producing chemicals: levulinates and phenolics. When methanol/dimethoxymethane as biphasic solvent, 46.51% methyl levulinate and 18.78% phenolics were obtained with a conversion of 80.59 wt% per 4 g rice straw under the mild reaction conditions. Levulinates were collected with a 87.5 wt% high purity of methyl levulinate with stepwise precipitation and extraction from the cellulose and hemicellulose. The results of acid value, freezing point, induction period, kinematic viscosity, and flash point supposed that the extracted methyl levulinate could meet the requirements of fuel additives. Depolymerized lignin was consisted of many low-molecular phenolics. These results illustrated that the biphasic system can promote the conversion of cellulose and hemicellulose to the same product methyl levulinate through different intermediate transition compounds, and the catalyst can contribute to directly cleave the glycosidic bonds, ß-O-4, and 4-O-5 with adequate protons.

Coral-like hierarchical structured carbon nanoscaffold with improved sensitivity for biomolecular detection in cancer tissue.

The development of flexible microelectrodes with large surface area and high activity has currently attracted enormous research interest for its promising use in in vitro and in vivo monitoring various physiological behaviors. Inspired by the unique morphological and structural features of dendritic coral, a coral-like hierarchical nanohybrid of carbon nanospheres (GNSs) wrapped hollow carbon tubes (HCT) has been designed and modified on flexible activated carbon fiber (ACF) microelectrode for sensitive electrochemical detection of biomarker in live cells and cancer tissue. The hierarchical nanohybrid microelectrode was fabricated by a novel dual-template strategy using ZnO nanorod arrays as the hard template and poly-glucose microspheres as both self-template and carbon source, which results in the formation of coral-like structured carbon nanoscaffold integrated with GNSs wrapped HCT hybrids (HCT@GNSs) on ACF substrate for homogeneous interfacial contacts and reaction. The as-obtained HCT@GNSs modified ACF (HCT@GNSs/ACF) microelectrode exhibits high specific surface area and good stability, and serves as an ideal support for anchoring functional nanomaterials. In order to improve the electrochemical activity of the modified microelectrode, HCT@GNSs has been decorated with dense and ultrafine Pt nanoparticles (PtNPs). Benefiting from the hierarchical feature of HCT@GNSs and uniformly distribution of electroactive PtNPs, the PtNPs decorated HCT@GNSs/ACF microelectrode demonstrates good electrochemical sensing performance toward H2O2, which enable the operating electrochemical platform be used for real-time tracking H2O2 generated from different types of live cells and in situ sensitive detection of H2O2 in cancer tissue from laboratory mice.

New Perspectives on the Electronic and Geometric Structure of Au70S20(PPh3)12 Cluster: Superatomic-Network Core Protected by Novel Au12(µ3-S)10 Staple Motifs.

In order to increase the understanding of the recently synthesized Au70S20(PPh3)12 cluster, we used the divide and protect concept and superatom network model (SAN) to study the electronic and geometric of the cluster. According to the experimental coordinates of the cluster, the study of Au70S20(PPh3)12 cluster was carried out using density functional theory calculations. Based on the superatom complex (SAC) model, the number of the valence electrons of the cluster is 30. It is not the number of valence electrons satisfied for a magic cluster. According to the concept of divide and protect, Au70S20(PPh3)12 cluster can be viewed as Au-core protected by various staple motifs. On the basis of SAN model, the Au-core is composed of a union of 2e-superatoms, and 2e-superatoms can be Au3, Au4, Au5, or Au6. Au70S20(PPh3)12 cluster should contain fifteen 2e-superatoms on the basis of SAN model. On analyzing the chemical bonding features of Au70S20(PPh3)12, we showed that the electronic structure of it has a network of fifteen 2e-superatoms, abbreviated as 15 × 2e SAN. On the basis of the divide and protect concept, Au70S20(PPh3)12 cluster can be viewed as Au4616+[Au12(µ3-S)108-]2[PPh3]12. The Au4616+ core is composed of one Au2212+ innermost core and ten surrounding 2e-Au4 superatoms. The Au2212+ innermost core can either be viewed as a network of five 2e-Au6 superatoms, or be considered as a 10e-superatomic molecule. This new segmentation method can properly explain the structure and stability of Au70S20(PPh3)12 cluster. A novel extended staple motif [Au12(µ3-S)10]8- was discovered, which is a half-cage with ten µ3-S units and six teeth. The six teeth staple motif enriches the family of staple motifs in ligand-protected Au clusters. Au70S20(PPh3)12 cluster derives its stability from SAN model and aurophilic interactions. Inspired by the half-cage motif, we design three core-in-cage clusters with cage staple motifs, Cu6@Au12(µ3-S)8, Ag6@Au12(µ3-S)8 and Au6@Au12(µ3-S)8, which exhibit high thermostability and may be synthesized in future.

Redox and pH Dual-Responsive Polymeric Micelles with Aggregation-Induced Emission Feature for Cellular Imaging and Chemotherapy.

Intelligent polymeric micelles for antitumor drug delivery and tumor bioimaging have drawn a broad attention because of their reduced systemic toxicity, enhanced efficacy of drugs, and potential application of tumor diagnosis. Herein, we developed a multifunctional polymeric micelle system based on a pH and redox dual-responsive mPEG-P(TPE- co-AEMA) copolymer for stimuli-triggered drug release and aggregation-induced emission (AIE) active imaging. These mPEG-P(TPE- co-AEMA)-based micelles showed excellent biocompatibility and emission property, exhibiting great potential application for cellular imaging. Furthermore, the antitumor drug doxorubicin (DOX) could be encapsulated during self-assembly process with high loading efficiency, and a DOX-loaded micelle system with a size of 68.2 nm and narrow size distribution could be obtained. DOX-loaded micelles demonstrated great tumor suppression ability in vitro, and the dual-responsive triggered intracellular drug release could be further traced. Moreover, DOX-loaded micelles could efficiently accumulate at the tumor site because of enhanced permeability and retention effect and long circulation of micelles. Compared with free DOX, DOX-loaded micelles exhibited better antitumor effect and significantly reduced adverse effects. Given the efficient accumulation targeting to tumor tissue, dual-responsive drug release, and excellent AIE property, this polymeric micelle would be a potential candidate for cancer therapy and diagnosis.

[CLINICAL EFFICACY OF MODIFIED POLYTETRAFLUOROETHYLENE PROSTHESIS RHINOPLASTY].

OBJECTIVE: To explore the clinical efficacy of modified polytetrafluoroethylene (PTFE) prosthesis rhinoplasty for correction of low nose and short columella. METHODS: Between August 2012 and August 2015, modified PTFE prosthesis rhinoplasty was used to correct low nose and short columella in 52 patients. There were 4 males and 48 females, aged 19 to 45 years (mean, 27 years). Primary rhinoplasty was performed in 47 cases; secondary rhinoplasty was performed in 5 cases, and it was 12-18 months from the first operation (mean, 15 months). During operation, a scaly sag ventral side was made by carving and moving cap shaped nose prosthesis was prepared, and nasal dorsumnasal columella prosthesis covered by tension-free flap was designed. At pre-operation and last follow-up, Image ProPlus 6.0 software was used to measure the nose length, nose depth, nose tip width, nostril/nose tip, nasolabial angle, and nasal tip rotation for evaluation of external nose shape correction; and ultrasound was used to measure the alar cartilage angle, alar two vertex distance, and nose tip to vertex distance for evaluation of internal soft tissue changes; the prosthesis position was observed by CT scan at 12 months. RESULTS: All incisions healed by first intention, with no complications. All patients were followed up 7-36 months (mean, 20.4 months). At 12 months after operation, CT scans showed that prosthesis located in the middle of the nose and above nasal bone, septal cartilage and crus mediale cartilaginis alaris majoris in 45 patients; no prosthesis displacement was observed. At last follow-up, image measurement and ultrasound results showed external nose shape parameters (except nostril/nose tip) and internal soft tissue structures were significantly improved when compared with preoperative values (P<0.05). CONCLUSIONS: Modified PTFE prosthesis rhinoplasty can effectively correct low nose and short columella, with small surgical trauma and good appearance.

Helical polydiacetylene prepared in the liquid crystal phase using circular polarized ultraviolet light.

Herein the enantio-selective polymerization of diacetylene (DA) units in the discotic hydrogen-bonding complex is carried out in an asymmetric reaction field consisting of the lamellar columnar LC phase and CPUL stimulus.

Thermochromism and supramolecular chirality of the coumarin-substituted polydiacetylene LB films.

Herein, a novel single-chain coumarin-substituted diacetylene monomer (CODA) was synthesized. CODA LB films exhibited obvious chirality although CODA monomer was achiral. Upon UV irradiation, CODA LB films could be polymerized into blue form and exhibit reversible thermochromism and chiroptical properties. Strong intermolecular interaction among the coumarin chromophores was assumed to be responsible for the complete reversibility of absorption and chiroptical changes for PCODA films upon thermal stimulus. And the helical packing of the coumarin chromophores seemed to play a dominating role in the subsequent formation of the helical PDA backbone. Moreover, the single-chain CODA monomer could be further photo-dimerized, and a novel gemini-type diacetylene monomer (DCODA) could be prepared. The effects of the photo-dimerization reaction of the coumarin moieties on the thermochromism and chiroptical properties of the resulting PDCODA films had been evaluated. The dimerization of head groups would enhance the thermal stability of PDCODA films but inhibit the chirality formation for PDA backbone.