Selenium-Containing Type-I Organic Photosensitizers with Dual Reactive Oxygen Species of Superoxide and Hydroxyl Radicals as Switch-Hitter for Photodynamic Therapy.

Organic type-I photosensitizers (PSs) which produce aggressive reactive oxygen species (ROS) with less oxygen-dependent exhibit attractive curative effect for photodynamic therapy (PDT), as they adapt better to hypoxia microenvironment in tumors. However, the reported type-I PSs are limited and its exacted mechanism of oxygen dependence is still unclear. Herein, new selenium-containing type-I PSs of Se6 and Se5 with benzoselenadiazole acceptor has been designed and possessed aggregation-induced emission characteristic. Benefited from double heavy-atom-effect of selenium and bromine, Se6 shows a smaller energy gap (ΔEST ) of 0.03 eV and improves ROS efficiency. Interestingly, type-I radicals of both long-lived superoxide anion (O2 •‾ ) and short-lived hydroxyl (• OH) are generated from them upon irradiation. This may provide a switch-hitter of dual-radical with complementary lifetimes for PDT. More importantly, simultaneous processes to produce • OH are revealed, including disproportionation of O2 •‾ and reaction between excited PS and water. Actually, Se6 displays superior in-vitro PDT performance to commercial chlorin e6 (Ce6), under normoxia or hypoxia. After intravenous injection, a significantly in-vivo PDT performance is demonstrated on Se6, where tumor growth inhibition rates of 99% is higher than Ce6. These findings offer new insights about both molecular design and mechanism study of type-I PSs.

Grafting Polyethyleneimine-Poly(ethylene glycol) Gel onto a Heat-Resistant Polyimide Nanofiber Separator for Improving Lithium-Ion Transporting Ability in Lithium-Ion Batteries.

To improve the lithium-ion transporting ability in lithium-ion batteries, a high-performance polyimide-based lithium-ion battery separator (PI-mod) was prepared by chemically grafting poly(ethylene glycol) (PEG) onto the surface of a heat-resistant polyimide nanofiber matrix with the assistance of amino-rich polyethyleneimine (PEI). The resulted PEI-PEG polymer coating exhibited unique gel-like properties with an electrolyte uptake rate of 168%, an area resistance as low as 2.60 Ω·cm2, and an ionic conductivity up to 2.33 mS·cm-1, which are 3.5, 0.10, and 12.3 times that of the commercial separator Celgard 2320, respectively. Meanwhile, the heat-resistant polyimide skeleton can effectively avoid thermal shrinkage of the modified separator even after 200 °C treatment for 0.5 h, which ensures the safety of the battery working under extreme conditions. The modified PI separator possessed a high electrochemical stability window of 4.5 V. Compared with the batteries from the commercial separator Celgard 2320 and the pure polyimide matrix, the assembled coin cell with the PI-mod separator showed much better rate capabilities and capacity retention due to the high electrolyte affinity of the PEI-PEG polymer coating. The developed strategy of using the electrolyte-swollen polymer to modify the thermal-resistant separator network provides an efficient way for establishing high-power lithium-ion batteries with good safety performance.

A Cationic Amphiphilic AIE Polymer for Mitochondrial Targeting and Imaging.

Mitochondria are important organelles that play key roles in generating the energy needed for life and in pathways such as apoptosis. Direct targeting of antitumor drugs, such as doxorubicin (DOX), to mitochondria into cells is an effective approach for cancer therapy and inducing cancer cell death. To achieve targeted and effective delivery of antitumor drugs to tumor cells, to enhance the therapeutic effect, and to reduce the side effects during the treatment, we prepared a cationic amphiphilic polymer with aggregation-induced emission (AIE) characteristic. The polymer could be localized to mitochondria with excellent organelle targeting, and it showed good mitochondrial targeting with low toxicity. The polymer could also self-assemble into doxorubicin-loaded micelles in phosphate buffer, with a particle size of about 4.3 nm, an encapsulation rate of 11.03%, and micelle drug loading that reached 0.49%. The results of in vitro cytotoxicity experiments showed that the optimal dosage was 2.0 µg/mL, which had better inhibitory effect on tumor cells and less biological toxicity on heathy cells. Therefore, the cationic amphiphilic polymer can partially replace expensive commercial mitochondrial targeting reagents, and it can be also used as a drug loading tool to directly target mitochondria in cells for corresponding therapeutic research.

Chirality in peptide-based materials: From chirality effects to potential applications.

Chirality is ubiquitous in nature with primary cellular functions that include construction of right-/left-handed helix and selective communications among diverse biomolecules. Of particularly intriguing are the chiral peptide-based materials that can be deliberately designed to change physicochemistry properties via tuning peptide sequences. Critically, understanding their chiral effects are fundamental for the development of novel materials in chemistry and biomedicine fields. Here, we review recent researches on chirality in peptide-based materials, summarizing relevant typical chiral effects towards recognition, amplification, and induction. Driven forces for the chiral discrimination in affinity interaction as well as the handedness preferences in supramolecular structure formation at both the macroscale and microscale are illustrated. The implementation of such chirality effects of artificial copolymers, assembled aggregates and their composites in the fields of bioseparation and bioenrichment, cell incubation, protein aggregation inhibitors, chiral smart gels, and bionic electro devices are also presented. At last, the challenges in these areas and possible directions are pointed out. The diversity of chiral roles in the origin of life and chirality design in different organic or composite systems as well as their applications in drug development and chirality detection in environmental protection are discussed.

"All Polyimide" Mixed Matrix Membranes for High Performance Gas Separation.

To improve the interfacial compatibility of mixed matrix membranes (MMMs) for gas separation, microporous polyimide particle (AP) was designed, synthesized, and introduced into intrinsic microporous polyimide matrix (6FDA-Durene) to form "all polyimide" MMMs. The AP fillers showed the feature of thermal stability, similar density with polyimide matrix, high porosity, high fractional free volume, large microporous dimension, and interpenetrating network architecture. As expected, the excellent interfacial compatibility between 6FDA-Durene and AP without obvious agglomeration even at a high AP loading of 10 wt.% was observed. As a result, the CO2 permeability coefficient of MMM with AP loading as low as 5 wt.% reaches up to 1291.13 Barrer, which is 2.58 times that of the pristine 6FDA-Durene membrane without the significant sacrificing of ideal selectivity of CO2/CH4. The improvement of permeability properties is much better than that of the previously reported MMMs, where high filler content is required to achieve a high permeability increase but usually leads to significant agglomeration or phase separation of fillers. It is believed that the excellent interfacial compatibility between the PI fillers and the PI matrix induce the effective utilization of porosity and free volume of AP fillers during gas transport. Thus, a higher diffusion coefficient of MMMs has been observed than that of the pristine PI membrane. Furthermore, the rigid polyimide fillers also result in the excellent anti-plasticization ability for CO2. The MMMs with a 10 wt.% AP loading shows a CO2 plasticization pressure of 300 psi.

A methylation-inspired mesoporous coordination polymer for identification and removal of organic pollutants in aqueous solutions.

Qualitative analysis of contamination events and rapid removal of hazardous substances from water are in urgent need for a sustainable environment and human health. Porous coordination polymers (PCPs) bridged by organic ligands through metal nodes in an extendable and periodic manner have emerged as competitive candidates for the detection and removal of hazardous substances. However, the majority of them suffer from high production costs, poor structural stability and environmental problems, which has become a bottleneck for commercial translation. Here, we report a class of phenylalanine-based metal-biomolecule complexes and discuss the impact of subtle sequence variations in modular ligands on their assembly behaviors and structural properties. The phenomenon in which the bioligands dominate the structure formation and surface wettability has been revealed. A Cu(ii)-aspartame coordination polymer, Cu(mDF), with satisfactory chemical stability was selected for removal of organic pollutants in aqueous solution. The mesoporous structure, surface charge and high specific surface area (233.71 m2 g-1, Dmean = 5.65 nm) promote its rapid equilibrium of anionic adsorption within 10 min. In addition, Cu(mDF) possessing an adsorption-induced color-shifting feature provides an ideal platform for organic pollutant detection. Furthermore, Cu(mDF) with biocompatibility and low cost fabrication exhibits antimicrobial properties against C. albicans, E. coli and S. aureus, and may be a potential purifier in wastewater treatment.

Soft salts based on platinum(II) complexes with high emission quantum efficiencies in the near infrared region for in vivo imaging.

Two soft salts (S1 and S2) based on platinum(ii) complexes with a near-infrared emission have been designed and synthesized. It has been demonstrated that S2 has a high photostability and a low cytotoxicity, and it has been successfully applied to in vivo imaging for the first time.

Amphiphilic Polymer-Mediated Aggregation-Induced Emission Nanoparticles for Highly Sensitive Organophosphorus Pesticide Biosensing.

Biosensing applications require signal reporters to be sufficiently stable and biosafe as well as highly efficient. Aggregation-induced emission (AIE) nanoparticles have proven to be capable of cell-imaging and cancer therapy; however, realizing sensitive detection of biomolecules remains a great challenge because of their instability, biotoxicity, and lack of modifiable functional groups. Herein, we report a self-assembling strategy to fabricate AIE nanoparticles (PTDNPs) through the dispersion of amphiphilic polymers (PTDs) in phosphate-buffered saline. The PTDs were prepared through radical copolymerization of N-(1,2,2-triphenylvinyl)-4-acetylaniline and dimethyl diallyl ammonium chloride. We found that the particle size, morphology, functional groups, and fluorescence property of PTDNPs can be fine-tuned. Further, PTDNPs-0.10 were chosen as signal reporters to detect organophosphorus pesticides (OPs) with the aid of gold nanoparticles. Their sensing performance on OPs is superior to that using C-dot/quantum dot/rhodamine B as the signal reporter. This study not only provides new possibilities to fabricate novel AIE nanoparticles with exceptional properties, but also facilitates the AIE nanoparticle's application for target analyte biosensing.

Organic Nanocrystals with Bright Red Persistent Room-Temperature Phosphorescence for Biological Applications.

Persistent room-temperature phosphorescence (RTP) in pure organic materials has attracted great attention because of their unique optical properties. The design of organic materials with bright red persistent RTP remains challenging. Herein, we report a new design strategy for realizing high brightness and long lifetime of red-emissive RTP molecules, which is based on introducing an alkoxy spacer between the hybrid units in the molecule. The spacer offers easy Br-H bond formation during crystallization, which also facilitates intermolecular electron coupling to favor persistent RTP. As the majority of RTP compounds have to be confined in a rigid environment to quench nonradiative relaxation pathways for bright phosphorescence emission, nanocrystallization is used to not only rigidify the molecules but also offer the desirable size and water-dispersity for biomedical applications.