Chirality at different levels is widely observed in nature, but the clue to connect it all together, and the way chirality transfers among different levels are still obscure. Herein, a l -/d -lysine-based self-assembly system was constructed, in which two-step chirality transfer among three different levels was observed in aqueous solution. The chirality originated from the point chirality of amino acid derivatives l -/d -PyLys hydrochloride, and was transferred to the planar conformational chirality of water-soluble pillar[5]arene pR-/pS-WP5. Then, with the aid of pR-/pS-WP5, nanoparticles were formed that exhibited L-/R-handed circularly polarized luminescence with a dissymmetry factor of up to ±0.001, arising from pyrene chiral excimers. This multilevel chirality transfer not only provides a perspective to trace potential clues, and to pursue certain ways by which the chirality transfers, but also offers a strategy to create controllable CPL emission in aqueous media. 相似文献
Peroxalate CL as an energy source to excite photosensitizers has attracted tremendous attention in photodynamic therapy (PDT). In this work, peroxyoxalate CPPO and hypocrellin B (HB)-based nanoparticles (CBNPs) for ultrasound (US)-enhanced self-exciting PDT were designed and prepared. CBNPs showed an excellent therapeutic effect against cancer cells with the assistance of US. This US-enhanced-chemiluminescence system avoids the dependence on external light and provides an example for inspiring more effective and precise strategies for cancer treatment. 相似文献
Two rhomboidal metallacycles based on metal-coordination-driven self-assembly are presented. Because metal-coordination interactions restrict the rotation of phenyl groups on tetraphenylethene units, these metallacycles were emissive both in solution and in solid state, and their aggregation-induced emission properties were well-retained. Moreover, the rhomboidal metallacyclic structures offer a platform for intermolecular packing beneficial for the formation of liquid crystalline phases. Therefore, although neither of building blocks shows mesogenic properties, both thermotropic and lyotropic (in DMF) mesophases were observed in one of metallacycles, indicating that mesophases could be induced by metal-coordination interactions. This study not only reveals the mechanism for the formation of cavity-cored liquid crystals, but also provides a convenient approach to preparing supramolecular luminescent liquid crystals, which will serve as good candidates for chemo sensors and liquid crystal displays. 相似文献
Two rhomboidal metallacycles based on metal‐coordination‐driven self‐assembly are presented. Because metal‐coordination interactions restrict the rotation of phenyl groups on tetraphenylethene units, these metallacycles were emissive both in solution and in solid state, and their aggregation‐induced emission properties were well‐retained. Moreover, the rhomboidal metallacyclic structures offer a platform for intermolecular packing beneficial for the formation of liquid crystalline phases. Therefore, although neither of building blocks shows mesogenic properties, both thermotropic and lyotropic (in DMF) mesophases were observed in one of metallacycles, indicating that mesophases could be induced by metal‐coordination interactions. This study not only reveals the mechanism for the formation of cavity‐cored liquid crystals, but also provides a convenient approach to preparing supramolecular luminescent liquid crystals, which will serve as good candidates for chemo sensors and liquid crystal displays. 相似文献
Hydrophobic photosensitizers greatly affect cell permeability and enrichment in tumors, but they cannot be used directly for clinical applications because they always aggregate in water, preventing their circulation in the blood and accumulation in tumor cells. As a result, amphiphilic photosensitizers are highly desirable. Although nanomaterial-based photosensitizers can solve water solubility, they have the disadvantages of complicated operation, poor reproducibility, low drug loading, and poor stability. In this work, an efficient synthesis strategy is proposed that converts small molecules into nanoparticles in 100 % aqueous solution by molecular assembly without the addition of any foreign species. Three photosensitizers with triphenylphosphine units and ethylene glycol chains of different lengths, TPP−PPh3, TPP−PPh3−2PEG and TPP−PPh3−4PEG, were synthesized to improve amphiphilicity. Of the three photosensitizers, TPP−PPh3−4PEG is the most efficient (singlet oxygen yield: 0.89) for tumor photodynamic therapy not only because of its definite constituent, but also because its amphiphilic structure allows it to self-assemble in water. 相似文献
Carbon dots (CDs), a kind of phototheranostic agent with the capability of simultaneous bioimaging and phototherapy [i.e., photodynamic therapy (PDT) or photothermal therapy (PTT)], have received considerable attention because of their remarkable properties, including flexibility for surface modification, high biocompatibility, low toxicity and photo‐induced activity for malignant tumor cells. Among numerous carbon sources, it has been found that natural biomass are good candidates for the preparation of CD phototheranostic agents. In this study, pheophytin, a type of Mg‐free chlorophyll derivative and also a natural product with low toxicity, was used as a raw carbon source for the synthesis of CDs by using a microwave method. The obtained hydrophobic CDs exhibited a maximum near‐infrared (NIR) emission peak at approximately 680 nm, and high singlet oxygen (1O2) generation with a quantum yield of 0.62. The self‐assembled CDs from the as‐prepared CDs with DSPE‐mPEG2000 retained efficient 1O2 generation. The obtained carbon dot assembly was not only an efficient fluorescence (FL) imaging agent but also a smart PDT agent. Our studies indicated that the obtained hydrophilic CD assembly holds great potential as a new phototheranostic agent for cancer therapy. This work provides a new route for synthesis of CDs and proposes a readily available candidate for tumor treatment. 相似文献
A shape-memory double network hydrogel consists of two polymer networks: a chemically crosslinked primary network that is responsible for the permanent shape and a physically crosslinked secondary network that is used to fix the temporary shapes. The formation/melting transition of the secondary network serves as an effective mechanism for the double network hydrogel's shape-memory effect. When the crosslinks in the secondary network are dissociated by applying an external stimulus, only the primary network is left to support the load. When the secondary network is re-formed by removing the stimulus, both the primary and secondary networks support the load. In the past, models have been developed for the constitutive behaviors of double network hydrogels, but the model of shape-memory double network hydrogels is still lacking. This work aims to build a constitutive model for the polyacrylamide-gelatin double network shape-memory hydrogel developed in our previous work. The model is first calibrated by experimental data of the double network shape-memory hydrogel under uniaxial loading and then employed to predict the shape-fixing performance of the hydrogel. The model is also implemented into a three-dimension finite element code and utilized to simulate the shape-memory behavior of the double network hydrogel with inhomogeneous deformations related to applications.
Graphic abstract
A shape-memory double network hydrogel consists of a chemically crosslinked primary network and a physically crosslinked secondary network. The formation/melting transition of the secondary network serves as an effective mechanism for the shape-memory effect of the double network hydrogel. This work built a constitutive model for the polyacrylamide-and-gelatin double network shape-memory hydrogel. The model was first calibrated by experimental data and then employed to predict the shape-fixing performance of the hydrogel. The model was also implemented into a three-dimension finite element code and utilized to simulate the shape-memory behavior of double network hydrogel in complex geometries.
Since the widespread plantation of oranges and the rapid development of the orange juice processing industry, orange peel has been one of the main wastes in today's food industry. Orange peel is rich in high value-added compounds. Recycling of these substances can reduce the environmental pollution and resource waste effectively. It can also bring quantities of products with economic and social value. To help readers deepen their understanding of orange peel further in reading, in this review paper, we introduce the composition, properties, usage and future directions of the essential oil, pectin, pigment, hesperidin and dietary fiber in orange peel. 相似文献