Latest ArticlesThe demand for injectable dermal filler has undergone significant growth with the rapid development of the beauty industry. Poly(lactic acid) (PLA) as a benefit of excellent biocompatibility and long-term promotion of collagen regeneration has been favored as a commonly used filler. However, the effects of chirality and particle size of PLA on the efficacy of dermal filler have not been studied. In this study, we prepared three kinds of microspheres (MSs) consisting of poly(D-lactic acid) (PDLA MS), poly(L-lactic acid) (PLLA MS), or meso-PLA (PDLLA MS) at 5, 10 and 20 μm to reveal the different biological functions as dermal filler. Following intradermal injection into guinea pig, it was found that PLLA MS induced the slightest inflammation, and the level of pro-inflammatory cytokine IL-1β induced by PLLA MS is only 0.3 or 0.7-fold of that induced by PDLA or PDLLA MS, respectively. More importantly, PLLA MS significantly stimulated the regeneration of collagen, which was 1.4 or 1.1 times higher than those stimulated by PDLA MS or PDLLA MS, respectively. The size of PLA MSs did not affect the levels of inflammation and collagen regeneration. The results confirmed the superiority of PLLA as a dermal filler.
The effects of concentration and an oriented external electric field on the transformations of hydrogenbonded structures of trimesic acid (TMA) and terephthalic acid (TPA) have been investigated at a liquid–solid interface by scanning tunneling microscopy (STM). The triangular periodic TMA framework can be transformed into a flower-like structure by changing the STM sample bias sign in situ. Networks of TMA and TPA are porous at a negative substrate bias, but typically change to relatively compact forms when the polarity of the applied bias is reversed. This change is reversible if the applied bias is reversed. The effects have potentials to locally control the capture and release of analytes in host-guest systems and the 2D morphology in multicomponent layers.
A Mn(Ⅲ) mediated radical reaction of new designed multi-functionalized 2-isocyano-6-alkenyl(alkynyl) benzonitriles with arylboronic acids has been developed. This reaction provides a method for the synthesis of pyrroloisoquinoline derivatives through the formation of two C—C bonds and one C—N bond via radical cascade cyclization in one step.
Two types of palladium(Ⅱ)-based metallacalixarenes [ML]2+ and [ML2]2+ have been synthesized through coordination-driven self-assembly from a series of flexible pyridine-bridged diimidazole ligands [2,6-bis ((1H-imidazol-1-yl)methyl) pyridine (L1), 2,6-bis((1H-benzo[d]imidazol-1-yl)methyl)pyridine (L2), 2,6-bis((1H-naphtho[2,3-d]imidazol-1-yl)methyl)pyridine (L3)], with palladium(Ⅱ)-based building blocks [Pd(BF4)2(M1-BF4) and (tmeda)Pd(NO3)2 (M2-NO3) (tmeda = N, N, N', N'-tetramethyl-ethylenediamine)]. All complexes were characterized by NMR spectroscopy (1H NMR and 13C NMR), mass spectrometry (CSI-MS, ESI-HRMS) and elemental analysis. The single crystal X-ray diffraction analysis of [M1L22](NO3)2, [M1L23](NO3)2, [M1L23](PF6)2 and [M2L3](NO3)2 further confirmed the uniquely single bowl-shape and double bowl-shape structures. The anion binding properties within the metallacalixarenes as receptors were also investigated by NMR titration experiments in DMSO.
Water-soluble thermoresponsive polymers present either upper critical solution temperature (UCST) or lower critical solution temperature (LCST) depending on the location of their miscibility range with water at high temperatures or at low temperatures. Compared with LCST polymers, the water-soluble UCST polymers are still less explored until now. In this work three copolymers of P(AAm-co-GAA) were synthesized by copolymerizing two acrylamide monomers, acrylamide (AAm) and acrylamide functionalized with natural glycyrrhetinic acid (GAA), using reversible addition-fragmentation chain transfer (RAFT) polymerization. These copolymers exhibited the typical UCST thermoresponsive behavior, and their phase transition temperatures could be easily tuned to around 37 ℃ for potential biological applications. Moreover, the UCST of P(AAm-co-GAA) can be adjusted not only by the content of glycyrrhetinic acid (GA) and polymer concentrations, but also by the host-guest interactions between GA and cyclodextrins (β- and γ-CD). The suitable value of UCST and the biocompatible nature of GA and CDs may endow these copolymers with practical applications in biomedical chemistry
In this work, a blue emitter with a 3D rigid structure composed of multiple spirobifluorene (3-Spiro) has been synthesized and characterized. Through a detailed study of the electrochemical and photophysical properties of 3-Spiro, we have evidenced that 3-Spiro can be applied as an active component of organic light-emitting diodes (OLEDs). The device with 5% doping rate of 4CzPNPh exhibits high external quantum efficiency (EQE) of 11%, which proves the potential of 3D rigid structure emitters for OLEDs.
Polymorphism is a common phenomenon in nature. Here, we report one-pot wet chemical method to synthesize two polymorphs of Au19Ag4(S-Adm)15 nanocluster protected by 1-adamantanethiol (HS-Adm), which adopt P-1 and P21/c space group respectively. The crystal structures of two polymorphs were determined by X-ray crystallography. Compared to the previously reported Au19Ag4(S-Adm)15 nanocluster adopting P21/n space group, polymorphs of Au19Ag4(S-Adm)15 with P-1 and P21/c space group show the different optical properties. Moreover, Au19Ag4(S-Adm)15 with P-1 space group exhibits good thermal stability. Meanwhile, we investigated the effect of solvent and molar ratio of metal precursors on the polymorphs. This work provides an insight to polymorphs of metal nanoclusters.
The donor: acceptor (D: A) blend ratio plays a very important role in affecting the progress of charge transfer and energy transfer in bulk heterojunction (BHJ) organic solar cells (OSCs). The proper D: A blend ratio can provide maximized D/A interfacial area for exciton dissociation and appropriate domain size of the exciton diffusion length, which is beneficial to obtain high-performance OSCs. Here, we comprehensively investigated the relationship between various D: A blend ratios and the charge transfer and energy transfer mechanisms in OSCs based on PBDB-T and non-fullerene acceptor IT-M. Based on various D: A blend ratios, it was found that the ratio of components is a key factor to suppress the formation of triplet states and recombination energy losses. Rational D: A blend ratios can provide appropriate donor/accepter surface for charge transfer which has been powerfully verified by various detailed experimental results from the time-resolved fluorescence measurement and transient absorption (TA) spectroscopy. Optimized coherence length and crystallinity are verified by grazing incident wide-angle X-ray scattering (GIWAXS) measurements. The results are beneficial to comprehend the effects of various D: A blend ratios on charge transfer and energy transfer dynamics and provides constructive suggestions for rationally designing new materials and feedback for photovoltaic performance optimization in non-fullerene OSCs
To discover novel fluorophores of solution and solid dual-state emission (DSE) materials, unique V-shape furo[2, 3-b]furans have been designed and synthesized by a one-pot method for the first time and their photoluminescent properties have been explored in benzene, THF, DMF and DMSO, as well as in the solid state. As the best example, 2, 5-bis(4-(9H-carbazol-9-yl)phenyl)-6a-amino-3a, 6a-dihydrofuro[2, 3-b] furan-3, 3a, 4-tricarbonitrile (3g) exhibited solution and solid DSE properties in THF, benzene, and in the solid state with quantum yields of 55%, 92%, and 45%, respectively.
The designed synthesis of chiral covalent organic frameworks (COFs) featuring intriguing properties is fairly scant and remains a daunting synthetic challenge. Here we develop a de novo synthesis of an enantiomeric pair of 2D hydroxyl-functionalized hydrazone-linked chiral COFs, (S)- and (R)-HthBta-OH COFs, using enantiopure 2, 5-bis(2-hydroxypropoxy)terephthalohydrazide (Hth) as monomers. The formation process of hydroxyl-functionalized chiral COFs was monitored using rigorous time-dependent PXRD, vibrational circular dichroism (VCD), and electronic circular dichroism (ECD) studies. Remarkably, VCD spectra indicated a unique chiral signal inversion from the positive Cotton effect of (S)-Hth monomer to the negative Cotton effect of (S)-HthBta-OH COF, which has never been reported in chiral COFs. Moreover, two unprecedented carboxyl-functionalized chiral COFs, (S)- and (R)-HthBta-COOH, were constructed by a post-synthetic modification of the corresponding hydroxyl chiral COFs with succinic anhydride. Notably, carboxyl-functionalized COFs retained homochirality and crystallinity without linker racemization and structural collapse after the chemical modification due to the chemically robust nature of pristine hydrazone-linked chiral COFs.
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