Cu(OTf)₂-Mediated Chan-Lam Reaction of Carboxylic Acids to Access Phenolic Esters

A Cu(OTf)2-mediated Chan-Lam reaction of carboxylic acids with arylboronic acids is described. It represents a facile and practical methodology to access phenolic esters in moderate to good yields. The procedure tolerates a series of functional groups, such as methoxycarbonyl, acetoxy, free phenolic hydroxyl, vinyl, nitro, trifluoromethyl, methoxyl, bromo, chloro, iodo, and acetyl groups

Additional file 1 of Umbilical cord-matrix stem cells induce the functional restoration of vascular endothelial cells and enhance skin wound healing in diabetic mice via the polarized macrophages

Additional file 1: Table S1. Quantitative real-time PCR primers used in this study. Figure S1. Cell survival and engraftment of PKH26-labeled UCMSCs into wound bed tissues in diabetic mice. Figure S2. Representative images of the chemotaxis assays. Figure S3. The concentrations of PGE2 were determined by ELISA in the UCMSC-CM and the CM derived from UCMSCs that were cultured in medium with the PGE2 inhibitors NS-398 or indomethacin. Figure S4. Representative images of the chemotaxis assays

Fabrication of Two Types of Shell-Cross-Linked Micelles with “Inverted” Structures in Aqueous Solution from Schizophrenic Water-Soluble ABC Triblock Copolymer via Click Chemistry

A well-defined ABC triblock copolymer, poly(2-(2-methoxyethoxy)ethyl methacrylate)-b-poly(2-(dimethylamino)ethyl methacrylate)-b-poly(2-(diethylamino)ethyl methacrylate) (PMEO2MA-b-PDMA-b-PDEA), was synthesized via sequential atom transfer radical polymerization using ethyl 2-bromoisobutyrate as the initiator. Reacting the triblock precursor with propargyl bromide in anhydrous tetrahydrofuran yielded PMEO2MA-b-P(DMA-co-QDMA)-b-PDEA triblock copolymer with “clickable” moieties, where QDMA was quaternized DMA residues. PMEO2MA-b-P(DMA-co-QDMA)-b-PDEA triblock copolymer exhibited “schizophrenic” micellization behavior in aqueous solution, forming three-layer onion-like PMEO2MA-core and PDEA-core micelles upon proper adjustment of the solution pH and temperature. For temperature-induced formation of PMEO2MA-core micelles at acidic pH, the critical micellization temperature can be tuned by incorporating oligo(ethylene glycol) methyl ether methacrylate (OEGMA; the mean degree of polymerization was 8−9) residues into the PMEO2MA block, shifting from 38 to 43 °C as the OEGMA contents varied in the range of 0−10 mol %. In both types of micelles, the inner shell layer consisted of the middle P(DMA-co-QDMA) segment. Subsequently, cross-linking with tetra(ethylene glycol) diazide via click chemistry in the presence of copper catalysts led to the facile preparation of two types of shell-cross-linked (SCL) micelles with “inverted” structures in purely aqueous solution. The cores and coronas of SCL micelles exhibited multiresponsive swelling/shrinking and collapse/aggregation behavior, respectively. To the best of our knowledge, this represents the first report of the fabrication of two types of SCL micelles with inverted structures from a single schizophrenic water-soluble triblock copolymer in purely aqueous solution

Micellar Nanoparticles of Coil–Rod–Coil Triblock Copolymers for Highly Sensitive and Ratiometric Fluorescent Detection of Fluoride Ions

We report on the fabrication of a novel type of ratiometric fluorescent polymeric probes for fluoride ions (F–) based on self-assembled micellar nanoparticles of P(MMA-co-NBDAE)-b-PF-b-P(MMA-co-NBDAE) coil–rod–coil triblock copolymer, where MMA, NBDAE, and PF are methyl methacrylate, 4-(2-acryloyloxyethylamino)-7-nitro-2,1,3-benzoxadiazole, and polyfluorene, respectively. Blue-emitting conjugated PF block and green-emitting NBDAE moieties with F– turn-off characteristics within the PMMA block serve as fluorescence resonance energy transfer (FRET) donors and switchable acceptors, respectively. For coil–rod–coil triblock copolymer in a good solvent such as THF, the blue emission of PF block dominates due to unimolecularly dissolved state associated with ineffective FRET process. The addition of F– ions only leads to ∼2.92-fold decrease of fluorescence intensity ratio, I515/I417, of characteristic NBDAE and PF emission bands. In acetone, the triblock copolymer spontaneously self-assembles into micelles possessing PF cores and NBDAE-labeled PMMA coronas. In the absence of F– ions, effective FRET processes between micellar cores and coronas occurs, resulting in prominently enhanced NBDAE emission. Upon addition of F– ions, the quenching of NBDAE emission bands leads to ∼8.75-fold decrease in the emission intensity ratio, I515/I417, which is also accompanied by naked eye-discernible fluorometric transition from cyan to blue emissions and colorimetric transition from green to yellowish. At a micellar concentration of 0.1 g/L in acetone at 25 °C, the detection limit of F– ions can be down to ∼4.78 μM (∼0.09 ppm). This work presents a new example of polymeric micelles-based optical F– probes and manifests that, upon proper structural design and optimization of spatial distribution of FRET donors and acceptors, self-assembled micelles of coil–rod–coil triblock copolymers serve as better ratiometric fluorescent F– ion sensors possessing visual detection capability, as compared to that of molecularly dissolved chains

Rh-Catalyzed Sequential Oxidative C–H and N–N Bond Activation: Conversion of Azines into Isoquinolines with Air at Room Temperature

A rhodium-catalyzed sequential oxidative C–H annulation reaction between ketazines and internal alkynes has been developed via C–H and N–N bond activation with air as an external oxidant, which led to an efficient approach toward isoquinolines with high atom efficiency at rt. Utilizing the distinctive reactivity of this catalysis, both N-atoms of the azines could be efficiently incorporated to the desired isoquinolines under very robust and mild reaction conditions

Efficient Synthesis of Single Gold Nanoparticle Hybrid Amphiphilic Triblock Copolymers and Their Controlled Self-Assembly

We report on a robust approach to the size-selective and template-free synthesis of asymmetrically functionalized ultrasmall (<4 nm) gold nanoparticles (AuNPs) stably anchored with a single amphiphilic triblock copolymer chain per NP. Directed NP self-assembly in aqueous solution can be facilely accomplished to afford organic/inorganic hybrid micelles, vesicles, rods, and large compound micelles by taking advantage of the rich microphase separation behavior of the as-synthesized AuNP hybrid amphiphilic triblock copolymers, PEO–AuNP–PS, which act as the polymer–metal–polymer analogue of conventional amphiphilic triblock copolymers. Factors affecting the size-selective fabrication and self-assembly characteristics and the time-dependent morphological evolution of NP assemblies were thoroughly explored

Palladium-Catalyzed Hydrocarbonylative C–N Coupling of Alkenes with Amides

An efficient palladium-catalyzed hydrocarbonylative C–N coupling of alkenes with amides has been developed. The reaction was performed via hydrocarbonylation of alkenes, followed by acyl metathesis with amides. Both intermolecular and intramolecular reactions proceed smoothly to give either branched or linear amides in high turnover number (3500) with NH₄Cl or NMP·HCl as a proton source under the palladium catalysis. This reaction offers a catalytic convenient approach to deuterated amides when inexpensive NMP·DCl served as a deuterium source

Highly Selective Fluorogenic Multianalyte Biosensors Constructed via Enzyme-Catalyzed Coupling and Aggregation-Induced Emission

The development of a highly selective and fast responsive fluorogenic biosensor for diverse analytes ranging from bioactive small molecules to specific antigens is highly desirable but remains a considerable challenge. We herein propose a new approach by integrating substrate-selective enzymatic reactions with fluorogens exhibiting aggregation-induced emission feature. Tyrosine-functionalized tetraphenylethene, TPE-Tyr, molecularly dissolves in aqueous media with negligible fluorescence emission; upon addition of horseradish peroxidase (HRP) and H₂O₂, effective cross-linking occurs due to HRP-catalyzed oxidative coupling of tyrosine moieties in TPE-Tyr. This leads to fluorescence emission turn-on and fast detection of H₂O₂ with high sensitivity and selectivity. As a validation of the new strategy’s generality, we further configure it into the biosensor design for glucose through cascade enzymatic reactions and for pathologically relevant antigens (e.g., human carcinoembryonic antigen) by combining with the ELISA kit

Rationally Engineering Phototherapy Modules of Eosin-Conjugated Responsive Polymeric Nanocarriers via Intracellular Endocytic pH Gradients

Spatiotemporal switching of respective phototherapy modes at the cellular level with minimum side effects and high therapeutic efficacy is a major challenge for cancer phototherapy. Herein we demonstrate how to address this issue by employing photosensitizer-conjugated pH-responsive block copolymers in combination with intracellular endocytic pH gradients. At neutral pH corresponding to extracellular and cytosol milieu, the copolymers self-assemble into micelles with prominently quenched fluorescence emission and low ¹O₂ generation capability, favoring a highly efficient photothermal module. Under mildly acidic pH associated with endolysosomes, protonation-triggered micelle-to-unimer transition results in recovered emission and enhanced photodynamic ¹O₂ efficiency, which synergistically actuates release of encapsulated drugs, endosomal escape, and photochemical internalization processes

Schizophrenic Core–Shell Microgels: Thermoregulated Core and Shell Swelling/Collapse by Combining UCST and LCST Phase Transitions

A variety of slightly cross-linked poly­(2-vinylpyridine)–poly­(<i>N</i>-isopropylacrylamide) (P2VP–PNIPAM) core–shell microgels with pH- and temperature-responsive characteristic were prepared via seeded emulsion polymerization. Negatively charged sodium 2,6-naphthalenedisulfonate (2,6-NDS) could be internalized into the inner core, followed by formation of (P2VPH⁺/SO₃^2–) supramolecular complex through the electrostatic attractive interaction in acid condition. The thermoresponsive characteristic feature of the (P2VPH⁺/SO₃^2–)–PNIPAM core–shell microgels was investigated by laser light scattering and UV–vis measurement, revealing an integration of upper critical solution temperature (UCST) and lower critical solution temperature (LCST) behaviors in the temperature range of 20–55 °C. The UCST performance arised from the compromised electrostatic attractive interaction between P2VPH⁺ and 2,6-NDS at elevated temperatures, while the subsequent LCST transition is correlated to the thermo-induced collapse of PNIPAM shells. The controlled release of 2,6-NDS was monitored by static fluorescence spectra as a function of temperature change. Moreover, stopped-flow equipped with a temperature-jump accessory was then employed to assess the dynamic process, suggesting a millisecond characteristic relaxation time of the 2,6-NDS diffusion process. Interestingly, the characteristic relaxation time is independent of the shell cross-link density, whereas it was significantly affected by shell thickness. We believe that these dual thermoresponsive core–shell microgels with thermotunable volume phase transition may augur promising applications in the fields of polymer science and materials, particularly for temperature-triggered release