22 research outputs found

    Effect of Molecular Structure on Stability of Organic Nanoparticles Formed by Bodipy Dimers

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    The objective was to evaluate the stability of organic nanoparticles made from Bodipy dimers. Bodipy dimers with different length of linkers were synthesized via multicomponent Passerini reaction, and could form the fluorescent nanoparticles (FNPs) through nanoprecipitation. Bodipy-dimers FNPs with long chain linker indicated better stability in biological condition than those with short one as revealed by changes of diameter and size distribution. The FNPs possessed high physical homogeneity and low cytotoxicity. The molecular structure dependent stability was also validated by confocal laser scanning microscope based on the dissociation-induced fluorescence recovering. Importantly, stable FNPs also could be used to load hydrophobic cargoes and deliver them into cytoplasm. We believe this systematic study between structure and stability might open new opportunities for designing stable nanoparticles for various applications

    One-Pot To Synthesize Multifunctional Carbon Dots for Near Infrared Fluorescence Imaging and Photothermal Cancer Therapy

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    It is an emerging focus to develop a simple and straightforward strategy to synthesize multifunctional nanomedicines for cancer imaging and treatment. In this work, a new carbon dot (named CyCD) with intrinsic theranostic properties was prepared from a hydrophobic cyanine dye [2-((<i>E</i>)-2-((<i>E</i>)-2-chloro-3-((<i>E</i>)-2-(1-(2-hydroxyethyl)-3,3-dimethylindolin-2-ylidene) ethylidene)­cyclohex-1-en-1-yl)­vinyl)-1-(2-hydroxyethyl)-3,3-dimethyl-3H-indol-1-ium iodide, CyOH] and poly­(ethylene glycol) (PEG800) via a simple solvothermal process. The as-prepared CyCD is well dispersed in water media with an average diameter of 2.9 ± 0.5 nm; it possesses favorable hydrophilicity and excellent photostability. More importantly, the strong absorption and near-IR (NIR) emission within the range from 600 to 900 nm, along with preferential uptake at tumors and high photothermal conversion efficiency (η = 38.7%), facilitate CyCD to act as an ideal theranostic agent for NIR fluorescent imaging and photothermal therapy in vitro and in vivo. This work highlights theranostic CDs as an excellent candidate for efficient cancer imaging and therapy

    Cyclodextrin/Paclitaxel Dimer Assembling Vesicles: Reversible Morphology Transition and Cargo Delivery

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    Here, we developed stable supramolecular binary vesicles on the basis of the host–guest interaction between β-cyclodextrins (β-CDs) and paclitaxel (PTX) dimer. The inclusion complexation between PTX dimer and β-CDs in water was studied by proton nuclear magnetic resonance spectroscopy and two-dimensional rotating-frame Overhauser effect spectroscopy. The resulting inclusion complex was amphiphilic and could self-assemble into vesicles with average diameter of 230 nm. The vesicles could evolve to nanoparticles (NPs) by adding competitive binding guest amantadine hydrochloride or by digesting β-CDs through α-amylase. Moreover, this process was reversible, and the NPs could also transform to vesicles by adding enough β-CDs again. The obtained hollow supramolecular vesicles were further explored to load hydrophilic dye indocyanine green molecule or hydrophobic anticancer drug doxorobicin for their controlled release under external stimulus. This work provides a new strategy for the design of supramolecular systems by using prodrug as building blocks

    Near-Infrared Polymeric Nanoparticles with High Content of Cyanine for Bimodal Imaging and Photothermal Therapy

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    The discovery and synthesis of theranostic nanomedicines with high loading of imaging and therapeutic agents is challenging. In this work, a polymer assembling strategy was used to make nanoparticles with exceptionally high loading of theranostic agent. As an example, poly­(heptamethine) was synthesized via multicomponent Passerini reaction, and then assembled into nanoparticles in the presence of poly­(ethylene glycol)<sub><i>2k</i></sub>-<i>block</i>-poly­(d,l-lactide)<sub><i>2k</i></sub> (PEG–PLA) with high heptamethine loading (>50%). The formed nanoparticles could be used for bimodal bioimaging and photothermal therapy. The bimodal bioimaging provided complementary message about biodistribution, and photothermal treatment inhibited the growth of cervical carcinoma upon laser irradiation. This assembly of polymers formed by imaging and therapeutic agents opens new possibilities for the construction of multifunctional nanomedicines

    Biodegradable Amphiphilic Copolymer Containing Nucleobase: Synthesis, Self-Assembly in Aqueous Solutions, and Potential Use in Controlled Drug Delivery

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    Biodegradable nucleobase-grafted amphiphilic copolymer, the methoxyl poly (ethylene glycol)-<i>b</i>-poly (L-lactide-<i>co</i>-2-methyl-2­(3-(2,3-dihydroxylpropylthio) propyloxycarbonyl)-propylene carbonate/1-carboxymethylthymine) (mPEG-<i>b</i>- P­(LA-<i>co</i>-MPT)), was synthesized. <sup>1</sup>H NMR titration and FT-IR spectroscopy indicated that the hydrogen-bonding could be formed between mPEG-<i>b</i>-P­(LA-<i>co</i>-MPT) and 9-hexadecyladenine (A-C16). The hydrophobic microenvironment of the amphiphilic copolymer can protect the complementary multiple hydrogen bonds between mPEG-<i>b</i>-P­(LA-<i>co</i>-MPT) and A-C16 from water effectively. The addition of A-C16 not only lowered the critical aggregation concentration (CAC) of mPEG-<i>b</i>-P­(LA-<i>co</i>-MPT)/A-C16 nanoparticles (NPs) in aqueous solution but also induced different morphologies, which can be observed by transmission electron microscopy (TEM). Meanwhile, dynamic light scattering (DLS) and turbidometry was utilized to evaluate the effect of temperature and pH change on the stability of mPEG-<i>b</i>-P­(LA-<i>co</i>-MPT)/A-C16 NPs. Cytotoxicity evaluation showed good biocompatibility of the mPEG-<i>b</i>-P­(LA-<i>co</i>-MPT)/A-C16 NPs. The <i>in vitro</i> drug release profile showed that with the increase of A-C16 content, the doxorubiucin (DOX) release at pH 7.4 decreased, while the faster release rate was observed with the addition of A-C16 with a pH of 5.0. Importantly, DOX-loaded NPs exerted comparable cytotoxicity against MDA-MB-231 cells. This work provided a new method to stabilize NP structure using hydrogen-bonds and would have the potential to be applied in controlled drug delivery

    Blue Thermally Activated Delayed Fluorescence Polymers with Nonconjugated Backbone and Through-Space Charge Transfer Effect

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    We demonstrate novel molecular design for thermally activated delayed fluorescence (TADF) polymers based on a nonconjugated polyethylene backbone with through-space charge transfer effect between pendant electron donor (D) and acceptor (A) units. Different from conventional conjugated D–A polymers with through-bond charge transfer effect, the nonconjugated architecture avoids direct conjugation between D and A units, enabling blue emission. Meanwhile, spatial π–π interaction between the physically separated D and A units results in both small singlet–triplet energy splitting (0.019 eV) and high photoluminescence quantum yield (up to 60% in film state). The resulting polymer with 5 mol % acceptor unit gives efficient blue electroluminescence with Commission Internationale de l’Eclairage coordinates of (0.176, 0.269), together with a high external quantum efficiency of 12.1% and low efficiency roll-off of 4.9% (at 1000 cd m<sup>–2</sup>), which represents the first example of blue TADF nonconjugated polymer

    Blends of Linear and Long-Chain Branched Poly(l‑lactide)s with High Melt Strength and Fast Crystallization Rate

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    The long-chain branched polylactides (LCB-PLAs) prepared by coupling the hydroxyl-terminated two-arm (linear) and triarm PLA prepolymers of identical arm length with hexamethylenediacianate (HDI) were used to improve the melt rheological and crystallization properties of linear polylactide resin, PLA 4032D from NatureWorks. The blends containing LCB-PLA displayed higher zero shear viscosities, more significant shear shinning, more melt elasticity, and much longer relaxation times together with significant strain hardening in elongational deformation. <i>T</i><sub>g</sub>, <i>T</i><sub>m</sub> and crystallinity (<i>X</i><sub>c</sub>) of linear PLA remained virtually unaffected, but the crystallization rate increased obviously, since the branch points of LCB-PLAs could play a role of nucleating agent. High melt strength, fast crystallization, and favorable miscibility improved the foaming ability of the linear/LCB-PLA blends, substantially

    Transferrin-Conjugated Micelles: Enhanced Accumulation and Antitumor Effect for Transferrin-Receptor-Overexpressing Cancer Models

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    As the transport protein for iron, transferrin can trigger cellular endocytosis once binding to its receptor (TfR) on the cell membrane. Using this property, we conjugated transferrin onto the surface of biodegradable polymeric micelles constructed from amphiphilic block copolymers. The core of micelle was either labeled with a near-infrared dye (NIR) or conjugated with a chemotherapeutic drug paclitaxel (PTX) to study the biodistribution or antitumor effect in nude mice bearing subcutaneous TfR-overexpressing cancers. DLS and TEM showed that the sizes of Tf-conjugated and Tf-free micelles were in the range of 85–110 nm. Confocal laser scanning microscopy and flow cytometry experiments indicated that the uptake efficiency of the micelles by the TfR-overexpressing cells was enhanced by Tf conjugation. Semiquantitative analysis of the NIR signals collected from the tumor site showed that the maximum accumulation was achieved at 28 h in the M­(NIR) group, while at 22 h in Tf–M­(NIR) groups; and the area under the intensity curve in the Tf–M­(NIR) groups was more than that in M­(NIR) group. Finally, the tumor inhibition effects of targeting micelles were studied with the gastric carcinoma model which overexpressed TfR. The analysis of tumor volumes and the observation of H&E-stained tumor sections showed that Tf–M­(PTX) had the best antitumor effect compared with the control groups (saline, PTX, and M­(PTX)). The results of this study demonstrated the potential application of Tf-conjugated polymeric micelles in the treatment of TfR-overexpressing cancers

    Enhancing Therapeutic Efficacy of Cisplatin by Blocking DNA Damage Repair

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    Self-repair of nuclear DNA damage is the most known reason that leads to drug resistance of cancer tissue and limited therapeutic efficacy of anticancer drugs. Inhibition of protein phosphatase 2A (PP2A) would block DNA damage-induced defense of cancer cells to suppress DNA repair for enhanced cancer treatment. Here, we combined a PP2A inhibitor LB (4-(3-carboxy-7-oxa-bicyclo[2.2.1]­heptane-2-carbonyl) piperazine-1-carboxylic acid <i>tert</i>-butyl ester) and the DNA damage chemotherapeutic drug cisplatin through a simple physical superposition. The two drugs administrated at a ratio of 1:1 exhibited an optional synergistic antitumor efficacy <i>in vitro</i> and <i>in vivo</i>. LB was demonstrated to specifically activate the protein kinase B (Akt) and mitogen-activated protein kinases (MAPK) signaling pathways by PP2A inhibition to overcome cell cycle arrest caused by cisplatin-induced DNA damage
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