Latest ArticlesStimuli-responsive polypeptides have been intensively investigated for controlled drug release, owing to their favorable biocompatibility and biodegradability. In this work, we designed and synthesized a new kind of polypeptide bearing 1, 4-dithiane pendants for reactive oxygen species (ROS)-responsive drug release. The polypeptide-based block copolymer was facilely synthesized by ring-opening polymerization (ROP) of 1, 4-dithian-substituted L-glutamate N-carboxyanhydride (DTG-NCA) monomer using an amino-terminated poly(ethylene glycol) methyl ether (mPEG-NH2) as the macromolecular initiator. The resultant block copolymer, mPEG-b-PDTG, could self-assemble into uniform micelles in aqueous medium owing to its amphiphilic structure. Then, the H2O2-triggered oxidation behaviors of the mPEG-b-PDTG micelles were studied by dynamic light scattering (DLS), FT-IR and turbidimetric assay. It was revealed that the oxidation of thioether into sulfoxide in the side chains would result in disassembly of the micelles. Furthermore, the ROS-responsive drug release behavior of the mPEG-b-PDTG micelles was verified by using Nile Red as a model drug. MTT assay also proved that mPEG-b-PDTG was non-toxic in B16F10 and L929 cells. Therefore, such a new class of oxidation-responsive polypeptide might provide a promising platform for ROS-responsive drug delivery.
Cancer therapy with nanoscale drug formulations has made significant progress in the past few decades. However, the selective accumulation and release of therapeutic agents in the lesion sites are still great challenges. To this end, we developed a cRGD-decorated pH-responsive polyion complex (PIC) micelle for intracellular targeted delivery of doxorubicin (DOX) to upregulate tumor inhibition and reduce toxicity. The PIC micelle was self-assembled via the electrostatic interaction between the positively charged cRGD-modified poly(ethylene glycol)-block-poly(L-lysine) and the anionic acid-sensitive 2, 3-dimethylmaleic anhydride-modified doxorubicin (DAD). The decoration of cRGD enhanced the cell internalization of PIC micelle through the specific recognition of αvβ3 integrin on the membrane of tumor cells. The active DOX was released under intracellular acidic microenvironment after endocytosis following the decomposition of DAD. Moreover, the targeted PIC micelle exhibited enhanced inhibition efficacies toward hepatoma in vitro and in vivo compared with the insensitive controls. The smart multifunctional micelle provides a promising platform for target intracellular delivery of therapeutic agent in cancer therapy.
Nanomaterials as drug carriers hold promise for the treatment of carcinomas, but integrating multiple functions into a single vector is difficult. In this study, we aim to develop efficient materials as vectors for co-delivery of microRNA-122 (miR-122) and sorafenib (SRF). We successfully synthesized amphiphilic galactose-modified PEGylated poly(amino-co-ester) (Gal-PEG-PPMS) copolymers consisted of hydrophilic Gal-PEG5k chain segments and hydrophobic poly(ω-pentadecalactone-co-N-methyldiethyleneamine-co-sebacic acid) chain segments, which self-assembled to form cationic micelles at pH 5.2. The results showed that the micelles could encapsulate SRF and bind miR122 simultaneously, increase cellular uptake efficiency. Furthermore, the micelles showed favorable transfection efficiency in enhancing miR122 expression level, the migration and invasion ability of hepatocellular carcinoma (HCC) cells were significantly inhibited after being transfected with miR122-loaded micelles. Most importantly, the co-delivery micelles decreased cell activities of HepG2 cells, which was more effective than miR122 or SRF loaded micelles alone. Collectively, Gal-PEG-PPMS nanoparticles are promising multifunctional carriers for miR122 and SRF co-delivery system to treat HCC.
Non-nerve cell-derived extracellular matrix (ECM) was coated on the aligned porous polypyrrole-poly(L-lactide) (PPy-PLLA) fiber-films with the conductivity of ~12 mS/m via L929 cells culture and lysing, resulting in~10% increase of PC12 cells attachment and 26 μm increase of neurites length. The neurite length of ~149 μm in EGF/NGF group (optimal concentration radio of 12.5/50 (ng/mL)) on aligned and ECM-conjugated fiber-films was significantly larger than ~94 μm in only NGF group (50 ng/mL), confirming the synergy of EGF, NGF and aligned ECM-conjuaged PPy-PLLA fibers. When differentiated PC12 cells were exerted electrical stimulation (ES) of 100 mV/cm for 4 h/day in 2 day through ECM-PPyPLLA fiber-films, their neurite length reached to ~251 μm, significantly larger than ~149 μm of group without ES, due to the higer expression of related neural proteins in ES group. A simple mechanism was proposed to analyze synergistical effect of ECM, EGF, NGF on axons adhesion and elongation along the aligned ECM-coated fibers under ES condition.
Herein, a WO3-CuWO4 nanostructured heterojunction was prepared by a facile two-step hydrothermal method. It is composed of a WO3 square microplate and CuWO4 nanoparticles. Then, the gas sensing properties were investigated under optimal operating temperature (120 ℃). The WO3-CuWO4 heterostructure shows good sensing performance towards n-butanol, with a response value up to 9.4 to towards 30 ppm n-butanol, and the response value is about 3 times higher than that of pristine WO3. Its detection limit for n-butanol is 0.1 ppm, which indicates a potential application in lower concentration detection. Moreover, the response time of WO3-CuWO4 nanostructured heterojunction and the pristine WO3 are 21 s and 240 s respectively, revealing that there is a faster gas sensing process in the heterostructure. A possible sensing mechanism was then proposed on the basis of experimental data and band structure analysis. The significant enhancement of WO3-CuWO4 heterostructure could be attributed to the formation of heterojunction, which brings electronic sensitization and electron transport pathway modulation. The work offered a kind of novel and cost-effective sensing materials, and inspired more novel devices based on nanostructured heterojunction mechanism.
Au or other metal nanostructures have the ability to strongly quench the fluorescence of fluorophores. This feature has made AuNP-conjugates attractive for the construction of platforms for various bioanalytes to overcome the limitations of small molecule fluorophores (poor solubility, long reaction time). In this paper, an ultrafast "Turn-On" fluorescent sensor for biothiols was constructed. The sensor is based on the fluorescent resonance energy transfer (FRET) effect between the fluorophore (PN) and AuNPs, which effectively quenches the fluorescence of the fluorophore. In the presence of thiols, PN is displaced and released from AuNP surfaces, and thus, the fluorescence is rapidly restored. The sensor features appreciable water solubility and ultrafast response time (a few seconds for Cys). In addition, it exhibits high selectivity and a detection limit as low as 12 nmol/L for Hcy. Moreover, the sensor presents good biocompatibility and has been successfully applied for imaging biothiols in living cells.
The widely accepted theory concerning the electrochemical energy storage mechanism of copper hexacyanoferrate (CuHCF) for supercapacitors is that CuHCF stores charge by the reversible redox processes of Fe3+/Fe2+ couple and Cu cations are electrochemically inactive. In this work, CuHCF nanocubes (CuHCF-NC) were synthesized in the presence of potassium citrate and its electrochemical properties were tentatively studied in 1 mol/L Na2SO4 aqueous electrolyte. Good supercapacitive performance was exhibited. The combined analyses of cyclic voltammogram (CV) and X-ray photoelectron spectroscopy (XPS) disclosed that the CuHCF nanocubes underwent the redox reactions of Fe3+/Fe2+ and Cu2+/Cu+ couples to store charges. The Cu2+/Cu+ redox couple was activated due to the strong coordination interaction between the carboxylate groups of citrate ions and surface Cu cations.
A series of novel 1, 2, 4-oxadiazole-containing N-pyridylpyrazole derivatives 12a-h were efficiently synthesized with pivaldehyde, pyridylpyrazole carboxylic acid and arylamine as raw materials via 1, 3-dipolar cycloaddition. Their structures were identified by melting points, 1H NMR, 13C NMR and elemental analysis or HRMS. The exploration on the single-crystal structures of 12c and 12g revealed the stereochemical and substituent oriental characteristics, and the relevance of the structure and the reaction activity of this type of compounds. The preliminary bioassays indicated that several compounds had good insecticidal activities, among which 12c showed a lethality rate of 80% towards Mythimna separata Walker at 200 μg/mL; some of the compounds exhibited favorable fungicidal activities at 50 μg/mL against Physalospora piricola, Rhizoctonia cereal, Sclerotinia sclerotiorum, etc. Among which, 12a, 12b, 12c and 12h could be considered as new fungicidal leading compounds for further structural optimization. These discoveries along with the structure-activity relationship analysis in this paper will provide useful guidance for the innovative studies on new pyridylpyrazole derivatives and their applications in agrochemical area.
Achieving stable deep blue organic light emitting diodes (OLEDs) with narrow full width at half maximum (FWHM) and color gamut in the range of the commission International de L'Eclairage (CIE) of y ≤ 0.10 is still challenging in display and lighting applications. In this investigation, three donor-acceptor (D-A) deep-blue emitters were designed and synthesized via integrating asymmetric quinazoline (PQ) acceptor with weak donating carbazole (Cz) donor. The effect of the position and number of Cz group in PQ unit are investigated, which is also first examples for systematic research about the effect of different position of asymmetric PQ as acceptor on deep OLEDs. Their bandgaps of 3.12~3.19 eV and the singlet state energy levels of 3.12~3.19 eV were found to be sufficiently large to achieve deep blue light. As expected, these emitters-based OLEDs exhibit deep blue emission with the maximum wavelength ≤ 450 nm and narrow FWHM ≈ 60 nm. Especially, a CIE of y=0.080 was achieved for 4PQ-Cz-based OLED. Significantly, the deep blue electroluminescence (EL) spectra of these three emitters-based OLEDs are very stable and the corresponding CIE coordinates deviation △CIE (x, y)) can be negligible under the applied voltage ranging from 5 V to 9 V.
Rapid and simultaneous in situ detection of multi-components is extremely crucial for the real-time monitoring of nutrients in fruits. Herein, a facile and user-friendly poly(carboxybetaine methacrylate)-coated paper-based microfluidic device (pCBMA-njPAD) has been exploited to synchronously identify and semi-quantify vitamin C, glucose, sucrose and fructose in fruits. The pCBMA was successfully grafted from the surface of paper sensor using a convenient and robust method, which was confirmed by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectrometry (XPS). The superior hydrophilicity and ultra-low fouling of pCBMA endowed the pCBMA-μPAD with remarkably rapid response (3 min), high sensitivity, good linear relationship and low detection limit (LOD) (vitamin C: y = 33.809 + 5.175x, R2 = 0.993, LOD = 0.179 mmol/L; glucose: y = -0.113 + 30.066lg(x), R2 = 0.988, LOD = 0.095 mmol/L; sucrose: y = -5.334 + 34.858lg(x), R2 = 0.996, LOD = 0.097 mmol/L; fructose: y = 4.996 + 23.325lg(x), R2 = 0.994, LOD = 0.140 mmol/L). Furthermore, satisfactory results were yielded in the detection of these nutrients in 9 fruits, which were much agreed well with those obtained by spectrophotometry. Such a portable and versatile pCBMA-μPAD will profoundly shape the future of food analysis, especially for the assessment of food quality and nutrition in the process of agricultural production and marketing.
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