ABSTRACT
Tungsten oxide (WO3) and bismuth vanadate (BiVO4) are one of the most attractive combinations to construct an efficient heterojunction for photoelectrochemical (PEC) applications. Here, we report an all-solution-processed WO3/BiVO4 heteronanostructure photoanode with highly enhanced photoactivity and stability for sustainable energy production. The vertically aligned WO3 nanorods were synthesized on a fluorine-doped tin oxide/glass substrate by the hydrothermal method without a seed layer and BiVO4 was deposited by pulsed electrodeposition for conformal coating. Owing to the long diffusion lengths of charge carriers in the WO3 nanorods, the ability to absorb the wider range of wavelengths, and appropriate band-edge positions of the WO3/BiVO4 heterojunction for spontaneous PEC reaction, the optimum WO3/BiVO4 photoanode has a photocurrent density of 4.15 mA/cm2 at 1.23 V versus RHE and an incident-photon-to-current efficiency of 75.9% at 430 nm under front illumination, which are a double and quadruple those of pristine WO3 nanorod arrays, respectively. Our work suggests an environment-friendly and low-cost all-solution process route to synthesize high-quality photoelectrodes.
ABSTRACT
We report charge-switching ionic nanocomplexes comprised of glycol chitosan grafted with 2,3-dimethylmaleic acid (DMA) (denoted as 'GCS-g-DMA' hereafter) and a proapoptotic peptide. This system allowed for improved peptide delivery to tumor sites via a mechanism of selective peptide release when the pH was dropped from 7.4 to 6.8.
Subject(s)
Antineoplastic Agents/administration & dosage , Chitosan/chemistry , Drug Carriers/chemistry , Maleates/chemistry , Neoplasms/drug therapy , Peptides/administration & dosage , Animals , Antineoplastic Agents/therapeutic use , Female , Humans , Hydrogen-Ion Concentration , Melanoma, Experimental/drug therapy , Mice , Peptides/therapeutic useABSTRACT
In this study, a novel pH-responsive nanogel composed of glycol chitosan (GCS) grafted with functional 3-diethylaminopropyl (DEAP) groups (denoted as GCS-g-DEAP hereafter) was fabricated. The GCS-g-DEAP was designed to have a self-assembled arrangement consisting of hydrophilic block (GCS) and hydrophobic block (DEAP) at physiological pH. As the pH decreased to tumor extracellular pH (pH(e)), the nanogel was destabilized due to the protonation of DEAP. The pH-responsive property of the nanogel at tumor extracellular pH (pH(e)) was characterized in drug-release kinetic studies. The release of doxorubicin (DOX) from DOX-loaded nanogels was significantly accelerated at lower pH values, which allowed for increased DOX uptake by non-small lung carcinoma A546 cells under a slightly acidic pH condition, as in tumor pH(e).
Subject(s)
Amines/chemistry , Chitosan/analogs & derivatives , Drug Delivery Systems/methods , Neoplasms/metabolism , Polyethylene Glycols/chemistry , Polyethyleneimine/chemistry , Cell Line, Tumor , Chitosan/chemistry , Doxorubicin/pharmacology , Humans , Hydrogen-Ion Concentration/drug effects , Microscopy, Electron, Scanning , Nanogels , Particle Size , SolutionsABSTRACT
A novel synthetic nanocomplex was constructed from glycol chitosan (GCS) grafted with 2,3-dimethylmaleic anhydride (DMA) (denoted as 'GCD' hereafter) and lysozyme (isoelectric point=10.9) as a model protein. This is a core-shell supramolecular assemble formed through electrostatic interactions between anionic GCD and cationic lysozyme at a pH 7.4. The pH-sensitivity of the nanocomplexes originates from the dissociation of DMA block from GCD at a slightly acidic pH (i.e., pH 6.8), resulting in an increased electrostatic repulsion between cationic GCS and cationic lysozyme. This pH-induced charge switching of GCD provides a mechanism for triggered protein drug release from the nanocomplexes triggered by the small change in pH (pH 7.4-6.8).
Subject(s)
Drug Carriers/chemistry , Muramidase/administration & dosage , Nanoparticles/chemistry , Polymers/chemistry , Chitosan/chemistry , Chromatography, High Pressure Liquid , Drug Carriers/chemical synthesis , Drug Compounding , Hydrogen-Ion Concentration , Maleic Anhydrides/chemistry , Microscopy, Electron, Scanning , Particle Size , Polymers/chemical synthesis , Solubility , Static Electricity , Surface PropertiesABSTRACT
A rapid, specific and sensitive multiresidue method based on the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) sample preparation method and gas chromatography with mass spectrometric detection by selected ion monitoring (GC/MS-SIM) has been developed for the routine analysis of 109 pesticides in rice. The method uses one quantification ion and two identification ions. Temperature control during sample preparation helps improve the recovery of thermally labile pesticides such as captan. The method was validated by the analysis of samples spiked at 0.025-0.150 mg/kg in rice matrix. The recoveries of all pesticides were between 80% and 115% with a relative standard deviation of less than 15%. The limit of quantitation (LOQ) for most compounds met the maximum residue limits (MRLs) for pesticides in rice in Korea.
