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Publication
Journal: Biosensors and Bioelectronics
January/16/2007
Abstract
A nanobiocomposite film consisted of polypyrrole (PPy), functionalized multiwalled carbon nanotubes (cMWNTs), and glucose oxidase (GOx) were electrochemically synthesized by electrooxidation of 0.1M pyrrole in aqueous solution containing appropriate amounts of cMWNTs and GOx. Potentiostatic growth profiles indicate that the anionic cMWNTs is incorporated within the growing PPy-cMWNTs nanocomposite for maintaining its electrical neutrality. The morphology of the PPy-cMWNTs nanocomposite was characterized by scanning electron microscopy (SEM). The PPy-cMWNTs nanocomposite was deposited homogeneously onto glassy carbon electrode. The amperometric responses vary proportionately to the concentration of hydrogen peroxide at the PPy-cMWNTs nanocomposite modified electrode at an operating potential of 0.7V versus Ag/AgCl (3M). The results indicate that the electroanalytical PPy-cMWNTs-GOx nanobiocomposite film was highly sensitive and suitable for glucose biosensor based on GOx function. The GOx concentration within the PPy-cMWNTs-GOx nanobiocomposite and the film thickness are crucial for the performance of the glucose biosensor. The amperometric responses of the optimized PPy-cMWNTs-GOx glucose biosensor (1.5 mgmL(-1) GOx, 141 mCcm(-2) total charge) displayed a sensitivity of 95 nAmM(-1), a linear range up to 4mM, and a response time of about 8s.
Publication
Journal: Sensors
January/24/2020
Abstract
Highly sensitive multicomponent materials designed for the recognition of hazardous compounds request control over interfacial chemistry. The latter is a key parameter in the construction of the sensing (macro) molecular architectures. In this work, multi-walled carbon nanotubes (CNTs) were deposited on diazonium-modified, flexible indium tin oxide (ITO) electrodes prior to the electropolymerization of pyrrole. This three-step process, including diazonium electroreduction, the deposition of CNTs and electropolymerization, provided adhesively-bonded, polypyrrole-wrapped CNT composite coatings on aminophenyl-modified flexible ITO sheets. The aminophenyl (AP) groups were attached to ITO by electroreduction of the in-situ generated aminobenzenediazonium compound in aqueous, acidic medium. For the first time, polypyrrole (PPy) was electrodeposited in the presence of both benzenesulfonic acid (dopant) and ethylene glycol-bis(2-aminoethylether)-tetraacetic acid (EGTA), which acts as a chelator. The flexible electrodes were characterized by XPS, Raman and scanning electron microscopy (SEM), which provided strong supporting evidence for the wrapping of CNTs by the electrodeposited PPy. Indeed, the CNT average diameter increased from 18 ± 2.6 nm to 27 ± 4.8, 35.6 ± 5.9 and 175 ± 20.1 after 1, 5 and 10 of electropolymerization of pyrrole, respectively. The PPy/CNT/NH2-ITO films generated by this strategy exhibit significantly improved stability and higher conductivity compared to a similar PPy coating without any embedded CNTs, as assessed by from electrochemical impedance spectroscopy measurements. The potentiometric response was linear in the 10-8-3 × 10-7 mol L-1 Pb(II) concentration range, and the detection limit was 2.9 × 10-9 mol L-1 at S/N = 3. The EGTA was found to drastically improve selectivity for Pb(II) over Cu(II). To account for this improvement, the density functional theory (DFT) was employed to calculate the EGTA-metal ion interaction energy, which was found to be -374.6 and -116.4 kJ/mol for Pb(II) and Cu(II), respectively, considering solvation effects. This work demonstrates the power of a subtle combination of diazonium coupling agent, CNTs, chelators and conductive polymers to design high-performance electrochemical sensors for environmental applications.
Publication
Journal: Materials Science and Engineering C
May/31/2019
Abstract
In this work intelligent and active films based on bacterial cellulose (BC) modified by polypyrrole-Zinc oxide nanocomposite (BC-PPy-ZnO) were provided. Chemical polymerization in the atmospheric condition was used for providing BC-PPy-ZnO film. Scanning electron microscopy (SEM) was used for studying BC-PPy-ZnO film morphology. The nanosized PPy-ZnO (50-150 nm) composites covered the BC surface. The BC-PPy-ZnO film was used for packaging of chicken thigh. The effects of storage time and storage temperature on the chicken thigh characteristics were studied based on a central composite design (CCD). The effects of BC-PPy-ZnO film on the chicken thigh characteristics, including pH, microbial property (Mesophilic and psychrophilic bacteria), color property, antioxidant and rheological properties were studied. The results showed that the BC-PPy-ZnO film could decrease the growth of microbial load in chicken thigh and could control the pH increasing. The BC-PPy-ZnO film could increase the shelf life and stabilize rheological properties of chicken thigh by increasing of antioxidant and antimicrobial activity as active packaging. According to the results there are good relations between film electrical resistance change and storage time-storage/temperature that this could help us to estimate the storage time and storage temperature of chicken thigh as intelligent packaging.
Publication
Journal: Chemical Communications
June/15/2015
Abstract
Polypyrrole (PPy) encapsulated 3D flower-like NiO was prepared to investigate the role of PPy coating for high-performance electrodes. NiO@PPy showed a better electrochemical performance than pure NiO, and a "trade-off effect" between electrical conductivity and ion diffusion resistance was observed with different PPy coating thickness.
Publication
Journal: Nanotechnology
August/19/2009
Abstract
In this study, a mesoporous silica nanoparticle (MSN)-based nerve growth factor (NGF) delivery system has been successfully embedded within an electroactive polypyrrol (Ppy). The spherical particles with approximately 100 nm diameter possess a large surface-to-volume ratio for the entrapment of NGF into the pores of MSNs while retaining their bioactivity. Direct incorporation of MSN-NGF within Ppy was achieved during electrochemical polymerization. The loading amount and release profile of NGF from the composite was investigated by sandwich ELISA. The NGF incorporation can be controllable by varying particle concentration or by extending electrodeposition time. The morphology and chemical composition of the Ppy/MSN-NGF composite was evaluated by atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy (XPS). Optical and electron microscopy revealed a characteristic attachment of PC 12 cells and the outgrowth of their neurites when grown on the Ppy/MSN-NGF composite as a result of a sustained and controlled release of NGF. In order to observe the effectiveness of electrical stimulation, neurite extension of cells cultured on unstimulated and stimulated Ppy/MSN-NGF was compared. The NGF release in the presence of electrical stimulation promoted significantly greater neurite extension.
Publication
Journal: Bioelectrochemistry
December/11/2018
Abstract
In this work, a sandwich-type electrochemical immunosensor was fabricated to quantitatively detect hepatitis B surface antigen (HBsAg). The immunosensor was based on Rh core and Pt shell nanodendrites loaded onto amino group functionalized graphene nanosheet (RhPt NDs/NH2-GS) as label and gold nanoparticles loaded onto polypyrrole nanosheet (Au NPs/PPy NS) as platform. RhPt NDs with abundant catalytic active sites because of the branched core-shell structure, RhPt NDs/NH2-GS as the label displayed high catalytic activity, amplifying the current signal of the immunosensor. Additionally, Au NPs/PPy NS enhanced the electron transfer and provided a good microenvironment to immobilize antibodies effectively, thus improving the sensitivity of the immunosensor. Based on above advantages, the immunosensor emerged a linear concentration ranging from 0.0005 to 10 ng/mL, a low detection limit of 166 fg/mL for HBsAg (S/N = 3) and good stability, selectivity, reproducibility. Furthermore, the satisfactory accuracy in analysis of actual serum samples implied the immunosensor had promising prospect in clinical analysis applications.
Publication
Journal: Materials Science and Engineering C
November/13/2018
Abstract
According to our previous study, polypyrrole (Ppy) possessed good conductivity and non-cytotoxicity. In this study, the surface of electrospun poly(l-lactic acid-co-ε-caprolactone)/silk fibroin (PLCL/SF) was coated with Ppy to fabricate Ppy-coated nerve guidance conduit (NGC). Firstly, the presence of Ppy on the prepared NGC was characterized and confirmed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopic spectra (XPS) and Fourier transforms infrared spectroscopy (FTIR). Subsequently, Ppy-coated NGC was used to repair a 10 mm sciatic nerve gap in vivo. 4 and 12 weeks after implantation, the regenerated nerve tissues on defect sites were removed and sectioned for further evaluation. Histological analysis with hematoxylin-eosin (HE), toluidine blue (TB), and luxol fast blue (LFB) staining indicated that the coated Ppy could promote SCs proliferation in early post-surgery, and enhance myelin formation in later post-surgery. In consideration of immunofluorescence and morphology observation with SEM and TEM, it showed that the nerve regeneration of Ppy-coated NGC group was close to autograft group, which was better than PLCL/SF NGC. In addition, walking track analysis indicated that Ppy-coated NGC group showed a similar performance compared with the autograft group, and significantly better than PLCL/SF NGC group. These promising results showed the potential of Ppy-coated NGC in peripheral nerve regeneration.
Publication
Journal: ACS Applied Materials & Interfaces
July/25/2018
Abstract
Localized drug-delivery systems (LDDSs) are a promising approach for cancer treatment because they decrease systematic toxicity and enhance the therapeutic effect of the drugs via site-specific delivery of active compounds and possible gradual release. However, the development of LDDS with rationally controlled drug release and intelligent functionality holds great challenge. To this end, we have developed a tailorable fibrous site-specific drug-delivery platform functionalized with pH- and near-infrared (NIR)-responsive polypyrrole (PPy), with the aim of cancer treatment via a combination of photothermal ablation and chemotherapy. First, a paclitaxel (PTX)-loaded polycaprolactone (PCL) (PCL-PTX) mat was prepared by electrospinning and subsequently in situ membrane surface-functionalized with different concentrations of PPy. The obtained PPy-functionalized mats exhibited excellent photostability and heating property in response to NIR exposure. PPy-coated mats exhibited enhanced PTX release in a pH 5.5 environment compared to pH 7.4. Release was further accelerated in response to NIR under both conditions; however, superior release was observed at pH 5.5 compared to pH 7.4, indicating a dual stimuli-responsive (pH and NIR) drug-delivery platform. More importantly, the 808 nm NIR irradiation enabled markedly accelerated PTX release from PPy-coated PCL-PTX mats and slowed and sustained release following termination of laser irradiation, confirming representative stepwise drug-release properties. PPy-coated PCL-PTX mats presented significantly enhanced in vitro and in vivo anticancer efficacy under NIR irradiation compared to PPy-coated PCL-PTX mats not exposed to NIR or uncoated mats (PCL-PTX). This study has thus developed a promising fibrous site-specific drug-delivery platform with NIR- and pH-triggering that notably utilizes PPy as a dopant for synergistic photothermal chemotherapy.
Publication
Journal: Scientific Reports
February/19/2017
Abstract
Electrode surfaces have been widely modified with electrically conductive polymers, including polypyrrole (PPY), to improve the performance of electrodes. To utilize conductive polymers for electrode modification, strong adhesion between the polymer films and electrode substrates should be ensured with high electrical/electrochemical activities. In this study, PPY films were electrochemically polymerized on electrodes (e.g., indium tin oxide (ITO)) with dopamine as a bio-inspired adhesive molecule. Efficient and fast PPY electrodeposition with dopamine (PDA/PPY) was found; the resultant PDA/PPY films exhibited greatly increased adhesion strengths of up to 3.7 ± 0.8 MPa and the modified electrodes had electrochemical impedances two to three orders of magnitude lower than that of an unmodified electrode. This electrochemical deposition of adhesive and conductive PDA/PPY offers a facile and versatile electrode modification for various applications, such as biosensors and batteries.
Publication
Journal: Talanta
May/8/2017
Abstract
Electrochemical patterning method has been developed to fabricate composite based on polypyrrole (PPy) film and poly(amidoamine) dendrimers of fourth generation (PAMAM G4). PPy layer was generated using electrochemical polymerization of pyrrole on a gold electrode. PPy film was then modified with PAMAM G4 using amines electro-oxidation method. Covalent bonding of PAMAM G4 and the formation of PPy-PAMAM composite was characterized using Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Photoelectron Spectroscopy (XPS). Ferrocenyl groups were then attached to such surface as a redox marker. Electrochemical properties of the modified nanomaterial (PPy-PAMAM-Fc) were studied using both amperometric and impedimetric methods to demonstrate the efficiency of electron transfer through the modified PPy layer. The obtained electrical and electrochemical properties were compared to a composite where PPy bearing carboxylic acid functions was chemically modified with PAMAM G4 by covalent attachment through formation of amid bond (PPy-CONH-PAMAM). The above mentioned studies showed that electrochemical patterning does not disturb the electronic properties of PPy. The effect of the number of functional groups introduced by the electrochemical patterning was demonstrated through the association of various compounds (ethylenediamine, PAMAM G2 and PAMAM G6). We demonstrated that such compounds could be applied in the biosensors technology. The modified PPy-PAMAM-Fc was evaluated as a platform for DNA sensing. High performance in the DNA detection by variation of the electrochemical signal of ferrocene was obtained with detection limit of 0.4 fM. Furthermore, such approach of electrochemical patterning by oxidation of amines could be applied for chemical modification of PPy and open a new way in various biosensing application involving functionalized PPy.
Publication
Journal: ACS Applied Materials & Interfaces
September/3/2014
Abstract
A conceptually new approach to the fabrication of polypyrrole (PPy)-coated multiwalled carbon nanotubes (MWCNT) for application in electrodes of electrochemical supercapacitors (ES) is proposed. Cetrimonium persulfate (CTA)2S2O8 in the form of nanocrystals is used as an oxidant for the chemical polymerization of PPy. Ponceau S (PS) dye is investigated as a new anionic dopant. Testing results show that PS allows reduced PPy particle size and improved electrochemical performance, whereas (CTA)2S2O8 nanocrystals promote the formation of PPy nanofibers. We demonstrate for the first time that MWCNT can be efficiently dispersed using (CTA)2S2O8 nanocrystals. The analysis of the dispersion mechanism indicates that (CTA)2S2O8 dissociation is catalyzed by MWCNT. This new finding opens a new and promising strategy in MWCNT dispersion for colloidal processing of nanomaterials and electrophoretic nanotechnology. Uniformly coated MWCNT are obtained using (CTA)2S2O8 as a dispersant for MWCNT and oxidant for PPy polymerization and utilizing advantages of PS as an efficient dopant and nanostructure controlling agent. The analysis of the testing results provides an insight into the influence of PS molecular structure on PPy nanostructure and electrochemical properties. The PPy-coated MWCNT show superior electrochemical performance compared to PPy nanoparticles. The proof-of-principle is demonstrated by the fabrication of ES electrodes with excellent electrochemical performance at high active material loadings, good capacitance retention at high charge-discharge rates, and excellent cycling stability.
Publication
Journal: Talanta
September/14/2020
Abstract
Uric acid-imprinted polypyrrole-based (MIP(UA)-Ppy) electrochemical quartz crystal microbalance sensor (EQCM) was developed. Experiments and theoretical calculations were focused on molecular interactions between uric acid molecule and: i) polypyrrole imprinted by uric acid (MIP(UA)-Ppy) ii) polypyrrole film without any molecular imprints (NIP-Ppy). Resonant frequency differences during electrochemical deposition of MIP(UA)-Ppy and NIP-Ppy films were observed and were attributed to the phenomenon of molecule capture within formed Ppy matrix. EQCM-resonators modified by MIP-Ppy showed the following advantages: selectivity, qualitative response, cost-effectiveness, and simple procedure. The selectivity of MIP(UA)-Ppy was tested by the replacement of uric acid in the PBS solution with several different concentrations of caffeine and glucose. Langmuir isotherm based molecular adsorption model was applied to evaluate the interaction of MIP(UA)-Ppy with uric acid. From experimental results calculated the standard Gibbs free energy of association (ΔGa) of uric acid with MIP(UA)-Ppy is -16.4 ± 2.05 kJ/mol and with NIP-Ppy is -13.3 ± 8.56 kJ/mol ΔG values illustrate that the formation of uric acid complex with MIP(UA)-Ppy is thermodynamically more favourable than that for complexation with NIP-Ppy.
Keywords: EQCM-Resonator; Electrochemical quartz crystal microbalance (EQCM); Molecularly imprinted polymer; Molecularly imprinted polypyrrole (MIP-Ppy); Polypyrrole (Ppy); Uric acid.
Publication
Journal: Nanomaterials
August/15/2017
Abstract
The performance of a modified electrode of nanocomposite films consisting of polypyrrole-chitosan-titanium dioxide (Ppy-CS-TiO₂) has been explored for the developing a non-enzymatic glucose biosensors. The synergy effect of TiO₂ nanoparticles (NPs) and conducting polymer on the current responses of the electrode resulted in greater sensitivity. The incorporation of TiO₂ NPs in the nanocomposite films was confirmed by X-ray photoelectron spectroscopy (XPS) spectra. FE-SEM and HR-TEM provided more evidence for the presence of TiO₂ in the Ppy-CS structure. Glucose biosensing properties were determined by amperommetry and cyclic voltammetry (CV). The interfacial properties of nanocomposite electrodes were studied by electrochemical impedance spectroscopy (EIS). The developed biosensors showed good sensitivity over a linear range of 1-14 mM with a detection limit of 614 μM for glucose. The modified electrode with Ppy-CS nanocomposite also exhibited good selectivity and long-term stability with no interference effect. The Ppy-CS-TiO₂ nanocomposites films presented high electron transfer kinetics. This work shows the role of nanomaterials in electrochemical biosensors and describes the process of their homogeneous distribution in composite films by a one-step electrochemical process, where all components are taken in a single solution in the electrochemical cell.
Publication
Journal: Sensors
January/22/2013
Abstract
Polypyrrole/single wall carbon nanotube composites were synthesized by in-situ chemical polymerization using pyrrole (PPy) as precursor and single wall carbon nanotubes (SWNTs) as additive component. Electron microscope images reveal that SWNTs component acts as nucleation sites for PPy growth in the form of spherical and cylindrical core-shell structures. The SWNTs/PPy core-shell results in thin n-p junctions which modify the PPy bandgap and reduce the work function of electrons. As a result of the strong coupling, Raman and IR spectra show that the PPy undergoes a transition from polaron to bipolaron state, i.e., indicating an increase in the conductivity. In the UV-Vis spectra, the 340 nm adsorption band (π*-π transition) exhibits a red shift, while the 460 nm adsorption band (bipolaron transition) experiences a blue shift indicating a change in electronic structure and a relocation of polaron levels in the band gap of PPy. The modification in PPy electronic structure brings in a synergistic effect in sensing feature. Upon exposure to oxygen (an oxidizing agent) and NH(3) gas (a reducing agent), the PPy/SWNTs nanocomposite shows an enhancement in sensitivity exceeding ten folds in comparison with those of PPy or SWNTs.
Publication
Journal: Nature Communications
July/18/2019
Abstract
Developing broadband and strong visible-light-absorbing photosensitizer is highly desired for dramatically improving the utilization of solar energy and boosting artificial photosynthesis. Herein, we develop a facile strategy to co-sensitize Ir-complex with Coumarins and boron dipyrromethene to explore photosensitizer with a broadband covering ca. 50% visible light region (Ir-4). This type of photosensitizer is firstly introduced into water splitting system, exhibiting significantly enhanced performance with over 21 times higher than that of typical Ir(ppy)2(bpy)+, and the turnover number towards Ir-4 reaches to 115840, representing the most active sensitizer among reported molecular photocatalytic systems. Experimental and theoretical investigations reveal that the Ir-mediation not only achieves a long-lived boron dipyrromethene-localized triplet state, but also makes an efficient excitation energy transfer from Coumarin to boron dipyrromethene to trigger the electron transfer. These findings provide an insight for developing broadband and strong visible-light-absorbing multicomponent arrays on molecular level for efficient artificial photosynthesis.
Publication
Journal: ACS Applied Materials & Interfaces
August/14/2014
Abstract
Metal and metal-oxide nanoparticles (NPs) are promising catalysts for dye degradation in wastewater treatment despite the challenges of NP recovery and recycling. In this study, water-dispersible NP superstructures with spherical morphology were constructed from hydrophobic Pd and Fe3O4 NPs by virtue of the oil droplets in an oil-in-water microemulsion as templates. Control of the evaporation rate of organic solvents in the oil droplets produces solid, hollow, and bowl-like superstructures. The component Fe3O4 and in particular Pd NPs can catalyze H2O2 degradation to create hydroxyl radicals and therewith degrade various dyes, and the magnetic Fe3O4 NPs also permit recycling of the superstructures with a magnet. Because the hollow and bowl-like superstructures increase the contact area of the NPs with their surroundings in comparison to solid superstructures, the catalytic activity is greatly enhanced. To improve the structural stability, the superstructures were further enveloped with a thin polypyrrole (PPy) shell, which does not weaken the catalytic activity. Because the current method is facile and feasible to create recyclable catalysts, it will promote the practicability of NP catalysts in treating industrial polluted water.
Publication
Journal: Science of the Total Environment
July/17/2018
Abstract
Polypyrrole nanofiber/Zn-Fe layered double hydroxide (Ppy NF/Zn-Fe LDH) was synthesized as nanocomposite of enhanced adsorption and photocatalytic properties. The formation of the composite was confirmed by XRD, FT-IR, HSEM, HRTEM, BET surface area and UV-vis spectrophotometer. Ppy NF/Zn-Fe LDH composite exhibits clear enhancing in the specific surface area and obvious reducing in the band gap energy (from 2.8 eV for Zn-Fe LDH to 2.31 eV for the composite). This was reflected in a considerable improvement in the adsorption capacity and photocatalytic removal of safranin dye. The adsorption capacity was enhanced by about 22% higher than Ppy NF and by 31% higher than Zn-Fe LDH. The photocatalytic removal was improved by 41.6% higher than Ppy NF and by about 54% higher than Zn-Fe LDH. The adsorption of safranin dye by the composite is chemisorption adsorption and occurs in a multilayer form. The complete photocatalytic removal of 5 mg/L of safranin dye can be achieved after 120 min illumination time using 0.05 g of the composite as photocatalyst and the best results can be obtained at neutral to alkaline conditions. Realistic application of the composite for the removal of dye from raw water samples revealed the applicability of the product for the purification of tap water, groundwater, and sewage water. Moreover, it can be used for six cycles of safranin dye removal from water. The photocatalytic degradation process appears to be controlled by the created hydroxyl radicals and formed photogenerated holes as the dominant active oxidizing radicals.
Publication
Journal: Chemistry - A European Journal
June/7/2015
Abstract
We demonstrate a new approach to manipulate the selective emission in mixed electrogenerated chemiluminescence (ECL) systems, where subtle changes in co-reactant properties are exploited to control the relative electron-transfer processes of excitation and quenching. Two closely related tertiary-amine co-reactants, tri-n-propylamine and N,N-diisopropylethylamine, generate remarkably different emission profiles: one provides distinct green and red ECL from [Ir(ppy)3] (ppy=2-phenylpyridinato-C2,N) and a [Ru(bpy)3](2+) (bpy=2,2'-bipyridine) derivative at different applied potentials, whereas the other generates both emissions simultaneously across a wide potential range. These phenomena can be rationalized through the relative exergonicities of electron-transfer quenching of the excited states, in conjunction with the change in concentration of the quenchers over the applied potential range.
Publication
Journal: Acta Pharmaceutica Sinica B
December/10/2020
Abstract
In many ways, cancer cells are different from healthy cells. A lot of tactical nano-based drug delivery systems are based on the difference between cancer and healthy cells. Currently, nanotechnology-based delivery systems are the most promising tool to deliver DNA-based products to cancer cells. This review aims to highlight the latest development in the lipids and polymeric nanocarrier for siRNA delivery to the cancer cells. It also provides the necessary information about siRNA development and its mechanism of action. Overall, this review gives us a clear picture of lipid and polymer-based drug delivery systems, which in the future could form the base to translate the basic siRNA biology into siRNA-based cancer therapies.
Keywords: 1,3-propanediol, PEG-b-PDMAEMA-b-Ppy; 2-propylacrylicacid, PAH-b-PDMAPMA-b-PAH; APOB, apolipoprotein B; AQP-5, aquaporin-5; AZEMA, azidoethyl methacrylate; Atufect01, β-l-arginyl-2,3-l-diaminopropionicacid-N-palmityl-N-oleyl-amide trihydrochloride; AuNPs, gold nanoparticles; B-PEI, branched polyethlenimine; BMA, butyl methacrylate; CFTR, cystic fibrosis transmembrane conductance regulator gene; CHEMS, cholesteryl hemisuccinate; CHOL, cholesterol; CMC, critical micelles concentration; Cancer; DC-Chol, 3β-[N-(N′,N′-dimethylaminoethane)carbamoyl]cholesterol; DMAEMA, 2-dimethylaminoethyl methacrylate; DNA, deoxyribonucleic acid; DOPC, dioleylphosphatidyl choline; DOPE, dioleylphosphatidyl ethanolamine; DOTAP, N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium methyl-sulfate; DOTMA, N-[1-(2,3-dioleyloxy)propy]-N,N,N-trimethylammoniumchloride; DOX, doxorubicin; DSGLA, N,N-dis-tearyl-N-methyl-N-2[N′-(N2-guanidino-l-lysinyl)] aminoethylammonium chloride; DSPC, 1,2-distearoyl-sn-glycero-3-phosphocholine; DSPE, 1,2-distearoyl-sn-glycero-3-phosphorylethanolamine; DSPE-MPEG, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (ammonium salt); DSPE-PEG-Mal: 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[maleimide(polyethylene glycol)-2000] (mmmonium salt), EPR; Liposomes; Micelles; N-acetylgalactosamine, HIF-1α; Nanomedicine; PE-PCL-b-PNVCL, pentaerythritol polycaprolactone-block-poly(N-vinylcaprolactam); PLA, poly-l-arginine; PLGA, poly lactic-co-glycolic acid; PLK-1, polo-like kinase 1; PLL, poly-l-lysine; PPES-b-PEO-b-PPES, poly(4-(phenylethynyl)styrene)-block-PEO-block-poly(4-(phenylethynyl)styrene); PTX, paclitaxel; PiRNA, piwi-interacting RNA; Polymer; RES, reticuloendothelial system; RGD, Arg-Gly-Asp peptide; RISC, RNA-induced silencing complex; RNA, ribonucleic acid; RNAi, RNA interference; RNAse III, ribonuclease III enzyme; SEM, scanning electron microscope; SNALP, stable nucleic acid-lipid particles; SiRNA, short interfering rNA; Small interfering RNA (siRNA); S–Au, thio‒gold; TCC, transitional cell carcinoma; TEM, transmission electron microscopy; Tf, transferrin; Trka, tropomyosin receptor kinase A; USPIO, ultra-small superparamagnetic iron oxide nanoparticles; UV, ultraviolet; VEGF, vascular endothelial growth factor; ZEBOV, Zaire ebola virus; enhanced permeability and retention, Galnac; hypoxia-inducible factor-1α, KSP; kinesin spindle protein, LDI; lipid-protamine-DNA/hyaluronic acid, MDR; lysine ethyl ester diisocyanate, LPD/LPH; messenger RNA, MTX; methotrexate, NIR; methoxy polyethylene glycol-polycaprolactone, mRNA; methoxypoly(ethylene glycol), MPEG-PCL; micro RNA, MPEG; multiple drug resistance, MiRNA; nanoparticle, NRP-1; near-infrared, NP; neuropilin-1, PAA; poly(N,N-dimethylacrylamide), PDO; poly(N-isopropyl acrylamide), pentaerythritol polycaprolactone-block-poly(N-isopropylacrylamide); poly(acrylhydrazine)-block-poly(3-dimethylaminopropyl methacrylamide)-block-poly(acrylhydrazine), PCL; poly(ethylene glycol)-block-poly(2-dimethylaminoethyl methacrylate)-block poly(pyrenylmethyl methacrylate), PEG-b-PLL; poly(ethylene glycol)-block-poly(l-lysine), PEI; poly(ethylene oxide)-block-poly(2-(diethylamino)ethyl methacrylate)-stat-poly(methoxyethyl methacrylate), PEO-b-PCL; poly(ethylene oxide)-block-poly(Ε-caprolactone), PE-PCL-b-PNIPAM; poly(Ε-caprolactone), PCL-PEG; poly(Ε-caprolactone)-polyethyleneglycol-poly(l-histidine), PCL-PEI; polycaprolactone-polyethyleneglycol, PCL-PEG-PHIS; polycaprolactone-polyethylenimine, PDMA; polyethylenimine, PEO-b-P(DEA-Stat-MEMA.
Publication
Journal: Clinical Infectious Diseases
October/9/2018
Abstract
UNASSIGNED
Mass drug administration (MDA) may further reduce malaria transmission in low transmission areas. The impact of MDA on dynamics of malaria transmission was determined in a prospective cohort study.
UNASSIGNED
Annual rounds of MDA with dihydroartemisinin-piperaquine (DP) were implemented over two years (2014 and 2015) in six village pairs before the malaria transmission season. Monthly blood samples were collected from all residents between July and December for microscopy and nested PCR. The incidence and prevalence of infection and clinical disease, and the risk of malaria re-infection post-MDA were determined.
UNASSIGNED
Coverage of three DP doses was 68.2% (2014) and 65.6% (2015), compliance was greater than 80%. Incidence of infection was significantly lower in 2014 (IR=0.2 PPY) than in 2013 (IR=1.1 PPY) (P<0.01); monthly infection prevalence declined in the first three months post-MDA. Clinical malaria incidence was significantly lower in 2014 (IR=0.1 PPY) and 2015 (IR=0.2 PPY) than in 2013 (IR=0.4 PPY) (P<0.01) but remained higher in eastern Gambia. Individuals infected before MDA had a 2-fold higher odds of re-infection post-MDA (AOR=2.5, 95% CI: 1.5-4.3, P<0.01).
UNASSIGNED
MDA reduced malaria infection and clinical disease during the first months of each transmission season. The reduction was maintained in low transmission areas, but not in eastern Gambia. One MDA round could be followed by focal MDA targeting individuals found infected during the dry season. Repeated MDA rounds, some of them during the dry season over a much larger geographical area, may result in a more marked and sustained decrease of malaria transmission.
Publication
Journal: Nanotechnology
November/7/2014
Abstract
Organic light-emitting diodes (OLED) were fabricated on flexible and transparent reconstituted cellulose obtained from wood pulp. Cellulose is naturally available, abundant, and biodegradable and offers a unique substrate alternative for the fabrication of flexible OLEDs. Transparent cellulose material was formed by dissolution of cellulose in an organic solvent (dimethyl acetamide) at elevated temperature (165 °C) in the presence of a salt (LiCl). The optical transmission of 40-μm thick transparent cellulose sheet averaged 85% over the visible spectrum. High brightness and high efficiency thin film OLEDs were fabricated on transparent cellulose films using phosphorescent Ir(ppy)3 as the emitter material. The OLEDs achieved current and luminous emission efficiencies as high as 47 cd A(-1) and 20 lm W(-1), respectively, and a maximum brightness of 10,000 cd m(-2).
Publication
Journal: European Journal of Medicinal Chemistry
June/15/2019
Abstract
This work mainly introduces the synthesis and characterization of three iridium(III) complexes [Ir(ppy)2(adppz)](PF6) (Ir-1), [Ir(bzq)2(addpz)](PF6) (Ir-2) and [Ir(piq)2(adppz)](PF6) (Ir-3). The complexes are more cytotoxic than cisplatin against tumor cell lines such as SGC-7901, A549, HeLa, Eca-109, HepG2 and BEL-7402. The toxicity test results indicated that complexes Ir-1, Ir-2 and Ir-3 can effectively inhibit the cell growth of SGC-7901 cells, and the measured IC50 values are 1.8 ± 0.4, 1.6 ± 0.3 and 0.8 ± 0.1 μM, respectively. AO/EB staining and flow apoptosis confirmed that SGC-7901 cells were caused apoptosis after being treated with the complexes. Along with the increase of endogenous ROS and Ca2+ levels, mitochondrial membrane potential collapse and massive release of cytochrome c, it is fully demonstrated that these complexes induce apoptosis through ROS-mediated mitochondrial pathway. At the same time, the complex Ir-3 is outstanding in the inhibition of tumor growth in vivo. Combined with the above results, it provides a favorable foundation for the future development of more effective anti-tumor drugs.
Publication
Journal: Materials
August/20/2017
Abstract
Improvement of the binding of polypyrrole with PVDF (polyvinylidene fluoride) thin film using low pressure plasma was studied. The effects of various plasma gases i.e., Ar, O₂ and Ar + O₂ gases on surface roughness, surface chemistry and hydrophilicity were noted. The topographical change of the PVDF film was observed by means of scanning electron microscopy and chemical changes by X-ray photoelectron spectroscopy, with adhesion of polypyrrole (PPy) by abrasion tests and sheet resistance measurements. Results showed that the increase in roughness and surface functionalization by oxygen functional groups contributed to improved adhesion and Ar + O₂ plasma gave better adhesion.
Publication
Journal: Lab on a Chip - Miniaturisation for Chemistry and Biology
February/24/2005
Abstract
This paper presents an integrated cell processor for the automatic handling of individual embryo cells. The integrated processor can perform various functions such as cell transport, isolation, orientation, and immobilization. These functions are indispensable and frequently used for the manipulation of single cells, but can only be carried out by a skillful operator. The purpose of this study was the integration and automation of these functions for effective cell manipulation, using a MEMS approach. The isolation of a cell was performed using polypyrrole (PPy) valves in a microchannel into which cells were transported. The orientation of cells was controlled by electrorotation (ER), and the target cell was immobilized by suction from a microhole. All of these functions were seamlessly realized on a single chip. Excellent experimental results with mouse (B6CBA) embryo cells showed that this device could substitute for routine and cumbersome manual work. It is expected that the integrated chip will contribute significantly to faster and more reliable manipulation of cells.
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