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Publication
Journal: Analytical Sciences
February/21/2002
Abstract
A convenient "one step" preparation process of molecularly imprinted overoxidized-polypyrrole (oPPy) colloids by chemical polymerization and their high uptake ability and enantioselectivity are described. Since an oxidizing agent gives a different standard redox potential and rate of polymerization, the property of the resulting oPPy colloid can be controlled by the kind and concentration of the oxidizing agent. At higher concentrations of (NH4)2S2O8 (0.3 M), the overoxidation of PPy colloid automatically occurred. The extraction of L-lactate as a dopant has created a shape-complementary cavity on the surface of the oPPy colloid through overoxidation following polymerization. The oPPy colloid exhibited an excellent selectivity not only on the alanine enantiomer but also on the difference in the side-chain size of amino acids. The uptake of oPPy colloid towards L-alanine over D-alanine was 11.3 micromol/g-colloid against 3.6 micromol/g. The molecularly imprinted cavity can also recognize the existences of the OH or CH3 substituents.
Publication
Journal: Analytical Chemistry
April/23/2002
Abstract
Methylamine dehydrogenase (MADH) may be immobilized in a polypyrrole (PPy) film on an electrode surface and used as an amperometric sensor for the determination of histamine. Using site-directed mutagenesis, phenylalanine 55 on the alpha subunit of MADH was converted to alanine. This alphaF55A MADH exhibits a 400-fold lower Km value for histamine than does native MADH when assayed in solution. An alphaF55A MADH-PPy sensor was constructed, and its properties were compared to that of the native MADH-PPy sensor. The alphaF55A MADH immobilized on the electrode exhibited Michaelis-Menten behavior in response to varied concentrations of histamine with an approximately 3-fold lower Km value than that exhibited by the immobilized native MADH. The detection limit for the native MADH-PPy sensor was approximately 20 microM while the alphaF55A MADH-PPy sensor exhibited a detection limit of approximately 5 microM, a 4-fold increase compared to the native MADH-PPy sensor. This work highlights the potential value of using site-directed mutagenesis to engineer enzymes to alter and improve biosensor performance.
Publication
Journal: Colloids and Surfaces B: Biointerfaces
November/16/2015
Abstract
Single walled carbon nanotube (SWNT)/polypyrrole (PPy) composite films with controlled pore size and strong adhesive force was prepared as electrode material for improving the performance of neural electrodes. SWNT film with controlled pore size was first fabricated through electrophoresis with a merit that the pore size can be well tuned by changing the concentration of metal ions in the electrolyte. An ultrathin conformal PPy layer around SWNT bundles in a uniform manner within the entire films was subsequently obtained by pulsed electropolymerization. The adhesion of the SWNT coated electrodes was tested by repeatedly inserting the coated electrode into agar gel to demonstrate the better adhesive force of the coating. Electrochemical results showed that the SWNT/PPy coated metal electrodes have much lower impedance and higher charge storage capacity than the bare metal substrates. Further in vitro culture of rat pheochromocytoma (PC12) cells revealed that the porous SWNT/PPy composite film was non-toxic and well supported the growth of neurons. We demonstrate that the prepared composite film has potential applications in chronic implantable neural electrodes for neural stimulation and recording.
Publication
Journal: Journal of Colloid and Interface Science
November/25/2013
Abstract
Cellulose fabrics were coated with polypyrrole-silver (PPy/Ag) nanocomposite films via one pot photopolymerization in aqueous media. This process was optimized for various concentrations of pyrrole/textile weight ratios with fixed molar ratio of [pyrrole]/[AgNO(3)] as 2.5. Simple weight measurements of the fabrics indicated progressive coating of PPy/Ag versus initial pyrrole/fabric weight ratio and photopolymerization time. X-ray diffraction (XRD) data confirm the nano-size (10-30 nm) and metallic state of Ag crystallites. The metallic state of silver particles was also confirmed by X-ray photoelectron spectroscopy (XPS). We demonstrate that UV-induced polymerization of pyrrole in the presence of AgNO(3) is simple and fast compared to chemical oxidative polymerization in the absence of UV light. More importantly, it permits to coat cellulose fabrics in one pot by polypyrrole/Ag nanocomposites films in environmentally friendly aqueous solutions at room temperature.
Publication
Journal: Chemistry - A European Journal
December/7/2009
Abstract
A new dual luminescent sensitive paint for barometric pressure and temperature (T) is presented. The green-emitting iridium(III) complex [Ir(ppy)(2)(carbac)] (ppy=2-phenylpyridine; carbac=1-(9H-carbazol-9-yl)-5,5-dimethylhexane-2,4-dione) was applied as a novel probe for T along with the red-emitting complex [Ir(btpy)(3)], (btpy=2-(benzo[b]thiophene-2-yl)pyridine) which functions as a barometric (in fact oxygen-sensitive) probe. Both iridium complexes were dissolved in different polymer materials to achieve optimal responses. The probe [Ir(ppy)(2)(carbac)] was dispersed in gas-blocking poly(acrylonitrile) microparticles in order to suppress any quenching of its luminescence by oxygen. The barometric probe [Ir(btpy)(3)], in turn, was incorporated in a cellulose acetate butyrate film which exhibits good permeability for oxygen. The effects of temperature on the response of the oxygen probe can be corrected by simultaneous optical determination of T, as the poly(acrylonitrile) microparticles containing the temperature indicator are incorporated into the film. The phosphorescent signals of the probes for T and barometric pressure, respectively, can be separated by optical filters due to the approximately 75 nm difference in their emission maxima. The dual sensor is applicable to luminescence lifetime imaging of T and barometric pressure. It is the first luminescent dual sensor material for barometric pressure/T based exclusively on the use of Ir(III) complexes in combination with luminescence lifetime imaging.
Publication
Journal: Carbohydrate Polymers
March/31/2017
Abstract
In the current work, flexible, lightweight, and strong conductive nanopapers based on cellulose nanofibers (CNFs) with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and/or polypyrrole (PPy) were prepared by following a mixing and in situ chemical polymerization method. A successful homogeneous coating of PEDOT:PSS on cellulose nanofibers occurred by means hydrogen-bonding interactions between the hydroxyl functionalized CNF and the electronically charged PEDOT:PSS, as shown by FTIR spectra. The electrical conductivity and the specific capacitance of CNF-PEDOT:PSS nanopapers were 2.58Scm-1 and 6.21Fg-1, respectively. Further coating of PPy produced a substantial improvement on the electrical conductivity (10.55Scm-1) and the specific capacitance (315.5Fg-1) of the resulting CNF-PEDOT:PSS-PPy nanopaper. A synergistic phenomenon between both conductive polymers supported the high electrical conductivity and specific capacitance of the ternary formulation. Moreover, CNF-PEDOT:PSS-PPy nanopaper showed higher mechanical properties and it was more flexible than the nanopaper containing only polypyrrole conducting polymer (CNF-PPy). It is concluded that the good mechanical, electrical and electrochemical properties of the ternary formulation can apply for smart nanopaper in flexible electronics and energy storage devices.
Publication
Journal: Small
November/2/2015
Abstract
Light-responsive hydrogel particles with multi-compartmental structure are useful for applications in microreactors, drug delivery and tissue engineering because of their remotely-triggerable releasing ability and combinational functionalities. The current methods of synthesizing multi-compartmental hydrogel particles typically involve multi-step interrupted gelation of polysaccharides or complicated microfluidic procedures with limited throughput. In this study, a two-step sequential gelation process is developed to produce agarose/alginate double network multi-compartmental hydrogel particles using droplets assemblies induced by superhydrophobic surface as templates. The agarose/alginate double network multi-compartmental hydrogel particles can be formed with diverse hierarchical structures showing combinational functionalities. The synthesized hydrogel particles, when loaded with polypyrrole (PPy) nanoparticles that act as photothermal nanotransducers, are demonstrated to function as near-infrared (NIR) light triggerable and deformation-free hydrogel materials. Periodic NIR laser switching is applied to stimulate these hydrogel particles, and pulsatile release profiles are collected. Compared with massive reagents released from single-compartmental hydrogel particles, more regulated release profiles of the multi-compartmental hydrogel particles are observed.
Publication
Journal: Biosensors and Bioelectronics
July/16/2006
Abstract
Alcohol oxidase (AOD) was immobilized in polypyrrole (PPy) and a random copolymer containing 3-methylthienyl methacrylate and p-vinylbenzyloxy poly(ethyleneoxide) matrices. Immobilization of enzyme was performed via entrapment in conducting polymers during electrochemical polymerization of pyrrole through the thiophene moiety of the copolymer. Three different alcohols, namely methanol, ethanol and n-propanol, were used as substrates. Maximum reaction rates, Michaelis-Menten constants, optimum temperature and pH values, operational stabilities and shelf life of the enzyme electrodes were investigated.
Publication
Journal: Analytical Chemistry
July/7/2014
Abstract
Continuous glucose monitoring (CGM) is an important aid for diabetic patients to optimize glycemic control and to prevent long-term complications. However, current CGM devices need further miniaturization and improved functional performance. We have coupled a previously described microfluidic chip with enzymatic microreactor (EMR) to a microdialysis probe and evaluated the performance of this system for monitoring subcutaneous glucose concentration in rats. Nanoliter volumes of microdialysis sample are efficiently reacted with continuously supplied glucose oxidase (GOx) solution in the EMR. The hydrogen peroxide produced is amperometrically detected at a (polypyrrole (PPy)-protected) thin-film Pt electrode. Subcutaneous glucose concentration was continuously monitored in anesthetized rats in response to intravenous injections of 20% glucose (w/v), 5 U/kg insulin, or saline as a control. In vitro evaluation showed a linear range of 2.1-20.6 mM and a sensitivity of 7.8 ± 1.0 nA/mM (n = 6). The physical lag time between microdialysis and the analytical signal was approximately 18 min. The baseline concentration of blood glucose was 10.2 ± 2.3 mM. After administering glucose to the rats, glucose levels increased by about 2 mM to 12.1 ± 2.3 mM in blood and 11.9 ± 1.5 mM in subcutaneous interstitial fluid (ISF). After insulin administration, glucose levels decreased by about 8 mM relative to baseline to 2.1 ± 0.6 mM in blood and 2.1 ± 0.9 mM in ISF. A microfluidic device with integrated chaotic mixer and EMR has been successfully combined with subcutaneous microdialysis to continuously monitor glucose in rats. This proof-of-principle demonstrates the feasibility of improved miniaturization in CGM based on microfluidics.
Publication
Journal: Journal of biomedical materials research. Part A
November/5/2017
Abstract
Peripheral nerve regeneration is a serious clinical problem. Presently, there are several nerve tube-guides available in the market, however with some limitations. The goal of this work was the development of a biomaterial with high electrical conductivity to produce tube-guides for nerve regeneration after neurotmesis injuries whenrver an end-to-end suture without tension is not possible. A matrix of poly(vinyl alcohol) (PVA) was used loaded with the following electrical conductive materials: COOH-functionalized multiwall carbon nanotubes (MWCNTs), poly(pyrrole) (PPy), magnesium chloride (MgCl2 ), and silver nitrate (AgNO3 ). The tube-guide production was carried out by a freezing/thawing process (physical crosslinking) with a final annealing treatment. After producing the tube-guide for nerve regeneration, the physicochemical characterization was performed. The most interesting results were achieved by loading PVA with 0.05% of PPy or COOH- functionalized CNTs. These tubes combined the electrical conductivity of carbon nanotubes (CNTs) and PPy with the biocompatibility of PVA matrix, with potential clinical application for nerve regeneration. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1981-1987, 2016.
Publication
Journal: ACS Applied Materials & Interfaces
August/11/2013
Abstract
Through a novel method, we successfully synthesized electromagnetic (EM) functional polystyrene@polypyrrole@nickel (PS@PPy@Ni) composite microspheres. The PS@PPy spheres with well-defined core/shell structure have been synthesized via an in situ chemical oxidative copolymerization of pyrrole (Py) and N-2-carboxyethylpyrrole (PyCOOH) templated by PS microspheres. The reaction was carried out under heterophase conditions using the mixture of ethanol and water as the continuous phase. Tailored by the carboxyl groups on the surface of microspheres, magnetic nickel layer has been steady deposited onto the P(Py-PyCOOH) layer of the microspheres through an activation-electroless plating technology. The fine PS@P(Py-PyCOOH)@Ni core/shell structures could be obtained with the PyCOOH content up to 50 wt % in the P(Py-PyCOOH) layer. Moreover, the as-prepared PS@P(Py-PyCOOH)@Ni composites are ferromagnetic materials and behave as a good electromagnetic (EM) absorption material due to the coating of Ni layer around the PS@P(Py-PyCOOH) spheres. The PS@P(Py-PyCOOH)@Ni composite spheres show the remarkable EM wave absorption property with the maximum reflection loss (around -20.06 dB) at 10.69 GHz. The EM wave absorption can retained lower than -10 dB within a broad frequency range from 9.16 to 13.75 GHz.
Publication
Journal: International Journal of Bioprinting
June/29/2020
Abstract
Bioprinting is increasingly being used for fabrication of engineered tissues for regenerative medicine, drug testing, and other biomedical applications. The success of this technology lies with the development of suitable bioinks and hydrogels that are specific to the intended tissue application. For applications such as neural tissue engineering, conductivity plays an important role in determining the neural differentiation and neural tissue regeneration. Although several conductive hydrogels based on metal nanoparticles (NPs) such as gold and silver, carbon-based materials such as graphene and carbon nanotubes and conducting polymers such as polypyrrole (PPy) and polyaniline were used, they possess several disadvantages. The long-term cytotoxicity of metal nanoparticles (NPs) and carbon-based materials restricts their use in regenerative medicine. The conductive polymers, on the other hand, are non-biodegradable and possess weak mechanical properties limiting their printability into three-dimensional constructs. The aim of this study is to develop a biodegradable, conductive, and printable hydrogel based on collagen and a block copolymer of PPy and polycaprolactone (PCL) (PPy-block-poly(caprolactone) [PPy-b-PCL]) for bioprinting of neural tissue constructs. The printability, including the influence of the printing speed and material flow rate on the printed fiber width; rheological properties; and cytotoxicity of these hydrogels were studied. The results prove that the collagen/PPy-b-PCL hydrogels possessed better printability and biocompatibility. Thus, the collagen/PPy-b-PCL hydrogels reported this study has the potential to be used in the bioprinting of neural tissue constructs for the repair of damaged neural tissues and drug testing or precision medicine applications.
Keywords: Conductive scaffolds; Nerve guide conduit; Peripheral nerve injury; Stem cells; Three-dimensional printing; Tissue engineering scaffolds.
Publication
Journal: Talanta
June/13/2012
Abstract
CNT/PPy/K(x)MnO(2), a novel ternary core-shell nanowires, was successfully prepared by a two-step self-assembly method and utilized as an electrocatalyst for the oxidation of hydrogen peroxide. The as-synthesized products were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy and Fourier-transform infrared spectra (FTIR) measurements. The results exhibited that the K(x)MnO(2) nanosheets were grown on the surface of CNT/PPy core-shell nanotubes. The planes of the K(x)MnO(2) nanosheets were more or less perpendicular to the CNT/PPy nanotubes. Cyclic voltammetry (CV) results demonstrated that the CNT/PPy/K(x)MnO(2) composite nanowires, as a nonenzyme catalyst, performed well with regards to the oxidation of hydrogen peroxide in 0.1M phosphate buffer solution (pH 7.0). The composite had a fast response with a linear range of 5.0 μM to 9.7 mM and a relatively low detection limit of 2.4 μM (S/N=3). The sensitivity of the sensor for H(2)O(2) was 114.6 μA mM(-1)cm(-2). These excellent properties might be due to the large surface area of the composite nanowires and the quick electron transfer promoted by the combination of CNT and PPy.
Publication
Journal: Biomacromolecules
June/10/2018
Abstract
Development of versatile nanoscale platforms for cancer diagnosis and therapy is of great importance for applications in translational medicine. In this work, we present the use of γ-polyglutamic acid (γ-PGA) nanogels (NGs) to load polypyrrole (PPy) for thermal/photoacoustic (PA) imaging and radiotherapy (RT)-sensitized tumor photothermal therapy (PTT). First, a double emulsion approach was used to prepare the cystamine dihydrochloride (Cys)-cross-linked γ-PGA NGs. Next, the cross-linked NGs served as a reactor to be filled with pyrrole monomers that were subjected to in situ oxidation polymerization in the existence of Fe(III) ions. The formed uniform PPy-loaded NGs having an average diameter of 38.9 ± 8.6 nm exhibited good water-dispersibility and colloid stability. The prominent near-infrared (NIR) absorbance feature due to the loaded PPy endowed the NGs with contrast enhancement in PA imaging. The hybrid NGs possessed excellent photothermal conversion efficiency (64.7%) and stability against laser irradiation, and could be adopted for PA imaging and PTT of cancerous cells and tumor xenografts. Importantly, we also explored the cooperative PTT and X-ray radiation-mediated RT for enhanced tumor therapy. We show that PTT of tumors can be more significantly sensitized by RT using the sequence of laser irradiation followed by X-ray radiation as compared to using the reverse sequence. Our study suggests a promising theranostic platform of hybrid NGs that may be potentially utilized for PA imaging and combination therapy of different types of tumors.
Publication
Journal: Angewandte Chemie - International Edition
June/15/2016
Abstract
Herein we report the development of solid-phase microextraction (SPME) devices designed to perform fast extraction/enrichment of target analytes present in small volumes of complex matrices (i.e. V≤10 μL). Micro-sampling was performed with the use of etched metal tips coated with a thin layer of biocompatible nano-structured polypyrrole (PPy), or by using coated blade spray (CBS) devices. These devices can be coupled either to liquid chromatography (LC), or directly to mass spectrometry (MS) via dedicated interfaces. The reported results demonstrated that the whole analytical procedure can be carried out within a few minutes with high sensitivity and quantitation precision, and can be used to sample from various biological matrices such as blood, urine, or Allium cepa L single-cells.
Publication
Journal: Annals of Biomedical Engineering
September/6/2017
Abstract
We investigated the use of polypyrrole (PPy)-coated polymer scaffolds and electrical stimulation (ES) to differentiate adipose stem cells (ASCs) towards smooth muscle cells (SMCs). Since tissue engineering lacks robust and reusable 3D ES devices we developed a device that can deliver ES in a reliable, repeatable, and cost-efficient way in a 3D environment. Long pulse (1 ms) or short pulse (0.25 ms) biphasic electric current at a frequency of 10 Hz was applied to ASCs to study the effects of ES on ASC viability and differentiation towards SMCs on the PPy-coated scaffolds. PPy-coated scaffolds promoted proliferation and induced stronger calponin, myosin heavy chain (MHC) and smooth muscle actin (SMA) expression in ASCs compared to uncoated scaffolds. ES with 1 ms pulse width increased the number of viable cells by day 7 compared to controls and remained at similar levels to controls by day 14, whereas shorter pulses significantly decreased viability compared to the other groups. Both ES protocols supported smooth muscle expression markers. Our results indicate that electrical stimulation on PPy-coated scaffolds applied through the novel 3D ES device is a valid approach for vascular smooth muscle tissue engineering.
Publication
Journal: Acta Dermato-Venereologica
May/10/2019
Abstract
Given the introduction of new therapies targeting specific immune pathways for atopic dermatitis (AD), information on the economic burden of AD patients is needed. Direct costs (medication use and healthcare resource utilization) and costs of productivity loss were studied in 90 adult patients with AD indicated for systemic treatment. Costs were calculated for patients with controlled (Investigator Global Assessment (IGA) 0-2) and uncontrolled (IGA 3-5) disease at inclusion. Mean (95% confidence interval (95% CI)) total direct costs were €5,191 (€4,382-6,019) per patient per year (PPY), €4,401 (€3,695-5,215) for patients with controlled AD vs. €6,993 (€5,552-8,406), mean difference €2,593 (€820-4,282) (p=0.014) for patients with uncontrolled AD. Costs of productivity loss were €10,040 (€6,260-14,012) PPY for the total group, €6,886 (€4,188-10,129) PPY for patients with controlled AD vs. €13,702 (€6,124-22,996) for patients with uncontrolled AD, mean difference €6,816 (-€1,638-16,677; p=0.148). Total costs (direct costs+costs of productivity loss) were €15,231 (€11,487-19,455) PPY for the total group, €11,287 (€7,974-15,436) for patients with controlled AD vs. €20,695 (€14,068-34,564), mean difference €9,408 (-€119-19,964) (p=0.077) for patients with uncontrolled AD. Patients with AD using systemic immunosuppressive treatment incur considerable direct costs and costs of productivity loss.
Publication
Journal: Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences
April/7/2009
Abstract
Poly(pyrrole) (PPY) coating was prepared on a stainless-steel (SS) wire for solid-phase microextraction (SPME) by electrochemical deposition (cyclic voltammetric). The PPY was evaluated by analyzing new-generation antidepressants (mirtazapine, citalopram, paroxetine, duloxetine, fluoxetine, and sertraline) in plasma sample by SPME and liquid chromatography with UV detection (LC-UV). The effect of electrolyte solution (lithium perchlorate or tetrabutylammonium perchlorate) and the number of cycles (50, 100 or 200) applied during the polymerization process on the SPME performance was evaluated. Important factors in the optimization of SPME efficiency such as extraction time, temperature, pH, influence of plasma proteins on sorption mechanisms, and desorption conditions are discussed. The SPME-PPY/LC method showed to be linear in concentrations ranging from the limit of quantification (LOQ) to 1200 ng mL(-1). The LOQ values range from 16 to 25 ng mL(-1). The inter-day precision of the SPME-PPY/LC method presented coefficient of variation (CV) lower than 15%. Based on analytical validation results, the SPME-PPY/LC methodology showed to be adequate for antidepressant analysis, from therapeutic to toxic levels. In order to evaluate the proposed method for clinical use, the SPME-PPY/LC method was applied to the analysis of plasma samples from elderly depressed patients.
Publication
Journal: PLoS Medicine
November/13/2018
Abstract
BACKGROUND
Intermittent preventive treatment of malaria in pregnancy (IPTp) with dihydroartemisinin-piperaquine (IPTp-DP) has been shown to reduce the burden of malaria during pregnancy compared to sulfadoxine-pyrimethamine (IPTp-SP). However, limited data exist on how IPTp regimens impact malaria risk during infancy. We conducted a double-blinded randomized controlled trial (RCT) to test the hypothesis that children born to mothers given IPTp-DP would have a lower incidence of malaria during infancy compared to children born to mothers who received IPTp-SP.
RESULTS
We compared malaria metrics among children in Tororo, Uganda, born to women randomized to IPTp-SP given every 8 weeks (SP8w, n = 100), IPTp-DP every 8 weeks (DP8w, n = 44), or IPTp-DP every 4 weeks (DP4w, n = 47). After birth, children were given chemoprevention with DP every 12 weeks from 8 weeks to 2 years of age. The primary outcome was incidence of malaria during the first 2 years of life. Secondary outcomes included time to malaria from birth and time to parasitemia following each dose of DP given during infancy. Results are reported after adjustment for clustering (twin gestation) and potential confounders (maternal age, gravidity, and maternal parasitemia status at enrolment).The study took place between June 2014 and May 2017. Compared to children whose mothers were randomized to IPTp-SP8w (0.24 episodes per person year [PPY]), the incidence of malaria was higher in children born to mothers who received IPTp-DP4w (0.42 episodes PPY, adjusted incidence rate ratio [aIRR] 1.92; 95% CI 1.00-3.65, p = 0.049) and nonsignificantly higher in children born to mothers who received IPT-DP8w (0.30 episodes PPY, aIRR 1.44; 95% CI 0.68-3.05, p = 0.34). However, these associations were modified by infant sex. Female children whose mothers were randomized to IPTp-DP4w had an apparently 4-fold higher incidence of malaria compared to female children whose mothers were randomized to IPTp-SP8w (0.65 versus 0.20 episodes PPY, aIRR 4.39, 95% CI 1.87-10.3, p = 0.001), but no significant association was observed in male children (0.20 versus 0.28 episodes PPY, aIRR 0.66, 95% CI 0.25-1.75, p = 0.42). Nonsignificant increases in malaria incidence were observed among female, but not male, children born to mothers who received DP8w versus SP8w. In exploratory analyses, levels of malaria-specific antibodies in cord blood were similar between IPTp groups and sex. However, female children whose mothers were randomized to IPTp-DP4w had lower mean piperaquine (PQ) levels during infancy compared to female children whose mothers received IPTp-SP8w (coef 0.81, 95% CI 0.65-1.00, p = 0.048) and male children whose mothers received IPTp-DP4w (coef 0.72, 95% CI 0.57-0.91, p = 0.006). There were no significant sex-specific differences in PQ levels among children whose mothers were randomized to IPTp-SP8w or IPTp-DP8w. The main limitations were small sample size and childhood provision of DP every 12 weeks in infancy.
CONCLUSIONS
Contrary to our hypothesis, preventing malaria in pregnancy with IPTp-DP in the context of chemoprevention with DP during infancy does not lead to a reduced incidence of malaria in childhood; in this setting, it may be associated with an increased incidence of malaria in females. Future studies are needed to better understand the biological mechanisms of in utero drug exposure on drug metabolism and how this may affect the dosing of antimalarial drugs for treatment and prevention during infancy.
BACKGROUND
ClinicalTrials.gov number NCT02163447.
Publication
Journal: Advanced healthcare materials
July/18/2017
Abstract
Cancer cells exhibit specific physiological differences compared to normal cells. Most surface membranes of cancer cells are characterized by high expression of given protein receptors, such as albumin, transferrin, and growth factors that are also present in the plasma of patients themselves, but are lacking on the surface of normal cells. These distinct features between cancer and normal cells can serve as a niche for developing specific treatment strategies. Near-infrared (NIR)-light-triggered therapy platforms are an interesting novel avenue for use in clinical nanomedicine. As a photothermal agent, conducting polymer nanoparticles, such as polypyrrole (PPy), of great NIR light photothermal effects and good biocompatibility, show promising applications in cancer treatments through the hyperthermia mechanism. Autologous plasma proteins coated PPy nanoparticles for hyperthermia therapy as a novel core technology platform to treat cancers through secreted protein acid and rich in cysteine targeting are developed here. This approach can provide unique features of specific targeting toward cancer cell surface markers and immune transparency to avoid recognition and attack by defense cells and achieve prolonged circulation half-life. This technology platform unveils new clinical options for treatment of cancer patients, supporting the emergence of innovative clinical products.
Publication
Journal: Biomaterials
July/6/2014
Abstract
A versatile oil-in-water emulsion method has been explored for constructing water-dispersible polypyrrole (PPy) nano-/microcapsules with a soluble PPy complex as multifunctional photothermal agents for tumor ablation. In this work, both PPy nanocapsules (280.4 ± 79.0 nm) and microcapsules (1.31 ± 0.45 μm) with liquid perfluorooctylbromide (PFOB) core could be obtained by simply tuning the process energy for emulsion formation from ultrasonication to homogenization. Owing to the encapsulated liquid PFOB and strong near-infrared (NIR) absorption of PPy shell, the resulted PPy capsules showed great promise in ultrasound imaging guided photothermal ablation of tumor cells without inducing any significant side effect. Thus, it is anticipated that fine-tuning of the other encapsulated drugs or functional materials in PPy capsules would foster avenues for the development of multifunctional platforms for cancer treatments.
Publication
Journal: Small
March/29/2015
Abstract
Among active pseudocapacitive materials, polypyrrole (PPy) is a promising electrode material in electrochemical capacitors. PPy-based materials research has thus far focused on its electrochemical performance as a positive electrode rather than as a negative electrode for asymmetric supercapacitors (ASCs). Here high-performance electrochemical supercapacitors are designed with tungsten oxide@PPy (WO3 @PPy) core-shell nanowire arrays and Co(OH)2 nanowires grown on carbon fibers. The WO3 @PPy core-shell nanowire electrode exhibits a high capacitance (253 mF/cm2) in negative potentials (-1.0-0.0 V). The ASCs packaged with CF-Co(OH)2 as a positive electrode and CF-WO3 @PPy as a negative electrode display a high volumetric capacitance up to 2.865 F/cm3 based on volume of the device, an energy density of 1.02 mWh/cm3 , and very good stability performance. These findings promote the application of PPy-based nanostructures as advanced negative electrodes for ASCs.
Publication
Journal: Journal of Physical Chemistry A
January/10/2011
Abstract
We investigated the relaxation dynamics of bis(2-phenylpyridinato-)(2,2'-bipyridine)iridium(III), [Ir(ppy)(2)bpy](+) using the technique of time-resolved spectroscopy. In the visible emission spectra this molecule exhibits triple phosphorescence: displaying blue, green, and orange bands. From the dependence of spectral shifts with polarity of solvent, decay lifetimes, and the results of calculations using time-dependent density functional theory, we assigned these three emitting states to be triplet interligand charge-transfer ((3)LLCT), metal-to-ligand ppy charge transfer ((3)MLCT(ppy)), and metal-to-ligand bpy charge transfer ((3)MLCT(bpy)) states. The blue states were formed promptly after excitation at wavelength 355 nm; the one lying at higher energy decaying with a time coefficient 0.79-2.56 ns is assigned to be a triplet MLCT, and the other at lower energy decaying in 1.5-2.8 μs is assigned to (3)LLCT(A), A symmetry. This decay time coefficient of (3)LLCT(A) decreases with increasing dielectric constant of the solvent indicating this state mixing of some MLCT character. The green state (3)MLCT(ppy) decays in 0.13-4.8 ns to a nearby intermediate state either (3)MLCT(ppy) or (3)MLCT(bpy). The orange state (3)MLCT(bpy) is coupled to the intermediate state to have a rise time about 0.36-0.84 ns and decays in 425-617 ns. Although many triplet states exist in a small energy range, they couple weakly to display triple emission. All (3)LLCT and (3)MCLT states are coupled to the singlet (1)LLCT manifold directly and/or indirectly and contribute to the emission in the visible range.
Publication
Journal: Inorganic Chemistry
April/19/2015
Abstract
Synthesis and photophysical properties of the highly emissive complex [Ir(Fppy)2(dmb)](+) are reported along with those of additional heteroleptic cyclometalated Ir(III) complexes, [Ir(ppy)2(NN)](PF6): FppyH = 2-(2,4-difluorophenyl)pyridine; ppyH = 2-phenylpyridine; NN = 4,4'-dimethyl-2,2'-bipyridine (dmb), 1,10-phenanthroline (phen), or 4,7-diphenyl-1,10-phenanthroline (Ph2phen). TD-DFT calculations and Franck-Condon emission spectral band shape analyses show that the broad and structureless emission from [Ir(Fppy)2(dmb)](+) in acetonitrile at 298 K mainly arises from a triplet metal-to-ligand charge-transfer excited state, (3)MLCTIr(ppy)→NN. The emission maximum varies systematically with variations in electron-donating or -withdrawing substituents on both the NN and the Xppy ligands, and emission efficiencies are high, with an impressive ϕ ≈ 1 for [Ir(Fppy)2(dmb)](+). At 77 K in propionitrile/butyronitrile (4/5, v/v), emission from [Ir(Fppy)2(dmb)](+) is narrow and highly structured consistent with a triplet ligand-centered transition ((3)LCNN) and an inversion in excited-state ordering between the (3)MLCTIr(ppy)→NN and (3)LCNN states. In a semirigid film of the poly(ethyleneglycol)dimethacrylate with nine ethylene glycol spacers, PEG-DMA550, emission from [Ir(Fppy)2(dmb)](+) is MLCT-based. The thermal sensitivity of the photophysical properties of this excited state points to a possible application as a temperature sensor in addition to its more known use in light-emitting devices.
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