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Publication
Journal: ACS Applied Materials & Interfaces
July/22/2014
Abstract
We report herein the synthesis and application of a novel G-quadruplex-selective luminescent iridium(III) complex [Ir(ppy)2(bcp)](+) (where ppy = 2-phenylpyridine and bcp = 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) for the sensitive detection of apurinic/apyrimidinic (AP) endonuclease activity. Using endonuclease IV (Endo IV) as a model enzyme, a duplex DNA substrate containing a G-quadruplex-forming sequence is cleaved by Endo IV at the abasic site. This releases the G-quadruplex sequence, which folds into a G-quadruplex and is recognised by the G-quadruplex-selective iridium(III) complex with an enhanced luminescence response. The assay achieved high sensitivity and selectivity for Endo IV over other tested enzymes.
Publication
Journal: Biosensors and Bioelectronics
June/2/2005
Abstract
A new material consisting of a water-dispersed complex of polypyrrole-polystyrensulfonate (PPy) embedded in polyacrylamide (PA) has been prepared and tested as enzyme immobilizing system for its use in amperometric biosensors. Glucose oxidase (GOx) and the water-dispersed polypyrrole complex were entrapped within polyacrylamide microgels by polymerization of acrylamide in the dispersed phase of concentrated emulsions containing GOx and PPy. Polymerization of the dispersed phase provides microparticles whose size lies between 3.5 and 7 microm. The aim of incorporating polypyrrole into the polyacrylamide microparticles was to facilitate the direct transfer of the electrons released in the enzymatic reaction from the catalytic site to the platinum electrode surface. The conductivity of the microparticles was measured by a four-point probe method and confirmed by the successful anaerobic detection of glucose by the biosensor. Thus, the polyacrylamide-polypyrrole (PAPPy) microparticles combine the conductivity of polypyrrole and the pore size control of polyacrylamide. The effects of the polyacrylamide-polypyrrole ratio and cross-linking on the biosensor response have been investigated, as well as the influence of analytical parameters such as pH and enzymatic loading. The PAPPy biosensor is free of interferences arising from ascorbic and uric acids, which allows its use for quantitative analysis in human blood serum.
Publication
Journal: Biosensors and Bioelectronics
September/19/2001
Abstract
A simple electropolymerisation process is described for the fabrication of an ultra-thin ( approximately 55 nm) polypyrrole (PPy)-glucose oxidase (GOD) film in a supporting electrolyte-free monomer solution for potentiometric biosensing of glucose. The optimum conditions for growing the ultra-thin film include 0.1 M pyrrole, 55-110 U/ml GOD, an applied current density of 0.05 mA/cm(2) and an electrical charge of 25 mC/cm(2). Long-term storage of the biosensor in acetate buffer improved the sensitivity of the biosensor by a factor of approximately two. The biosensor can also be used repeatedly for over 2 months with little or no loss in sensitivity. The interference effect of ascorbic acid was successfully reduced by inclusion of an outer PPy-Cl layer.
Publication
Journal: Journal of the American Chemical Society
November/4/2002
Abstract
The first method for the catalytic enantioselective addition of amines (specifically, pyrroles) to ketenes has been developed, and it has been demonstrated that the resulting acylpyrroles can be transformed into a broad spectrum of useful derivatives. On the basis of mechanistic studies, it is suggested that the planar-chiral catalyst plays an unanticipated role in this process as a chiral Brønsted acid.
Publication
Journal: Nanoscale Research Letters
July/13/2011
Abstract
An improved approach to assemble ultrathin and thickness-tunable polypyrrole (PPy) films onto multiwall carbon nanotubes (MWCNTs) has been investigated. A facile procedure is demonstrated for controlling the morphology and thickness of PPy film by adding ethanol in the reaction system and a possible mechanism of the coating formation process is proposed. The coated PPy films can be easily tuned by adding ethanol and adjusting a mass ratio of pyrrole to MWCNTs. Moreover, the thickness of PPy significantly influences the electronic conductivity and capacitive behavior of the PPy/MWCNT composites. The method may provide a facile strategy for tailoring the polymer coating on carbon nanotubes (CNTs) for carbon-based device applications.
Publication
Journal: Synthetic Metals
February/19/2017
Abstract
Electrically conductive polymers, such as polypyrrole (PPy), show promise for modifying the dimensions and properties of micro- and nanoscale structures. Mechanisms for controlling the formation of PPy films of nanoscale thickness were evaluated by electrochemically synthesizing and examining PPy films on planar gold electrodes under a variety of growth conditions. Tunable PPy coatings were then deposited by electropolymerization on the sidewalls of individual, electrically addressable carbon nanofibers (CNFs). The ability to modify the physical size of specific nanofibers in controllable fashion is demonstrated. The biocompatibility, potential for chemical functionalization, and ability to effect volume changes of this nanocomposite can lead to advanced functionality, such as specific, nanoscale valving of materials and morphological control at the nanoscale.
Publication
Journal: Biotechnology and Applied Biochemistry
February/22/2006
Abstract
In the present study we purified a cold-active PNL (pectin lyase) from the extracellular fraction of the PPY (pectinolytic and psychrophilic yeast) Cystofilobasidium capitatum strain PPY-1. The purified PNL has a molecular mass of approx. 42 kDa, and its N-terminal amino acid sequence is ATGVTGSAYGFATGTTGGGSATPAY, which exhibits 72% identity with that of PNL F from Aspergillus niger. The purified PNL exhibited high activity at 10 degrees C, although its optimum temperature was 40 degrees C. Moreover, Km and Vmax for pectin as a substrate were found to have values 36.6 mg/ml and 3000 units/mg respectively. These findings may indicate that this enzyme from strain PPY-1 is a cold-active PNL that is able to degrade pectin compounds at low temperature.
Publication
Journal: Applied Biochemistry and Biotechnology
June/27/2002
Abstract
Immobilization of urease and glutamate dehydrogenase enzymes in electrochemically prepared polypyrrole-polyvinyl sulfonate films (PPY-PVS) was carried out using physical adsorption and electrochemical entrapment techniques. Detailed studies on optimum pH, Fourier transform infrared spectroscopy, cyclic voltammetry, and scanning electron microscopy of the enzymes in the immobilized state were conducted. The value of the apparent Michaelis-Menten constant was experimentally determined to be 2.5 and 2.7 for physically adsorbed and electrochemically entrapped urease in PPY-PVS films, respectively.
Publication
Journal: Biomaterials
January/29/1997
Abstract
Polypyrrole (PPy) is a conducting polymer and is obtained electrochemically on an electrode such as indium-tin oxide (ITO). In this study, in order to develop a novel cell-culture system which makes it possible to communicate with cultured mammalian cells, bovine adrenal chromaffin cells were cultured on PPy-coated ITO plates for 7 days and the influence of PPy-coating on the cell functions was investigated. Since the chromaffin cells synthesize and secrete catecholamines such as adrenaline and noradrenaline, the amount of synthesized and released catecholamines from the chromaffin cells cultured on PPy-coating and ITO itself were measured. The cells on the PPy-coated ITO plate could be kept in culture, without any significant changes in morphology and in the secretory responsiveness to acetylcholine as compared with those of the cells cultured on collagen. On the contrary, the cells on the ITO plate lost the responsiveness, while the amount of catecholamines synthesized was affected little by both PPy and ITO surfaces. It is suggested that PPy supports the secretory function of the chromaffin cells when they are cultured on it. This paper describes that PPy films are applicable as a polymer-modified electrode which support the cell function without collagen.
Publication
Journal: Development Genes and Evolution
February/9/2011
Abstract
In the genome of Drosophila melanogaster, there are 19 phosphoprotein phosphatase (PPP) catalytic subunit coding genes. Seven of the novel members of the gene family turned out to be Drosophila-specific. The expression and evolution of these genes was investigated in the present study. CG11597 is a recently evolved gene that is expressed during all stages of morphogenesis in D. melanogaster. In contrast, the transcription of PpD5, PpD6, Pp1-Y1, and Pp1-Y2 genes is restricted to the pupa and imago developmental stages and to the testis of the males, just as that of the previously characterized PpY-55A and PpN58A. With the exception of the Y-localized Pp1-Y1 and Pp1-Y2, the testis-specific phosphatase genes are expressed in X/0 males, while none of them are expressed in XX/Y females. The mRNA of PpD5, Pp1-Y1, and PpY-55A were detected in the developing cysts by in situ hybridization, in contrast with the PpD6 transcript that was found in the distal ends of elongating spermatids. The latter localization suggests post-meiotic expression. The comparison of PPP genes in five Drosophila species revealed that the sequence of the six testis-specific phosphatases changed more rapidly than that of the housekeeping phosphatases. Our results support the "faster male" hypothesis. On the other hand, the male-biased expression of the six genes remained conserved during evolution despite the fact that Pp1-Y1, Pp1-Y2, and PpD6 moved from autosomes to the Y chromosome. Interestingly, the PpD6 gene was found to be Y-linked only in Drosophila ananassae.
Publication
Journal: Sensors
June/3/2012
Abstract
The CombiMatrix microarray with 12,544 electrodes supports in situ electrochemical synthesis of user-defined DNA probes. As an alternative, we immobilized commercially synthesized DNA probes on individual electrodes coated with electropolymerized polypyrrole (Ppy). Hybridization was measured using a biotinylated target oligonucleotide and either Cy5-streptavidin and fluorescence detection or horseradish peroxidase-streptavidin and enzyme-enhanced electrochemical detection. Detection efficiencies were optimized by varying the deposition of the Ppy, the terminal groups on the DNA probes, and other factors that impacted fluorescence quenching and electrical conductivity. Optimized results were compared against those obtained using a microarray with the same DNA sequences synthesized in situ. Immobilized probes produced higher fluorescence signals, possibly by providing a greater stand off between the Cy5 on the target oligonucleotide and the quenching effects of the Ppy and the platinum electrode.
Publication
Journal: PLoS ONE
November/21/2011
Abstract
Phosphoprotein phosphatases (PPP), these ancient and important regulatory enzymes are present in all eukaryotic organisms. Based on the genome sequences of 12 Drosophila species we traced the evolution of the PPP catalytic subunits and noted a substantial expansion of the gene family. We concluded that the 18-22 PPP genes of Drosophilidae were generated from a core set of 8 indispensable phosphatases that are present in most of the insects. Retropositons followed by tandem gene duplications extended the phosphatase repertoire, and sporadic gene losses contributed to the species specific variations in the PPP complement. During the course of these studies we identified 5, up till now uncharacterized phosphatase retrogenes: PpY+, PpD5+, PpD6+, Pp4+, and Pp6+ which are found only in some ancient Drosophila. We demonstrated that all of these new PPP genes exhibit a distinct male specific expression. In addition to the changes in gene numbers, the intron-exon structure and the chromosomal localization of several PPP genes was also altered during evolution. The G-C content of the coding regions decreased when a gene moved into the heterochromatic region of chromosome Y. Thus the PPP enzymes exemplify the various types of dynamic rearrangements that accompany the molecular evolution of a gene family in Drosophilidae.
Publication
Journal: Genomics
June/28/1995
Abstract
The immunoglobulin kappa genes of nonhuman primates were studied by using sequence information and hybridization probes derived from the human kappa gene regions. The following results were obtained: (1) V kappa gene probes of the three major human kappa subgroups hybridized to restriction nuclease digests of DNA from the chimpanzees Pan troglodytes (PTR) and Pan paniscus (PPA), the gorilla Gorilla gorilla (GGO), the orangutan Pongo pygmaeus (PPY), the macaque Macaca mulatta (MMU), the marmoset Callithrix geoffrei (CGE), and the bushbaby Galago demidovii (GDE), yielding patterns of decreasing similarity to the patterns of the human V kappa multigene family. (2) The C kappa gene segments of PTR, GGO, and PPY were 99.6, 97, and 93%, respectively, identical in sequence to the human C kappa gene. A V kappa gene in PTR, GGO, PPY, and MMU was 98, 96, 96, and 95%, respectively, identical to the most C kappa proximal V kappa gene, called B3. The other two J kappa-C kappa proximal V kappa genes in human, B1 and B2, hybridize to restriction fragments of sizes identical to that of DNA from humans and great apes. (3) The long-range restriction maps of the human (HSA), PTR, and GGO kappa loci as established by pulsed-field gel electrophoresis (PFGE) are quite homologous. According to the maps, however, and to hybridization studies with 11 duplication-differentiating probes, there is only one copy of the locus in PTR and GGO. This means that the duplication of large parts of the kappa locus as found in humans occurred after the branch-point of human and great ape evolution.(ABSTRACT TRUNCATED AT 250 WORDS)
Publication
Journal: Biochemical Pharmacology
December/30/1996
Abstract
Suicide inhibitors of cytochrome P450 families are excellent tools to predict which isoforms mediate the metabolism/activation of a variety of chemical agents. We compared the inhibitory effects of several arylalkynes on mouse cytochromes P450 with published data for the rat model. The inhibition of P4502b specific dealkylation of benzyloxyresorufin by 2-ethynylnaphthalene (2-EN), 5-phenyl-1-pentyne (PPY), 4-phenyl-1-butyne (PBY), and 9-ethynylphenanthrene (9-EPh) was measured in hepatic microsomes from male mice treated with 1,4-bis[2-(3,5-dichloropyridyloxy)]-benzene (TCPOBOP) to induce cytochrome P4502b. Pulmonary microsomes were prepared from untreated mice. 9-EPh, 2-EN, and PPY caused a time-, concentration-, and NADPH-dependent loss in P4502b activity in both tissues. PBY, however, demonstrated this type of inhibition only in liver microsomes. The IC50 was calculated for both liver and lung microsomes and compared with published Ki (concentration required for half-maximal inhibition) or KI (concentration required for half-maximal inactivation) values for the rat. PPY, PBY, and 9-EPh were equally effective inhibitors of mouse P4502b and rat P4502B1. 2-EN was a 5- to 10-fold less potent inhibitor of mouse P4502b, as compared with the rat, even though it was shown to bind to the active site of the mouse isoform as demonstrated by its metabolism to 2-naphthylacetic acid. These data suggest that the active site of the mouse P4502b enzyme is functionally similar to the rat P4502B isoform, with the exception of the disparity in its susceptibility to inactivation by 2-EN as measured by the Ki values.
Publication
Journal: Nanotechnology
July/27/2010
Abstract
The deposition of carboxylic acid-terminated conducting polymer into two- or three-dimensional structures made up of colloidal particles has been successfully completed. This was accomplished using electrochemical deposition of ordered arrays of mesoporous silica nanoparticles (MSNs) as a template. Subsequent removal of the template yielded a porous polypyrrole surface. The co-polymerization of pyrrole with carboxylic acid-terminated pyrrole derivatives overcame the limitations of a lack of reactive functional groups--by facilitating the direct coupling of the film with biomolecules or drugs on the surface. Such Ppy films were characterized by several techniques: (1) scanning electron microscope (SEM) to evaluate surface topography, (2) x-ray photoelectron spectroscopy (XPS) to assess the chemical composition of the films, (3) four-point probe to measure the conductivity, and cyclic voltammogram to observe surface electroactivity. To assay the biological effectiveness of this preparation, we used phase-contrast light microscopy to compare neurite outgrowth from PC 12 cells grown on Ppy films in the presence and absence of electrical stimulation. These electrically functional, biocompatible composites show promise as novel neural implants that would deliver specific biologically active molecules in a highly localized manner to damaged or otherwise vulnerable cells such as found in the nervous system.
Publication
Journal: Biomacromolecules
June/15/2015
Abstract
In this work, flexible and free-standing composite films of nanofibrillated cellulose/polypyrrole (NFC/PPy) and NFC/PPy-silver nanoparticles (NFC/PPy-Ag) have been synthesized for the first time via in situ one-step chemical polymerization and applied in potential biomedical applications. Incorporation of NFC into PPy significantly improved its film formation ability resulting in composite materials with good mechanical and electrical properties. It is shown that the NFC/PPy-Ag composite films have strong inhibition effect against the growth of Gram-positive bacteria, e.g., Staphylococcus aureus. The electrical conductivity and strong antimicrobial activity makes it possible to use the silver composites in various applications aimed at biomedical treatments and diagnostics. Additionally, we report here the structural and morphological characterization of the composite materials with Fourier-transform infrared spectroscopy, atomic force microscopy, and scanning and transmission electron microscopy techniques.
Publication
Journal: Chemical Communications
May/11/2015
Abstract
To prepare a hydrogel with robust mechanical properties and programmable remotely-controlled releasing ability, we synthesized an agarose/alginate double network hydrogel incorporating polypyrrole (PPy) nanoparticles as a near-infrared (NIR) laser responsive releasing system. This hydrogel exhibited pulsatile releasing behaviours according to the laser switching while maintaining its morphology and mechanical strength.
Publication
Journal: Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences
November/14/2010
Abstract
In this study, polypyrrole (PPy) and polythiophene (PTh) SPME coatings and their ability to extract selected adrenolytic drugs with different physico-chemical properties from standard solutions and human plasma samples were evaluated. In measurements metoprolol, oxprenolol, mexiletine, propranolol, and propaphenon were investigated. The main parameters such as extraction time, desorption conditions and pH influence were examined. Inter-day precisions were in range 0.1-2.0%, 1.1-2.9%, 1.3-2.6%, 0.1-2.6% and 0.3-2.1% for metoprolol, oxprenolol, mexiletine, propranolol and propaphenon, respectively. Accuracies were less than 15%, which was evaluated by analyzing preparation samples of five replicates. The method was successfully applied to human plasma samples spiked with selected adrenolytic drugs. The method was linear in the concentration range from 1 to 10microg/ml for all of studied adrenolytic drugs using human plasma samples. The PTh-SPME coating displayed higher extraction efficiency towards the target analytes in comparison to PPy-SPME. The reproducibility of the extraction using polypyrrole and polythiophene fibers was confirmed by variation coefficients lower than 8% and 3%, respectively.
Publication
Journal: Biosensors and Bioelectronics
February/6/2011
Abstract
A novel electrocatalytic biosensing platform was designed by the functionalization of reduced graphene oxide sheets (RGO) with conducting polypyrrole graft copolymer, poly(styrenesulfonic acid-g-pyrrole) (PSSA-g-PPY), via π-π noncovalent interaction. The resulting nanocomposite could well disperse in water for at least 2 months with a solubility of 3.0 mg mL(-1). The nanocomposite was characterized with atomic force microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible absorption, contact angle measurement, and electrochemical impedance spectroscopy. Based on the advantageous functions of PSSA-g-PPY and RGO, the functional nanocomposite modified platinum electrode showed high electrocatalytic activity toward the oxidation of hydrogen peroxide and uric acid in neutral media. Further, a hypoxanthine biosensor was constructed by combining the modified electrode with the enzymatic reaction of xanthine oxidase. The biosensor exhibited a wide linear response ranging from 3.0×10(-8) to 2.8×10(-5) M with a high sensitivity of 673±4 μA M(-1) cm(-2). The detection limit of 10nM at a signal-to-noise ratio of 3 was one order of magnitude lower than that reported previously. The assay results of hypoxanthine in fish samples were in a good agreement with the reference values. The water-soluble conducting copolymer could serve as an efficient species for functionalization and solubilization of graphene sheets in biosensing and biocatalytic applications.
Publication
Journal: International Journal of Biological Macromolecules
August/30/2017
Abstract
This study is based on the construction of an enzymatic bioanode adopting the exclusively reported layer-by-layer (LBL) assembly of Ppy-Ag-GO/ferritin (Frt)/glucose oxidase (GOx). The glassy carbon (GC) electrode was immobilised with the conducting polypyrrole (Ppy)-silver nanoparticles (Ag)-graphene oxide (GO) based biocomposite as electron transfer elevator, horse spleen ferritin (Frt) protein as electron transfer mediator and glucose oxidase (GOx) enzyme in layer by layer configuration. The fabricated bioanode exhibited good electrochemical performance with a maximum current response of 5.7mAcm-2 accompanied with biocompatibility and environmental stability because of the synergistic effect between outstanding properties of PPy, silver and GO, thereby, showing superior catalytic efficiency for the oxidation of glucose.
Publication
Journal: Sensors and Actuators, B: Chemical
February/11/2019
Abstract
This research work presents, for the first time, a screen-printed electrode (SPE) made on a PCB board with silver tracks (Ag) and a three electrode configuration (AgxO-working, AgxO-counter and Ag/AgxO-reference electrodes), following the same approach as printed-circuit boards (PCBs). This low cost and disposable device was tested for screening a cancer biomarker in point-of-care. The selected biomarker was carcinogenic embryonic antigen (CEA) protein, routinely used to follow-up the progression of specific cancer diseases. The biosensor was constructed by assembling a plastic antibody on the Ag-working electrode area, acting as the biorecognition element of the device. The protein molecules that were entrapped on the polymer and positioned at the outer surface of the polypyrrole (PPy) film were removed by protease action. The imprinting effect was tested by preparing non-imprinted (NPPy) material, including only PPy as biorecognition element. Infrared and Raman studies confirmed the surface modification of these electrodes. The ability of the sensing material to rebind CEA was measured by several electrochemical techniques: cyclic voltammetry (CV), impedance spectroscopy (EIS) and square wave voltammetry (SWV). The linear response ranged from 0.05 to 1.25 pg/mL against logarithm concentration. Overall, producing screen-printed electrodes by means of conventional PCB technology showed promising features, mostly regarding cost and prompt availability. The plastic antibody-based biosensor also seems to be a promising tool for screening CEA in point-of-care, with low response time, low cost, good sensitivity and high stability.
Publication
Journal: Epilepsy and Behavior
December/27/2020
Abstract
Objective: This retrospective study examined patients with probable Lennox-Gastaut syndrome (LGS) identified from German healthcare data.
Methods: This 10-year study (2007-2016) assessed healthcare insurance claims information from the Vilua Healthcare research database. A selection algorithm considering diagnoses and drug prescriptions identified patients with probable LGS. To increase the sensitivity of the identification algorithm, two populations were defined: all patients with probable LGS (broadly defined) and only those with a documented epilepsy diagnosis before 6 years of age (narrowly defined). This specific criterion was used as LGS typically has a peak seizure onset between age 3 and 5 years. Primary analyses were prevalence and demographics; secondary analyses included healthcare costs, hospitalization rate and length of stay (LOS), medication use, and mortality.
Results: In the final year of the study, 545 patients with broadly defined probable LGS (mean [range] age: 31.4 [2-89] years; male: 53%) were identified. Using the narrowly defined probable LGS definition, the number of patients was reduced to 102 (mean [range] age: 7.4 [2-14] years; male: 52%). Prevalence of broadly defined and narrowly defined probable LGS was 39.2 and 6.5 per 100,000 people. During the 10-year study, 208 patients with narrowly defined probable LGS were identified and followed up for 1379 patient-years. The mean annual cost of healthcare was €22,787 per patient-year (PPY); greatest costs were attributable to inpatient care (33%), home nursing care (13%), and medication (10%). Mean annual healthcare costs were significantly greater for those with prescribed rescue medication (45% of patient-years) versus those without (€33,872 vs. €13,785 PPY, p < 0.001). Mean (standard deviation [SD]) annual hospitalization rate was 1.6 (2.0) PPY with mean (SD) annual LOS of 22.7 (46.0) days. Annual hospitalization rate was significantly greater in those who were prescribed rescue medication versus those who were not (2.2 [2.3] vs. 1.1 [1.6] PPY, p < 0.001). The mean (SD) number of different medications prescribed was 11.3 (7.3) PPY and 33.8 (17.0) over the entire observable time per patient (OET); antiepileptic drugs only accounted for 2.1 (1.1) of the medications prescribed PPY and 3.8 (2.0) OET. Over the 10-year study period, mortality in patients with narrowly defined probable LGS was significantly higher than the matched control population (six events [2.88%] vs. oneevent [0.01%], p < 0.001).
Conclusion: Annual healthcare costs incurred by patients with probable LGS in Germany were substantial, and mostly attributable to inpatient care, home nursing care, and medication. Patients prescribed with rescue medication incurred significantly greater costs than those who were not. Patients with narrowly defined probable LGS had a higher mortality rate versus control populations.
Keywords: Burden of illness; Healthcare costs; Healthcare resource utilization; Lennox-Gastaut syndrome; Prevalence; Rescue medication.
Publication
Journal: Advanced healthcare materials
March/7/2019
Abstract
TiO2 nanoparticles have emerged as satisfactory sonosensitizers in sonodynamic therapy over the years, but shortcomings such as poor drug loading capability and inadequate techniques to construct suitable TiO2 nanoparticles, limit their broader applications. Hence, in this paper, versatile nanocomposites that combine mesoporous TiO2 nanoparticles (mTiO2 s) with the promising photothermal material, polypyrrole (PPY) to exert synergistic therapeutic effects on tumors are fabricated. The PPY-coated mesoporous TiO2 nanocomposites (mTiO2 @PPYs) act as drug delivery vehicles and ultrasonically activated sonosensitizers as well as photothermal agents. Besides, mTiO2 @PPY may have potential as an ultrasound/photoacoustic (US/PA) imaging contrast agent. The mTiO2 @PPY shows a favorable drug loading and good photothermal conversion ability. Moreover, intracellular reactive oxygen species generation is verified. The in vitro cell experiments on HepG2 and 4T1 cells demonstrate that honokiol (HNK)-loaded mTiO2 @PPY has satisfactory cytotoxicity under laser and US irradiation, and the results are further validated by animal experiments. The ability of mTiO2 @PPY as a contrast agent for US and PA imaging is investigated both in vitro and in vivo. The results indicate that mTiO2 @PPY-HNK has multitherapeutic effects and bimodal imaging property, which shows great prospect as a novel nanosystem in antitumor applications.
Publication
Journal: Nano Letters
September/29/2016
Abstract
High-tap-density silicon nanomaterials are highly desirable as anodes for lithium ion batteries, due to their small surface area and minimum first-cycle loss. However, this material poses formidable challenges to polymeric binder design. Binders adhere on to the small surface area to sustain the drastic volume changes during cycling; also the low porosities and small pore size resulting from this material are detrimental to lithium ion transport. This study introduces a new binder, poly(1-pyrenemethyl methacrylate-co-methacrylic acid) (PPyMAA), for a high-tap-density nanosilicon electrode cycled in a stable manner with a first cycle efficiency of 82%-a value that is further improved to 87% when combined with graphite material. Incorporating the MAA acid functionalities does not change the lowest unoccupied molecular orbital (LUMO) features or lower the adhesion performance of the PPy homopolymer. Our single-molecule force microscopy measurement of PPyMAA reveals similar adhesion strength between polymer binder and anode surface when compared with conventional polymer such as homopolyacrylic acid (PAA), while being electronically conductive. The combined conductivity and adhesion afforded by the MAA and pyrene copolymer results in good cycling performance for the high-tap-density Si electrode.
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