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1.
J Comput Phys ; 4052020.
Artigo em Inglês | MEDLINE | ID: mdl-33093685

RESUMO

A numerical scheme is developed for the evaluation of Abramowitz functions Jn in the right half of the complex plane. For n = - 1, … , 2, the scheme utilizes series expansions for ∣z∣ < 1, asymptotic expansions for ∣z∣ > R with R determined by the required precision, and least squares Laurent polynomial approximations on each sub-region in the intermediate region 1 ≤ ∣z∣ ≤ R. For n > 2, Jn is evaluated via a forward recurrence relation. The scheme achieves nearly machine precision for n = -1, … , 2 at a cost that is competitive as compared with software packages for the evaluation of other special functions in the complex domain.

2.
ACS Appl Mater Interfaces ; 12(12): 13731-13738, 2020 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-32155326

RESUMO

Pseudomonas aeruginosa (P. aeruginosa) biofilms are associated with a wide range of infections, from chronic tissue diseases to implanted medical devices. In a biofilm, the extracellular polymeric substance (EPS) causes an inhibited penetration of antibacterial agents, leading to a 100-1000 times tolerance of the bacteria. In view of the water-filled channels in biofilms and the highly negative charge of EPS, we design a chitosan-polyethylene glycol-peptide conjugate (CS-PEG-LK13) in this study. The CS-PEG-LK13 prefers a neutrally charged assembly at a size of ∼100 nm in aqueous environment, while undergoes disassembly to expose the α-helical peptide at the bacterial cell membrane. This behavior provides CS-PEG-LK13 superiorities in both penetrating the biofilms and inactivating the bacteria. At a concentration of 8 times the minimum inhibitory concentration, CS-PEG-LK13 has a much higher antibacterial efficiency (72.70%) than LK13 peptide (15.24%) and tobramycin (33.57%) in an in vitro P. aeruginosa biofilm. Moreover, CS-PEG-LK13 behaves comparable capability of combating an implanted P. aeruginosa biofilm to highly excess tobramycin. This work has implications for the design of new antibacterial agents in biofilm combating.


Assuntos
Infecções Bacterianas/tratamento farmacológico , Biofilmes/efeitos dos fármacos , Quitosana/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Antibacterianos , Infecções Bacterianas/microbiologia , Quitosana/análogos & derivados , Quitosana/química , Humanos , Testes de Sensibilidade Microbiana , Peptídeos/química , Peptídeos/farmacologia , Polietilenoglicóis/química , Polietilenoglicóis/farmacologia , Pseudomonas aeruginosa/patogenicidade
3.
J Chem Phys ; 151(2): 024112, 2019 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-31301698

RESUMO

Modern particle-based simulations increasingly incorporate polarization charges arising from spatially nonuniform permittivity. For complex dielectric geometries, calculation of these induced many-body effects typically requires numerical solvers based upon boundary-element methods, which very significantly increase the required computational effort. For the special case of dielectric spheres, such as colloids or nanoparticles, we recently proposed a semianalytical spectrally accurate hybrid method that combines the method of moments, the image-charge method, and the fast multipole method. The hybrid method is efficient and accurate even when dielectric spheres are closely packed. Here, we extend the method to the evaluation of direct and induced electrostatic forces and demonstrate how this can be incorporated in molecular dynamics simulations. The choice of the relevant numerical parameters for molecular dynamics simulations is discussed in detail, as well as comparisons to the boundary-element method. As a concrete example, we examine the challenging case of binary crystal structures composed of close-packed dielectric colloidal spheres.

4.
Ground Water ; 57(3): 479-484, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30044902

RESUMO

An exposition is given of a finite-element method (FEM) software package to calculate solutions for the continuous time random walk (CTRW) integro-differential equation for non-Fickian (and Fickian) conservative or reactive transport in disordered media. The solutions encompass one-dimensional/two-dimensional (1D/2D) breakthrough curves and spatial concentration profiles for general geometry and grid. The velocity field, used as input to the 2D solutions, may also be calculated by applying a compatible Darcy flow 2D solver. The software enables both "forward" modeling (1D/2D) and "inverse" (best-fit) modeling (1D) of experimental data. Various inlet and outlet boundary conditions are implemented. The CTRW-FEM Package is freely downloadable and contains a User's Guide, source and executable files, and accompanying files with easy-to-use format, including descriptions of input/output files and pre- and post-processing. Several examples are provided to clearly demonstrate how to work with the CTRW-FEM Package in many typical analyses. The CTRW-FEM Package also allows users to adapt the software to specific needs, such as, for example, first- and second-order chemical reactions.


Assuntos
Água Subterrânea , Porosidade , Software
5.
J Nanosci Nanotechnol ; 19(4): 2269-2275, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30486980

RESUMO

Phenotype conversion of smooth muscle cells (SMCs) plays a key role in the formation of atherosclerosis. Understanding how SMCs respond to a micro/nano-topology and elucidating the cellular mechanism of phenotype conversion is critical to the atherosclerosis treatment. Herein, we prepared poly(ɛ-caprolactone) (PCL) spherulites with a radius more than 350 µm for the studying of radial microstructure influence on SMCs behaviors. We found that on the PCL spherulitic films, SMCs grew aligning the radial direction of PCL spherulites, overexpressed α-SMA gene than OPN gene, and preferred contractile phenotype. FAK signaling pathway and ROCK1 signaling pathway both contributed to the contractile phenotype maintenance of SMCs. This work illustrated the feasibility of spherulites in regulating SMCs behaviors, and elucidated the mechanism how SMCs respond to a radial micro/nano-topology. This research may provide theoretical basis for the atherosclerosis formation and treatment.


Assuntos
Caproatos , Miócitos de Músculo Liso , Cristalização , Lactonas , Fenótipo
6.
Nanoscale ; 10(25): 11732-11736, 2018 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-29911244

RESUMO

Tobacco mosaic virus coat protein was modified with a small molecular fluorous ponytail at specific sites, and self-assembled into spherical nanoparticles through fluorous interaction induced self-assembly. By loading the anti-cancer drug cisplatin through metal-ligand coordination, this spherical assembly with high stability has potential as a drug carrier.


Assuntos
Proteínas do Capsídeo/química , Cisplatino/administração & dosagem , Portadores de Fármacos/química , Nanopartículas/química , Flúor/química , Células HeLa , Humanos
7.
J Mater Chem B ; 6(23): 3884-3893, 2018 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-32254316

RESUMO

Infection control and the promotion of healing are two key factors during the wound repair process. However, it is still a major challenge for one material to inhibit bacterial growth efficiently and promote wound healing at the same time. Here, a bifunctional chitosan derivative (CS-G/mPEG) was prepared by the successive modification of chitosan with carboxymethoxypolyethylene glycol (mPEG-COOH) and aminoiminomethanesulfonic acid (AIMSOA). We demonstrated that CS-G/mPEG can selectively disrupt bacterial membranes with high efficiency and thus kill Gram-positive bacteria without inducing hemolysis or cytotoxicity. In rats with full-thickness skin wounds infected with Staphylococcus aureus bacteria, CS-G/mPEG inhibited the growth of the bacteria and accelerated the healing of the wounds. Owing to the balance between the antimicrobial activity and biological safety of CS-G/mPEG, this bifunctional chitosan derivative is promising as an ideal anti-infective wound-repairing material for managing wounds with Gram-positive bacterial infections.

8.
J Mater Chem B ; 5(11): 2078-2085, 2017 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-32263681

RESUMO

Plant viruses have been applied broadly in nanomedical applications profiting from their monodisperse structure, biocompatibility, easy modification, and non-pathogenicity in animals. Here we report a tobacco mosaic virus (TMV) based drug delivery system bearing carbohydrates as targeting ligands. Mannose (Man) and lactose (Lac) moieties were separately conjugated to the exterior surface of TMV (TMV-Man and TMV-Lac) through an efficient copper(i)-catalyzed azide-alkyne cycloaddition. Cisplatin (CDDP), an anticancer drug, was directly loaded into the TMV cavity (CDDP@TMV, CDDP@TMV-Man and CDDP@TMV-Lac) via a metal coordination bond. Through the specific recognition between carbohydrates and glycoproteins in cell membranes, these TMV based vectors show specificity in different cell lines: in the galectin-rich MCF-7 cell line, CDDP@TMV-Man shows enhanced endocytosis and apoptosis efficiency; in the asialoglycoprotein receptor (ASGPR)-overexpressing HepG2 cell line, CDDP@TMV-Lac shows superiority in endocytosis and apoptosis. This research provides a new strategy for tumor-targeted cisplatin delivery.

9.
Opt Express ; 24(22): 24872-24882, 2016 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-27828428

RESUMO

There has been increasing interest in making photonic devices more and more compact in the integrated photonics industry, and one of the important questions for manufacturers and design engineers is how to quantify the effect of the finite cladding thickness on the modal confinement loss of photonic waveguides. This requires at least six to seven digits of accuracy for the computation of propagation constant ß since the modal confinement loss is proportional to the imaginary part of ß that is six to seven orders of magnitude smaller than its real part by the industrial standard. In this paper, we present an accurate and efficient method to compute the propagation constant of the electromagnetic modes of photonic waveguides with an arbitrary number of (nonsmooth) inclusions in a layered media. The method combines a well-conditioned boundary integral equation formulation for photonic waveguides which requires the discretization of the material interface only, and efficient Sommerfeld integral representations to treat the effect of the layered medium. Our scheme is capable of calculating the propagation loss of the electromagnetic modes with high fidelity, even for waveguides with corners embedded in a cladding material of finite thickness. The numerical results, with a more than 10-digit accuracy, show quantitatively that the modal confinement loss of the rectangular waveguide increases exponentially fast as the cladding thickness decreases.

10.
Sci Rep ; 6: 24567, 2016 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-27080246

RESUMO

Understanding the cellular internalization mechanism of nanoparticles is essential to study their biological fate. Especially, due to the anisotropic properties, rod-like nanoparticles have attracted growing interest for the enhanced internalization efficiency with respect to spherical nanoparticles. Here, to elucidate the effect of aspect ratio of rod-like nanoparticles on cellular uptake, tobacco mosaic virus (TMV), a typical rod-like bionanoparticle, is developed as a model. Nanorods with different aspect ratios can be obtained by ultrasound treatment and sucrose density gradient centrifugation. By incubating with epithelial and endothelial cells, we found that the rod-like bionanoparticles with various aspect ratios had different internalization pathways in different cell lines: microtubules transport in HeLa and clathrin-mediated uptake in HUVEC for TMV4 and TMV8; caveolae-mediated pathway and microtubules transport in HeLa and HUVEC for TMV17. Differently from most nanoparticles, for all the three TMV nano-rods with different aspect ratios, macropinocytosis takes no effect on the internalization in both cell types. This work provides a fundamental understanding of the influence of aspect ratio on cellular uptake decoupled from charge and material composition.


Assuntos
Modelos Biológicos , Nanopartículas , Vírus do Mosaico do Tabaco , Eletroforese em Gel de Poliacrilamida , Endocitose , Células HeLa , Células Endoteliais da Veia Umbilical Humana , Humanos , Microscopia Eletrônica de Transmissão , Pinocitose
11.
ACS Appl Mater Interfaces ; 8(17): 10800-7, 2016 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-27062971

RESUMO

For cancer therapy, viruses have been utilized as excellent delivery vehicles because of their facile transfection efficiency in their host cells. However, their inherent immunogenicity has become the major obstacle for their translation into approved pharmaceuticals. Herein, we utilized rodlike plant virus, tobacco mosaic virus (TMV), which is nontoxic to mammals and mainly infects tobacco species, as anticancer nanorod-drug vector for cancer therapy study. Doxorubicin (DOX) was installed in the inner cavity of TMV by hydrazone bond, which enabled the pH-sensitive drug release property. Conjugation of cyclic Arg-Gly-Asp (cRGD) on the surface of TMV can enhance HeLa cell uptake of the carrier via the integrin-mediated endocytosis pathway. Comparing with free DOX, the cRGD-TMV-hydra-DOX vector had similar cell growth inhibition and much higher apoptosis efficiency on HeLa cells. Moreover, the in vivo assay assumed that cRGD-TMV-hydra-DOX behaved similar antitumor efficiency but much lower side effect on HeLa bearing Balb/c-nu mice. Our work provides novel insights into potentially cancer therapy based on rodlike plant viral nanocarriers.


Assuntos
Nanotubos , Animais , Doxorrubicina , Portadores de Fármacos , Endocitose , Humanos , Integrinas , Vírus do Mosaico do Tabaco
12.
Nat Commun ; 7: 10601, 2016 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-26830732

RESUMO

Sulfur is a promising cathode material for lithium-sulfur batteries because of its high theoretical capacity (1,675 mA h g(-1)); however, its low electrical conductivity and the instability of sulfur-based electrodes limit its practical application. Here we report a facile in situ method for preparing three-dimensional porous graphitic carbon composites containing sulfur nanoparticles (3D S@PGC). With this strategy, the sulfur content of the composites can be tuned to a high level (up to 90 wt%). Because of the high sulfur content, the nanoscale distribution of the sulfur particles, and the covalent bonding between the sulfur and the PGC, the developed 3D S@PGC cathodes exhibit excellent performance, with a high sulfur utilization, high specific capacity (1,382, 1,242 and 1,115 mA h g(-1) at 0.5, 1 and 2 C, respectively), long cycling life (small capacity decay of 0.039% per cycle over 1,000 cycles at 2 C) and excellent rate capability at a high charge/discharge current.

13.
Artigo em Inglês | MEDLINE | ID: mdl-26172793

RESUMO

The coarse-grained molecular dynamics (MD) or Brownian dynamics (BD) simulation is a particle-based approach that has been applied to a wide range of biological problems that involve interactions with surrounding fluid molecules or the so-called hydrodynamic interactions (HIs). In this paper, an efficient algorithm is proposed to simulate the motion of a single DNA molecule in linear flows. The algorithm utilizes the integrating factor to cope with the effect of the linear flow of the surrounding fluid and applies the Metropolis method (MM) by Bou-Rabee, Donev, and Vanden-Eijnden [Multiscale Model. Simul. 12, 781 (2014)] to achieve more efficient BD simulation. Thus our method permits much larger time step size than previous methods while still maintaining the stability of the BD simulation, which is advantageous for long-time BD simulation. Our numerical results on λ-DNA agree very well with both experimental data and previous simulation results. Finally, when combined with fast algorithms such as the fast multipole method which has nearly optimal complexity in the total number of beads, the resulting method is parallelizable, scalable to large systems, and stable for large time step size, thus making the long-time large-scale BD simulation within practical reach. This will be useful for the study of membranes, long-chain molecules, and a large collection of molecules in the fluids.


Assuntos
DNA/metabolismo , Hidrodinâmica , Simulação de Dinâmica Molecular , Algoritmos , DNA/química , Conformação de Ácido Nucleico
15.
Langmuir ; 28(33): 11957-61, 2012 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-22877605

RESUMO

Efficient delivery of therapeutic proteins to a target site remains a challenge due to rapid clearance from the body. Here, we selected tobacco mosaic virus (TMV) as a model protein system to investigate the interactions between the protein and a nonionic block copolymer as a possible protecting agent for the protein. By varying the temperature, we were able to obtain core-shell structures based on hydrophobic interactions among PO blocks and noncovalent interactions between TMV and EO blocks. The protein-polymer interactions were characterized by dynamic light scattering and isothermal titration calorimetry. This study establishes principles for the possible design of clinically useful protein delivery systems.


Assuntos
Nanopartículas/química , Poloxâmero/química , Vírus do Mosaico do Tabaco/química , Proteínas Virais/química , Adsorção , Micelas , Modelos Moleculares , Conformação Proteica , Propriedades de Superfície
16.
J Phys Chem B ; 115(46): 13449-54, 2011 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-22007677

RESUMO

Crystallization of P3HT on highly oriented PE ultrathin films via solution-deposition has been studied by means of optical microscopy, atomic force microscopy, Fourier transform infrared spectroscopy (FTIR), and electron diffraction. The results clearly indicated the occurrence of heteroepitaxy of P3HT on the PE substrate, which results in a parallel alignment of P3HT on the PE substrate. FTIR spectra and electron diffraction analyses demonstrate that molecular chains of P3HT are oriented in the film plane and aligned parallel to the chain direction of PE substrate crystals, while the (100) lattice plane of P3HT is in contact with the PE substrate. The observed epitaxy can be explained in terms of an excellent one-dimensional lattice matching between the interchain distances of PE in the (110) lattice plane and P3HT in the (100) lattice plane. This kind of epitaxial crystallization provides an efficient way for fabricating large area P3HT films with unique oriented structures.

17.
J Am Chem Soc ; 133(1): 1-3, 2011 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-21142155

RESUMO

Solution-processed, high-performance 1D single-crystalline nanoribbon transistors fabricated from dithioperylene are described. The integration of two sulfur atoms into the perylene skeleton induces a compressed highly ordered packing mode directed by S···S interactions. The mobilities of up to 2.13 cm(2) V(-1) s(-1) for a dithioperylene individual nanoribbon make it particularly attractive for electronic applications.

18.
J Am Chem Soc ; 131(47): 17315-20, 2009 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-19891486

RESUMO

In this paper, we show that well-defined, highly crystalline nanowires of a rigid rod conjugated polymer, a poly(para-phenylene ethynylene)s derivative with thioacetate end groups (TA-PPE), can be obtained by self-assembling from a dilute solution. Structural analyses demonstrate the nanowires with an orthorhombic crystal unit cell wherein the lattice parameters are a approximately = 13.63 A, b approximately = 7.62 A, and c approximately = 5.12 A; in the nanowires the backbones of TA-PPE chains are parallel to the nanowire long axis with their side chains standing on the substrate. The transport properties of the nanowires examined by organic field-effect transistors (OFETs) suggest the highest charge carrier mobility approaches 0.1 cm(2)/(V s) with an average value at approximately 10(-2) cm(2)/(V s), which is 3-4 orders higher than that of thin film transistors made by the same polymer, indicating the high performance of the one-dimensional polymer nanowire crystals. These results are particular intriguing and valuable for both examining the intrinsic properties of PPEs polymer semiconductors and advancing their potential applications in electronic devices.

20.
J Chem Phys ; 123(6): 64901, 2005 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-16122343

RESUMO

The analytical solutions for the general-four-wave-mixing hyperpolarizabilities chi(3)[-(omega1 + omega2 + omega3);omega1,omega2,omega3] on infinite chains under both Su-Shrieffer-Heeger and Takayama-Lin-Liu-Maki models of trans-polyacetylene are obtained through the scheme of dipole-dipole correlation. Analytical expressions of dc Kerr effect chi(3)(-omega;0,0,omega), dc-induced second-harmonic generation chi(3)(-2omega;0,omega,omega), optical Kerr effect chi(3)(-omega;omega,-omega,omega), and dc electric-field-induced optical rectification chi(3)(0;omega,-omega,0) are derived. By including or excluding nabla(k) terms in the calculations, comparisons show that the intraband contributions dominate the hyperpolarizabilities if they are included. nabla(k) term or intraband transition leads to the break of the overall permutation symmetry in chi(3) even for the low-frequency and nonresonant regions. Hence it breaks the Kleinman [Phys. Rev. 126, 1977 (1962)] symmetry that is directly based on the overall permutation symmetry. Our calculations provide a clear understanding of the Kleinman symmetry breaks that are widely observed in many experiments. We also suggest a feasible experiment on chi(3) to test the validity of overall permutation symmetry and our theoretical prediction. Finally, our calculations show the following trends for the various third-order nonlinear optical processes in the low-frequency and nonresonant region: chi(nonres)(3)(-3omega;omega,omega,omega)>chi(nonres)(3)(-2omega;0,omega,omega)>chi(nonres)(3)(-omega;omega,-omega,omega)>chi(nonres)(3)(-omega;0,0,omega) > or = chi(nonres)(3)(0;omega,-omega,0), and in the resonant region: chi(res)(3)(-omega;0,0,omega)>chi(res)(3)(-omega;omega,-omega,omega)>chi(res)(3)(-2omega;0,omega,omega)>chi(res)(3)(0;omega,-omega,0)>chi(res)(3)(-3omega;omega,omega,omega).

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