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21.
Wong SY Moskowitz JS Veselinovic J Rosario RA Timachova K Blaisse MR Fuller RC Klibanov AM Hammond PT 《Journal of the American Chemical Society》2010,132(50):17840-17848
Here we present a new bifunctional layer-by-layer (LbL) construct made by combining a permanent microbicidal polyelectrolyte multilayered (PEM) base film with a hydrolytically degradable PEM top film that offers controlled and localized delivery of therapeutics. Two degradable film architectures are presented: (1) bolus release of an antibiotic (gentamicin) to eradicate initial infection at the implant site, or (2) sustained delivery of an anti-inflammatory drug (diclofenac) to cope with inflammation at the site of implantation due to tissue injury. Each degradable film was built on top of a permanent base film that imparts the implantable device surface with microbicidal functionality that prevents the formation of biofilms. Controlled-delivery of gentamicin was demonstrated over hours and that of diclofenac over days. Both drugs retained their efficacy upon release. The permanent microbicidal base film was biocompatible with A549 epithelial cancer cells and MC3T3-E1 osteoprogenitor cells, while also preventing bacteria attachment from turbid media for the entire duration of the two weeks studied. The microbicidal base film retains its functionality after the biodegradable films have completely degraded. The versatility of these PEM films and their ability to prevent biofilm formation make them attractive as coatings for implantable devices. 相似文献
22.
Zhang X Jiang X Zhang K Mao L Luo J Chi C Chan HS Wu J 《The Journal of organic chemistry》2010,75(23):8069-8077
A facile route has been developed for the preparation of a new family of contorted 1.2,3.4,7.8,9.10-tetrabenzocoronenes (TBCs). A two-step cyclization reaction, i.e., oxidative photocyclization followed by FeCl(3)-mediated intramolecular cyclodehydrogenation, was carried out on the olefin precursors to obtain the final TBC compounds. These new TBC molecules have contorted conformation due to steric overcrowding as disclosed by single-crystal crystallographic analysis. Nevertheless, they showed extended π-conjugation compared with coronene and exhibited strong aggregation in solution. The thermal behavior and self-assembly of TBC-C8 in solid were studied by a combination of thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). Compound TBC-C8 showed very good thermal and photostability and exhibited long-range ordered π-stacking in the bulk state. Moreover, uniform nanofibers with tens of micrometer length are formed in the drop-casted thin films. TBC-C8 also possesses a desirable HOMO energy level (-5.10 eV), which allows efficient charge injection from electrodes such as gold electrode. The charge carrier mobilities were determined by using the space-charge limited-current (SCLC) technique and high average hole mobility of 0.61 cm(2) V(-1) s(-1) was obtained for TBC-C8. 相似文献
23.
A series of different composition of polymer electrolytes-based on poly(vinyl chloride) (PVC) as host polymer, lithium tetraborate
(Li2B4O7) as dopant salt, and dibutyl phthalate (DBP) as plasticizer were prepared by solution casting method. The interaction between
the PVC, Li2B4O7, and DBP were studied by Fourier transform infrared. The shifting, broadening, and splitting of transmission peaks were the
evidences of complexation. The highest ionic conductivity polymer electrolyte of 2.83 × 10−6 S/cm was achieved at ambient temperature upon addition of 30 wt.% of DBP. In addition, the temperature-dependent conductivity,
frequency-dependent conductivity, dielectric permittivity, and modulus studies were performed. The temperature-dependent conductivity
of the polymer electrolytes was found to obey the Arrhenius behavior. The thermal stability of polymer electrolytes was verified
by thermogravimetric analysis. The lower in glass transition temperature was proven in differential scanning calorimetry,
whereas the higher amorphous region within the polymer matrix was demonstrated in X-ray diffraction. 相似文献
24.
Nga Sze Ieong Caroline I. Biggs Marc Walker Matthew I. Gibson 《Journal of polymer science. Part A, Polymer chemistry》2017,55(7):1200-1208
Carbohydrates dictate many biological processes including infection by pathogens. Glycosylated polymers and nanomaterials which have increased affinity due to the cluster glycoside effect, are therefore useful tools to probe function, but also as prophylactic therapies or diagnostic tools. Here, the effect of polymer structure on the coating of gold nanoparticles is studied in the context of grafting density, buffer stability, and in a lectin binding assay. RAFT polymerization is used to generate poly(oligoethyleneglycol methacrylates) and poly(N‐vinylpyrrolidones) with a thiol end‐group for subsequent immobilization onto the gold. It is observed that poly(oligoethylene glycol methacrylates), despite being widely used particle coatings, lead to low grafting densities which in turn resulted in lower stability in biological buffers. A depression of the cloud point upon nanoparticle immobilization is also seen, which might compromise performance. In comparison poly(vinylpyrrolidones) resulted in stable particles with higher grafting densities due to the compact size of each monomer unit. The higher grafting density also enabled an increase in the number of carbohydrates which can be installed per nanoparticle at the chain ends, and gave increased binding in a lectin recognition assay. These results will guide the development of new nanoparticle biosensors with enhanced specificity, affinity, and stability. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55, 1200–1208 相似文献
25.
Yong Mei Hu Guang Hai Su Stephen Cho‐Wing Sze Wencai Ye Yao Tong 《Biomedical chromatography : BMC》2010,24(4):438-453
A simple method based on liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry (LC‐DAD‐ESI‐MS) was developed for the quality assessment of Cortex Phellodendri (CP), which was mainly derived from two species of Phellodendron chinense Schneid and Phellodendron amurense Rupr. Total 41 compounds, including 14 phenols, 24 alkaloids and three liminoidal triterpenes were identified or tentatively characterized from the 75% methanol extract of CP samples by online ESI‐MSn fragmentation and UV spectra analysis. Among them, two phenols and six alkaloids were simultaneously quantified using HPLC‐DAD method. The validated HPLC‐DAD method showed a good linearity, precision, repeatability and accuracy for the quantification of eight marker compounds. Furthermore, the plausible fragmentation pathway of the representative compounds were proposed in the present study. The differences of the chemical constituents content and the comprehensive HPLC profiles between the two CP species using LC‐DAD‐ESI‐MS method are reported for the first time, indicating that the CP drugs from different resources should be used separately in the clinic. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
26.
17.2 GHz, the highest fundamental-mode repetition rate to our knowledge, of a carbon nanotube-based passively mode-locked laser is realized at 1570 nm by employing purified single-walled carbon nanotubes as saturable absorbers. The ultrashort linear laser cavity configured with a approximately 9 mm length is designed and demonstrated with our extremely miniaturized nanotube mode locker and a mirror-coated semiconductor optical amplifier as gain medium. The demonstrated pulsed laser has the inferred temporal pulse width of 14 ps and a 3 dB spectral bandwidth of 0.73 nm. 相似文献
27.
Anthony J. Veloso Tiffiny Chan Vinci Wing Sze Hung Leayen Lam Kagan Kerman 《Electroanalysis》2011,23(12):2753-2756
The amyloid‐β (Aβ) aggregation pathway is an important target for the discovery of drugs that can prevent or delay the onset of Alzheimer’s disease (AD). The electrochemistry of Congo Red (CR) represents a particularly promising tool for screening of Aβ‐binding therapeutics in a rapid and cost‐effective format. The results of the differential pulse voltammetry (DPV) measurements were confirmed using simultaneous UV‐vis analysis of the same incubated Aβ samples. The early changes in the electrochemical signals were attributed to the interaction of the Aβ oligomers with CR. The electrochemical approach, in principle, allowed monitoring small molecule‐Aβ interactions on the time scale of aggregation. 相似文献
28.
H-shaped bridged oligothiophenes HT-1 and HT-2 were synthesized by two different approaches. Different from normal oligothiophenes, HT-1 and HT-2 showed low band gaps and amphoteric redox behaviors due to intramolecular charge transfer, which is further supported by time-dependent DFT calculations. 相似文献
29.
Jyh-Rou Sze An-Chi Wei Fong-Zhi Chen 《Applied Physics A: Materials Science & Processing》2010,101(1):173-178
We design three types of diffractive optical elements (DOEs) which generate pseudo-nondiffracting beams (PNDBs) in different
regions by using the conjugate gradient method. In order to analyze the influence of the tilt angles of the DOEs, the coordinate-transformation
method is used to simplify the calculation. The uniformity of the out-coupling illuminance along the optical axis is calculated.
The analyzed results show that when the tilt angle increases, the uniformity in the region [140 mm, 200 mm] has more violent
fluctuations than those in the regions [280 mm, 340 mm] and [380 mm, 520 mm]. The analyses also reveal that the uniformity
of DOEs with a longer focal length is less sensitive to the tilt angle, and some points within the PNDB region have small
variations of axial illuminance while the tilt angle increases. 相似文献
30.