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141.
Daniel Wechsler Cynthia Carolina Fernndez Julia Kbl Lisa-Marie Augustin Corinna Stumm Norbert Jux Hans-Peter Steinrück Federico Jos Williams Ole Lytken 《Molecules (Basel, Switzerland)》2021,26(10)
Porphyrins are large organic molecules that are interesting for different applications, such as photovoltaic cells, gas sensors, or in catalysis. For many of these applications, the interactions between adsorbed molecules and surfaces play a crucial role. Studies of porphyrins on surfaces typically fall into one of two groups: (1) evaporation onto well-defined single-crystal surfaces under well-controlled ultrahigh vacuum conditions or (2) more application-oriented wet chemical deposition onto less well-defined high surface area surfaces under ambient conditions. In this study, we will investigate the wet chemical deposition of 5-(monocarboxyphenyl)-10,15,20-triphenylporphyrin (MCTPP) on well-defined rutile TiO2(110) single crystals under ambient conditions. Prior to deposition, the TiO2(110) crystals were also cleaned wet-chemically under ambient conditions, meaning none of the preparation steps were done in ultrahigh vacuum. However, after each preparation step, the surfaces were characterized in ultrahigh vacuum with X-ray photoelectron spectroscopy (XPS) and the result was compared with porphyrin layers prepared in ultrahigh vacuum (UHV) by evaporation. The differences of both preparations when exposed to zinc ion solutions will also be discussed. 相似文献
142.
Marta Lima Rita Teixeira-Santos Luciana C. Gomes Sara I. Faria Jesus Valcarcel Jos Antonio Vzquez Miguel A. Cerqueira Lorenzo Pastrana Ana I. Bourbon Filipe J. Mergulho 《Molecules (Basel, Switzerland)》2021,26(14)
Implantable medical devices (IMDs) are susceptible to microbial adhesion and biofilm formation, which lead to several clinical complications, including the occurrence of implant-associated infections. Polylactic acid (PLA) and its composites are currently used for the construction of IMDs. In addition, chitosan (CS) is a natural polymer that has been widely used in the medical field due to its antimicrobial and antibiofilm properties, which can be dependent on molecular weight (Mw). The present study aims to evaluate the performance of CS-based surfaces of different Mw to inhibit bacterial biofilm formation. For this purpose, CS-based surfaces were produced by dip-coating and the presence of CS and its derivatives onto PLA films, as well surface homogeneity were confirmed by contact angle measurements, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The antimicrobial activity of the functionalized surfaces was evaluated against single- and dual-species biofilms of Staphylococcus aureus and Pseudomonas aeruginosa. Chitosan-based surfaces were able to inhibit the development of single- and dual-species biofilms by reducing the number of total, viable, culturable, and viable but nonculturable cells up to 79%, 90%, 81%, and 96%, respectively, being their activity dependent on chitosan Mw. The effect of CS-based surfaces on the inhibition of biofilm formation was corroborated by biofilm structure analysis using confocal laser scanning microscopy (CLSM), which revealed a decrease in the biovolume and thickness of the biofilm formed on CS-based surfaces compared to PLA. Overall, these results support the potential of low Mw CS for coating polymeric devices such as IMDs where the two bacteria tested are common colonizers and reduce their biofilm formation. 相似文献
143.
M. Francisca Portilha-Cunha Teresa I. A. Gouveia Alicia L. Garcia-Costa Arminda Alves Mnica S. F. Santos 《Molecules (Basel, Switzerland)》2021,26(18)
Cytostatics are toxic pharmaceuticals, whose presence in surfaces puts healthcare workers at risk. These drugs might also end up in hospital effluents (HWW), potentially damaging aquatic ecosystems. Bicalutamide is a cytostatic extensively consumed worldwide, but few analytical methods exist for its quantification and most of them require advanced techniques, such as liquid chromatography mass spectrometry (LC-MS), which are very complex and expensive for large monitoring studies. Therefore, a simple but reliable multi-matrix high performance liquid chromatographic method, with fluorescence detection, was developed and validated to rapidly screen abnormal concentrations of bicalutamide in HWW and relevant contamination levels of bicalutamide in indoor surfaces (>100 pg/cm2), prior to confirmation by LC-MS. The method presents good linearity and relatively low method detection limits (HWW: 0.14 ng/mL; surfaces: 0.28 pg/cm2). Global uncertainty was below 20% for concentrations higher than 25 ng/mL (HWW) and 50 pg/cm2 (surfaces); global uncertainty was little affected by the matrix. Therefore, a multi-matrix assessment could be achieved with this method, thus contributing to a holistic quantification of bicalutamide along the cytostatic circuit. Bicalutamide was not detected in any of the grab samples from a Portuguese hospital, but an enlarged sampling is required to conclude about its occurrence and exposure risks. 相似文献
144.
En-Ming You Hai-Long Wang Jun-Rong Zheng Zhao-Dong Meng Mao-Xin Zhang Song-Yuan Ding Zhong-Qun Tian 《Journal of Raman spectroscopy : JRS》2021,52(2):446-457
The surface-enhanced Raman scattering (SERS) effect was discovered by Richard Van Duyne et al. in 1977. He and coworkers also first utilized an innovative strategy that used SERS to record spectra on such SERS-inactive substrate surfaces as n-gallium arsenide (100) surfaces, which were modified by silver nano-islands. This nanostructure-enhanced Raman spectroscopy on flat surfaces (NERSoFS) enabled such SERS applications to be expanded to a variety of materials by virtue of SERS-active nanostructures such as Au or Ag nanoparticles and shell-isolated nanoparticles. However, most of such systems, although yielding Raman spectra, produce rather low enhancements, especially when used to record spectra on flat surfaces of SERS-inactive materials. In this work, along with the direction of Van Duyne's borrowing-SERS strategy and on the basis of the strategy of cascading optical coupling, we consider a theoretically designed optical configuration, based on an attenuated total reflection-cascading nanostructure to produce enhanced Raman spectroscopy (ATRc-NERS) on flat surfaces. This system can effectively harvest the incident light, thereby boosting the local optical field of the incident light and also moderately increasing the radiation field of the Raman-scattered signals. In this way, one can gain 1–2 additional orders of magnitude in Raman enhancement over present NERSoFS systems both on metallic and nonmetallic flat surfaces, which are otherwise SERS-inactive. This ATRc-NERS strategy can potentially be used to develop ultrasensitive and versatile tools for surface science, material science, catalysis, electrochemistry, and micro-electronics and micro-LED industries. 相似文献
145.
We report an experimental investigation of free falling super-hydrophobic (SH) spheres in glycerine-water mixtures over a wide range of Reynolds number. SH coatings have the ability to reduce the contact area between the surrounding liquid and the solid surface by entrapping an air layer in the surface roughness. We investigate the effect of this air plastron on the hydrodynamic performance of spheres, focusing our attention on the onset of wake instabilities. Our results emphasise the key role of the surface roughness properties on the triggering of wake instabilities. It is shown that, unlike what was reported in previous numerical studies on SH bluff-bodies, local deformation of the interface may act as a by-pass mechanism promoting earlier transition, yielding a decrease of the critical Reynolds number at which the wake becomes unstable. A scenario coupling the hydrodynamic instabilities (scaling with the Reynolds number) and the interface deformation (scaling with the roughness-based Weber number) is proposed to describe the different transition mechanisms in presence of SH surfaces. It is found that the promotion of wake instabilities over SH surfaces occurs when the roughness-based Weber number is larger than a critical threshold. These findings are of primary importance for guiding the design of resilient and efficient SH surfaces. 相似文献
146.
《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2021,38(6):1929-1941
Soap films hanging from a wire frame are studied in the framework of capillarity theory. Minimizers in the corresponding variational problem are known to consist of positive volume regions with boundaries of constant mean curvature/pressure, possibly connected by “collapsed” minimal surfaces. We prove here that collapsing only occurs if the mean curvature/pressure of the bulky regions is negative, and that, when this last property holds, the whole soap film lies in the convex hull of its boundary wire frame. 相似文献
148.
Murphy MR Faucher KM Sun XL Chaikof EL Dluhy RA 《Colloids and surfaces. B, Biointerfaces》2005,46(4):226-232
A method has been developed to investigate the extent of polymer cross-linking that results following in situ photopolymerization of an acrylate-functionalized phospholipid assembly adsorbed onto a stabilized, membrane-mimetic film produced from a polyelectrolyte multilayer (PEM) on polytetrafluoroethylene (PTFE) grafts. The acrylate phospholipid monomer was synthesized, prepared as a unilamellar vesicle, and fused onto closed-packed acyl chains that make up the PEM membrane-mimetic barrier on the PTFE graft. Both broad band white light and 514.5 nm laser radiation were used as excitation sources for photoinitiation; eosin Y was used as the photoinitiator. The use of 514.5 nm excitation reduced the time for maximum polymerization of the acrylate lipid from 60 min to 240 s. Infrared spectroscopy was successfully used to analyze the extent of photopolymerization in simplified model acrylate lipid systems; however, this method could not be used to analyze acrylate polymerization in heterogeneous, multicomponent PEM membrane-mimetic barriers on PTFE grafts. A near-infrared Raman microscopy method based on the ratio of the integrated areas of the CC and CN vibrations was shown to provide equivalent information to the IR method for analysis of the extent of polymerization efficiency in acrylate lipids. In addition, it proved feasible to extend this near-IR Raman method to the in situ analysis of the extent of polymerization in a stabilized acrylate lipid membrane on a PEM film in a PTFE vascular graft. This work describes a new approach for generating and analyzing the robustness of a membrane-mimetic coating on biomaterial surfaces, and may improve our ability to predict the long-term stability of polymeric membrane-mimetic films on implantable medical devices. 相似文献
149.