Isoflavonoid-Antibiotic Thin Films Fabricated by MAPLE with Improved Resistance to Microbial Colonization

Staphylococcus aureus (Gram-positive) and Pseudomonas aeruginosa (Gram-negative) bacteria represent major infectious threats in the hospital environment due to their wide distribution, opportunistic behavior, and increasing antibiotic resistance. This study reports on the deposition of polyvinylpyrrolidone/antibiotic/isoflavonoid thin films by the matrix-assisted pulsed laser evaporation (MAPLE) method as anti-adhesion barrier coatings, on biomedical surfaces for improved resistance to microbial colonization. The thin films were characterized by Fourier transform infrared spectroscopy, infrared microscopy, and scanning electron microscopy. In vitro biological assay tests were performed to evaluate the influence of the thin films on the development of biofilms formed by Gram-positive and Gram-negative bacterial strains. In vitro biocompatibility tests were assessed on human endothelial cells examined for up to five days of incubation, via qualitative and quantitative methods. The results of this study revealed that the laser-fabricated coatings are biocompatible and resistant to microbial colonization and biofilm formation, making them successful candidates for biomedical devices and contact surfaces that would otherwise be amenable to contact transmission.     

Thermal properties of tetraethylammonium tetrachloro-, bromotrichloro-and tribromochloroferrates(III)

A new synthesized 4CN type azomonoether, exhibiting dying properties, crystalline nature and generating interest as a material for non-linear optical applications was investigated. Modern devices incorporating liquid crystals tend to use thin films of such materials because of their special characteristics. Thermal stability studies are indispensable before attempting any deposition experiment. We have investigated the thermal behaviour of 4-[(4-chlorobenzyl)oxy]-4′-cyano-azobenzene (TG, DTG, DTA and DSC) in inert flow atmosphere, under non-isothermal conditions. The phase transitions were studied by repeated heating-cooling regimes, with intercalated isothermal steps. The thin films were deposited on silicon and quartz substrates by matrix assisted pulsed laser evaporation (MAPLE) using a Nd:YAG laser working at 266 nm. FTIR spectroscopy of the obtained thin films confirmed the preservation of the compound’s structure.     

Electrocatalytic activity of a new nanostructured polymeric tetraruthenated porphyrin film for nitrite detection

The preparation of the monomer and thin films of a new polymeric tetraruthenated porphyrin material and their characterization by spectroscopic and electrochemical techniques, are described. This material is one of the most active electrocatalyst for the oxidation of nitrite ions to nitrate, exhibiting a heterogeneous cross-exchange rate constant (k_f=(6.2±0.1×10⁴) M^-1 s^-1) 30 times higher than that previously described for the electrostatic assembled porphyrin films. The polymeric films were obtained by electropolymerization of the corresponding molecular films, previously prepared by dip-coating. This strategy leads to an increase in the efficiency of the reticulation process while minimizing the amount of monomer necessary for the preparation of the modified electrodes. The conductivity of the thin films close to the E_1/2 of the Ru(III/II) redox pair is very good, decreasing rapidly as the applied potential departs from it, as expected for a redox polymer. The conductivity decreases when the surface concentration becomes higher than 1.2×10^-8 mol cm⁻² also, reflecting a higher impedance for electrolyte diffusion inside the polymeric material. The high electrocatalytic activity associated with the high conductivity make this new nanostructured material suitable for sensor applications.     

A cationic porphyrin-based self-assembled film for mercury ion detection

A cationic 5,15-(p-(9,9-bis(6-trimethylammoniumhexyl)fluorenylethynyl)phenyl)porphyrin tetrabromide was synthesized and the self-assembled films were used for Hg²⁺ detection in aqueous media. The detection response is based on fluorescence quenching of the porphyrin molecule upon coordination with Hg²⁺. The detection shows high selectivity for Hg²⁺ over Cu²⁺, Zn²⁺, Pb²⁺, Cd²⁺, Mn²⁺, Ni²⁺, Co²⁺ and Ca²⁺. A linear response toward Hg²⁺ in a concentration range of 1 × 10⁻¹⁰-1 × 10⁻⁶ M was observed for the film with a detection limit of 0.1 nM. The cationic porphyrin film shows higher stability and significant improvement in detection sensitivity, as compared to other porphyrin-based sensors. The amphiphilic cationic nature of the porphyrin synthesized also allows for the direct deposition of a porphyrin layer on a bare glass surface through self-assembly.     

Matrix-assisted pulsed laser evaporation of polyimide thin films and the XPS study

Compared with the traditional thin film techniques, the matrix-assisted pulsed laser evaporation (MAPLE) technique has many advantages in the deposition of polymer and organic thin films. It has a wide range of applications in many fields, such as non-linear optics, luminescent devices, electronics, various sensors. We have successfully deposited polyimide thin films by using the MAPLE technique. These films were characterized with XPS. The XPS spectra showed that the single-photon effect is ob-vious at low laser fluence and the chemical bonds will be broken, resulting in decomposition of the films. Contrarily, the single-photon effect will decrease and the multi-photon effect and the photothermal effect will increase at high laser fluence, resulting in the protection of the structure of the polyimide thin films and the obvious decrease in decomposition. High laser fluence is more suitable for the deposition of polymer and organic thin films than low laser fluence.     

Development of Zn(II) sensors based on the assisted transfer of metal ions by hydrophobic ligands through gel-supported microinterfaces

Square-wave voltammetry (SWV) has been used to study the transfer of zinc(II) ion under static conditions, assisted by 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine (DPT), through gel-supported microinterfaces. Microhole arrays created by laser photoablation of thin polyester films were used to support an organic gel phase prepared by addition of 1,3?:?2,4-dibenzylidenesorbitol (DBS) to a solution of o-nitrophenyloctyl ether (o-NPOE) with the appropriate supporting electrolyte. The results show that SWV can be used with the gel-supported microinterfaces if a gelified aqueous reference is used for the organic phase. Under such conditions a preliminary estimate of the detection limit for the determination of Zn²⁺ is 5 × 10^–8 mol L^–1.     

Conductive Fused Porphyrin Tapes on Sensitive Substrates by a Chemical Vapor Deposition Approach

Oxidative polymerization of nickel(II) 5,15‐diphenyl porphyrin and nickel(II) 5,15‐bis(di‐3,5‐tert‐butylphenyl) porphyrin by oxidative chemical vapor deposition (oCVD) yields multiply fused porphyrin oligomers in thin film form. The oCVD technique enables one‐step formation, deposition, and p‐doping of conjugated poly(porphyrins) coatings without solvents or post‐treatments. The decisive reactions and side reactions during the oCVD process are shown by high‐resolution mass spectrometry. Owing to the highly conjugated structure of the fused tapes, the thin films exhibit an electrical conductivity of 3.6×10^?2 S cm^?1 and strong absorption in the visible to near‐infrared spectral region. The formation of smooth conjugated poly(porphyrins) coatings, even on sensitive substrates, is demonstrated by deposition and patterning on glass, silicon, and paper. Formation of conductive poly(porphyrins) thin films could enable the design of new optoelectronic devices using the oCVD approach.     

Highly Luminescent Thin Films of the Dense Framework 3∞[EuIm2] with Switchable Transparency Formed by Scanning Femtosecond‐Pulse Laser Deposition

Highly luminescent switchable thin films of the dense framework ³_∞[EuIm₂] were deposited by a scanning laser ablation technique using a femtosecond laser. The films can be controlled in terms of film thickness and amount of material deposited such that the material properties of the bulk material are retained on the nanometer scale. Polycrystalline films are formed that can be switched between transparent at visible light and nontransparent at UV light due to the intrinsic luminescence of the hybrid material, expanding the concept of smart films. The new femtosecond pulsed laser deposition method also provides a novel approach for coatings with framework compounds and coordination polymers.     

High-resolution transmission electron microscopy investigation of nanostructures in SnO2 thin films prepared by pulsed laser deposition

Pulsed laser deposition (PLD) was used to grow nanocrystalline SnO₂ thin films onto glass substrates. The nanocrystallites and microstructures in SnO₂ thin films grown by PLD techniques have been investigated in detail by using X-ray diffraction and high-resolution transmission electron microscopy (HRTEM). The PLD process was carried out at room temperature under a working pressure of about 2×10⁻⁶ mbar. Experimental results indicate that thin films are composed of a polycrystalline SnO₂ and an amorphous SnO phase. In particular, the presence of such an amorphous SnO phase in the thin films greatly limits their practical use as gas-sensing devices. HRTEM observations revealed that SnO₂ nanocrystallites with tetragonal rutile structure embed in an amorphous SnO matrix, which are approximatively equiaxed. These approximatively equiaxed SnO₂ nanocrystallites contain a high density of defects, such as twin boundaries and edge dislocations. The grain growth of SnO₂ thin films may be discussed in terms of the coalescent particle growth mechanism.     

Local symmetry breaking in PrFeO3 thin films and other similar systems after Ni doping: A brief Raman study

Raman study of PrFe_1−xNi_xO₃ (0 ≤ x ≤ 0.5) thin films deposited on LaAlO₃ substrate by pulsed laser deposition is presented. With doping, a new band is developed at around 574 cm⁻¹. After a certain doping range, there is a decrease in the observed intensity of this band and it becomes hard to resolve it from other observed bands. The generation of this new band in other systems with Ni is also established. The present study is a direct indication of symmetry breaking. The established orthorhombic structure for the present system is doubtful.     

Preparation and properties of rare earth (Eu, Tb, Ho) and transition metal (Co) co-doped BiFeO3 thin films

Ferroelectric (Bi_0.9 RE _0.1)(Fe_0.975Co_0.025)O_3-δ (RE = Eu, Tb and Ho) thin films were prepared on Pt(111)/Ti/SiO₂/Si(100) substrates via a chemical solution deposition method. All thin films were crystallized in a distorted rhombohedral perovskite structure confirmed by using an X-ray diffraction and a Raman scattering analyses. Compared to the pure BiFeO₃ thin film, improved electrical and ferroelectric properties were observed for the co-doped thin films. Among the thin films, the lowest leakage current density of 4.28 × 10^?5 A/cm² was measured at an applied electric field of 100 kV/cm for the (Bi_0.9Ho_0.1)(Fe_0.975Co_0.025)O_3-δ thin film. This value is approximately three orders lower than that of the pure BFO thin film. Furthermore, a large remnant polarization (2P _r) of 60.2 μC/cm² and a low coercive field (2E _c ) of 561 kV/cm at 980 kV/cm were observed from the (Bi_0.9Ho_0.1)(Fe_0.975Co_0.025)O_3-δ thin film.     

Molecular weight dependent structure and charge transport in MAPLE‐deposited poly(3‐hexylthiophene) thin films

In this work, poly(3‐hexylthiophene) (P3HT) films prepared using the matrix‐assisted pulsed laser evaporation (MAPLE) technique are shown to possess morphological structures that are dependent on molecular weight (MW). Specifically, the structures of low MW samples of MAPLE‐deposited film are composed of crystallites/aggregates embedded within highly disordered environments, whereas those of high MW samples are composed of aggregated domains connected by long polymer chains. Additionally, the crystallite size along the side‐chain (100) direction decreases, whereas the conjugation length increases with increasing molecular weight. This is qualitatively similar to the structure of spin‐cast films, though the MAPLE‐deposited films are more disordered. In‐plane carrier mobilities in the MAPLE‐deposited samples increase with MW, consistent with the notion that longer chains bridge adjacent aggregated domains thereby facilitating more effective charge transport. The carrier mobilities in the MAPLE‐deposited simples are consistently lower than those in the solvent‐cast samples for all molecular weights, consistent with the shorter conjugation length in samples prepared by this deposition technique. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 652–662     

Molecular organization in MAPLE‐deposited conjugated polymer thin films and the implications for carrier transport characteristics

The morphological structure of poly(3‐hexylthiophene) (P3HT) thin films deposited by both Matrix Assisted Pulsed Laser Evaporation (MAPLE) and solution spin‐casting methods are investigated. The MAPLE samples possessed a higher degree of disorder, with random orientations of polymer crystallites along the side‐chain stacking, π–π stacking, and conjugated backbone directions. Moreover, the average molecular orientations and relative degrees of crystallinity of MAPLE‐deposited polymer films are insensitive to the chemistries of the substrates onto which they were deposited; this is in stark contrast to the films prepared by the conventional spin‐casting technique. Despite the seemingly unfavorable molecular orientations and the highly disordered morphologies, the in‐plane charge carrier transport characteristics of the MAPLE samples are comparable to those of spin‐cast samples, exhibiting similar transport activation energies (56 vs. 54 meV) to those reported in the literature for high mobility polymers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 39–48     

脉冲激光沉积法制备FeSe薄膜电极及其电化学性质

采用脉冲激光溅射Fe和Se粉末的混合靶制备FeSe薄膜并用XRD、充放电和循环伏安测试研究了薄膜的结构和电化学性质. XRD结果显示, 当基片温度为200 ℃时, 薄膜主要由晶态的FeSe组成. 在电压1.0～3.0 V范围内, 该薄膜的可逆容量为360.8 mAh•g^－1, 经过100次循环之后的放电容量为396.5 mAh•g^－1, 具有很好的循环性能. ex situ XRD结果显示FeSe能够和Li发生可逆的电化学反应, 颗粒尺寸大于5 nm的纳米铁颗粒能够驱动Li₂Se的分解并在充电过程中重新生成FeSe. FeSe具有较高的可逆容量和较好的循环性能, 可能成为一种优良的锂二次电池正极材料.     

Novel analytical applications of porphyrin to HPLC post-column flow injection system for determination of the lanthanides

A novel indirect substitution spectrophotometric methodology using porphyrin is developed for the determination of some metals that do not react with porphyrin directly. The methodology is concerned with a multistep reaction system, which consists of 3 complexation reactions that occur in a sequence of EDTA with metal, EDTA with Cu(II) and porphyrin with Cu(II). The complexation reaction of Cu(II) with a cationic porphyrin, meso-tetrakis (4-N-trimethylaminophenyl)-porphine (ttmapp), which has a high molar absorptivity about 5 × 10⁵ l mol⁻¹ cm⁻¹, serves for spectrophotometric detection. This methodology was verified through individual determinations of 14 species of lanthanides following a batchwise procedure, which was further developed to an automatic procedure on a HPLC post-column flow injection system for simultaneous analysis of the lanthanides. Compared with the conventional post-column derivatization method using 4-(2-pyridylazo) resorcinol (PAR), the analytical sensitivity was greatly improved in this method and the results also showed good linearity.     

Characterization of nano-composite oxide ceramics and monitoring of oxide thin film growth by laser-induced breakdown spectroscopy

Multi-component oxide ceramics and epitaxial oxide thin films are analyzed by laser-induced breakdown spectroscopy (LIBS). Furthermore, pulsed-laser deposition (PLD) of thin films is investigated by long-term monitoring of the optical plasma emission. Both nano-composite high-temperature superconductors (HTS) consisting of YBa₂Cu₃O_7 − δ bulk and Y₂Ba₄MCuO_x (M-2411, M = Ag, Nb) nano-particles, and semiconducting ZnO doped with Aluminum and Lithium are ablated by nano-second laser pulses. The plasma emission is recorded using grating spectrometers with intensified gated detectors. The LIBS signals of nano-particles correlate with the nominal content of the M-2411 phase (0–15 mol%) and reveal a strong signal of Ytterbium impurity (3–35 ppm). In situ monitoring of the PLD process shows element signals that are stable for more than 10,000 laser pulses for both HTS and ZnO ceramics. The relative concentration of elements in thin films and ceramics as determined by LIBS is almost the same.     

MONOLAYER STUDIES OF 5-(4-CARB- OXYPHENYL)-10,15,20-TRITOLYL-PORPHYRIN-II. PHOTOVOLTAIC STUDY OF MULTILAYER SANDWICH CELLS*

The photovoltaic behavior of multilayer sandwich cells fabricated from the title compound has been examined. These multilayers are amorphous and contain a wide range of aggregated species. The action spectrum of the photocurrent agrees qualitatively with the absorption spectrum. This indicates that the photocurrent arises from all species in the film. The shape of the dark current-voltage characteristics varied with the porphyrin thickness. For thin films, (1 and 3 monolayers) the current can be described by a tunnelling mechanism. For thick cells (29 monolayers) the current-voltage characteristic can be fitted using either of two models: a modified Shockley equation (suggesting that the dye acts as a p-type semiconductor) or a combination of Schottky and Frenkel–Poole emission (suggesting that the porphyrin acts as an insulator). The former interpretation is preferred because it is consistent with the observed rectification characteristics; nevertheless, the latter is in agreement with the magnitude of the conductivity of the films. The power-conversion efficiencies of these cells were quite low (∼4 × 10^-4% for incident white light of intensity 2.72 W m^-2) owing to the very large internal resistance of the cells. The high resistance can be explained by observing that the molecules are in a very unfavorable orientation; maximum conductivity would be expected for the porphyrin ring systems perpendicular to the direction of current flow to give maximum overlap of the systems.     

Reversible fluorous phase-switching of pyridyl-tagged porphyrins: Application to the sensing of histamine in water

Upon stirring a chloroform/perfluorodecalin biphasic system, the 5,10,15,20-tetrapyridyl porphyrin (TPyP) solubilized in the organic phase was almost quantitatively extracted (∼99.9%) into the fluorous phase containing an excess of the “heavy fluorous” copper(II)-carboxylate complex 1. The porphyrin was quantitatively and almost instantaneously released into the chloroform after addition of excess tetrahydrofuran (THF), which successfully competed with the pyridine ligand for binding sites on complex 1. Metallation of TPyP by copper(II) ions was never observed during the “catch-and-release” process. With the 5,10,15-tripyridyl-20-phenylporphyrin (TPyMPP) or the 5,15-dipyridyl-10,20-diphenylporphyrin (trans-DPyDPP) both efficient extraction (98%) and metallation occurred simultaneously leading to the immobilization of the metallated copper(II)-porphyrins in the fluorous phase. The metalloporphyrins were quantitatively released in the organic phase by addition of THF. With the 5-pyridyl-10,15,20-triphenylporphyrin (MPyTPP) no extraction but rapid metallation was observed under biphasic stirring leading to the quantitative recovery of the Cu²⁺-metalloporphyrin in the organic phase. The “catch-and-release” methodology of TpyP was exploited to develop a triphasic C₆F₁₄/DCM/water indicator displacement assay (IDA) for histamine in which the receptor–indicator complex is compartimentalized in the perfluorocarbon. It has been shown that in such IDA methodology the fluorous phase can play the role of a membrane impervious to water, allowing the detection of histamine in water at micromolar concentrations.     

Structural and electrical properties of chemical solution deposited (Bi0.9Tb0.1)(Fe0.975 TM 0.025)O3±δ (TM = Ni, Mn and Ti) thin films

Effects of Tb and transition metal (TM = Ni, Mn and Ti) ions co-doping on the structural, electrical and ferroelectric properties of the BiFeO₃ thin films prepared by using a chemical solution deposition method were reported. From X-ray diffraction and Raman scattering analyses, distorted rhombohedral perovskite structures were observed for all thin films. Improved electrical and ferroelectric properties were observed for the co-doped thin films. Among the thin films, the lowest leakage current density of 2.67 × 10^?6 A/cm² (at 100 kV/cm), large remnant polarization (2P _r ) of 82.2 μC/cm² and low coercive field (2E_c) of 680 kV/cm (at 1,036 kV/cm) were measured for the (Tb, Mn) co-doped thin film.     

Synthesis, morphology and specific magnetization of the electrodeposited Zn-Ni-P thin films on copper substrate from non-cyanide electrolyte

Thin films of Zn-Ni-P on a copper substrate were synthesized by electrodeposition from chloride baths. It was found that the diffraction reflections of the crystal structure of Zn-Ni-P thin layers occur at thicknesses d ≥ 5 µm. The X-ray diffraction studies results confirm the formation in the Zn-Ni-P films of ZnNi₁₀P₃ compound. The morphology of the obtained films was analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectrometry (EDS). The films are continuous and have a typical topography with many homogeneous globular features. EDS confirmed the formation of Zn-Ni-P coating only in 2 samples with Zn:Ni:P atomic ratios of 1:8:4 and 4:8:3, respectively. X-ray Photoelectron Spectroscopy (XPS) revealed the chemistry and the thickness of the studied thin films. At room temperature and thickness d ≥ 5 µm the investigated thin layers exhibit high values of the specific magnetizations in the range (25–37) A m² kg^?1, leading to the potential use in devices, appliances and electronics. The Curie temperature values of the synthesized Zn-Ni-P films were determined. It was found that by heating Zn-Ni-P thin layers of thicknesses d ≥ 5 µm up to a temperature T=900 K an interaction was detected with the copper substrate leading to a lower specific magnetization.