scholarly journals Novel N-chloramine precursors for antimicrobial application: synthesis and facile covalent immobilization on polyurethane surface based on perfluorophenyl azide (PFPA) chemistry

2018 ◽  
Vol 96 (10) ◽  
pp. 939-948 ◽  
Author(s):  
Lingdong Li ◽  
Fengxiang Zhang ◽  
Fangyuan Gai ◽  
Hao Zhou ◽  
Xiaofang Chi ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Uv Light ◽  
Covalent Immobilization ◽  
Material Surface ◽  
Biocidal Activity ◽  
Force Microscopy ◽  
Atomic Force ◽  
Antimicrobial Materials ◽  
Surface Modified ◽  
Perfluorophenyl Azide

To control the pathogen cross contaminations on medical material surface, there is a pressing need to develop antimicrobial materials with highly efficacious surface biocidal activity. In this work, N-chloramine precursors containing a quaternary ammonium unit and perfluorophenyl azide unit were synthesized and covalently immobilized on inert polyurethane (PU) film upon UV light irradiation. The surface modification was confirmed by contact angle, Fourier transform infrared (ATR FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) analyses. After bleaching treatment, satisfactory biocidal activity was achieved for the surface-modified PU films. It was found that the introduced surface QA center contributed an even faster surface contact killing behavior and that precursors with a longer structural linker caused higher surface chlorine content and higher antimicrobial efficacy. This approach provides a novel and facile method that enables the covalent immobilization of N-chloramine precursors on inert polymeric surface to produce durable antimicrobial materials.

Interaction of salicylic acid with zirconium diphosphate and its reactivity toward uranium (VI)

2018 ◽  
Vol 106 (4) ◽  
pp. 291-300
Author(s):  
Nidia García-González ◽  
Eduardo Ordoñez-Regil ◽  
María Guadalupe Almazán-Torres ◽  
Eric Simoni
Keyword(s):  
Salicylic Acid ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Analytical Techniques ◽  
Batch Method ◽  
Sorption Data ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Surface Modified

AbstractThe interaction of salicylic acid with zirconium diphosphate surface and its reactivity toward uranium (VI) was investigated. The interaction of salicylic acid with zirconium diphosphate was firstly studied using several analytical techniques including atomic force microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. The sorption of uranium (VI) onto surface-modified zirconium diphosphate was evaluated by the classical batch method at room temperature. This study showed that the uranium (VI) sorption onto zirconium diphosphate is influenced by the presence of salicylic acid. A fluorescence spectroscopy study revealed the presence of a uranyl specie onto the modified solid surface. The spectroscopy results were then used to restrain the modeling of experimental sorption data, which are interpreted in terms of a constant capacitance model using the FITEQL code. The results indicated that interaction between the uranium (VI) and the surface of zirconium diphosphate modified with salicylic acid leads to the formation of a ternary surface complex.

scholarly journals Electron transfer between anatase TiO2 and an O2 molecule directly observed by atomic force microscopy

2017 ◽  
Vol 114 (13) ◽  
pp. E2556-E2562 ◽  
Author(s):  
Martin Setvin ◽  
Jan Hulva ◽  
Gareth S. Parkinson ◽  
Michael Schmid ◽  
Ulrike Diebold
Keyword(s):  
Atomic Force Microscopy ◽  
Electron Transfer ◽  
Photoelectron Spectroscopy ◽  
Uv Light ◽  
Atomic Scale ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Near Surface ◽  
Force Microscopy ◽  
Atomic Force

Activation of molecular oxygen is a key step in converting fuels into energy, but there is precious little experimental insight into how the process proceeds at the atomic scale. Here, we show that a combined atomic force microscopy/scanning tunneling microscopy (AFM/STM) experiment can both distinguish neutral O2 molecules in the triplet state from negatively charged (O2)− radicals and charge and discharge the molecules at will. By measuring the chemical forces above the different species adsorbed on an anatase TiO2 surface, we show that the tip-generated (O2)− radicals are identical to those created when (i) an O2 molecule accepts an electron from a near-surface dopant or (ii) when a photo-generated electron is transferred following irradiation of the anatase sample with UV light. Kelvin probe spectroscopy measurements indicate that electron transfer between the TiO2 and the adsorbed molecules is governed by competition between electron affinity of the physisorbed (triplet) O2 and band bending induced by the (O2)− radicals. Temperature–programmed desorption and X-ray photoelectron spectroscopy data provide information about thermal stability of the species, and confirm the chemical identification inferred from AFM/STM.

Structural, Morphological, Optical and Photocatalytic Properties of Os and N Co-Doped TiO2 Films

2020 ◽  
Vol 853 ◽  
pp. 235-242
Author(s):  
Zhi Li ◽  
Chun Yu Ma
Keyword(s):  
Photocatalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Uv Light ◽  
Rf Magnetron Sputtering ◽  
Photocatalytic Properties ◽  
X Ray ◽  
Force Microscopy ◽  
Co Doping ◽  
Atomic Force ◽  
Co Doped

In the present work, Os and N co-doped TiO2 films were first prepared using a reactive RF magnetron sputtering of Ti–Os metallic target. The effect of Os concentration varying from 0 to 3.0at.% on structure as well as morphology and subsequent changes in optical and photocatalytic properties were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), optical absorption spectra and photoluminescence (PL) spectroscopy. XRD and SEM results show that the co-doping of Os and N favors the crystal growth of TiO2 and leads to a low anatase thermal stability relative to N monodoping. The band gap of the N/Os co-doped films is reduced from 3.42 eV to 3.22 eV compared with the N-TiO2 film. PL investigation further exhibits the effects of Os doping on the electronic structures and defects in N-TiO2.The photocatalytic activities of the films were evaluated by the degradation of methylene blue in aqueous solution under UV light. It was found that the photocatalytic activity increases with increasing Os content first, and then decreases after the optimal Os content. Therefore, the photocatalytic activity of Os/N co-modified TiO2 photocatalysts can be adjusted by the Os content.

scholarly journals Enzymatic Conversion of Oleuropein to Hydroxytyrosol Using Immobilized β-Glucosidase on Porous Carbon Cuboids

Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1166 ◽  
Author(s):  
Chatzikonstantinou ◽  
Gkantzou ◽  
Thomou ◽  
Chalmpes ◽  
Lyra ◽  
...  
Keyword(s):  
Porous Carbon ◽  
Photoelectron Spectroscopy ◽  
Thermotoga Maritima ◽  
Covalent Immobilization ◽  
Force Microscopy ◽  
Atomic Force ◽  
Repeated Use ◽  
First Time ◽  
Hydrolysis Of

In the present study, we developed novel β-glucosidase-based nano-biocatalysts for the bioconversion of oleuropein to hydroxytyrosol. Using non-covalent or covalent immobilization approaches, β-glucosidases from almonds and Thermotoga maritima were attached for the first time on oxidized and non-oxidized porous carbon cuboids (PCC). Various methods were used for the characterization of the bio-nanoconjugates, such as Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and fluorescence spectroscopy. The oxidation state of the nanο-support and the immobilization procedure play a key role for the immobilization efficiency or the catalytic activity of the immobilized β-glucosidases. The nano-biocatalysts were successfully used for the hydrolysis of oleuropein, which leads to the formation of its bioactive derivative, hydroxytyrosol (up to 2.4 g L−1), which is a phenolic compound with numerous health benefits. The bio-nanoconjugates exhibited high thermal and operational stability (up to 240 hours of repeated use), which indicated that they are efficient tools for various bio-transformations.

scholarly journals Structure and Oligonucleotide Binding Efficiency of Differently Prepared Click Chemistry-Type DNA Microarray Slides Based on 3-Azidopropyltrimethoxysilane

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2855
Author(s):  
Emilia Frydrych-Tomczak ◽  
Tomasz Ratajczak ◽  
Łukasz Kościński ◽  
Agnieszka Ranecka ◽  
Natalia Michalak ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Dna Microarrays ◽  
Structural Characteristics ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Glass Slides ◽  
Surface Modified ◽  
Oligonucleotide Binding

The structural characterization of glass slides surface-modified with 3-azidopropyltrimethoxysilane and used for anchoring nucleic acids, resulting in the so-called DNA microarrays, is presented. Depending on the silanization conditions, the slides were found to show different oligonucleotide binding efficiency, thus, an attempt was made to correlate this efficiency with the structural characteristics of the silane layers. Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and X-ray reflectometry (XRR) measurements provided information on the surface topography, chemical composition and thickness of the silane films, respectively. The surface for which the best oligonucleotides binding efficiency is observed, has been found to consist of a densely-packed silane layer, decorated with a high-number of additional clusters that are believed to host exposed azide groups.

scholarly journals Self-assembled anchor layers/polysaccharide coatings on titanium surfaces: a study of functionalization and stability

2015 ◽  
Vol 6 ◽  
pp. 617-631 ◽  
Author(s):  
Ognen Pop-Georgievski ◽  
Dana Kubies ◽  
Josef Zemek ◽  
Neda Neykova ◽  
Roman Demianchuk ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Covalent Immobilization ◽  
Biologically Active ◽  
Force Microscopy ◽  
Atomic Force ◽  
Infrared Reflection ◽  
Alginate Immobilization ◽  
Titanium Surfaces ◽  
Self Assembled ◽  
The Stability

Composite materials based on a titanium support and a thin, alginate hydrogel could be used in bone tissue engineering as a scaffold material that provides biologically active molecules. The main objective of this contribution is to characterize the activation and the functionalization of titanium surfaces by the covalent immobilization of anchoring layers of self-assembled bisphosphonate neridronate monolayers and polymer films of 3-aminopropyltriethoxysilane and biomimetic poly(dopamine). These were further used to bind a bio-functional alginate coating. The success of the titanium surface activation, anchoring layer formation and alginate immobilization, as well as the stability upon immersion under physiological-like conditions, are demonstrated by different surface sensitive techniques such as spectroscopic ellipsometry, infrared reflection–absorption spectroscopy and X-ray photoelectron spectroscopy. The changes in morphology and the established continuity of the layers are examined by scanning electron microscopy, surface profilometry and atomic force microscopy. The changes in hydrophilicity after each modification step are further examined by contact angle goniometry.

Surface Modification of Polyvinylidenefluoride-Trifluoroethylene Film Using Argon Gas Plasma

2012 ◽  
Vol 626 ◽  
pp. 317-323 ◽  
Author(s):  
Rozana Mohd Dahan ◽  
Muhamad Naiman Sarip ◽  
Yap Seong Ling ◽  
Mohamad Hafiz Mohd Wahid ◽  
Adillah Nurashikin Arshad ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Photoelectron Spectroscopy ◽  
Argon Plasma ◽  
Water Contact ◽  
Force Microscopy ◽  
Atomic Force ◽  
Gas Plasma ◽  
Good Biocompatibility ◽  
Surface Modified

This study investigates the surface properties of plasma surface modified spin coated PVDF-TrFE (70/30) film using Atomic Force Microscopy (AFM), Water Contact Angle (WCA) and X-ray Photoelectron Spectroscopy (XPS). The surfaces of the spin coated PVDF-TrFE film were modified using 13.56 MHz rf Argon plasma. The exposure time of the charged particle PVDF-TrFE films were varied for 1, 3 and 5mins. Prior to modification, the average surface roughness obtained was 8.615nm, but upon modification, the surface roughness was found to increase to 12.466nm. The value of the contact angle of the modified film was reduced from 90o to 43o and the XPS analysis showed dehydrofluorination of PVDF-TrFE films surfaces. The improved in surface roughness and the increased in wettability of the modified film, resulted in good biocompatibility of the modified PVDF-TrFE thin films. This phenomenon has created interest in researchers for developing functional polymer used for applications in areas such are biomedical, bio-analytical assays, textile and even food industry.

Investigation of the Effect of Uv-Assisted Oxidation and Nitridation of Hafnium Metal Films

2003 ◽  
Vol 780 ◽  
Author(s):  
C. Essary ◽  
V. Craciun ◽  
J. M. Howard ◽  
R. K. Singh
Keyword(s):  
Uv Radiation ◽  
Photoelectron Spectroscopy ◽  
Grazing Angle ◽  
X Ray Diffraction ◽  
Metal Thin Films ◽  
X Ray ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Silicon Interface

AbstractHf metal thin films were deposited on Si substrates using a pulsed laser deposition technique in vacuum and in ammonia ambients. The films were then oxidized at 400 °C in 300 Torr of O2. Half the samples were oxidized in the presence of ultraviolet (UV) radiation from a Hg lamp array. X-ray photoelectron spectroscopy, atomic force microscopy, and grazing angle X-ray diffraction were used to compare the crystallinity, roughness, and composition of the films. It has been found that UV radiation causes roughening of the films and also promotes crystallization at lower temperatures.Furthermore, increased silicon oxidation at the interface was noted with the UVirradiated samples and was shown to be in the form of a mixed layer using angle-resolved X-ray photoelectron spectroscopy. Incorporation of nitrogen into the film reduces the oxidation of the silicon interface.

scholarly journals Photocatalytic reduction of graphene oxide with cuprous oxide film under UV-vis irradiation

2020 ◽  
Vol 59 (1) ◽  
pp. 207-214 ◽  
Author(s):  
Yao Wang ◽  
Jianqing Feng ◽  
Lihua Jin ◽  
Chengshan Li
Keyword(s):  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Low Cost ◽  
Photocatalytic Reduction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Reduced Graphene ◽  
Reduction Efficiency ◽  
Metal Organic ◽  
Reduction Effect

AbstractWe have grown Cu2O films by different routes including self-oxidation and metal-organic deposition (MOD). The reduction efficiency of Cu2O films on graphene oxide (GO) synthesized by modified Hummer’s method has been studied. Surface morphology and chemical state of as-prepared Cu2O film and GO sheets reduced at different conditions have also been investigated using atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). Results show that self-oxidation Cu2O film is more effective on phtocatalytic reduction of GO than MOD-Cu2O film. Moreover, reduction effect of self-oxidation Cu2O film to GO is comparable to that of environmental-friendly reducing agent of vitamin C. The present results offer a potentially eco-friendly and low-cost approach for the manufacture of reduced graphene oxide (RGO) by photocatalytic reduction.

scholarly journals Interface Structures and Electronic States of Epitaxial Tetraazanaphthacene on Single-Crystal Pentacene

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1088
Author(s):  
Yuki Gunjo ◽  
Hajime Kamebuchi ◽  
Ryohei Tsuruta ◽  
Masaki Iwashita ◽  
Kana Takahashi ◽  
...  
Keyword(s):  
Single Crystal ◽  
Photoelectron Spectroscopy ◽  
Grazing Incidence ◽  
Force Microscopy ◽  
Interface Dipole ◽  
Atomic Force ◽  
Interfacial Structures ◽  
Donor And Acceptor ◽  
A Charge ◽  
Interface Structures

The structural and electronic properties of interfaces composed of donor and acceptor molecules play important roles in the development of organic opto-electronic devices. Epitaxial growth of organic semiconductor molecules offers a possibility to control the interfacial structures and to explore precise properties at the intermolecular contacts. 5,6,11,12-tetraazanaphthacene (TANC) is an acceptor molecule with a molecular structure similar to that of pentacene, a representative donor material, and thus, good compatibility with pentacene is expected. In this study, the physicochemical properties of the molecular interface between TANC and pentacene single crystal (PnSC) substrates were analyzed by atomic force microscopy, grazing-incidence X-ray diffraction (GIXD), and photoelectron spectroscopy. GIXD revealed that TANC molecules assemble into epitaxial overlayers of the (010) oriented crystallites by aligning an axis where the side edges of the molecules face each other along the [1¯10] direction of the PnSC. No apparent interface dipole was found, and the energy level offset between the highest occupied molecular orbitals of TANC and the PnSC was determined to be 1.75 eV, which led to a charge transfer gap width of 0.7 eV at the interface.

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