The Experts below are selected from a list of 66360 Experts worldwide ranked by ideXlab platform
Marek Procházka - One of the best experts on this subject based on the ideXlab platform.
-
Drop Coating Deposition of a liposome suspension on surfaces with different wettabilities: "coffee ring" formation and suspension preconcentration.
Physical chemistry chemical physics : PCCP, 2016Co-Authors: Eva Kočišová, Hana Šípová, Martin Petr, Ondřej Kylián, Marek ProcházkaAbstract:Evaporation of a drop of biomolecular solution on a solid surface typically creates a ring-shaped drying pattern, formed by the so-called "coffee ring" effect. The size and shape of the "coffee ring" pattern is strongly dependent on the properties of the surface as well as on the deposited molecular solution or suspension. In this paper, we tested six types of surfaces differing in their physico-chemical surface characteristics (contact angles, wettability and roughness) as well as in the presence or absence of a base metal layer. The tested surfaces include two fluorocarbon coated metallic surfaces (commercial SpectRIM™ from Tienta Sciences, Inc. based on a smoothed stainless steel and non-commercial aluminium surface), three silanized glass surfaces and polished CaF2. The results showed that the formation of a "coffee ring" was influenced by surface wettability as well as by lipid concentration in the drop. Drop Coating Deposition Raman (DCDR) spectroscopy was used to compare the ability of the tested surfaces to preconcentrate molecules in the ring and therefore improve detection sensitivity. It was shown that surfaces with a contact angle of 90° and higher produce smaller drying patterns than more hydrophilic surfaces. In these drying patterns, the model liposomes were more efficiently preconcentrated, which resulted in a higher Raman signal of the liposomes. The applicability of surfaces with static contact angles less than 90°, high water contact angle hysteresis and no metal layer (silanized glass, CaF2) is limited to samples with high liposome concentrations.
-
Thiol‐modified gold‐coated glass as an efficient hydrophobic substrate for drop Coating Deposition Raman (DCDR) technique
Journal of Raman Spectroscopy, 2016Co-Authors: Eva Kočišová, Marek Procházka, Hana ŠípováAbstract:In this paper we report an easy and low-cost way to prepare a hydrophobic substrate for drop Coating Deposition Raman (DCDR) spectroscopy. This substrate is formed by a thiol-modified Au-coated glass and provides the Raman spectra with the same quality as the commercial Teflon-coated stainless steel substrate (SpectRIM™, Tienta Sciences, Inc.) for model molecular systems – albumin solution and liposome suspension. Gold layer, similarly to polished steel in the commercial substrate, served as a highly refractive layer strongly increasing the Raman signal. The main advantage of introduced substrate is that it is simple and a low-cost preparation easily manageable in every standard laboratory. Thus, it represents a promising alternative to commercial Teflon-coated stainless steel substrate. Copyright © 2016 John Wiley & Sons, Ltd.
-
Drop-Coating Deposition Raman (DCDR) Spectroscopy as a Tool for Membrane Interaction Studies: Liposome-Porphyrin Complex.
Applied spectroscopy, 2015Co-Authors: Eva Kočišová, Marek Procházka, Lenka VaculčiakováAbstract:Drop-Coating Deposition Raman (DCDR) spectroscopy is based on the measurement of a sample that has been preconcentrated by being dried on a special hydrophobic plate. In addition to its higher sensitivity, the advantage of DCDR over the conventional Raman spectroscopy is the small sample volume needed, the lack of interference from solvents, and the capability of segregating any impurities present and separating components in more complex samples. In this study, DCDR spectroscopy was employed to investigate the complex of the cationic copper(II) 5,10,15,20-tetrakis(1-methyl-4-pyridyl) porphyrin (CuTMPyP) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) liposomes. Drop-Coating Deposition Raman spectra were treated using factor analysis (FA), which led to the following conclusions: (i) the distribution of CuTMPyP in the complex is not homogenous, (ii) the DCDR technique segregates complexed and noncomplexed parts of the sample, (iii) the spectral changes caused by the drying process and by the interaction of CuTMPyP with the DPPC liposomes can be distinguished, and (iv) the porphyrin molecules interacting with DPPC affect both the order-disorder properties of the lipid chains and the lipid head.
-
Drop‐Coating Deposition Raman spectroscopy of porphyrins
Journal of Raman Spectroscopy, 2015Co-Authors: Eva Kočišová, Marek ProcházkaAbstract:We report an improvement of the Raman detection sensitivity of porphyrins by factor of 105 using drop-Coating Deposition Raman spectroscopy (DCDR). We were able to obtain Raman spectra from ~20 nM initial (deposited) concentrations of cationic and anionic porphyrin. This detection limit is comparable with or even better than that of surface-enhanced Raman scattering spectroscopy using Ag nanoparticles. Moreover, DCDR spectrum of protoporphyrin IX, which is known as a marker in clinical diagnostics of cancer, was also obtained from 10 nM deposited concentration. To our knowledge, it is the first demonstration of the resonance DCDR spectroscopy. Copyright © 2015 John Wiley & Sons, Ltd.
-
Drop Coating Deposition Raman spectroscopy of liposomes: role of cholesterol.
Chemistry and physics of lipids, 2013Co-Authors: Eva Kočišová, Andrej Antalík, Marek ProcházkaAbstract:Drop Coating Deposition Raman (DCDR) spectroscopy was used to study liposomes (DPPC and asolectin) with growing proportion of cholesterol. Deposited samples of both liposomes on special hydrophobic surface formed a dried drop with a circular shape with a ring of concentrated liposomes at the outer edge. The presence of cholesterol in liposome causes a diminishing of the drop size and an increasing in diameter of the ring, but DPPC with 20% of cholesterol forms the compact drop without the ring. Raman spectra contain characteristics of both lipids and cholesterol, liposomes do not change their initial phase state after drying. Spectral mapping shows that maximum Raman intensity originated from the inner part of the ring. Our results suggest that DCDR spectroscopy can be used for studying lipids containing cholesterol in situ.
Eva Kočišová - One of the best experts on this subject based on the ideXlab platform.
-
Drop Coating Deposition of a liposome suspension on surfaces with different wettabilities: "coffee ring" formation and suspension preconcentration.
Physical chemistry chemical physics : PCCP, 2016Co-Authors: Eva Kočišová, Hana Šípová, Martin Petr, Ondřej Kylián, Marek ProcházkaAbstract:Evaporation of a drop of biomolecular solution on a solid surface typically creates a ring-shaped drying pattern, formed by the so-called "coffee ring" effect. The size and shape of the "coffee ring" pattern is strongly dependent on the properties of the surface as well as on the deposited molecular solution or suspension. In this paper, we tested six types of surfaces differing in their physico-chemical surface characteristics (contact angles, wettability and roughness) as well as in the presence or absence of a base metal layer. The tested surfaces include two fluorocarbon coated metallic surfaces (commercial SpectRIM™ from Tienta Sciences, Inc. based on a smoothed stainless steel and non-commercial aluminium surface), three silanized glass surfaces and polished CaF2. The results showed that the formation of a "coffee ring" was influenced by surface wettability as well as by lipid concentration in the drop. Drop Coating Deposition Raman (DCDR) spectroscopy was used to compare the ability of the tested surfaces to preconcentrate molecules in the ring and therefore improve detection sensitivity. It was shown that surfaces with a contact angle of 90° and higher produce smaller drying patterns than more hydrophilic surfaces. In these drying patterns, the model liposomes were more efficiently preconcentrated, which resulted in a higher Raman signal of the liposomes. The applicability of surfaces with static contact angles less than 90°, high water contact angle hysteresis and no metal layer (silanized glass, CaF2) is limited to samples with high liposome concentrations.
-
Thiol‐modified gold‐coated glass as an efficient hydrophobic substrate for drop Coating Deposition Raman (DCDR) technique
Journal of Raman Spectroscopy, 2016Co-Authors: Eva Kočišová, Marek Procházka, Hana ŠípováAbstract:In this paper we report an easy and low-cost way to prepare a hydrophobic substrate for drop Coating Deposition Raman (DCDR) spectroscopy. This substrate is formed by a thiol-modified Au-coated glass and provides the Raman spectra with the same quality as the commercial Teflon-coated stainless steel substrate (SpectRIM™, Tienta Sciences, Inc.) for model molecular systems – albumin solution and liposome suspension. Gold layer, similarly to polished steel in the commercial substrate, served as a highly refractive layer strongly increasing the Raman signal. The main advantage of introduced substrate is that it is simple and a low-cost preparation easily manageable in every standard laboratory. Thus, it represents a promising alternative to commercial Teflon-coated stainless steel substrate. Copyright © 2016 John Wiley & Sons, Ltd.
-
Drop-Coating Deposition Raman (DCDR) Spectroscopy as a Tool for Membrane Interaction Studies: Liposome-Porphyrin Complex.
Applied spectroscopy, 2015Co-Authors: Eva Kočišová, Marek Procházka, Lenka VaculčiakováAbstract:Drop-Coating Deposition Raman (DCDR) spectroscopy is based on the measurement of a sample that has been preconcentrated by being dried on a special hydrophobic plate. In addition to its higher sensitivity, the advantage of DCDR over the conventional Raman spectroscopy is the small sample volume needed, the lack of interference from solvents, and the capability of segregating any impurities present and separating components in more complex samples. In this study, DCDR spectroscopy was employed to investigate the complex of the cationic copper(II) 5,10,15,20-tetrakis(1-methyl-4-pyridyl) porphyrin (CuTMPyP) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) liposomes. Drop-Coating Deposition Raman spectra were treated using factor analysis (FA), which led to the following conclusions: (i) the distribution of CuTMPyP in the complex is not homogenous, (ii) the DCDR technique segregates complexed and noncomplexed parts of the sample, (iii) the spectral changes caused by the drying process and by the interaction of CuTMPyP with the DPPC liposomes can be distinguished, and (iv) the porphyrin molecules interacting with DPPC affect both the order-disorder properties of the lipid chains and the lipid head.
-
Drop‐Coating Deposition Raman spectroscopy of porphyrins
Journal of Raman Spectroscopy, 2015Co-Authors: Eva Kočišová, Marek ProcházkaAbstract:We report an improvement of the Raman detection sensitivity of porphyrins by factor of 105 using drop-Coating Deposition Raman spectroscopy (DCDR). We were able to obtain Raman spectra from ~20 nM initial (deposited) concentrations of cationic and anionic porphyrin. This detection limit is comparable with or even better than that of surface-enhanced Raman scattering spectroscopy using Ag nanoparticles. Moreover, DCDR spectrum of protoporphyrin IX, which is known as a marker in clinical diagnostics of cancer, was also obtained from 10 nM deposited concentration. To our knowledge, it is the first demonstration of the resonance DCDR spectroscopy. Copyright © 2015 John Wiley & Sons, Ltd.
-
Drop Coating Deposition Raman spectroscopy of liposomes: role of cholesterol.
Chemistry and physics of lipids, 2013Co-Authors: Eva Kočišová, Andrej Antalík, Marek ProcházkaAbstract:Drop Coating Deposition Raman (DCDR) spectroscopy was used to study liposomes (DPPC and asolectin) with growing proportion of cholesterol. Deposited samples of both liposomes on special hydrophobic surface formed a dried drop with a circular shape with a ring of concentrated liposomes at the outer edge. The presence of cholesterol in liposome causes a diminishing of the drop size and an increasing in diameter of the ring, but DPPC with 20% of cholesterol forms the compact drop without the ring. Raman spectra contain characteristics of both lipids and cholesterol, liposomes do not change their initial phase state after drying. Spectral mapping shows that maximum Raman intensity originated from the inner part of the ring. Our results suggest that DCDR spectroscopy can be used for studying lipids containing cholesterol in situ.
E R Leite - One of the best experts on this subject based on the ideXlab platform.
-
nanostructured hematite thin films produced by spin Coating Deposition solution application in water splitting
Solar Energy Materials and Solar Cells, 2009Co-Authors: Flavio L Souza, Kirian Pimenta Lopes, P A P Nascente, E R LeiteAbstract:Doped and undoped hematite films for photoelectrochemical hydrogen production were prepared by spin-Coating Deposition solution (SCDS). To understand the influence of the Si-doping and identify the critical parameters of the proposed SCDS method an extensive characterization was conducted. The Si-doped hematite exhibited higher photocurrent response when compared with undoped films. We have shown that the crystallographic orientation degree of the films appears to be a dominant factor affecting the photocurrent. The performance of our hematite electrodes is well below the maximum theoretical efficiency and the conceivable explanation could be given by the high value of recombination phenomena (electron/hole pair).
Flavio L Souza - One of the best experts on this subject based on the ideXlab platform.
-
Effect of thermal treatment on solid-solid interface of hematite thin film synthesized by spin-Coating Deposition solution
Thin Solid Films, 2016Co-Authors: Daniel Angel Bellido-aguilar, Flavio L Souza, Aryane Tofanello, Leonardo N. Furini, Carlos J. L. ConstantinoAbstract:Abstract This work describes hematite films prepared by a spin-Coating Deposition solution (SCDS) method that is a sol–gel method derived technique. Hematite films were prepared at two heat treatment temperatures (500 °C and 800 °C) and the influence of thermal treatment on the photoelectrochemical performance was studied. In addition, since the SCDS method allows an optimal control of stoichiometry and impurity incorporation, hematite films modified with Zn 2 + and Sn 4 + were also prepared. The 800 °C-treated hematite films had a higher wettability and roughness that enabled them to have a better photocatalytic response in comparison with that of 500 °C-treated hematite films. Moreover, modified hematite films demonstrated to have a performance slightly better than that of undoped hematite film as shown in linear sweep voltammetry and chronoamperometry results. Although an improvement in the performance of hematite films was achieved by annealing at higher temperatures and incorporating Zn 2 + or Sn 4 + , the general photocatalytic response of the films was poor. Two plausible hypotheses were discussed related to the (i) dopant segregation at grain boundary, and (ii) poor contact between the hematite and fluorine doped tin oxide layer (from the glass substrate), which was experimentally confirmed by a cross-sectional analysis conducted using scanning electron microscopy (SEM). In fact, additional experiments need to be done in order to improve the hematite Deposition and make the SCDS a promise method for industrial application.
-
nanostructured hematite thin films produced by spin Coating Deposition solution application in water splitting
Solar Energy Materials and Solar Cells, 2009Co-Authors: Flavio L Souza, Kirian Pimenta Lopes, P A P Nascente, E R LeiteAbstract:Doped and undoped hematite films for photoelectrochemical hydrogen production were prepared by spin-Coating Deposition solution (SCDS). To understand the influence of the Si-doping and identify the critical parameters of the proposed SCDS method an extensive characterization was conducted. The Si-doped hematite exhibited higher photocurrent response when compared with undoped films. We have shown that the crystallographic orientation degree of the films appears to be a dominant factor affecting the photocurrent. The performance of our hematite electrodes is well below the maximum theoretical efficiency and the conceivable explanation could be given by the high value of recombination phenomena (electron/hole pair).
Alexander I. Ryabchikov - One of the best experts on this subject based on the ideXlab platform.
-
High-frequency short-pulse bias potential as a universal method of ion-beam and plasma treatment of conductive and dielectric materials using vacuum-arc and ablation plasma
2012 7th International Forum on Strategic Technology (IFOST), 2012Co-Authors: Alexander I. Ryabchikov, I.b. Stepanov, D. O. Sivin, P. S. Ananin, S. V. DektyarevAbstract:The results of investigations of applicability of the method of high-frequency short-pulsed plasma-immersion ion implantation and (or) Coating Deposition using vacuum-arc and ablation plasma to conductive and dielectric substrates are presented. It is shown that ion implantation with the ion sputtering compensation by Coating Deposition from plasma and ion-assisted Coating Deposition can be realized for the metal and dielectric samples through alteration of the negative bias potential within 0-4·103 V, with the pulse repetition rate of (1- 4.4)·105 pps, pulse duration 0.5-2 μs and duty factor of 0.1-0.9. It is experimentally established that at Coating Deposition from ablation plasma obtained by the influence of the high-intensity ion beam (j = 3·102 A/m2, E = 350 keV, τ = 90 ns) on the target, the micro-arc effects on the substrate surface are observed at a dc bias potential of more than -60 V. The transition to pulses of 0.5 μs duration enabled to increase the bias potential up to -4 kV. The possibility of application of the high-frequency, short-pulse bias potentials for the formation of Coatings from vacuum-arc and ablation plasma with high adhesive strength and improved exploitation characteristics is discussed.
-
Coating Deposition using vacuum arc and ablation metal plasma
Surface & Coatings Technology, 2009Co-Authors: Alexander I. Ryabchikov, V.m. Matvienko, I.b. StepanovAbstract:Abstract An innovative concept in the development of advanced Coating Deposition and ion implantation method including an application of filtered DC metal plasma or ablation plasma and high-frequency short-pulsed negative bias voltage with a duty factor in the range 10–99% is considered. The regularities of metal ion implantation and vacuum arc metal plasma or ablation plasma Deposition for conducting and insulating materials are considered. It was shown that plasma based ion implantation as well as high-concentration plasma ion implantation with compensation of ion surface sputtering by plasma Deposition as well as ion-assisted Coating Deposition may be realized for metal and dielectric samples by variation of negative bias potential in the range of 0–4·10 3 V, pulse repetition rate smoothly adjusted in the range of (2–4.4) × 10 5 pps and pulse duration in the range of 0.5–2 µs. It was experimentally shown that at Coating Deposition from ablation plasma obtained by high intensity ion beam ( j = 300 A/cm 2 , E = 350 keV, τ = 90 ns) influence on the target, the breakdown of the plasma sheet occurred at dc negative bias potential on a substrate more than 60 V. The transfer to 0.5 µs duration pulses allowed us to increase the bias potential up to − 4 kV. The possibility of high-frequency, short-pulsed plasma-immersion ion implantation and Deposition method application for Coating Deposition from vacuum arc and ablation plasma with high adhesive strength and improved exploitation characteristics is discussed in the paper.
-
high frequency short pulsed metal plasma immersion ion implantation or Deposition using filtered dc vacuum arc plasma
Surface & Coatings Technology, 2007Co-Authors: Alexander I. Ryabchikov, I.b. Stepanov, I.a. Ryabchikov, Yu P UsovAbstract:Abstract A new approach to the development of advanced Coating Deposition and ion implantation method including an application of filtered dc metal plasma and high-frequency short-pulsed negative bias voltage with a duty factor in the range of 10–99% are considered. The ion energy spectrum for different negative bias potential pulse durations (120–1100 ns) was measured. The chart of various methods of ion beam and plasma material treatment using high-frequency short pulse metal plasma immersion ion implantation or Deposition depending on bias pulse duty factor and amplitude for Cu plasma is presented. The ion assisted Coating Deposition has been examined depending on samples conductivity and thickness, plasma concentration, pulse repetition rate, amplitude, and duty factor.
-
High current vacuum-arc ion source for ion implantation and Coating Deposition technologies
Review of Scientific Instruments, 2006Co-Authors: Alexander I. Ryabchikov, I.b. Stepanov, I.a. Ryabchikov, S. V. DektyarevAbstract:This work is devoted to the development and investigation of a high current ion source based on dc vacuum-arc plasma generation. Extraction and acceleration of ion beams are realized in a repetitively pulsed mode with the pulse repetition rate up to 200 pps, the pulse duration up to 400μs, the accelerating voltage up to 40 kV, and the pulsed ion-beam current up to 2 A. To remove microparticles from the vacuum-arc plasma a straight-line plasma filter is used. Examples of the source use for realization of high-intensity and high-concentration ion implantation regimes including those with formation of doped layers at depths that exceed ion projective range for more than an order of magnitude are presented. At the expense of change in order and intensity of ion and plasma material treatment, the advantage of application of one source for execution of material surface pretreatment and activation regimes, formation of wide transition layers between the substrate and Coating, Coating Deposition, and high-intensi...
-
Development of filtered DC metal plasma ion implantation and Coating Deposition methods based on high-frequency short-pulsed bias voltage application☆
Vacuum, 2005Co-Authors: Alexander I. Ryabchikov, I.a. Ryabchikov, I.b. StepanovAbstract:Abstract An innovative concept in the development of advanced Coating Deposition and ion implantation method including an application of filtered DC metal plasma source and high-frequency short-pulsed negative bias voltage with a duty factor in the range 10–99% are considered. The regularities of ion implantation and metal plasma Deposition for metal and dielectric samples are experimentally investigated. Experimentally, it has been shown that metal plasma-based ion implantation, high-concentration metal plasma ion implantation with compensation of ion surface sputtering by metal plasma Deposition and ion-assisted Coating Deposition can be realized by variation of bias potential ranging from 0 V to 4 kV, with pulse repetition rate smoothly adjusted in the range (2–4.4)×10 5 pps and pulse duration ranging from 0.5 to 2 μs. Special features of the material treatment method depending on plasma concentration, pulse repetition rate and duty factor have been examined.