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Tselekidou D, Papadopoulos K, Foris V, Kyriazopoulos V, Andrikopoulos KC, Andreopoulou AK, Kallitsis JK, Laskarakis A, Logothetidis S, Gioti M. A Comparative Study between Blended Polymers and Copolymers as Emitting Layers for Single-Layer White Organic Light-Emitting Diodes. Materials (Basel) 2023; 17:76. [PMID: 38203932 PMCID: PMC10780062 DOI: 10.3390/ma17010076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 12/18/2023] [Accepted: 12/19/2023] [Indexed: 01/12/2024]
Abstract
Extensive research has been dedicated to the solution-processable white organic light-emitting diodes (WOLEDs), which can potentially influence future solid-state lighting and full-color flat-panel displays. The proposed strategy based on WOLEDs involves blending two or more emitting polymers or copolymerizing two or more emitting chromophores with different doping concentrations to produce white light emission from a single layer. Toward this direction, the development of blends was conducted using commercial blue poly(9,9-di-n-octylfluorenyl2,7-diyl) (PFO), green poly(9,9-dioctylfluorenealt-benzothiadiazole) (F8BT), and red spiro-copolymer (SPR) light-emitting materials, whereas the synthesized copolymers were based on different chromophores, namely distyryllanthracene, distyrylcarbazole, and distyrylbenzothiadiazole, as yellow, blue, and orange-red emitters, respectively. A comparative study between the two approaches was carried out to examine the main challenge for these doping systems, which is ensuring the proper balance of emissions from all the units to span the entire visible range. The emission characteristics of fabricated WOLEDs will be explored in terms of controlling the emission from each emitter, which depends on two possible mechanisms: energy transfer and carrier trapping. The aim of this work is to achieve pure white emission through the color mixing from different emitters based on different doping concentrations, as well as color stability during the device operation. According to these aspects, the WOLED devices based on the copolymers of two chromophores exhibit the most encouraging results regarding white color emission coordinates (0.28, 0.31) with a CRI value of 82.
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Affiliation(s)
- Despoina Tselekidou
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece; (K.P.); (A.L.); (S.L.)
| | - Kyparisis Papadopoulos
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece; (K.P.); (A.L.); (S.L.)
| | - Vasileios Foris
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece; (K.P.); (A.L.); (S.L.)
| | - Vasileios Kyriazopoulos
- Organic Electronic Technologies P.C. (OET), 20th KM Thessaloniki—Tagarades, GR-57001 Thermi, Greece;
| | - Konstantinos C. Andrikopoulos
- Department of Chemistry, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras, Greece; (K.C.A.); (A.K.A.); (J.K.K.)
| | - Aikaterini K. Andreopoulou
- Department of Chemistry, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras, Greece; (K.C.A.); (A.K.A.); (J.K.K.)
| | - Joannis K. Kallitsis
- Department of Chemistry, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras, Greece; (K.C.A.); (A.K.A.); (J.K.K.)
| | - Argiris Laskarakis
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece; (K.P.); (A.L.); (S.L.)
| | - Stergios Logothetidis
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece; (K.P.); (A.L.); (S.L.)
- Organic Electronic Technologies P.C. (OET), 20th KM Thessaloniki—Tagarades, GR-57001 Thermi, Greece;
| | - Maria Gioti
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece; (K.P.); (A.L.); (S.L.)
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Gioti M. Spectroscopic Ellipsometry Studies on Solution-Processed OLED Devices: Optical Properties and Interfacial Layers. Materials (Basel) 2022; 15:9077. [PMID: 36556883 PMCID: PMC9784439 DOI: 10.3390/ma15249077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 12/12/2022] [Accepted: 12/15/2022] [Indexed: 06/17/2023]
Abstract
Τhe fabrication of organic light-emitting diodes (OLEDs) from solution involves the major problem of stack integrity, setting the determination of the composition and the characteristics of the resulting interfaces prerequisite for the optimization of the growth processes and the achievement of high devices' performance. In this work, a poly(9,9-dioctylfluorene) (F8) and poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) blend is used for the emissive layer (EML), poly-3,4-ethylene dioxythiophene; poly-styrene sulfonate (PEDOT:PSS) is used for a hole transport layer (HTL), and Poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylammoinium-propyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluore-ne))dibromide (PFN-Br) for an electron transport layer (ETL) to produce the OLED device. All the layers are developed using the slot-die process, onto indium tin oxide (ITO)-coated polyethylene terephthalate (PET) flexible substrates, whereas Ag cathode was formed by ink-jet printing under ambient conditions. Spectroscopic ellipsometry measurements were performed upon completion of the successive films' growth, in sequential steps, for the multilayer OLED development. Ellipsometry analysis using different models demonstrate the degree of intermixing within the layers and provide information about the interfaces. These interfacial properties are correlated with the emission characteristics as well as the final performance of the OLED devices.
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Affiliation(s)
- Maria Gioti
- Nanotechnology Laboratory LTFN, Physics Department, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
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Gioti M, Tselekidou D, Foris V, Kyriazopoulos V, Papadopoulos K, Kassavetis S, Logothetidis S. Influence of Dopant Concentration and Annealing on Binary and Ternary Polymer Blends for Active Materials in OLEDs. Nanomaterials (Basel) 2022; 12:4099. [PMID: 36432386 PMCID: PMC9699568 DOI: 10.3390/nano12224099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 11/10/2022] [Accepted: 11/17/2022] [Indexed: 06/16/2023]
Abstract
Obtaining white light from organic LEDs is a considerable challenge and, to realize white light emission, many studies have been conducted, primarily addressing two- or three-color blend systems as a promising strategy. In this work, pristine films, grown by spin coating, consisting of commercial blue Poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO), green Poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT), and red spiro-copolymer (SPR) light-emitting materials, were studied as reference materials. Afterward, binary (SPR doped in host PFO) and ternary (SPR and F8BT doped in host PFO) thin films were successfully prepared with various ratios. The characterization of the as-grown and thermally-treated blend films was focused on their optical and photophysical properties. After, the fabrication of OLED devices on glass substrates was carried out for the evaluation of a blend's composition and annealing in terms of the devices' electrical characteristics and electro-emission properties in order to achieve white light emission. Their analysis provided insights into the energy transfer mechanisms between the constituent materials, which were correlated to host-guest interactions as well as to the structural changes originated by thermal treatment, leading to the crystallization of PFO. Finally, the OLEDs based on ternary blends approach the white light emission with (x, y) of (0.272, 0.346). These fabricated devices also exhibit turn-on voltages as low as 3 V, accompanied by remarkable luminance values above 3000 cd/m2.
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Affiliation(s)
- Maria Gioti
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
| | - Despoina Tselekidou
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
| | - Vasileios Foris
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
| | - Vasileios Kyriazopoulos
- Organic Electronic Technologies P.C. (OET), 20th KM Thessaloniki—Tagarades, GR-57001 Thermi, Greece
| | - Kyparisis Papadopoulos
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
| | - Spyros Kassavetis
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
| | - Stergios Logothetidis
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece
- Organic Electronic Technologies P.C. (OET), 20th KM Thessaloniki—Tagarades, GR-57001 Thermi, Greece
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Tselekidou D, Papadopoulos K, Kyriazopoulos V, Andrikopoulos KC, Andreopoulou AK, Kallitsis JK, Laskarakis A, Logothetidis S, Gioti M. Photophysical and Electro-Optical Properties of Copolymers Bearing Blue and Red Chromophores for Single-Layer White OLEDs. Nanomaterials (Basel) 2021; 11:nano11102629. [PMID: 34685063 PMCID: PMC8539096 DOI: 10.3390/nano11102629] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/28/2021] [Accepted: 09/30/2021] [Indexed: 01/13/2023]
Abstract
In this study, novel copolymers consisting of blue and red chromophores are presented to induce emission tuning, enabling the definition of white light emission in a single polymeric layer. These aromatic polyether sulfones exhibit high molecular weights, excellent solubility and processability via solution deposition techniques. In addition, by carefully controlling the molar ratios of chromophores composition, the energy transfer mechanism, from blue to red chromophores, takes place enabling us to define properly the emission covering the entire range of the visible spectrum. The optical and photophysical properties of the monomers and copolymers were thoroughly investigated via NIR-Vis-far UV Spectroscopic Ellipsometry (SE), Absorbance and Photoluminescence (PL). These copolymers are used as an emissive layer and applied in solution-processed WOLED devices. The fabricated WOLED devices have been subsequently studied and characterized in terms of their electroluminescence properties. Finally, the WOLED devices possess high color stability and demonstrate CIE Coordinates (0.33, 0.38), which approach closely the pure white light CIE coordinates.
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Affiliation(s)
- Despoina Tselekidou
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece; (D.T.); (K.P.); (V.K.); (A.L.); (S.L.)
| | - Kyparisis Papadopoulos
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece; (D.T.); (K.P.); (V.K.); (A.L.); (S.L.)
| | - Vasileios Kyriazopoulos
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece; (D.T.); (K.P.); (V.K.); (A.L.); (S.L.)
- Organic Electronic Technologies P.C. (OET), Antoni Tritsi 21B, GR-57001 Thessaloniki, Greece
| | - Konstantinos C. Andrikopoulos
- Department of Chemistry, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras, Greece; (K.C.A.); (A.K.A.); (J.K.K.)
| | - Aikaterini K. Andreopoulou
- Department of Chemistry, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras, Greece; (K.C.A.); (A.K.A.); (J.K.K.)
| | - Joannis K. Kallitsis
- Department of Chemistry, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras, Greece; (K.C.A.); (A.K.A.); (J.K.K.)
| | - Argiris Laskarakis
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece; (D.T.); (K.P.); (V.K.); (A.L.); (S.L.)
| | - Stergios Logothetidis
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece; (D.T.); (K.P.); (V.K.); (A.L.); (S.L.)
| | - Maria Gioti
- Nanotechnology Lab LTFN, Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece; (D.T.); (K.P.); (V.K.); (A.L.); (S.L.)
- Correspondence:
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Lamprogiannis L, Karamitsos A, Karagkiozaki V, Tsinopoulos I, Gioti M, Fatouros DG, Dimitrakos S, Logothetidis S. Design and fabrication of drug‐eluting polymeric thin films for applications in ophthalmology. IET Nanobiotechnol 2018; 12:1074-1079. [DOI: 10.1049/iet-nbt.2018.5151] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Lampros Lamprogiannis
- Second Department of OphthalmologySchool of Medicine, Aristotle University of ThessalonikiThessalonikiGreece
- Lab for Thin Films – Nanobiomaterials – Nanosystems and Nanometrology (LTFN)Department of PhysicsAristotle University of ThessalonikiThessalonikiGreece
| | - Athanasios Karamitsos
- Second Department of OphthalmologySchool of Medicine, Aristotle University of ThessalonikiThessalonikiGreece
- Lab for Thin Films – Nanobiomaterials – Nanosystems and Nanometrology (LTFN)Department of PhysicsAristotle University of ThessalonikiThessalonikiGreece
| | - Varvara Karagkiozaki
- Lab for Thin Films – Nanobiomaterials – Nanosystems and Nanometrology (LTFN)Department of PhysicsAristotle University of ThessalonikiThessalonikiGreece
| | - Ioannis Tsinopoulos
- Second Department of OphthalmologySchool of Medicine, Aristotle University of ThessalonikiThessalonikiGreece
| | - Maria Gioti
- Lab for Thin Films – Nanobiomaterials – Nanosystems and Nanometrology (LTFN)Department of PhysicsAristotle University of ThessalonikiThessalonikiGreece
| | - Dimitrios G. Fatouros
- Department of Pharmaceutical TechnologySchool of Pharmacy, Aristotle University of ThessalonikiThessalonikiGreece
| | - Stavros Dimitrakos
- Second Department of OphthalmologySchool of Medicine, Aristotle University of ThessalonikiThessalonikiGreece
| | - Stergios Logothetidis
- Lab for Thin Films – Nanobiomaterials – Nanosystems and Nanometrology (LTFN)Department of PhysicsAristotle University of ThessalonikiThessalonikiGreece
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Borges BGAL, Veiga AG, Gioti M, Laskarakis A, Tzounis L, Logothetidis S, Rocco MLM. Surface, interface and electronic properties of F8:F8BT polymeric thin films used for organic light-emitting diode applications. POLYM INT 2018. [DOI: 10.1002/pi.5552] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Bruno GAL Borges
- Institute of Chemistry; Federal University of Rio de Janeiro; Rio de Janeiro RJ Brazil
| | - Amanda G Veiga
- Institute of Chemistry; Federal University of Rio de Janeiro; Rio de Janeiro RJ Brazil
| | - Maria Gioti
- Laboratory for Thin Films, Nanobiomaterials - Nanosystems and Nanometrology (LTFN), Physics Department; Aristotle University of Thessaloniki; Thessaloniki Greece
| | - Argiris Laskarakis
- Laboratory for Thin Films, Nanobiomaterials - Nanosystems and Nanometrology (LTFN), Physics Department; Aristotle University of Thessaloniki; Thessaloniki Greece
| | - Lazaros Tzounis
- Laboratory for Thin Films, Nanobiomaterials - Nanosystems and Nanometrology (LTFN), Physics Department; Aristotle University of Thessaloniki; Thessaloniki Greece
| | - Stergios Logothetidis
- Laboratory for Thin Films, Nanobiomaterials - Nanosystems and Nanometrology (LTFN), Physics Department; Aristotle University of Thessaloniki; Thessaloniki Greece
| | - Maria Luiza M Rocco
- Institute of Chemistry; Federal University of Rio de Janeiro; Rio de Janeiro RJ Brazil
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Karagkiozaki V, Karagiannidis PG, Gioti M, Kavatzikidou P, Georgiou D, Georgaraki E, Logothetidis S. Bioelectronics meets nanomedicine for cardiovascular implants: PEDOT-based nanocoatings for tissue regeneration. Biochim Biophys Acta Gen Subj 2013; 1830:4294-304. [PMID: 23291427 DOI: 10.1016/j.bbagen.2012.12.019] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 12/13/2012] [Accepted: 12/18/2012] [Indexed: 11/17/2022]
Abstract
BACKGROUND An exciting direction in nanomedicine would be to analyze how living cells respond to conducting polymers. Their application for tissue regeneration may advance the performance of drug eluting stents by addressing the delayed stent re-endothelialization and late stent thrombosis. METHODS The suitability of poly (3, 4-ethylenedioxythiophene) (PEDOT) thin films for stents to promote cell adhesion and proliferation is tested in correlation with doping and physicochemical properties. PEDOT doped either with poly (styrenesulfonate) (PSS) or tosylate anion (TOS) was used for films' fabrication by spin coating and vapor phase polymerization respectively. PEGylation of PEDOT: TOS for reduced immunogenicity and biofunctionalization of PEDOT: PSS with RGD peptides for induced cell proliferation was further applied. Atomic Force Microscopy and Spectroscopic Ellipsometry were implemented for nanotopographical, structural, optical and conductivity measurements in parallel with wettability and protein adsorption studies. Direct and extract testing of cell viability and proliferation of L929 fibroblasts on PEDOT samples by MTT assay in line with SEM studies follow. RESULTS All PEDOT thin films are cytocompatible and promote human serum albumin adsorption. PEDOT:TOS films were found superior regarding cell adhesion as compared to controls. Their nanotopography and hydrophilicity are significant factors that influence cytocompatibility. PEGylation of PEDOT:TOS increases their conductivity and hydrophilicity with similar results on cell viability with bare PEDOT:TOS. The biofunctionalized PEDOT:PSS thin films show enhanced cell proliferation. CONCLUSIONS The application of PEDOT polymers has evolved as a new perspective to advance stents. GENERAL SIGNIFICANCE In this work, nanomedicine involving nanotools and novel nanomaterials merges with bioelectronics to stimulate tissue regeneration for cardiovascular implants. This article is part of a Special Issue entitled Organic Bioelectronics - Novel Applications in Biomedicine.
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Affiliation(s)
- V Karagkiozaki
- Lab for Thin Films-Nanosystems and Nanometrology LTFN, Physics Department, Aristotle University of Thessaloniki, GR-54124, Greece
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Karagkiozaki V, Vavoulidis E, Karagiannidis PG, Gioti M, Fatouros DG, Vizirianakis IS, Logothetidis S. Development of a nanoporous and multilayer drug-delivery platform for medical implants. Int J Nanomedicine 2012; 7:5327-38. [PMID: 23071394 PMCID: PMC3469098 DOI: 10.2147/ijn.s31185] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Biodegradable polymers can be applied to a variety of implants for controlled and local drug delivery. The aim of this study is to develop a biodegradable and nanoporous polymeric platform for a wide spectrum of drug-eluting implants with special focus on stent-coating applications. It was synthesized by poly(DL-lactide-co-glycolide) (PLGA 65:35, PLGA 75:25) and polycaprolactone (PCL) in a multilayer configuration by means of a spin-coating technique. The antiplatelet drug dipyridamole was loaded into the surface nanopores of the platform. Surface characterization was made by atomic force microscopy (AFM) and spectroscopic ellipsometry (SE). Platelet adhesion and drug-release kinetic studies were then carried out. The study revealed that the multilayer films are highly nanoporous, whereas the single layers of PLGA are atomically smooth and spherulites are formed in PCL. Their nanoporosity (pore diameter, depth, density, surface roughness) can be tailored by tuning the growth parameters (eg, spinning speed, polymer concentration), essential for drug-delivery performance. The origin of pore formation may be attributed to the phase separation of polymer blends via the spinodal decomposition mechanism. SE studies revealed the structural characteristics, film thickness, and optical properties even of the single layers in the triple-layer construct, providing substantial information for drug loading and complement AFM findings. Platelet adhesion studies showed that the dipyridamole-loaded coatings inhibit platelet aggregation that is a prerequisite for clotting. Finally, the films exhibited sustained release profiles of dipyridamole over 70 days. These results indicate that the current multilayer phase therapeutic approach constitutes an effective drug-delivery platform for drug-eluting implants and especially for cardiovascular stent applications.
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Affiliation(s)
- Varvara Karagkiozaki
- Lab for Thin Films-Nanosystems and Nanometrology, Physics Department, Aristotle University of Thessaloniki, Greece
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Lousinian S, Logothetidis S, Laskarakis A, Gioti M. Haemocompatibility of amorphous hydrogenated carbon thin films, optical properties and adsorption mechanisms of blood plasma proteins. ACTA ACUST UNITED AC 2006; 24:107-12. [PMID: 16843059 DOI: 10.1016/j.bioeng.2006.05.014] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Haemocompatibility is one of the most important properties, together with the tissue compatibility and corrosion and wear resistance that determine the biocompatibility of the artificial implants. Carbon-based thin films, such as amorphous carbon (a-C) and amorphous hydrogenated diamond-like carbon (a-C:H or DLC) are considered as excellent candidates for use as biocompatible coatings on biomedical implants. The aim of this work is the comparative study of the haemocompatibility of the a-C:H thin films developed by magnetron sputtering under various deposition conditions, the development of a methodology in order to study the haemocompatibility of thin films, the optical properties of the adsorbed proteins (human serum albumin and fibrinogen) and their adsorption mechanisms. Haemocompatibility and the optical properties of a-C:H thin films and the adsorbed proteins were studied by spectroscopic ellipsometry (SE). The films grown under floating conditions performed better haemocompatibility compared with those deposited under application of bias voltage. In the range of vis-UV, proteins are transparent, while they present an absorption peak at higher energies, but except these characteristics, their optical functions are rather featureless. Adsorption mechanisms were studied through AFM technique too. AFM results are in accordance with those derived by SE. Combination of the two techniques gives us a more accurate description of protein adsorption mechanisms.
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Affiliation(s)
- S Lousinian
- Aristotle University of Thessaloniki, Department of Physics, GR-54124 Thessaloniki, Greece
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