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Papers by Konstantinos Kapnisis

AIP Advances, 2017

We investigate the employment of carefully selected solvent additives in the processing of a comm... more We investigate the employment of carefully selected solvent additives in the processing of a commercial perovskite precursor ink and analyze their impact on the performance of organometal trihalide perovskite (CH 3 NH 3 PbI 3x Cl x) photovoltaic devices. We provide evidence that the use of benzaldehyde can be used as an effective method to preserve the stoichiometry of the perovskite precursors in solution. Benzaldehyde based additive engineering shows to improve perovskite solid state film morphology and device performance of CH 3 NH 3 PbI 3x Cl x based solar cells.

Applied Sciences, 2021

In this study, it was demonstrated that ice-templating via freeze drying with custom-made moulds,... more In this study, it was demonstrated that ice-templating via freeze drying with custom-made moulds, in combination with air brushing, allows for the fabrication of poly(glycerol sebacate urethane) (PGSU) scaffolds with hierarchical multilayer microstructures to replicate various native soft tissues. The PGSU scaffolds were either monolayered but exhibited an anisotropic microstructure, or bilayered and trilayered, with each layer showing different microstructures. By using freeze drying with custom-made moulds, the ice crystals of the solvent were grown unidirectionally, and after freeze-drying, the scaffolds had an anisotropic microstructure, mimicking tissues such as tendon and skeletal muscle. The anisotropic PGSU scaffolds were also examined for their tensile strength, and a range of mechanical properties were obtained by altering the reactants’ molar ratio and polymer concentration. This is of importance, since soft tissues exhibit different mechanical properties depending on the...

Human Molecular Genetics

Myotonic dystrophy type 1 (DM1) is the most common form of adult-onset muscular dystrophy, which ... more Myotonic dystrophy type 1 (DM1) is the most common form of adult-onset muscular dystrophy, which is characterised by progressive muscle wasting and the discovery of reliable blood-based biomarkers could be useful for the disease progress monitoring. There have been some reports showing that the presence of specific miRNAs in blood correlates with DM1. In one of these, our group identified four muscle-specific miRNAs, miR-1, miR-133a, miR-133b and miR-206, which correlated with the progression of muscle wasting observed in DM1 patients. The levels of the four muscle-specific miRNAs were elevated in the serum of DM1 patients compared to healthy participants and were also elevated in the serum of progressive muscle wasting DM1 patients compared to disease-stable DM1 patients. The aim of this work was to characterise the ontology of these four muscle-specific miRNAs in the blood circulation of DM1 patients. Here we show that the four musclespecific miRNAs are encapsulated within exosomes isolated from DM1 patients. Our results show for the first time, the presence of miRNAs encapsulated within exosomes in blood circulation of DM1 patients. More interestingly, the levels of the four exosomal muscle-specific miRNAs are associated with the progression of muscle wasting in DM1 patients. We propose that exosomal muscle-specific miRNAs may be useful molecular biomarkers for monitoring the progress of muscle wasting in

Applied Catalysis B: Environmental, 2017

ACS Applied Energy Materials

We present the functionalization process of a conductive and transparent CuAlO 2 /Cu−O hole-trans... more We present the functionalization process of a conductive and transparent CuAlO 2 /Cu−O hole-transporting layer (HTL). The CuAlO 2 / Cu−O powders were developed by flame spray pyrolysis and their stabilized dispersions were treated by sonication and centrifugation methods. We show that when the supernatant part of the treated CuAlO 2 /Cu−O dispersions is used for the development of CuAlO 2 /Cu−O HTLs the corresponding inverted perovskite-based solar cells show improved functionality and power conversion efficiency of up to 16.3% with negligible hysteresis effect.

ASME 2011 Summer Bioengineering Conference, Parts A and B, 2011

ABSTRACT Despite advances in endovascular stent design, stent structural integrity and in-stent r... more ABSTRACT Despite advances in endovascular stent design, stent structural integrity and in-stent restenosis remains a significant clinical problem worldwide. The role of stent corrosion and metallic ion release has not been thoroughly studied and little attention has been given to the interaction of stent materials with the surrounding vessel wall and the mechanical forces involved after implantation. Our recent studies on Stainless Steel (SS), Cobalt-Chromium (CoCr) and Nickel-Titanium (NiTi) stents obtained from a tissue retrieval resource from cadavers with accompanying clinical histories, have revealed that these stents undergo corrosion in vivo, with significant release of metallic ions into surrounding tissues [1]. It is believed that high concentrations of metal ions from stents are toxic to vascular smooth muscle cells [2] and stimulate both inflammatory and fibrotic reactions leading to neointimal formation and a predisposition to device failure [3]. When this is combined with altered biomechanics of flow and motion, it creates a favourable environment for the development of restenosis. To separate the mechanical effects from the local environmental effects on the stent surface, we performed in-vitro mechanical studies on various combinations of stents under low and high curvature and in overlapping positions to compare the results of fretting, pitting and gouging with the explanted stents.

2012 IEEE 12th International Conference on Bioinformatics & Bioengineering (BIBE), 2012

We report a new approach for potential monitoring of tumor burden in experimental animals using m... more We report a new approach for potential monitoring of tumor burden in experimental animals using multichannel in vivo flow cytometry, a novel optical technique that enables the real-time, continuous detection and quantification of fluorescently labeled cells in the circulation without the need for blood extraction. The ability to non-invasively track circulating cells in real time and in their native environment, opens up enormous possibilities for new investigations into the mechanisms that govern the complex trafficking and tissue interactions of these cells in a wide range of clinical and biological fields such as cancer, stem cell biology and immunology. We have developed the in vivo flow cytometer in order to track circulating cancer cells in a mouse model and provide a new, non-invasive method for the monitoring of cancer disease progression as well as the response to therapeutic intervention.

ASME 2011 Summer Bioengineering Conference, Parts A and B, 2011

ABSTRACT Despite advances in endovascular stent design, stent structural integrity and in-stent r... more ABSTRACT Despite advances in endovascular stent design, stent structural integrity and in-stent restenosis remains a significant clinical problem worldwide. The role of stent corrosion and metallic ion release has not been thoroughly studied and little attention has been given to the interaction of stent materials with the surrounding vessel wall and the mechanical forces involved after implantation. Our recent studies on Stainless Steel (SS), Cobalt-Chromium (CoCr) and Nickel-Titanium (NiTi) stents obtained from a tissue retrieval resource from cadavers with accompanying clinical histories, have revealed that these stents undergo corrosion in vivo, with significant release of metallic ions into surrounding tissues [1]. It is believed that high concentrations of metal ions from stents are toxic to vascular smooth muscle cells [2] and stimulate both inflammatory and fibrotic reactions leading to neointimal formation and a predisposition to device failure [3]. When this is combined with altered biomechanics of flow and motion, it creates a favourable environment for the development of restenosis. To separate the mechanical effects from the local environmental effects on the stent surface, we performed in-vitro mechanical studies on various combinations of stents under low and high curvature and in overlapping positions to compare the results of fretting, pitting and gouging with the explanted stents.

Journal of the Mechanical Behavior of Biomedical Materials, 2014

In-stent restenosis (ISR) Fracture Nanoindentation Mechanical properties a b s t r a c t In-stent... more In-stent restenosis (ISR) Fracture Nanoindentation Mechanical properties a b s t r a c t In-stent restenosis (ISR) remains a significant limitation despite the considerable previous clinical and investigative emphasis on the problem. Complications arising from the interaction of stent materials with the surrounding vessel wall as well as from the mechanical forces developing after implantation, play an important role in the development of ISR. To investigate the relation between mechanical factors and stent structural integrity, and to identify any structural weakness points on the geometry of commercially available Stainless Steel and Cobalt-Chromium stents, accelerated pulsatile durability tests were carried out in a simulated physiological environment. Potential spatial variations in the mechanical properties on stent struts and their role in the observed premature failures of the stent devices during operation

Journal of the Mechanical Behavior of Biomedical Materials, 2013

Corrosion Fracture a b s t r a c t Preliminary studies have revealed that some stents undergo cor... more Corrosion Fracture a b s t r a c t Preliminary studies have revealed that some stents undergo corrosion and fatigue-induced fracture in vivo, with significant release of metallic ions into surrounding tissues. A direct link between corrosion and in-stent restenosis has not been clearly established; nonetheless in vitro studies have shown that relatively high concentrations of heavy metal ions can stimulate both inflammatory and fibrotic reactions, which are the main steps in the process of restenosis. To isolate the mechanical effects from the local biochemical effects, accelerated biomechanical testing was performed on single and overlapping Nickel-Titanium (NiTi) stents subjected to various degrees of curvature. Post testing, stents were evaluated using Scanning Electron Microscopy (SEM) to identify the type of surface alterations. Fretting wear was observed in overlapping cases, in both straight and curved configurations. Stent strut fractures occurred in the presence of geometric curvature. Fretting wear and fatigue fractures observed on stents following mechanical simulation were similar to those from previously reported human stent explants. It has been shown that biomechanical factors such as arterial curvature combined with stent overlapping enhance the incidence and degree of wear and fatigue fracture when compared to single stents in a straight tube configuration.

Journal of Biomechanics, 2009

Glaucoma is a common cause of blindness. Studies of this disease can involve collection of aqueou... more Glaucoma is a common cause of blindness. Studies of this disease can involve collection of aqueous humor (AH) fluid from eyes of patients undergoing surgery, which involves aspirating a small fluid volume from the anterior region of the eye through a fine-bore needle. Unfortunately, the composition of the AH is spatially non-uniform in the eye, and thus the composition of the aspirated fluid is uncertain. Our goal was to numerically simulate the AH aspiration process to determine where the aspirated fluid was being collected from and thus gain insight into the composition of the collected fluid.

Solar Energy Materials and Solar Cells, 2015

ABSTRACT Solution processed inverted organic photovoltaics (OPVs) usually use (Poly(3,4-ethylened... more ABSTRACT Solution processed inverted organic photovoltaics (OPVs) usually use (Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) PEDOT:PSS derivatives as hole selective contact. In this study the effect of different PEDOT:PSS formulations, Al4083, PH and PH500 in inverted structured OPVs is investigated. Through detailed device physics analysis PEDOT:PSS PH is proposed as most suitable hole selective contact for inverted OPVs device function. Furthermore, PEDOT:PSS PH hole selective contact is treated with 3 different wetting agents, Zonyl FS-300 fluorosurfactant (Zonyl), 2,5,8,11-tetramethyl-6-dodecyn-5,8-diol ethoxylate (Dynol) and Zonyl:Dynol mixture and the corresponding non-encapsulated inverted OPVs investigated under accelerated humidity lifetime conditions. The inverted OPVs incorporating PEDOT:PSS:Zonyl hole selective contact shown limitations on humidity lifetime performance due to the poorest adhesion properties of Zonyl-treated PEDOT:PSS PH compared with Dynol and Zonyl/Dynol mixture treaded PEDOT:PSS PH.

AIP Advances, 2017

We investigate the employment of carefully selected solvent additives in the processing of a comm... more We investigate the employment of carefully selected solvent additives in the processing of a commercial perovskite precursor ink and analyze their impact on the performance of organometal trihalide perovskite (CH 3 NH 3 PbI 3x Cl x) photovoltaic devices. We provide evidence that the use of benzaldehyde can be used as an effective method to preserve the stoichiometry of the perovskite precursors in solution. Benzaldehyde based additive engineering shows to improve perovskite solid state film morphology and device performance of CH 3 NH 3 PbI 3x Cl x based solar cells.

Applied Sciences, 2021

In this study, it was demonstrated that ice-templating via freeze drying with custom-made moulds,... more In this study, it was demonstrated that ice-templating via freeze drying with custom-made moulds, in combination with air brushing, allows for the fabrication of poly(glycerol sebacate urethane) (PGSU) scaffolds with hierarchical multilayer microstructures to replicate various native soft tissues. The PGSU scaffolds were either monolayered but exhibited an anisotropic microstructure, or bilayered and trilayered, with each layer showing different microstructures. By using freeze drying with custom-made moulds, the ice crystals of the solvent were grown unidirectionally, and after freeze-drying, the scaffolds had an anisotropic microstructure, mimicking tissues such as tendon and skeletal muscle. The anisotropic PGSU scaffolds were also examined for their tensile strength, and a range of mechanical properties were obtained by altering the reactants’ molar ratio and polymer concentration. This is of importance, since soft tissues exhibit different mechanical properties depending on the...

Human Molecular Genetics

Myotonic dystrophy type 1 (DM1) is the most common form of adult-onset muscular dystrophy, which ... more Myotonic dystrophy type 1 (DM1) is the most common form of adult-onset muscular dystrophy, which is characterised by progressive muscle wasting and the discovery of reliable blood-based biomarkers could be useful for the disease progress monitoring. There have been some reports showing that the presence of specific miRNAs in blood correlates with DM1. In one of these, our group identified four muscle-specific miRNAs, miR-1, miR-133a, miR-133b and miR-206, which correlated with the progression of muscle wasting observed in DM1 patients. The levels of the four muscle-specific miRNAs were elevated in the serum of DM1 patients compared to healthy participants and were also elevated in the serum of progressive muscle wasting DM1 patients compared to disease-stable DM1 patients. The aim of this work was to characterise the ontology of these four muscle-specific miRNAs in the blood circulation of DM1 patients. Here we show that the four musclespecific miRNAs are encapsulated within exosomes isolated from DM1 patients. Our results show for the first time, the presence of miRNAs encapsulated within exosomes in blood circulation of DM1 patients. More interestingly, the levels of the four exosomal muscle-specific miRNAs are associated with the progression of muscle wasting in DM1 patients. We propose that exosomal muscle-specific miRNAs may be useful molecular biomarkers for monitoring the progress of muscle wasting in

Applied Catalysis B: Environmental, 2017

ACS Applied Energy Materials

We present the functionalization process of a conductive and transparent CuAlO 2 /Cu−O hole-trans... more We present the functionalization process of a conductive and transparent CuAlO 2 /Cu−O hole-transporting layer (HTL). The CuAlO 2 / Cu−O powders were developed by flame spray pyrolysis and their stabilized dispersions were treated by sonication and centrifugation methods. We show that when the supernatant part of the treated CuAlO 2 /Cu−O dispersions is used for the development of CuAlO 2 /Cu−O HTLs the corresponding inverted perovskite-based solar cells show improved functionality and power conversion efficiency of up to 16.3% with negligible hysteresis effect.

ASME 2011 Summer Bioengineering Conference, Parts A and B, 2011

ABSTRACT Despite advances in endovascular stent design, stent structural integrity and in-stent r... more ABSTRACT Despite advances in endovascular stent design, stent structural integrity and in-stent restenosis remains a significant clinical problem worldwide. The role of stent corrosion and metallic ion release has not been thoroughly studied and little attention has been given to the interaction of stent materials with the surrounding vessel wall and the mechanical forces involved after implantation. Our recent studies on Stainless Steel (SS), Cobalt-Chromium (CoCr) and Nickel-Titanium (NiTi) stents obtained from a tissue retrieval resource from cadavers with accompanying clinical histories, have revealed that these stents undergo corrosion in vivo, with significant release of metallic ions into surrounding tissues [1]. It is believed that high concentrations of metal ions from stents are toxic to vascular smooth muscle cells [2] and stimulate both inflammatory and fibrotic reactions leading to neointimal formation and a predisposition to device failure [3]. When this is combined with altered biomechanics of flow and motion, it creates a favourable environment for the development of restenosis. To separate the mechanical effects from the local environmental effects on the stent surface, we performed in-vitro mechanical studies on various combinations of stents under low and high curvature and in overlapping positions to compare the results of fretting, pitting and gouging with the explanted stents.

2012 IEEE 12th International Conference on Bioinformatics & Bioengineering (BIBE), 2012

We report a new approach for potential monitoring of tumor burden in experimental animals using m... more We report a new approach for potential monitoring of tumor burden in experimental animals using multichannel in vivo flow cytometry, a novel optical technique that enables the real-time, continuous detection and quantification of fluorescently labeled cells in the circulation without the need for blood extraction. The ability to non-invasively track circulating cells in real time and in their native environment, opens up enormous possibilities for new investigations into the mechanisms that govern the complex trafficking and tissue interactions of these cells in a wide range of clinical and biological fields such as cancer, stem cell biology and immunology. We have developed the in vivo flow cytometer in order to track circulating cancer cells in a mouse model and provide a new, non-invasive method for the monitoring of cancer disease progression as well as the response to therapeutic intervention.

ASME 2011 Summer Bioengineering Conference, Parts A and B, 2011

ABSTRACT Despite advances in endovascular stent design, stent structural integrity and in-stent r... more ABSTRACT Despite advances in endovascular stent design, stent structural integrity and in-stent restenosis remains a significant clinical problem worldwide. The role of stent corrosion and metallic ion release has not been thoroughly studied and little attention has been given to the interaction of stent materials with the surrounding vessel wall and the mechanical forces involved after implantation. Our recent studies on Stainless Steel (SS), Cobalt-Chromium (CoCr) and Nickel-Titanium (NiTi) stents obtained from a tissue retrieval resource from cadavers with accompanying clinical histories, have revealed that these stents undergo corrosion in vivo, with significant release of metallic ions into surrounding tissues [1]. It is believed that high concentrations of metal ions from stents are toxic to vascular smooth muscle cells [2] and stimulate both inflammatory and fibrotic reactions leading to neointimal formation and a predisposition to device failure [3]. When this is combined with altered biomechanics of flow and motion, it creates a favourable environment for the development of restenosis. To separate the mechanical effects from the local environmental effects on the stent surface, we performed in-vitro mechanical studies on various combinations of stents under low and high curvature and in overlapping positions to compare the results of fretting, pitting and gouging with the explanted stents.

Journal of the Mechanical Behavior of Biomedical Materials, 2014

In-stent restenosis (ISR) Fracture Nanoindentation Mechanical properties a b s t r a c t In-stent... more In-stent restenosis (ISR) Fracture Nanoindentation Mechanical properties a b s t r a c t In-stent restenosis (ISR) remains a significant limitation despite the considerable previous clinical and investigative emphasis on the problem. Complications arising from the interaction of stent materials with the surrounding vessel wall as well as from the mechanical forces developing after implantation, play an important role in the development of ISR. To investigate the relation between mechanical factors and stent structural integrity, and to identify any structural weakness points on the geometry of commercially available Stainless Steel and Cobalt-Chromium stents, accelerated pulsatile durability tests were carried out in a simulated physiological environment. Potential spatial variations in the mechanical properties on stent struts and their role in the observed premature failures of the stent devices during operation

Journal of the Mechanical Behavior of Biomedical Materials, 2013

Corrosion Fracture a b s t r a c t Preliminary studies have revealed that some stents undergo cor... more Corrosion Fracture a b s t r a c t Preliminary studies have revealed that some stents undergo corrosion and fatigue-induced fracture in vivo, with significant release of metallic ions into surrounding tissues. A direct link between corrosion and in-stent restenosis has not been clearly established; nonetheless in vitro studies have shown that relatively high concentrations of heavy metal ions can stimulate both inflammatory and fibrotic reactions, which are the main steps in the process of restenosis. To isolate the mechanical effects from the local biochemical effects, accelerated biomechanical testing was performed on single and overlapping Nickel-Titanium (NiTi) stents subjected to various degrees of curvature. Post testing, stents were evaluated using Scanning Electron Microscopy (SEM) to identify the type of surface alterations. Fretting wear was observed in overlapping cases, in both straight and curved configurations. Stent strut fractures occurred in the presence of geometric curvature. Fretting wear and fatigue fractures observed on stents following mechanical simulation were similar to those from previously reported human stent explants. It has been shown that biomechanical factors such as arterial curvature combined with stent overlapping enhance the incidence and degree of wear and fatigue fracture when compared to single stents in a straight tube configuration.

Journal of Biomechanics, 2009

Glaucoma is a common cause of blindness. Studies of this disease can involve collection of aqueou... more Glaucoma is a common cause of blindness. Studies of this disease can involve collection of aqueous humor (AH) fluid from eyes of patients undergoing surgery, which involves aspirating a small fluid volume from the anterior region of the eye through a fine-bore needle. Unfortunately, the composition of the AH is spatially non-uniform in the eye, and thus the composition of the aspirated fluid is uncertain. Our goal was to numerically simulate the AH aspiration process to determine where the aspirated fluid was being collected from and thus gain insight into the composition of the collected fluid.

Solar Energy Materials and Solar Cells, 2015

ABSTRACT Solution processed inverted organic photovoltaics (OPVs) usually use (Poly(3,4-ethylened... more ABSTRACT Solution processed inverted organic photovoltaics (OPVs) usually use (Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) PEDOT:PSS derivatives as hole selective contact. In this study the effect of different PEDOT:PSS formulations, Al4083, PH and PH500 in inverted structured OPVs is investigated. Through detailed device physics analysis PEDOT:PSS PH is proposed as most suitable hole selective contact for inverted OPVs device function. Furthermore, PEDOT:PSS PH hole selective contact is treated with 3 different wetting agents, Zonyl FS-300 fluorosurfactant (Zonyl), 2,5,8,11-tetramethyl-6-dodecyn-5,8-diol ethoxylate (Dynol) and Zonyl:Dynol mixture and the corresponding non-encapsulated inverted OPVs investigated under accelerated humidity lifetime conditions. The inverted OPVs incorporating PEDOT:PSS:Zonyl hole selective contact shown limitations on humidity lifetime performance due to the poorest adhesion properties of Zonyl-treated PEDOT:PSS PH compared with Dynol and Zonyl/Dynol mixture treaded PEDOT:PSS PH.