Low-level red laser (LLRL)-tissue interactions have a wide range of medical applications and are ... more Low-level red laser (LLRL)-tissue interactions have a wide range of medical applications and are garnering increased attention. Although the positive effects of low-level laser therapy (LLLT) have frequently been reported and enhanced collagen accumulation has been identified as one of the most important mechanisms involved, little is known about LLRL-collagen interactions. In this study, we aimed to investigate the influence of LLRL irradiation on collagen, in correlation with fibroblast response. Atomic force microscopy (AFM) and fluorescence spectroscopy were used to characterize surfaces and identify conformational changes in collagen before and after LLRL irradiation. Irradiated and non-irradiated collagen thin films were used as culturing substrates to investigate fibroblast response with fluorescence microscopy. The results demonstrated that LLRL induced small alterations in fluorescence emission and had a negligible effect on the topography of collagen thin films. However, fibroblasts cultured on LLRL-irradiated collagen thin films responded to LRLL. The results of this study show for the first time the effect of LLRL irradiation on pure collagen. Although irradiation did not affect the nanotopography of collagen, it influenced cell behavior. The role of collagen appears to be crucial in the LLLT mechanism, and our results demonstrated that LLRL directly affects collagen and indirectly affects cell behavior.
Elastin is an extracellular matrix protein, providing elasticity to the organs, such as skin, blo... more Elastin is an extracellular matrix protein, providing elasticity to the organs, such as skin, blood vessels, lungs and elastic ligaments, presenting self-assembling ability to form elastic fibers. The elastin protein, as a component of elastin fibers, is one of the major proteins found in connective tissue and is responsible for the elasticity of tissues. It provides resilience to the human body, assembled as a continuous mesh of fibers that require to be deformed repetitively and reversibly. Thus, it is of great importance to investigate the development of the nanostructural surface of elastin-based biomaterials. The purpose of this research was to image the self-assembling process of elastin fiber structure under different experimental parameters such as suspension medium, elastin concentration, temperature of stock suspension and time interval after the preparation of the stock suspension. atomic force microscopy (AFM) was applied in order to investigate how different experimenta...
The fingerprint is one of the most important biometrics, with many acquisition methods developed ... more The fingerprint is one of the most important biometrics, with many acquisition methods developed over the years. Traditional 2D acquisition techniques produce nonlinear distortions due to the forced flattening of the finger onto a 2D surface. These random elastic deformations often introduce matching errors, making 2D techniques less reliable. Inevitably non-contact 3D capturing techniques were developed in an effort to deal with these problems. In this study we present a novel non-contact single camera 3D fingerprint reconstruction system based on fringe projection and a new model for approximating the epidermal ridges. The 3D shape of the fingerprint is reconstructed from a single 2D shading image in two steps. First the original image is decomposed into structure and texture components by an advanced Meyer algorithm. The structural component is reconstructed by a classical fringe projection technique. The textural component, containing the fingerprint information, is restored usi...
ABSTRACT Collagen due to its filamentous shape and unique properties is a very promising molecule... more ABSTRACT Collagen due to its filamentous shape and unique properties is a very promising molecule for the development of nanostructures, scaffolds, cell culture platforms and nanobiomaterials. Furthermore, collagen thin films are of great interest as they can cover non-biological surfaces in medical devices and sensors so as to offer them biocompatibility. Since surface nanotopography and mechanical properties can influence cell-biomaterial interactions it is of crucial importance to nano-characterize collagen surface and heterogeneity. Nano-characterization can be performed with Atomic Force Microscopy (AFM), which operates in a variety of modes/techniques and can offer a wide range of information, from topography to mechanical properties. In this paper it was sought to gain insights of structural and mechanical heterogeneity of collagen fibers in thin films by combining AFM multimode-imaging, including phase imaging, with quantitative measurements through nanoindentation. The results demonstrated that the overlap-gap regions on collagen fibers (D-periodicity) yield a significant phase contrast, due to different mechanical properties. In addition, phase contrast was also demonstrated in collagen ‘kinks’, which provides evidence that collagen fiber shell and core possess different properties. The mechanical heterogeneity of the collagen fibers in the kink areas was confirmed by AFM-nanoindentation and the obtained quantitative measurements. In addition, AFM multimode imaging performance was demonstrated on fibroblasts cultured on collagen thin films. The correlation between the heterogeneous structure and the mechanical properties of collagen fibers in thin films will enable the design and development of biomaterials and tissue scaffolds with improved properties.
ABSTRACT The adsorption of collagen and the morphology of its assemblies at solid surfaces play a... more ABSTRACT The adsorption of collagen and the morphology of its assemblies at solid surfaces play an important role in a variety of research areas and applications, such as biomaterials, biocompatibility, tissue mechanics and cell studies. In this paper the nanoscale organization of type I collagen on polystyrene particle surfaces with controlled patterns was investigated by high-resolution atomic force microscopy. The results showed that patterned surfaces with a well-ordered morphology could be formed by spin coating polystyrene particles dispersions (20 sec at 1000 rpm) and appropriate annealing conditions (at 90°C for 2h). Collagen thin films consisting of fibers with natural characteristics, such as the typical 67nm periodicity (D-band), were formed on these nano-patterns. This kind of surfaces provides a useful substrate for studying the regulation of collagen assembly on substrates with different nano-topographical and environmental conditions and offers a potential way to create surfaces of functionalized and nano-patterend materials for biotechnological and biomedical applications.
Abstract Collagen is the most abundant extracellular matrix protein and is important for a varie... more Abstract Collagen is the most abundant extracellular matrix protein and is important for a variety of functions, including tissue scaffolding, cell adhesion, cell migration, angiogenesis, tissue morphogenesis and tissue repair. Collagen is considered as one of the most useful biomaterials since it is ...
2009 9th International Conference on Information Technology and Applications in Biomedicine, 2009
Collagen is the most abundant protein in mammals and is important for a variety of functions and ... more Collagen is the most abundant protein in mammals and is important for a variety of functions and its concentration, structure and function is associated with different pathological states. In this research we correlate structural changes with those changes in the Second Harmonic Generation (SHG) signal. The combination of Atomic Force Microscopy (AFM) imaging with information included in SHG signal can
2008 8th IEEE International Conference on BioInformatics and BioEngineering, 2008
... Fluorescence Molecular Imaging Dimitris Gorpas, Kostas Politopoulos, and Dido Yova ... Phys. ... more ... Fluorescence Molecular Imaging Dimitris Gorpas, Kostas Politopoulos, and Dido Yova ... Phys. Lett. B, vol. 18, pp. 1-29, 2004. [10] F. Meyer and P. Maragos, "Multiscale Morphological Segmentations Based on Watershed, Flooding, and Eikonal PDE," Proc. ...
Collagen is the major fibrous protein in the extracellular matrix and consists a significant comp... more Collagen is the major fibrous protein in the extracellular matrix and consists a significant component of skin, bone, cartilage and tendon. Due to its unique properties, it has been widely used as scaffold or culture substrate for tissue regeneration or/and cell-substrate interaction studies. The ultraviolet light-collagen interaction investigations are crucial for the improvement of many applications such as that of the UV irradiation in the field of biomaterials, as sterilizing and photo-cross-linking method. The aim of this paper was to investigate the mechanisms of UV-collagen interactions by developing a collagen-based, well characterized, surface with controlled topography of collagen thin films in the nanoscale range. The methodology was to quantify the collagen surface modification induced on ultraviolet radiation and correlate it with changes induced in cells. Surface nanoscale characterization was performed by Atomic Force Microscopy (AFM) which is a powerful tool and offers quantitative and qualitative information with a non-destructive manner. In order to investigate cells behavior, the irradiated films were used for in vitro cultivation of human skin fibroblasts and the cells morphology, migration and alignment were assessed with fluorescence microscopy imaging and image processing methods. The clarification of the effects of UV light on collagen thin films and the way of cells behavior to the different modifications that UV induced to the collagen-based surfaces will contribute to the better understanding of cell-matrix interactions in the nanoscale and will assist the appropriate use of UV light for developing biomaterials.
Due to the heterogeneity and complexity of the skin, photo-shading techniques are suitable for 3D... more Due to the heterogeneity and complexity of the skin, photo-shading techniques are suitable for 3D reconstruction in cases where small scale (<1mm) features are present. That is because high scattering surfaces, like the skin, diffuse the projected light patterns used in range scanners, and thus reduce their accuracy. Shape-from-Shading (SfS) algorithms are free from such drawbacks, as they use shading information and exploit the full resolution of the imaging system. In this paper an improved SfS method, called Shape-from-Isophotes, is introduced. This method aims to overcome most of the disadvantages of classical SfS methods, like numerical instability. The SfI improvements include the addition of a constraint deriving from the properties of isophote curves, and the decomposition of the original shading image into two frequency bands. The first feature attempts to increase the numerical stability of the equation system, and the second to reconstruct both small scale and large scale surface variations with the same accuracy. These new features combined with the Lambertian model for skin reflectance aim to create an accurate reproduction of the human skin surface, both in three-dimensional shape and reflective behavior.
Low-level red laser (LLRL)-tissue interactions have a wide range of medical applications and are ... more Low-level red laser (LLRL)-tissue interactions have a wide range of medical applications and are garnering increased attention. Although the positive effects of low-level laser therapy (LLLT) have frequently been reported and enhanced collagen accumulation has been identified as one of the most important mechanisms involved, little is known about LLRL-collagen interactions. In this study, we aimed to investigate the influence of LLRL irradiation on collagen, in correlation with fibroblast response. Atomic force microscopy (AFM) and fluorescence spectroscopy were used to characterize surfaces and identify conformational changes in collagen before and after LLRL irradiation. Irradiated and non-irradiated collagen thin films were used as culturing substrates to investigate fibroblast response with fluorescence microscopy. The results demonstrated that LLRL induced small alterations in fluorescence emission and had a negligible effect on the topography of collagen thin films. However, fibroblasts cultured on LLRL-irradiated collagen thin films responded to LRLL. The results of this study show for the first time the effect of LLRL irradiation on pure collagen. Although irradiation did not affect the nanotopography of collagen, it influenced cell behavior. The role of collagen appears to be crucial in the LLLT mechanism, and our results demonstrated that LLRL directly affects collagen and indirectly affects cell behavior.
Elastin is an extracellular matrix protein, providing elasticity to the organs, such as skin, blo... more Elastin is an extracellular matrix protein, providing elasticity to the organs, such as skin, blood vessels, lungs and elastic ligaments, presenting self-assembling ability to form elastic fibers. The elastin protein, as a component of elastin fibers, is one of the major proteins found in connective tissue and is responsible for the elasticity of tissues. It provides resilience to the human body, assembled as a continuous mesh of fibers that require to be deformed repetitively and reversibly. Thus, it is of great importance to investigate the development of the nanostructural surface of elastin-based biomaterials. The purpose of this research was to image the self-assembling process of elastin fiber structure under different experimental parameters such as suspension medium, elastin concentration, temperature of stock suspension and time interval after the preparation of the stock suspension. atomic force microscopy (AFM) was applied in order to investigate how different experimenta...
The fingerprint is one of the most important biometrics, with many acquisition methods developed ... more The fingerprint is one of the most important biometrics, with many acquisition methods developed over the years. Traditional 2D acquisition techniques produce nonlinear distortions due to the forced flattening of the finger onto a 2D surface. These random elastic deformations often introduce matching errors, making 2D techniques less reliable. Inevitably non-contact 3D capturing techniques were developed in an effort to deal with these problems. In this study we present a novel non-contact single camera 3D fingerprint reconstruction system based on fringe projection and a new model for approximating the epidermal ridges. The 3D shape of the fingerprint is reconstructed from a single 2D shading image in two steps. First the original image is decomposed into structure and texture components by an advanced Meyer algorithm. The structural component is reconstructed by a classical fringe projection technique. The textural component, containing the fingerprint information, is restored usi...
ABSTRACT Collagen due to its filamentous shape and unique properties is a very promising molecule... more ABSTRACT Collagen due to its filamentous shape and unique properties is a very promising molecule for the development of nanostructures, scaffolds, cell culture platforms and nanobiomaterials. Furthermore, collagen thin films are of great interest as they can cover non-biological surfaces in medical devices and sensors so as to offer them biocompatibility. Since surface nanotopography and mechanical properties can influence cell-biomaterial interactions it is of crucial importance to nano-characterize collagen surface and heterogeneity. Nano-characterization can be performed with Atomic Force Microscopy (AFM), which operates in a variety of modes/techniques and can offer a wide range of information, from topography to mechanical properties. In this paper it was sought to gain insights of structural and mechanical heterogeneity of collagen fibers in thin films by combining AFM multimode-imaging, including phase imaging, with quantitative measurements through nanoindentation. The results demonstrated that the overlap-gap regions on collagen fibers (D-periodicity) yield a significant phase contrast, due to different mechanical properties. In addition, phase contrast was also demonstrated in collagen ‘kinks’, which provides evidence that collagen fiber shell and core possess different properties. The mechanical heterogeneity of the collagen fibers in the kink areas was confirmed by AFM-nanoindentation and the obtained quantitative measurements. In addition, AFM multimode imaging performance was demonstrated on fibroblasts cultured on collagen thin films. The correlation between the heterogeneous structure and the mechanical properties of collagen fibers in thin films will enable the design and development of biomaterials and tissue scaffolds with improved properties.
ABSTRACT The adsorption of collagen and the morphology of its assemblies at solid surfaces play a... more ABSTRACT The adsorption of collagen and the morphology of its assemblies at solid surfaces play an important role in a variety of research areas and applications, such as biomaterials, biocompatibility, tissue mechanics and cell studies. In this paper the nanoscale organization of type I collagen on polystyrene particle surfaces with controlled patterns was investigated by high-resolution atomic force microscopy. The results showed that patterned surfaces with a well-ordered morphology could be formed by spin coating polystyrene particles dispersions (20 sec at 1000 rpm) and appropriate annealing conditions (at 90°C for 2h). Collagen thin films consisting of fibers with natural characteristics, such as the typical 67nm periodicity (D-band), were formed on these nano-patterns. This kind of surfaces provides a useful substrate for studying the regulation of collagen assembly on substrates with different nano-topographical and environmental conditions and offers a potential way to create surfaces of functionalized and nano-patterend materials for biotechnological and biomedical applications.
Abstract Collagen is the most abundant extracellular matrix protein and is important for a varie... more Abstract Collagen is the most abundant extracellular matrix protein and is important for a variety of functions, including tissue scaffolding, cell adhesion, cell migration, angiogenesis, tissue morphogenesis and tissue repair. Collagen is considered as one of the most useful biomaterials since it is ...
2009 9th International Conference on Information Technology and Applications in Biomedicine, 2009
Collagen is the most abundant protein in mammals and is important for a variety of functions and ... more Collagen is the most abundant protein in mammals and is important for a variety of functions and its concentration, structure and function is associated with different pathological states. In this research we correlate structural changes with those changes in the Second Harmonic Generation (SHG) signal. The combination of Atomic Force Microscopy (AFM) imaging with information included in SHG signal can
2008 8th IEEE International Conference on BioInformatics and BioEngineering, 2008
... Fluorescence Molecular Imaging Dimitris Gorpas, Kostas Politopoulos, and Dido Yova ... Phys. ... more ... Fluorescence Molecular Imaging Dimitris Gorpas, Kostas Politopoulos, and Dido Yova ... Phys. Lett. B, vol. 18, pp. 1-29, 2004. [10] F. Meyer and P. Maragos, &amp;quot;Multiscale Morphological Segmentations Based on Watershed, Flooding, and Eikonal PDE,&amp;quot; Proc. ...
Collagen is the major fibrous protein in the extracellular matrix and consists a significant comp... more Collagen is the major fibrous protein in the extracellular matrix and consists a significant component of skin, bone, cartilage and tendon. Due to its unique properties, it has been widely used as scaffold or culture substrate for tissue regeneration or/and cell-substrate interaction studies. The ultraviolet light-collagen interaction investigations are crucial for the improvement of many applications such as that of the UV irradiation in the field of biomaterials, as sterilizing and photo-cross-linking method. The aim of this paper was to investigate the mechanisms of UV-collagen interactions by developing a collagen-based, well characterized, surface with controlled topography of collagen thin films in the nanoscale range. The methodology was to quantify the collagen surface modification induced on ultraviolet radiation and correlate it with changes induced in cells. Surface nanoscale characterization was performed by Atomic Force Microscopy (AFM) which is a powerful tool and offers quantitative and qualitative information with a non-destructive manner. In order to investigate cells behavior, the irradiated films were used for in vitro cultivation of human skin fibroblasts and the cells morphology, migration and alignment were assessed with fluorescence microscopy imaging and image processing methods. The clarification of the effects of UV light on collagen thin films and the way of cells behavior to the different modifications that UV induced to the collagen-based surfaces will contribute to the better understanding of cell-matrix interactions in the nanoscale and will assist the appropriate use of UV light for developing biomaterials.
Due to the heterogeneity and complexity of the skin, photo-shading techniques are suitable for 3D... more Due to the heterogeneity and complexity of the skin, photo-shading techniques are suitable for 3D reconstruction in cases where small scale (<1mm) features are present. That is because high scattering surfaces, like the skin, diffuse the projected light patterns used in range scanners, and thus reduce their accuracy. Shape-from-Shading (SfS) algorithms are free from such drawbacks, as they use shading information and exploit the full resolution of the imaging system. In this paper an improved SfS method, called Shape-from-Isophotes, is introduced. This method aims to overcome most of the disadvantages of classical SfS methods, like numerical instability. The SfI improvements include the addition of a constraint deriving from the properties of isophote curves, and the decomposition of the original shading image into two frequency bands. The first feature attempts to increase the numerical stability of the equation system, and the second to reconstruct both small scale and large scale surface variations with the same accuracy. These new features combined with the Lambertian model for skin reflectance aim to create an accurate reproduction of the human skin surface, both in three-dimensional shape and reflective behavior.
Atomic Force Microscopy (AFM) operates in a variety of modes and techniques. AFM can offer a wide... more Atomic Force Microscopy (AFM) operates in a variety of modes and techniques. AFM can offer a wide range of information, from topography to mechanical properties of surfaces and interfaces, including those of biomaterials and scaffolds. In this paper it was sought to gain insights of structural and mechanical heterogeneity of collagen fibers in thin films by combining AFM multimode imaging, including phase imaging, with quantitative measurements through nanoindetation. Due to its filamentous shape and its associative properties collagen type I is a very promising molecule for the development of nanostructures, scaffolds in tissue engineering and nanobiomaterials Since collagen based materials nanotopography and mechanical properties can influence cellbiomaterial/scaffold interactions it is of crucial importance to characterize its surface and heterogeneity in the nanoscale. Among the different collagen-based biomaterials, collagen thin films are of great interest since they possess unique properties and can be used for forming novel biomaterials or for covering non-biological surfaces in order to offer them biocompatibility. The results demonstrated that the overlap and gap region on collagen fibers (D-periodicity) yield a significant phase contrast, due to different mechanical properties. In addition, phase contrast was also demonstrated in kinks (areas where collagen fibers changes abruptly direction) which provides evidence that collagen fiber shell and core possess different properties. The quantitative measurements with nanoindentation method confirmed the heterogeneity of collagen fibers D-periodicity since overlapping zones were characterized by a higher Young modulus (0.7 GPa) than the gap zones (0.46 GPa). The correlation between the heterogeneous structure and the mechanical properties of collagen fibrils in thin films will enable the design and development of biomaterials and tissue scaffolds with improved properties, as well as it will enable the investigation of cell response on different nanoscale features.
Uploads
Papers by Dido K Yova