International Journal of Biological Macromolecules, 2013
Thermosensitive chitosan hydrogels containing sodium beta-glycerophosphate (-GP), whose gelation... more Thermosensitive chitosan hydrogels containing sodium beta-glycerophosphate (-GP), whose gelation is induced by increasing temperature to body temperature, were functionalized by incorporation of alkaline phosphatase (ALP), an enzyme involved in mineralization of bone. ALP incorporation led to acceleration of gelation upon increase of temperature for four different chitosan preparations of differing molecular weight, as demonstrated by rheometric time sweeps at 37 • C. Hydrogels containing ALP were subsequently incubated in calcium glycerophosphate (Ca-GP) solution to induce their mineralization with calcium phosphate (CaP) in order to improve their suitability as materials for bone replacement. Incorporated ALP retained its bioactivity and induced formation of CaP mineral, as confirmed by SEM, FTIR, Raman spectroscopy, XRD, ICP-OES, and increases in dry mass percentage, which rose with increasing ALP concentration and incubation time in Ca-GP solution. The results demonstrate that ALP accelerates formation of thermosensitive chitosan/-GP hydrogels and induces their mineralization with CaP, which paves the way for applications as injectable bone replacement materials.
Hydrogels of biocompatible calcium-crosslinkable polysaccharide gellan gum (GG) were enriched wit... more Hydrogels of biocompatible calcium-crosslinkable polysaccharide gellan gum (GG) were enriched with bioglass particles to enhance (i) mineralization with calcium phosphate (CaP); (ii) antibacterial properties and (iii) growth of bone-forming cells for future bone regeneration applications.
Journal of Tissue Engineering and Regenerative Medicine, 2014
Mineralization of hydrogels, desirable for bone regeneration applications, may be achieved enzyma... more Mineralization of hydrogels, desirable for bone regeneration applications, may be achieved enzymatically by incorporation of alkaline phosphatase (ALP). ALP-loaded gellan gum (GG) hydrogels were mineralized by incubation in mineralization media containing calcium and/or magnesium glycerophosphate (CaGP, MgGP). Mineralization media with CaGP:MgGP concentrations 0.1:0, 0.075:0.025, 0.05:0.05, 0.025:0.075 and 0:0.1 (all values mol/dm 3 , denoted A, B, C, D and E, respectively) were compared. Mineral formation was confirmed by IR and Raman, SEM, ICP-OES, XRD, TEM, SAED, TGA and increases in the the mass fraction of the hydrogel not consisting of water. Ca was incorporated into mineral to a greater extent than Mg in samples mineralized in media A-D. Mg content and amorphicity of mineral formed increased in the order A < B < C < D. Mineral formed in media A and B was calcium-deficient hydroxyapatite (CDHA). Mineral formed in medium C was a combination of CDHA and an amorphous phase. Mineral formed in medium D was an amorphous phase. Mineral formed in medium E was a combination of crystalline and amorphous MgP. Young's moduli and storage moduli decreased in dependence of mineralization medium in the order A > B > C > D, but were significantly higher for samples mineralized in medium E. The attachment and vitality of osteoblastic MC3T3-E1 cells were higher on samples mineralized in media B-E (containing Mg) than in those mineralized in medium A (not containing Mg). All samples underwent degradation and supported the adhesion of RAW 264.7 monocytic cells, and samples mineralized in media A and B supported osteoclast-like cell formation.
Alkaline phosphatase (ALP), an enzyme involved in mineralization of bone, is incorporated into th... more Alkaline phosphatase (ALP), an enzyme involved in mineralization of bone, is incorporated into three hydrogel biomaterials to induce their mineralization with calcium phosphate (CaP). These are collagen type I, a mussel-protein-inspired adhesive consisting of PEG substituted with catechol groups, cPEG, and the PEG/fumaric acid copolymer OPF. After incubation in Ca-GP solution, FTIR, EDS, SEM, XRD, SAED, ICP-OES, and von Kossa staining confirm CaP formation. The amount of mineral formed decreases in the order cPEG > collagen > OPF. The mineral:polymer ratio decreases in the order collagen > cPEG > OPF. Mineralization increases Young's modulus, most profoundly for cPEG. Such enzymatically mineralized hydrogel/CaP composites may find application as bone regeneration materials.
Polycaprolactone (PCL) is a biodegradable and biocompatible polyester whose low melting point fac... more Polycaprolactone (PCL) is a biodegradable and biocompatible polyester whose low melting point facilitates production of 3D porous scaffolds with precisely defined dimensions and internal architecture by rapid prototyping techniques. To improve the suitability of such PCL scaffolds for bone regeneration applications, they were coated with inorganic layers of calcium phosphate (CaP) and CaP doped with 0.6% w/v magnesium (CaP þ Mg) using pulsed laser deposition (PLD) and characterized in vitro using osteoblast-like Saos-2 cells. Saos-2 cells were able to adhere to all scaffolds. CaP þMg coatings significantly increased activity of alkaline phosphatase (ALP), an early differentiation marker, after 7 days. However, gene expression of ALP after 7 days was markedly lower on the same scaffolds.
Hydrogel biomaterials can be easily enriched with bioactive substances such as the mineralization... more Hydrogel biomaterials can be easily enriched with bioactive substances such as the mineralizationpromoting enzyme alkaline phosphatase (ALP). In this study, poly(vinyl alcohol) (PVA) hydrogels designed for osteochondral regeneration containing incorporated ALP were mineralized with calcium phosphate (CaP) and magnesium phosphate (MgP) by incubation in solutions of 0.1 M calcium or magnesium glycerophosphate (CaGP, MgGP). Hydrogels incubated in water served as controls.
International Journal of Biological Macromolecules, 2013
Thermosensitive chitosan hydrogels containing sodium beta-glycerophosphate (-GP), whose gelation... more Thermosensitive chitosan hydrogels containing sodium beta-glycerophosphate (-GP), whose gelation is induced by increasing temperature to body temperature, were functionalized by incorporation of alkaline phosphatase (ALP), an enzyme involved in mineralization of bone. ALP incorporation led to acceleration of gelation upon increase of temperature for four different chitosan preparations of differing molecular weight, as demonstrated by rheometric time sweeps at 37 • C. Hydrogels containing ALP were subsequently incubated in calcium glycerophosphate (Ca-GP) solution to induce their mineralization with calcium phosphate (CaP) in order to improve their suitability as materials for bone replacement. Incorporated ALP retained its bioactivity and induced formation of CaP mineral, as confirmed by SEM, FTIR, Raman spectroscopy, XRD, ICP-OES, and increases in dry mass percentage, which rose with increasing ALP concentration and incubation time in Ca-GP solution. The results demonstrate that ALP accelerates formation of thermosensitive chitosan/-GP hydrogels and induces their mineralization with CaP, which paves the way for applications as injectable bone replacement materials.
Hydrogels of biocompatible calcium-crosslinkable polysaccharide gellan gum (GG) were enriched wit... more Hydrogels of biocompatible calcium-crosslinkable polysaccharide gellan gum (GG) were enriched with bioglass particles to enhance (i) mineralization with calcium phosphate (CaP); (ii) antibacterial properties and (iii) growth of bone-forming cells for future bone regeneration applications.
Journal of Tissue Engineering and Regenerative Medicine, 2014
Mineralization of hydrogels, desirable for bone regeneration applications, may be achieved enzyma... more Mineralization of hydrogels, desirable for bone regeneration applications, may be achieved enzymatically by incorporation of alkaline phosphatase (ALP). ALP-loaded gellan gum (GG) hydrogels were mineralized by incubation in mineralization media containing calcium and/or magnesium glycerophosphate (CaGP, MgGP). Mineralization media with CaGP:MgGP concentrations 0.1:0, 0.075:0.025, 0.05:0.05, 0.025:0.075 and 0:0.1 (all values mol/dm 3 , denoted A, B, C, D and E, respectively) were compared. Mineral formation was confirmed by IR and Raman, SEM, ICP-OES, XRD, TEM, SAED, TGA and increases in the the mass fraction of the hydrogel not consisting of water. Ca was incorporated into mineral to a greater extent than Mg in samples mineralized in media A-D. Mg content and amorphicity of mineral formed increased in the order A < B < C < D. Mineral formed in media A and B was calcium-deficient hydroxyapatite (CDHA). Mineral formed in medium C was a combination of CDHA and an amorphous phase. Mineral formed in medium D was an amorphous phase. Mineral formed in medium E was a combination of crystalline and amorphous MgP. Young's moduli and storage moduli decreased in dependence of mineralization medium in the order A > B > C > D, but were significantly higher for samples mineralized in medium E. The attachment and vitality of osteoblastic MC3T3-E1 cells were higher on samples mineralized in media B-E (containing Mg) than in those mineralized in medium A (not containing Mg). All samples underwent degradation and supported the adhesion of RAW 264.7 monocytic cells, and samples mineralized in media A and B supported osteoclast-like cell formation.
Journal of tissue engineering and regenerative medicine, Jan 15, 2015
Porous biodegradable scaffolds represent promising candidates for tissue-engineering applications... more Porous biodegradable scaffolds represent promising candidates for tissue-engineering applications because of their capability to be preseeded with cells. We report an uncrosslinked chitosan scaffold designed with the aim of inducing and supporting enzyme-mediated formation of apatite minerals in the absence of osteogenic growth factors. To realize this, natural enzyme alkaline phosphatase (ALP) was incorporated into uncrosslinked chitosan scaffolds. The uncrosslinked chitosan makes available amine and alcohol functionalities to enhance the biomineralization process. The physicochemical findings revealed homogeneous mineralization, with the phase structure of the formed minerals resembling that of apatite at low mineral concentrations, and similar to dicalcium phosphate dihydrate (DCPD) with increasing ALP content. The MC3T3 cell activity clearly showed that the mineralization of the chitosan scaffolds was effective in improving cellular adhesion, proliferation and colonization. Copy...
Journal of the Society for Information Display, 2013
A contact lens embeddable display using electro-optic modulation was designed and fabricated. Usi... more A contact lens embeddable display using electro-optic modulation was designed and fabricated. Using a guest-host liquid crystal configuration, a spherically deformed liquid crystal cell was fabricated comprising poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT : PSS) as a conductive layer and obliquely evaporated SiO 2 as an alignment layer. An additional SiO 2 buffer layer was evaporated on top of the PEDOT : PSS to overcome compatibility problems with the patterning of the photolithographically defined spacers. Although the contrast is modest, a patterned modulation could clearly be observed, indicating that our approach and fabrication process could eventually lead to a fully pixelated contact lens display.
Despite promising results of Er:YAG laser in periodontal debridement, to date there is no consens... more Despite promising results of Er:YAG laser in periodontal debridement, to date there is no consensus about the ideal settings for clinical use. This experimental clinical trial aimed to determine the effects of debridement using Er:YAG laser and to compare with ultrasonic treatment. Sixty-four teeth were divided into two in vivo and in vitro subgroups. Each tooth received ultrasonic treatment on one side and Er:YAG laser debridement at either 60, 100, 160 or 250 mJ pulse(-1) and at 10 Hz on the other side on a random basis. All samples were morphologically analyzed afterwards under scanning electron microscope for surface changes and dentinal tubules exposure. Treatment duration (d) was also recorded. Laser debridement produced an irregular, rough and flaky surface free of carbonization or meltdown while ultrasound produced a relatively smoother surface. The number of exposed dentinal tubules (n) followed an energy-dependent trend. The number of exposed tubules among the in vivo lase...
In the last decade, substantial research in the field of post-plasma grafting surface modificatio... more In the last decade, substantial research in the field of post-plasma grafting surface modification has focussed on the introduction of carboxylic acids on surfaces by grafting acrylic acid (AAc). In the present work, we report on an alternative approach for biomaterial surface functionalisation. Thin poly-ε-caprolactone (PCL) films were subjected to a dielectric barrier discharge Ar-plasma followed by the grafting of 2-aminoethyl methacrylate (AEMA) under UV-irradiation. X-ray photoelectron spectroscopy (XPS) confirmed the presence of nitrogen. The ninhydrin assay demonstrated, both quantitatively and qualitatively, the presence of free amines on the surface. Confocal fluorescence microscopy (CFM), atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to visualise the grafted surfaces, indicating the presence of pAEMA. Static contact angle (SCA) measurements indicated a permanent increase in hydrophilicity. Furthermore, the AEMA grafted surfaces were applied for comparing the physisorption and covalent immobilisation of gelatin. CFM demonstrated that only the covalent immobilisation lead to a complete coverage of the surface. Those gelatin-coated surfaces obtained were further coated using fibronectin. Osteosarcoma cells demonstrated better cell-adhesion and cell-viability on the modified surfaces, compared to the pure PCL films.
Journal of Tissue Engineering and Regenerative Medicine, 2014
Mineralization of hydrogels, desirable for bone regeneration applications, may be achieved enzyma... more Mineralization of hydrogels, desirable for bone regeneration applications, may be achieved enzymatically by incorporation of alkaline phosphatase (ALP). ALP-loaded gellan gum (GG) hydrogels were mineralized by incubation in mineralization media containing calcium and/or magnesium glycerophosphate (CaGP, MgGP). Mineralization media with CaGP:MgGP concentrations 0.1:0, 0.075:0.025, 0.05:0.05, 0.025:0.075 and 0:0.1 (all values mol/dm 3 , denoted A, B, C, D and E, respectively) were compared. Mineral formation was confirmed by IR and Raman, SEM, ICP-OES, XRD, TEM, SAED, TGA and increases in the the mass fraction of the hydrogel not consisting of water. Ca was incorporated into mineral to a greater extent than Mg in samples mineralized in media A-D. Mg content and amorphicity of mineral formed increased in the order A < B < C < D. Mineral formed in media A and B was calcium-deficient hydroxyapatite (CDHA). Mineral formed in medium C was a combination of CDHA and an amorphous phase. Mineral formed in medium D was an amorphous phase. Mineral formed in medium E was a combination of crystalline and amorphous MgP. Young's moduli and storage moduli decreased in dependence of mineralization medium in the order A > B > C > D, but were significantly higher for samples mineralized in medium E. The attachment and vitality of osteoblastic MC3T3-E1 cells were higher on samples mineralized in media B-E (containing Mg) than in those mineralized in medium A (not containing Mg). All samples underwent degradation and supported the adhesion of RAW 264.7 monocytic cells, and samples mineralized in media A and B supported osteoclast-like cell formation.
The presence of polyamine groups on the surface of dielectrics potentially improves the adhesion ... more The presence of polyamine groups on the surface of dielectrics potentially improves the adhesion with electrochemically deposited metals. In this article, first cyanuric chloride is covalently bound to the surface hydroxyl groups of the epoxy resin. The remaining reactive sites on the ...
The fast-growing market of organic electronics stimulates the development of versatile technologi... more The fast-growing market of organic electronics stimulates the development of versatile technologies for structuring thin-film materials. Ultraviolet lasers have proven their full potential for patterning organic thin films, but only a few studies report on interaction with thin-film barrier layers. In this paper, we present an approach in which the laser patterning process is optimized together with the barrier film, leading to a highly selective patterning technology without introducing barrier damage. This optimization is crucial, as the barrier damage would lead to moisture and oxygen ingress, with accelerated device degradation as a result. Following process optimization, a laser processed flexible organic LED has been fabricated and thin-film encapsulated and its operation is shown for the first time in atmospheric conditions.
The presence of polyamine groups on the surface of dielectrics potentially improves the adhesion ... more The presence of polyamine groups on the surface of dielectrics potentially improves the adhesion with electrochemically deposited metals. In this article, first cyanuric chloride is covalently bound to the surface hydroxyl groups of the epoxy resin. The remaining reactive sites on the ...
International Journal of Biological Macromolecules, 2013
Thermosensitive chitosan hydrogels containing sodium beta-glycerophosphate (-GP), whose gelation... more Thermosensitive chitosan hydrogels containing sodium beta-glycerophosphate (-GP), whose gelation is induced by increasing temperature to body temperature, were functionalized by incorporation of alkaline phosphatase (ALP), an enzyme involved in mineralization of bone. ALP incorporation led to acceleration of gelation upon increase of temperature for four different chitosan preparations of differing molecular weight, as demonstrated by rheometric time sweeps at 37 • C. Hydrogels containing ALP were subsequently incubated in calcium glycerophosphate (Ca-GP) solution to induce their mineralization with calcium phosphate (CaP) in order to improve their suitability as materials for bone replacement. Incorporated ALP retained its bioactivity and induced formation of CaP mineral, as confirmed by SEM, FTIR, Raman spectroscopy, XRD, ICP-OES, and increases in dry mass percentage, which rose with increasing ALP concentration and incubation time in Ca-GP solution. The results demonstrate that ALP accelerates formation of thermosensitive chitosan/-GP hydrogels and induces their mineralization with CaP, which paves the way for applications as injectable bone replacement materials.
Hydrogels of biocompatible calcium-crosslinkable polysaccharide gellan gum (GG) were enriched wit... more Hydrogels of biocompatible calcium-crosslinkable polysaccharide gellan gum (GG) were enriched with bioglass particles to enhance (i) mineralization with calcium phosphate (CaP); (ii) antibacterial properties and (iii) growth of bone-forming cells for future bone regeneration applications.
Journal of Tissue Engineering and Regenerative Medicine, 2014
Mineralization of hydrogels, desirable for bone regeneration applications, may be achieved enzyma... more Mineralization of hydrogels, desirable for bone regeneration applications, may be achieved enzymatically by incorporation of alkaline phosphatase (ALP). ALP-loaded gellan gum (GG) hydrogels were mineralized by incubation in mineralization media containing calcium and/or magnesium glycerophosphate (CaGP, MgGP). Mineralization media with CaGP:MgGP concentrations 0.1:0, 0.075:0.025, 0.05:0.05, 0.025:0.075 and 0:0.1 (all values mol/dm 3 , denoted A, B, C, D and E, respectively) were compared. Mineral formation was confirmed by IR and Raman, SEM, ICP-OES, XRD, TEM, SAED, TGA and increases in the the mass fraction of the hydrogel not consisting of water. Ca was incorporated into mineral to a greater extent than Mg in samples mineralized in media A-D. Mg content and amorphicity of mineral formed increased in the order A < B < C < D. Mineral formed in media A and B was calcium-deficient hydroxyapatite (CDHA). Mineral formed in medium C was a combination of CDHA and an amorphous phase. Mineral formed in medium D was an amorphous phase. Mineral formed in medium E was a combination of crystalline and amorphous MgP. Young's moduli and storage moduli decreased in dependence of mineralization medium in the order A > B > C > D, but were significantly higher for samples mineralized in medium E. The attachment and vitality of osteoblastic MC3T3-E1 cells were higher on samples mineralized in media B-E (containing Mg) than in those mineralized in medium A (not containing Mg). All samples underwent degradation and supported the adhesion of RAW 264.7 monocytic cells, and samples mineralized in media A and B supported osteoclast-like cell formation.
Alkaline phosphatase (ALP), an enzyme involved in mineralization of bone, is incorporated into th... more Alkaline phosphatase (ALP), an enzyme involved in mineralization of bone, is incorporated into three hydrogel biomaterials to induce their mineralization with calcium phosphate (CaP). These are collagen type I, a mussel-protein-inspired adhesive consisting of PEG substituted with catechol groups, cPEG, and the PEG/fumaric acid copolymer OPF. After incubation in Ca-GP solution, FTIR, EDS, SEM, XRD, SAED, ICP-OES, and von Kossa staining confirm CaP formation. The amount of mineral formed decreases in the order cPEG > collagen > OPF. The mineral:polymer ratio decreases in the order collagen > cPEG > OPF. Mineralization increases Young's modulus, most profoundly for cPEG. Such enzymatically mineralized hydrogel/CaP composites may find application as bone regeneration materials.
Polycaprolactone (PCL) is a biodegradable and biocompatible polyester whose low melting point fac... more Polycaprolactone (PCL) is a biodegradable and biocompatible polyester whose low melting point facilitates production of 3D porous scaffolds with precisely defined dimensions and internal architecture by rapid prototyping techniques. To improve the suitability of such PCL scaffolds for bone regeneration applications, they were coated with inorganic layers of calcium phosphate (CaP) and CaP doped with 0.6% w/v magnesium (CaP þ Mg) using pulsed laser deposition (PLD) and characterized in vitro using osteoblast-like Saos-2 cells. Saos-2 cells were able to adhere to all scaffolds. CaP þMg coatings significantly increased activity of alkaline phosphatase (ALP), an early differentiation marker, after 7 days. However, gene expression of ALP after 7 days was markedly lower on the same scaffolds.
Hydrogel biomaterials can be easily enriched with bioactive substances such as the mineralization... more Hydrogel biomaterials can be easily enriched with bioactive substances such as the mineralizationpromoting enzyme alkaline phosphatase (ALP). In this study, poly(vinyl alcohol) (PVA) hydrogels designed for osteochondral regeneration containing incorporated ALP were mineralized with calcium phosphate (CaP) and magnesium phosphate (MgP) by incubation in solutions of 0.1 M calcium or magnesium glycerophosphate (CaGP, MgGP). Hydrogels incubated in water served as controls.
International Journal of Biological Macromolecules, 2013
Thermosensitive chitosan hydrogels containing sodium beta-glycerophosphate (-GP), whose gelation... more Thermosensitive chitosan hydrogels containing sodium beta-glycerophosphate (-GP), whose gelation is induced by increasing temperature to body temperature, were functionalized by incorporation of alkaline phosphatase (ALP), an enzyme involved in mineralization of bone. ALP incorporation led to acceleration of gelation upon increase of temperature for four different chitosan preparations of differing molecular weight, as demonstrated by rheometric time sweeps at 37 • C. Hydrogels containing ALP were subsequently incubated in calcium glycerophosphate (Ca-GP) solution to induce their mineralization with calcium phosphate (CaP) in order to improve their suitability as materials for bone replacement. Incorporated ALP retained its bioactivity and induced formation of CaP mineral, as confirmed by SEM, FTIR, Raman spectroscopy, XRD, ICP-OES, and increases in dry mass percentage, which rose with increasing ALP concentration and incubation time in Ca-GP solution. The results demonstrate that ALP accelerates formation of thermosensitive chitosan/-GP hydrogels and induces their mineralization with CaP, which paves the way for applications as injectable bone replacement materials.
Hydrogels of biocompatible calcium-crosslinkable polysaccharide gellan gum (GG) were enriched wit... more Hydrogels of biocompatible calcium-crosslinkable polysaccharide gellan gum (GG) were enriched with bioglass particles to enhance (i) mineralization with calcium phosphate (CaP); (ii) antibacterial properties and (iii) growth of bone-forming cells for future bone regeneration applications.
Journal of Tissue Engineering and Regenerative Medicine, 2014
Mineralization of hydrogels, desirable for bone regeneration applications, may be achieved enzyma... more Mineralization of hydrogels, desirable for bone regeneration applications, may be achieved enzymatically by incorporation of alkaline phosphatase (ALP). ALP-loaded gellan gum (GG) hydrogels were mineralized by incubation in mineralization media containing calcium and/or magnesium glycerophosphate (CaGP, MgGP). Mineralization media with CaGP:MgGP concentrations 0.1:0, 0.075:0.025, 0.05:0.05, 0.025:0.075 and 0:0.1 (all values mol/dm 3 , denoted A, B, C, D and E, respectively) were compared. Mineral formation was confirmed by IR and Raman, SEM, ICP-OES, XRD, TEM, SAED, TGA and increases in the the mass fraction of the hydrogel not consisting of water. Ca was incorporated into mineral to a greater extent than Mg in samples mineralized in media A-D. Mg content and amorphicity of mineral formed increased in the order A < B < C < D. Mineral formed in media A and B was calcium-deficient hydroxyapatite (CDHA). Mineral formed in medium C was a combination of CDHA and an amorphous phase. Mineral formed in medium D was an amorphous phase. Mineral formed in medium E was a combination of crystalline and amorphous MgP. Young's moduli and storage moduli decreased in dependence of mineralization medium in the order A > B > C > D, but were significantly higher for samples mineralized in medium E. The attachment and vitality of osteoblastic MC3T3-E1 cells were higher on samples mineralized in media B-E (containing Mg) than in those mineralized in medium A (not containing Mg). All samples underwent degradation and supported the adhesion of RAW 264.7 monocytic cells, and samples mineralized in media A and B supported osteoclast-like cell formation.
Journal of tissue engineering and regenerative medicine, Jan 15, 2015
Porous biodegradable scaffolds represent promising candidates for tissue-engineering applications... more Porous biodegradable scaffolds represent promising candidates for tissue-engineering applications because of their capability to be preseeded with cells. We report an uncrosslinked chitosan scaffold designed with the aim of inducing and supporting enzyme-mediated formation of apatite minerals in the absence of osteogenic growth factors. To realize this, natural enzyme alkaline phosphatase (ALP) was incorporated into uncrosslinked chitosan scaffolds. The uncrosslinked chitosan makes available amine and alcohol functionalities to enhance the biomineralization process. The physicochemical findings revealed homogeneous mineralization, with the phase structure of the formed minerals resembling that of apatite at low mineral concentrations, and similar to dicalcium phosphate dihydrate (DCPD) with increasing ALP content. The MC3T3 cell activity clearly showed that the mineralization of the chitosan scaffolds was effective in improving cellular adhesion, proliferation and colonization. Copy...
Journal of the Society for Information Display, 2013
A contact lens embeddable display using electro-optic modulation was designed and fabricated. Usi... more A contact lens embeddable display using electro-optic modulation was designed and fabricated. Using a guest-host liquid crystal configuration, a spherically deformed liquid crystal cell was fabricated comprising poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT : PSS) as a conductive layer and obliquely evaporated SiO 2 as an alignment layer. An additional SiO 2 buffer layer was evaporated on top of the PEDOT : PSS to overcome compatibility problems with the patterning of the photolithographically defined spacers. Although the contrast is modest, a patterned modulation could clearly be observed, indicating that our approach and fabrication process could eventually lead to a fully pixelated contact lens display.
Despite promising results of Er:YAG laser in periodontal debridement, to date there is no consens... more Despite promising results of Er:YAG laser in periodontal debridement, to date there is no consensus about the ideal settings for clinical use. This experimental clinical trial aimed to determine the effects of debridement using Er:YAG laser and to compare with ultrasonic treatment. Sixty-four teeth were divided into two in vivo and in vitro subgroups. Each tooth received ultrasonic treatment on one side and Er:YAG laser debridement at either 60, 100, 160 or 250 mJ pulse(-1) and at 10 Hz on the other side on a random basis. All samples were morphologically analyzed afterwards under scanning electron microscope for surface changes and dentinal tubules exposure. Treatment duration (d) was also recorded. Laser debridement produced an irregular, rough and flaky surface free of carbonization or meltdown while ultrasound produced a relatively smoother surface. The number of exposed dentinal tubules (n) followed an energy-dependent trend. The number of exposed tubules among the in vivo lase...
In the last decade, substantial research in the field of post-plasma grafting surface modificatio... more In the last decade, substantial research in the field of post-plasma grafting surface modification has focussed on the introduction of carboxylic acids on surfaces by grafting acrylic acid (AAc). In the present work, we report on an alternative approach for biomaterial surface functionalisation. Thin poly-ε-caprolactone (PCL) films were subjected to a dielectric barrier discharge Ar-plasma followed by the grafting of 2-aminoethyl methacrylate (AEMA) under UV-irradiation. X-ray photoelectron spectroscopy (XPS) confirmed the presence of nitrogen. The ninhydrin assay demonstrated, both quantitatively and qualitatively, the presence of free amines on the surface. Confocal fluorescence microscopy (CFM), atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to visualise the grafted surfaces, indicating the presence of pAEMA. Static contact angle (SCA) measurements indicated a permanent increase in hydrophilicity. Furthermore, the AEMA grafted surfaces were applied for comparing the physisorption and covalent immobilisation of gelatin. CFM demonstrated that only the covalent immobilisation lead to a complete coverage of the surface. Those gelatin-coated surfaces obtained were further coated using fibronectin. Osteosarcoma cells demonstrated better cell-adhesion and cell-viability on the modified surfaces, compared to the pure PCL films.
Journal of Tissue Engineering and Regenerative Medicine, 2014
Mineralization of hydrogels, desirable for bone regeneration applications, may be achieved enzyma... more Mineralization of hydrogels, desirable for bone regeneration applications, may be achieved enzymatically by incorporation of alkaline phosphatase (ALP). ALP-loaded gellan gum (GG) hydrogels were mineralized by incubation in mineralization media containing calcium and/or magnesium glycerophosphate (CaGP, MgGP). Mineralization media with CaGP:MgGP concentrations 0.1:0, 0.075:0.025, 0.05:0.05, 0.025:0.075 and 0:0.1 (all values mol/dm 3 , denoted A, B, C, D and E, respectively) were compared. Mineral formation was confirmed by IR and Raman, SEM, ICP-OES, XRD, TEM, SAED, TGA and increases in the the mass fraction of the hydrogel not consisting of water. Ca was incorporated into mineral to a greater extent than Mg in samples mineralized in media A-D. Mg content and amorphicity of mineral formed increased in the order A < B < C < D. Mineral formed in media A and B was calcium-deficient hydroxyapatite (CDHA). Mineral formed in medium C was a combination of CDHA and an amorphous phase. Mineral formed in medium D was an amorphous phase. Mineral formed in medium E was a combination of crystalline and amorphous MgP. Young's moduli and storage moduli decreased in dependence of mineralization medium in the order A > B > C > D, but were significantly higher for samples mineralized in medium E. The attachment and vitality of osteoblastic MC3T3-E1 cells were higher on samples mineralized in media B-E (containing Mg) than in those mineralized in medium A (not containing Mg). All samples underwent degradation and supported the adhesion of RAW 264.7 monocytic cells, and samples mineralized in media A and B supported osteoclast-like cell formation.
The presence of polyamine groups on the surface of dielectrics potentially improves the adhesion ... more The presence of polyamine groups on the surface of dielectrics potentially improves the adhesion with electrochemically deposited metals. In this article, first cyanuric chloride is covalently bound to the surface hydroxyl groups of the epoxy resin. The remaining reactive sites on the ...
The fast-growing market of organic electronics stimulates the development of versatile technologi... more The fast-growing market of organic electronics stimulates the development of versatile technologies for structuring thin-film materials. Ultraviolet lasers have proven their full potential for patterning organic thin films, but only a few studies report on interaction with thin-film barrier layers. In this paper, we present an approach in which the laser patterning process is optimized together with the barrier film, leading to a highly selective patterning technology without introducing barrier damage. This optimization is crucial, as the barrier damage would lead to moisture and oxygen ingress, with accelerated device degradation as a result. Following process optimization, a laser processed flexible organic LED has been fabricated and thin-film encapsulated and its operation is shown for the first time in atmospheric conditions.
The presence of polyamine groups on the surface of dielectrics potentially improves the adhesion ... more The presence of polyamine groups on the surface of dielectrics potentially improves the adhesion with electrochemically deposited metals. In this article, first cyanuric chloride is covalently bound to the surface hydroxyl groups of the epoxy resin. The remaining reactive sites on the ...
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Papers by D. Schaubroeck