Håkan Engqvist | Uppsala University (original) (raw)

Papers by Håkan Engqvist

Research paper thumbnail of Co-loading of bisphosphonates and antibiotics to a biomimetic hydroxyapatite coating

Biotechnology Letters, 2011

Research paper thumbnail of Co-loading of bisphosphonates and antibiotics to a biomimetic hydroxyapatite coating

Biotechnology Letters, 2011

Research paper thumbnail of Cytotoxicity of modified glass ionomer cement on odontoblast cells

Journal of materials science. Materials in medicine, 2016

Recently a modified glass ionomer cement (GIC) with enhanced bioactivity due to the incorporation... more Recently a modified glass ionomer cement (GIC) with enhanced bioactivity due to the incorporation of wollastonite or mineral trioxide aggregate (MTA) has been reported. The aim of this study was to evaluate the cytotoxic effect of the modified GIC on odontoblast-like cells. The cytotoxicity of a conventional GIC, wollastonite modified GIC (W-mGIC), MTA modified GIC (M-mGIC) and MTA cement has been evaluated using cement extracts, a culture media modified by the cement. Ion concentration and pH of each material in the culture media were measured and correlated to the results of the cytotoxicity study. Among the four groups, conventional GIC showed the most cytotoxicity effect, followed by W-mGIC and M-mGIC. MTA showed the least toxic effect. GIC showed the lowest pH (6.36) while MTA showed the highest (8.62). In terms of ion concentration, MTA showed the largest Ca(2+) concentration (467.3 mg/L) while GIC showed the highest concentration of Si(4+) (19.9 mg/L), Al(3+) (7.2 mg/L) and S...

Research paper thumbnail of The effect of oligo(trimethylene carbonate) addition on the stiffness of acrylic bone cement

Research paper thumbnail of Mechanical Testing of Chemically Bonded Bioactive Ceramic Materials

Key Engineering Materials, 2004

Research paper thumbnail of Synthetic Geopolymers for Controlled Delivery of Oxycodone: Adjustable and Nanostructured Porosity Enables Tunable and Sustained Drug Release

Research paper thumbnail of Injectable Bone Cements for Vertebroplasty Studied in Sheep Vertebrae with Electron Microscopy

Key Engineering Materials, 2007

Vertebral compression fractures were simulated by making a hole into sheep vertebrae and by injec... more Vertebral compression fractures were simulated by making a hole into sheep vertebrae and by injecting a stabilizing material. The injectable bio-ceramic Xeraspine™ was evaluated together with a commercially available PMMA (Vertebroplastic™) as the reference material. The Vertebrae were harvested after 7 days and prepared for microscopy. The samples were deposited with gold on the surface and thereafter subjected to SEM and EDX analysis. It was found that the Xeraspine-bone interface was composed of a mixture of elements. The Vertebroplastic implant was embedded in a carbon containing tissue, likely a soft tissue capsule. The Xeraspine sample was subjected to high resolution analysis in the TEM combined with EDX measurements. The TEM sample was prepared with a novel technique for preparation of the tissue-material interface (FIB). In the TEM analysis it was found that the interface region consists of ZrO2 together with a mixture possibly consisting of katoite and apatite formed during setting and/or originating from the boneapatite.

Research paper thumbnail of Spark plasma sintered β-phase silicon nitride with Sr and Ca as a sintering aid for load bearing medical applications

Journal of the European Ceramic Society, 2012

Research paper thumbnail of Characterization of the Tissue-Bioceramic Interface In Vivo Using New Preparation and Analytical Tools

Advances in Science and Technology, 2006

A key feature in the understanding of the mechanisms of integration of implant materials is a dee... more A key feature in the understanding of the mechanisms of integration of implant materials is a deepened in-sight of the elemental and molecular composition of the interface zone between the implant and tissue. To analyze the interface at the ultrastructural level, transmission electron microscopy (TEM) is needed. However, techniques to fabricate thin foils for TEM are difficult and time consuming. By using focused ion beam microscopy (FIB) for site-specific preparation of TEM-samples, intact interfaces between bioceramics and calcified tissue can be prepared. The site-specific accuracy of the technique is about 1 mm. By using a dual-beam FIB, which is a combined scanning electron and focused ion beam microscope, the sample can be imaged with both electrons and ions (generating both secondary electrons and ions). Results from interface studies between Ca-aluminate based orthopaedic cement, dental materials, HA-coated Ti-implants and bone are presented. The interfaces were imaged in sc...

Research paper thumbnail of Effect of Calcium and Strontium on Mesoporous Titania Coatings for Implant Applications

Journal of Biomaterials and Nanobiotechnology, 2013

Research paper thumbnail of Phase formation of CaAl2O4 from CaCO3–Al2O3 powder mixtures

Journal of the European Ceramic Society, 2008

In this paper the formation of CaAl 2 O 4 from CaCO 3 –Al 2 O 3 powder mixtures has been studied,... more In this paper the formation of CaAl 2 O 4 from CaCO 3 –Al 2 O 3 powder mixtures has been studied, varying holding times between 1 and 40 h and temperatures between 1300 and 1500 °C. Phase formation was studied in samples both quenched from the holding ...

Research paper thumbnail of Mesoporous titania implant coatings with and without calcium and strontium ion incorporation

Research paper thumbnail of In Vitro Mechanical Properties of a Calcium Silicate Based Bone Void Filler

Key Engineering Materials, 2006

Research paper thumbnail of Development of a Dental Hybrid Material between a Biomineral and a Glass Ionomer Cement

Key Engineering Materials, 2005

Research paper thumbnail of Evaluation of In Vitro Bioactivity of Different Types of Biomaterials

INTRODUCTION: Biomaterials are often classified as inert, biodegradable or bioactive materials. F... more INTRODUCTION: Biomaterials are often classified as inert, biodegradable or bioactive materials. For all known bioactive materials an interfacial layer of apatite towards the tissue is formed (1-2). This finding is used in in vitro tests in screening potentially bioactive materials. In this study different types of potentially bioactive materials including a metal, an oxide and some chemically bonded ceramics were

Research paper thumbnail of Comparative Study of the Behaviour of a Novel Injectable Bioceramic in Sheep Vertebrae

Research paper thumbnail of In Vitro Bioactivity of Injectable Ceramic Orthopaedic Cements

Key Engineering Materials, 2006

Research paper thumbnail of The influence of Sr content in calcium phosphate coatings

Materials science & engineering. C, Materials for biological applications, 2015

In this study calcium phosphate coatings with different amounts of strontium (Sr) were prepared u... more In this study calcium phosphate coatings with different amounts of strontium (Sr) were prepared using a biomineralization method. The incorporation of Sr changed the composition and morphology of coatings from plate-like to sphere-like morphology. Dissolution testing indicated that the solubility of the coatings increased with increased Sr concentration. Evaluation of extracts (with Sr concentrations ranging from 0 to 2.37μg/mL) from the HA, 0.06Sr, 0.6Sr, and 1.2Sr coatings during in vitro cell cultures showed that Sr incorporation into coatings significantly enhanced the ALP activity in comparison to cells treated with control and HA eluted media. These findings show that calcium phosphate coatings could promote osteogenic differentiation even in a low amount of strontium.

Research paper thumbnail of Bioceramic microneedles with flexible and self-swelling substrate

European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V, Jan 27, 2015

To reduce the effort required to penetrate the skin and optimize drug release profiles, biocerami... more To reduce the effort required to penetrate the skin and optimize drug release profiles, bioceramic microneedle arrays with higher-aspect-ratio needles and a flexible and self-swelling substrate have been developed. Swelling of the substrate can assist in separating it from the needles and leave them in the skin as a drug depot. The preparation procedures for this bioceramic microneedle are described in the paper. Clonidine hydrochloride, the model drug, was released in a controlled manner by the microneedle device in vitro. Results showed that the microneedle array with a flexible and self-swelling substrate released the drug content faster than the array with a rigid substrate. Disintegration of the needle material and diffusion of the drug molecules are believed as the main control mechanisms of the drug release from these microneedle arrays. Ex vivo skin penetration showed that they can effectively penetrate the stratum corneum without an extra device. This work represents a prog...

Research paper thumbnail of Transmission Electron Microscopy studies of bio-implant interfaces using Focused Ion Beam microscopy for sample preparation

Biocompatibility of metallic implants is governed by surface characteristics. TEM sample preparat... more Biocompatibility of metallic implants is governed by surface characteristics. TEM sample preparation using FIB microscopy very much facilitates our research concerning implant-tissue interfaces as well as studies of bioactive surfaces. This talk will cover some of our research on bioactive titanium surfaces and interfaces of titanium and bone.

Research paper thumbnail of Co-loading of bisphosphonates and antibiotics to a biomimetic hydroxyapatite coating

Biotechnology Letters, 2011

Research paper thumbnail of Co-loading of bisphosphonates and antibiotics to a biomimetic hydroxyapatite coating

Biotechnology Letters, 2011

Research paper thumbnail of Cytotoxicity of modified glass ionomer cement on odontoblast cells

Journal of materials science. Materials in medicine, 2016

Recently a modified glass ionomer cement (GIC) with enhanced bioactivity due to the incorporation... more Recently a modified glass ionomer cement (GIC) with enhanced bioactivity due to the incorporation of wollastonite or mineral trioxide aggregate (MTA) has been reported. The aim of this study was to evaluate the cytotoxic effect of the modified GIC on odontoblast-like cells. The cytotoxicity of a conventional GIC, wollastonite modified GIC (W-mGIC), MTA modified GIC (M-mGIC) and MTA cement has been evaluated using cement extracts, a culture media modified by the cement. Ion concentration and pH of each material in the culture media were measured and correlated to the results of the cytotoxicity study. Among the four groups, conventional GIC showed the most cytotoxicity effect, followed by W-mGIC and M-mGIC. MTA showed the least toxic effect. GIC showed the lowest pH (6.36) while MTA showed the highest (8.62). In terms of ion concentration, MTA showed the largest Ca(2+) concentration (467.3 mg/L) while GIC showed the highest concentration of Si(4+) (19.9 mg/L), Al(3+) (7.2 mg/L) and S...

Research paper thumbnail of The effect of oligo(trimethylene carbonate) addition on the stiffness of acrylic bone cement

Research paper thumbnail of Mechanical Testing of Chemically Bonded Bioactive Ceramic Materials

Key Engineering Materials, 2004

Research paper thumbnail of Synthetic Geopolymers for Controlled Delivery of Oxycodone: Adjustable and Nanostructured Porosity Enables Tunable and Sustained Drug Release

Research paper thumbnail of Injectable Bone Cements for Vertebroplasty Studied in Sheep Vertebrae with Electron Microscopy

Key Engineering Materials, 2007

Vertebral compression fractures were simulated by making a hole into sheep vertebrae and by injec... more Vertebral compression fractures were simulated by making a hole into sheep vertebrae and by injecting a stabilizing material. The injectable bio-ceramic Xeraspine™ was evaluated together with a commercially available PMMA (Vertebroplastic™) as the reference material. The Vertebrae were harvested after 7 days and prepared for microscopy. The samples were deposited with gold on the surface and thereafter subjected to SEM and EDX analysis. It was found that the Xeraspine-bone interface was composed of a mixture of elements. The Vertebroplastic implant was embedded in a carbon containing tissue, likely a soft tissue capsule. The Xeraspine sample was subjected to high resolution analysis in the TEM combined with EDX measurements. The TEM sample was prepared with a novel technique for preparation of the tissue-material interface (FIB). In the TEM analysis it was found that the interface region consists of ZrO2 together with a mixture possibly consisting of katoite and apatite formed during setting and/or originating from the boneapatite.

Research paper thumbnail of Spark plasma sintered β-phase silicon nitride with Sr and Ca as a sintering aid for load bearing medical applications

Journal of the European Ceramic Society, 2012

Research paper thumbnail of Characterization of the Tissue-Bioceramic Interface In Vivo Using New Preparation and Analytical Tools

Advances in Science and Technology, 2006

A key feature in the understanding of the mechanisms of integration of implant materials is a dee... more A key feature in the understanding of the mechanisms of integration of implant materials is a deepened in-sight of the elemental and molecular composition of the interface zone between the implant and tissue. To analyze the interface at the ultrastructural level, transmission electron microscopy (TEM) is needed. However, techniques to fabricate thin foils for TEM are difficult and time consuming. By using focused ion beam microscopy (FIB) for site-specific preparation of TEM-samples, intact interfaces between bioceramics and calcified tissue can be prepared. The site-specific accuracy of the technique is about 1 mm. By using a dual-beam FIB, which is a combined scanning electron and focused ion beam microscope, the sample can be imaged with both electrons and ions (generating both secondary electrons and ions). Results from interface studies between Ca-aluminate based orthopaedic cement, dental materials, HA-coated Ti-implants and bone are presented. The interfaces were imaged in sc...

Research paper thumbnail of Effect of Calcium and Strontium on Mesoporous Titania Coatings for Implant Applications

Journal of Biomaterials and Nanobiotechnology, 2013

Research paper thumbnail of Phase formation of CaAl2O4 from CaCO3–Al2O3 powder mixtures

Journal of the European Ceramic Society, 2008

In this paper the formation of CaAl 2 O 4 from CaCO 3 –Al 2 O 3 powder mixtures has been studied,... more In this paper the formation of CaAl 2 O 4 from CaCO 3 –Al 2 O 3 powder mixtures has been studied, varying holding times between 1 and 40 h and temperatures between 1300 and 1500 °C. Phase formation was studied in samples both quenched from the holding ...

Research paper thumbnail of Mesoporous titania implant coatings with and without calcium and strontium ion incorporation

Research paper thumbnail of In Vitro Mechanical Properties of a Calcium Silicate Based Bone Void Filler

Key Engineering Materials, 2006

Research paper thumbnail of Development of a Dental Hybrid Material between a Biomineral and a Glass Ionomer Cement

Key Engineering Materials, 2005

Research paper thumbnail of Evaluation of In Vitro Bioactivity of Different Types of Biomaterials

INTRODUCTION: Biomaterials are often classified as inert, biodegradable or bioactive materials. F... more INTRODUCTION: Biomaterials are often classified as inert, biodegradable or bioactive materials. For all known bioactive materials an interfacial layer of apatite towards the tissue is formed (1-2). This finding is used in in vitro tests in screening potentially bioactive materials. In this study different types of potentially bioactive materials including a metal, an oxide and some chemically bonded ceramics were

Research paper thumbnail of Comparative Study of the Behaviour of a Novel Injectable Bioceramic in Sheep Vertebrae

Research paper thumbnail of In Vitro Bioactivity of Injectable Ceramic Orthopaedic Cements

Key Engineering Materials, 2006

Research paper thumbnail of The influence of Sr content in calcium phosphate coatings

Materials science & engineering. C, Materials for biological applications, 2015

In this study calcium phosphate coatings with different amounts of strontium (Sr) were prepared u... more In this study calcium phosphate coatings with different amounts of strontium (Sr) were prepared using a biomineralization method. The incorporation of Sr changed the composition and morphology of coatings from plate-like to sphere-like morphology. Dissolution testing indicated that the solubility of the coatings increased with increased Sr concentration. Evaluation of extracts (with Sr concentrations ranging from 0 to 2.37μg/mL) from the HA, 0.06Sr, 0.6Sr, and 1.2Sr coatings during in vitro cell cultures showed that Sr incorporation into coatings significantly enhanced the ALP activity in comparison to cells treated with control and HA eluted media. These findings show that calcium phosphate coatings could promote osteogenic differentiation even in a low amount of strontium.

Research paper thumbnail of Bioceramic microneedles with flexible and self-swelling substrate

European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V, Jan 27, 2015

To reduce the effort required to penetrate the skin and optimize drug release profiles, biocerami... more To reduce the effort required to penetrate the skin and optimize drug release profiles, bioceramic microneedle arrays with higher-aspect-ratio needles and a flexible and self-swelling substrate have been developed. Swelling of the substrate can assist in separating it from the needles and leave them in the skin as a drug depot. The preparation procedures for this bioceramic microneedle are described in the paper. Clonidine hydrochloride, the model drug, was released in a controlled manner by the microneedle device in vitro. Results showed that the microneedle array with a flexible and self-swelling substrate released the drug content faster than the array with a rigid substrate. Disintegration of the needle material and diffusion of the drug molecules are believed as the main control mechanisms of the drug release from these microneedle arrays. Ex vivo skin penetration showed that they can effectively penetrate the stratum corneum without an extra device. This work represents a prog...

Research paper thumbnail of Transmission Electron Microscopy studies of bio-implant interfaces using Focused Ion Beam microscopy for sample preparation

Biocompatibility of metallic implants is governed by surface characteristics. TEM sample preparat... more Biocompatibility of metallic implants is governed by surface characteristics. TEM sample preparation using FIB microscopy very much facilitates our research concerning implant-tissue interfaces as well as studies of bioactive surfaces. This talk will cover some of our research on bioactive titanium surfaces and interfaces of titanium and bone.