Antimicrobial agents and chemotherapy, Jan 9, 2015
In the past, biofilm-related research has mainly focused on axenic biofilms. However, in nature, ... more In the past, biofilm-related research has mainly focused on axenic biofilms. However, in nature, biofilms are often composed of multiple species and the resulting polymicrobial interactions influence industrially and clinically relevant outcomes such as performance and drug resistance. In this study we show that Escherichia coli does not affect Candida albicans tolerance to amphotericin or caspofungin in an E. coli/C. albicans biofilm. In contrast, ofloxacin-tolerance of E. coli is significantly increased in a polymicrobial E. coli/C. albicans biofilm as compared to an axenic E. coli biofilm. The increased ofloxacin-tolerance of E. coli is mainly biofilm-specific as ofloxacin-tolerance of E. coli is less pronounced in polymicrobial E. coli/C. albicans planktonic cultures. Moreover, we found that ofloxacin-tolerance of E. coli decreased significantly when E. coli/C. albicans biofilms were treated with matrix-degrading enzymes such as the β-1,3-glucan-degrading enzyme lyticase. In lin...
Antimicrobial agents and chemotherapy, Jan 9, 2015
In the past, biofilm-related research has mainly focused on axenic biofilms. However, in nature, ... more In the past, biofilm-related research has mainly focused on axenic biofilms. However, in nature, biofilms are often composed of multiple species and the resulting polymicrobial interactions influence industrially and clinically relevant outcomes such as performance and drug resistance. In this study we show that Escherichia coli does not affect Candida albicans tolerance to amphotericin or caspofungin in an E. coli/C. albicans biofilm. In contrast, ofloxacin-tolerance of E. coli is significantly increased in a polymicrobial E. coli/C. albicans biofilm as compared to an axenic E. coli biofilm. The increased ofloxacin-tolerance of E. coli is mainly biofilm-specific as ofloxacin-tolerance of E. coli is less pronounced in polymicrobial E. coli/C. albicans planktonic cultures. Moreover, we found that ofloxacin-tolerance of E. coli decreased significantly when E. coli/C. albicans biofilms were treated with matrix-degrading enzymes such as the β-1,3-glucan-degrading enzyme lyticase. In lin...
ABSTRACT In implant technology, open porous Ti coatings are applied as functional surface layers ... more ABSTRACT In implant technology, open porous Ti coatings are applied as functional surface layers on prosthetic devices to improve osseointegration. Since a successful clinical performance strongly depends on the (initial) quality of bone ingrowth in the porous structure, surface functionalization of the porous Ti to incorporate an additional osteoconductive capacity is recommended. In this paper, a bioactive glass–ceramic coating is applied into the open porous network of Ti coatings with a pore throat size of 1–20 μm through a sol–gel process. Using an all-alkoxide precursor route, homogeneous amorphous powders of three- (SiO2–CaO–P2O5) and four-component (SiO2–CaO–Na2O–P2O5) bioactive glass compositions are prepared. By sol impregnation followed by a heat treatment, it is possible to deposit a micrometer thin bioactive glass–ceramic layer on the walls of the internal pore surface, while the original porosity and the open pore structure of the Ti coatings are maintained. The tensile adhesion strength of the Ti/bioactive glass–ceramic composite coatings is 22 to 29 MPa, suggesting a good mechanical adhesion.
Surface modification of Ti alloys towards an improved osteoinductive behaviour is one of the majo... more Surface modification of Ti alloys towards an improved osteoinductive behaviour is one of the major challenges in orthopaedic implant technology nowadays. One way to achieve this is by applying a bioactive coating which can increase the rate of osseointegration and chemical bonding of surrounding bone to the implant. In the present work, the production of a bioactive glass-ceramic coating on flat Ti alloys by electrophoretic deposition is demonstrated. The coatings are applied by cathodic deposition from non-aqueous suspensions followed by sintering in vacuum, avoiding uncontrolled oxidation of the Ti substrates. The use of nonaqueous suspensions both allowed to reduce the deposition time and yielded homogeneous coatings with a uniform thickness of 8 μm. Evaluation of the coating adhesion confirmed the good mechanical performance of the coatings with a tensile bond strength of 41.0 ± 11.1 MPa. Additionally, a feasibility study demonstrated the potential of electrophoretic deposition as a coating technique for commercial complex implants.
Amorphous microporous silica (AMS) serving as a reservoir for controlled release of a bioactive a... more Amorphous microporous silica (AMS) serving as a reservoir for controlled release of a bioactive agent was applied in the open porosity of a titanium coating on a Ti-6Al-4V metal substrate. The pores of the AMS emptied by calcination were loaded with chlorhexidine diacetate (CHX) via incipient wetness impregnation with CHX solution, followed by solvent evaporation. Using this CHX loaded AMS system on titanium substrate sustained release of CHX into physiological medium was obtained over a 10 day-period. CHX released from the AMS coating was demonstrated to be effective in killing planktonic cultures of the human pathogens Candida albicans and Staphylococcus epidermidis. This surface modification of titanium bodies with AMS controlled release functionality for a bioactive compound potentially can be applied on dental and orthopaedic implants to abate implant-associated microbial infection.
Titanium-based implants are widely used in modern clinical practice, but their &a... more Titanium-based implants are widely used in modern clinical practice, but their "optimal" properties in terms of porosity and topology, roughness and hydrophilic parameters are being a subject of intensive discussions. Recent in vitro results have shown a possibility to optimize the surface of an implant with maximal repelling of bacteria (Staphylococcus aureus, Staphylococcus epidermidis) and improvement in human osteogenic and endothelial cell adhesion, proliferation and differentiation. In this work, these different grades titanium implants were tested in vivo using the same analytical methodology. In addition to material parameters, key histomorphometrical parameters such a regeneration area, bone adaptation area and bone-to-implant contact were determined after 2 and 4weeks of implantation in rabbit animal model. Porous implants have more clear differences than non-porous ones, with the best optimum values obtained on hydrothermally treated electrophoretically deposited titanium. These in vivo data correlate well with the optimal prediction made by in vitro tests.
ABSTRACT Current orthopaedic implant technology focuses on fixation by osseointegration to maximi... more ABSTRACT Current orthopaedic implant technology focuses on fixation by osseointegration to maximise the implant longevity and reduce the need for burdensome and expensive revision surgery. In this respect, porous Ti coated implants, which enable bone ingrowth into the porous structure and the establishment of biological anchoring of the implant, are of interest. In previous work a new powder metallurgical processing route was reported for the application of porous Ti coatings on Ti alloy substrates by electrophoretic deposition (EPD) of TiH2 powder suspensions. To validate the function of these coatings for potential clinical applications, the early peri-implant bone response was evaluated in vivo in a rabbit model. The results clearly demonstrate bone ingrowth in porous coatings with pore channels down to 10 μm, as opposed to the minimum pore size of 50–100 μm commonly claimed in the literature. Moreover, the observed inter-connectivity with surrounding cortical bone confirmed the envisaged mechanical interlocking of the implant.
Background: Topography and presence of bio-mimetic coatings are known to improve osseointegration... more Background: Topography and presence of bio-mimetic coatings are known to improve osseointegration. The objective of this study was to evaluate the bone regeneration potential of porous and osteogenic coatings.
... Porous Titanium Coatings Through Electrophoretic Deposition of TiH 2 Suspensions . Annabel B... more ... Porous Titanium Coatings Through Electrophoretic Deposition of TiH 2 Suspensions . Annabel Braem,; Tina Mattheys,; Bram Neirinck,; Jan Schrooten,; Omer Van der Biest,; Jef Vleugels. Article first published online: 24 MAR 2011. ... K. Salama, Mater. Sci. Eng, A 2003, 356, 190. ...
Bone growth on and into implants exhibiting substantial surface porosity is a promising strategy ... more Bone growth on and into implants exhibiting substantial surface porosity is a promising strategy in order to improve the long-term stable fixation of bone implants. However, the reliability in clinical applications remains a point of discussion. Most attention has been dedicated to the role of macroporosity, leading to the general consensus of a minimal pore size of 50-100 μm in order to allow bone ingrowth. In this in vivo study, we assessed the feasibility of early bone ingrowth into a predominantly microporous Ti coating with an average thickness of 150 μm and the hypothesis of improving the bone response through surface modification of the porous coating. Implants were placed in the cortical bone of rabbit tibiae for periods of 2 and 4 weeks and evaluated histologically and histomorphometrically using light microscopy and scanning electron microscopy. Bone with osteocytes encased in the mineralized matrix was found throughout the porous Ti coating up to the coating/substrate interface, highlighting that osseointegration of microporosities (<10 μm) was achievable. The bone trabeculae interweaved with the pore struts, establishing a large contact area which might enable an improved load transfer and stronger implant/bone interface. Furthermore, there was a clear interconnection with the surrounding cortical bone, suggesting that mechanical interlocking of the coating in the host bone in the long term is possible. When surface modifications inside the porous structure further reduced the interconnective pore size to the submicrometer level, bone ingrowth was impaired. On the other hand, application of a sol-gel-derived bioactive glass-ceramic coating without altering the pore characteristics was found to significantly improve bone regeneration around the coating, while still supporting bone ingrowth.
Antimicrobial agents and chemotherapy, Jan 9, 2015
In the past, biofilm-related research has mainly focused on axenic biofilms. However, in nature, ... more In the past, biofilm-related research has mainly focused on axenic biofilms. However, in nature, biofilms are often composed of multiple species and the resulting polymicrobial interactions influence industrially and clinically relevant outcomes such as performance and drug resistance. In this study we show that Escherichia coli does not affect Candida albicans tolerance to amphotericin or caspofungin in an E. coli/C. albicans biofilm. In contrast, ofloxacin-tolerance of E. coli is significantly increased in a polymicrobial E. coli/C. albicans biofilm as compared to an axenic E. coli biofilm. The increased ofloxacin-tolerance of E. coli is mainly biofilm-specific as ofloxacin-tolerance of E. coli is less pronounced in polymicrobial E. coli/C. albicans planktonic cultures. Moreover, we found that ofloxacin-tolerance of E. coli decreased significantly when E. coli/C. albicans biofilms were treated with matrix-degrading enzymes such as the β-1,3-glucan-degrading enzyme lyticase. In lin...
Antimicrobial agents and chemotherapy, Jan 9, 2015
In the past, biofilm-related research has mainly focused on axenic biofilms. However, in nature, ... more In the past, biofilm-related research has mainly focused on axenic biofilms. However, in nature, biofilms are often composed of multiple species and the resulting polymicrobial interactions influence industrially and clinically relevant outcomes such as performance and drug resistance. In this study we show that Escherichia coli does not affect Candida albicans tolerance to amphotericin or caspofungin in an E. coli/C. albicans biofilm. In contrast, ofloxacin-tolerance of E. coli is significantly increased in a polymicrobial E. coli/C. albicans biofilm as compared to an axenic E. coli biofilm. The increased ofloxacin-tolerance of E. coli is mainly biofilm-specific as ofloxacin-tolerance of E. coli is less pronounced in polymicrobial E. coli/C. albicans planktonic cultures. Moreover, we found that ofloxacin-tolerance of E. coli decreased significantly when E. coli/C. albicans biofilms were treated with matrix-degrading enzymes such as the β-1,3-glucan-degrading enzyme lyticase. In lin...
Antimicrobial agents and chemotherapy, Jan 9, 2015
In the past, biofilm-related research has mainly focused on axenic biofilms. However, in nature, ... more In the past, biofilm-related research has mainly focused on axenic biofilms. However, in nature, biofilms are often composed of multiple species and the resulting polymicrobial interactions influence industrially and clinically relevant outcomes such as performance and drug resistance. In this study we show that Escherichia coli does not affect Candida albicans tolerance to amphotericin or caspofungin in an E. coli/C. albicans biofilm. In contrast, ofloxacin-tolerance of E. coli is significantly increased in a polymicrobial E. coli/C. albicans biofilm as compared to an axenic E. coli biofilm. The increased ofloxacin-tolerance of E. coli is mainly biofilm-specific as ofloxacin-tolerance of E. coli is less pronounced in polymicrobial E. coli/C. albicans planktonic cultures. Moreover, we found that ofloxacin-tolerance of E. coli decreased significantly when E. coli/C. albicans biofilms were treated with matrix-degrading enzymes such as the β-1,3-glucan-degrading enzyme lyticase. In lin...
ABSTRACT In implant technology, open porous Ti coatings are applied as functional surface layers ... more ABSTRACT In implant technology, open porous Ti coatings are applied as functional surface layers on prosthetic devices to improve osseointegration. Since a successful clinical performance strongly depends on the (initial) quality of bone ingrowth in the porous structure, surface functionalization of the porous Ti to incorporate an additional osteoconductive capacity is recommended. In this paper, a bioactive glass–ceramic coating is applied into the open porous network of Ti coatings with a pore throat size of 1–20 μm through a sol–gel process. Using an all-alkoxide precursor route, homogeneous amorphous powders of three- (SiO2–CaO–P2O5) and four-component (SiO2–CaO–Na2O–P2O5) bioactive glass compositions are prepared. By sol impregnation followed by a heat treatment, it is possible to deposit a micrometer thin bioactive glass–ceramic layer on the walls of the internal pore surface, while the original porosity and the open pore structure of the Ti coatings are maintained. The tensile adhesion strength of the Ti/bioactive glass–ceramic composite coatings is 22 to 29 MPa, suggesting a good mechanical adhesion.
Surface modification of Ti alloys towards an improved osteoinductive behaviour is one of the majo... more Surface modification of Ti alloys towards an improved osteoinductive behaviour is one of the major challenges in orthopaedic implant technology nowadays. One way to achieve this is by applying a bioactive coating which can increase the rate of osseointegration and chemical bonding of surrounding bone to the implant. In the present work, the production of a bioactive glass-ceramic coating on flat Ti alloys by electrophoretic deposition is demonstrated. The coatings are applied by cathodic deposition from non-aqueous suspensions followed by sintering in vacuum, avoiding uncontrolled oxidation of the Ti substrates. The use of nonaqueous suspensions both allowed to reduce the deposition time and yielded homogeneous coatings with a uniform thickness of 8 μm. Evaluation of the coating adhesion confirmed the good mechanical performance of the coatings with a tensile bond strength of 41.0 ± 11.1 MPa. Additionally, a feasibility study demonstrated the potential of electrophoretic deposition as a coating technique for commercial complex implants.
Amorphous microporous silica (AMS) serving as a reservoir for controlled release of a bioactive a... more Amorphous microporous silica (AMS) serving as a reservoir for controlled release of a bioactive agent was applied in the open porosity of a titanium coating on a Ti-6Al-4V metal substrate. The pores of the AMS emptied by calcination were loaded with chlorhexidine diacetate (CHX) via incipient wetness impregnation with CHX solution, followed by solvent evaporation. Using this CHX loaded AMS system on titanium substrate sustained release of CHX into physiological medium was obtained over a 10 day-period. CHX released from the AMS coating was demonstrated to be effective in killing planktonic cultures of the human pathogens Candida albicans and Staphylococcus epidermidis. This surface modification of titanium bodies with AMS controlled release functionality for a bioactive compound potentially can be applied on dental and orthopaedic implants to abate implant-associated microbial infection.
Titanium-based implants are widely used in modern clinical practice, but their &a... more Titanium-based implants are widely used in modern clinical practice, but their "optimal" properties in terms of porosity and topology, roughness and hydrophilic parameters are being a subject of intensive discussions. Recent in vitro results have shown a possibility to optimize the surface of an implant with maximal repelling of bacteria (Staphylococcus aureus, Staphylococcus epidermidis) and improvement in human osteogenic and endothelial cell adhesion, proliferation and differentiation. In this work, these different grades titanium implants were tested in vivo using the same analytical methodology. In addition to material parameters, key histomorphometrical parameters such a regeneration area, bone adaptation area and bone-to-implant contact were determined after 2 and 4weeks of implantation in rabbit animal model. Porous implants have more clear differences than non-porous ones, with the best optimum values obtained on hydrothermally treated electrophoretically deposited titanium. These in vivo data correlate well with the optimal prediction made by in vitro tests.
ABSTRACT Current orthopaedic implant technology focuses on fixation by osseointegration to maximi... more ABSTRACT Current orthopaedic implant technology focuses on fixation by osseointegration to maximise the implant longevity and reduce the need for burdensome and expensive revision surgery. In this respect, porous Ti coated implants, which enable bone ingrowth into the porous structure and the establishment of biological anchoring of the implant, are of interest. In previous work a new powder metallurgical processing route was reported for the application of porous Ti coatings on Ti alloy substrates by electrophoretic deposition (EPD) of TiH2 powder suspensions. To validate the function of these coatings for potential clinical applications, the early peri-implant bone response was evaluated in vivo in a rabbit model. The results clearly demonstrate bone ingrowth in porous coatings with pore channels down to 10 μm, as opposed to the minimum pore size of 50–100 μm commonly claimed in the literature. Moreover, the observed inter-connectivity with surrounding cortical bone confirmed the envisaged mechanical interlocking of the implant.
Background: Topography and presence of bio-mimetic coatings are known to improve osseointegration... more Background: Topography and presence of bio-mimetic coatings are known to improve osseointegration. The objective of this study was to evaluate the bone regeneration potential of porous and osteogenic coatings.
... Porous Titanium Coatings Through Electrophoretic Deposition of TiH 2 Suspensions . Annabel B... more ... Porous Titanium Coatings Through Electrophoretic Deposition of TiH 2 Suspensions . Annabel Braem,; Tina Mattheys,; Bram Neirinck,; Jan Schrooten,; Omer Van der Biest,; Jef Vleugels. Article first published online: 24 MAR 2011. ... K. Salama, Mater. Sci. Eng, A 2003, 356, 190. ...
Bone growth on and into implants exhibiting substantial surface porosity is a promising strategy ... more Bone growth on and into implants exhibiting substantial surface porosity is a promising strategy in order to improve the long-term stable fixation of bone implants. However, the reliability in clinical applications remains a point of discussion. Most attention has been dedicated to the role of macroporosity, leading to the general consensus of a minimal pore size of 50-100 μm in order to allow bone ingrowth. In this in vivo study, we assessed the feasibility of early bone ingrowth into a predominantly microporous Ti coating with an average thickness of 150 μm and the hypothesis of improving the bone response through surface modification of the porous coating. Implants were placed in the cortical bone of rabbit tibiae for periods of 2 and 4 weeks and evaluated histologically and histomorphometrically using light microscopy and scanning electron microscopy. Bone with osteocytes encased in the mineralized matrix was found throughout the porous Ti coating up to the coating/substrate interface, highlighting that osseointegration of microporosities (<10 μm) was achievable. The bone trabeculae interweaved with the pore struts, establishing a large contact area which might enable an improved load transfer and stronger implant/bone interface. Furthermore, there was a clear interconnection with the surrounding cortical bone, suggesting that mechanical interlocking of the coating in the host bone in the long term is possible. When surface modifications inside the porous structure further reduced the interconnective pore size to the submicrometer level, bone ingrowth was impaired. On the other hand, application of a sol-gel-derived bioactive glass-ceramic coating without altering the pore characteristics was found to significantly improve bone regeneration around the coating, while still supporting bone ingrowth.
Antimicrobial agents and chemotherapy, Jan 9, 2015
In the past, biofilm-related research has mainly focused on axenic biofilms. However, in nature, ... more In the past, biofilm-related research has mainly focused on axenic biofilms. However, in nature, biofilms are often composed of multiple species and the resulting polymicrobial interactions influence industrially and clinically relevant outcomes such as performance and drug resistance. In this study we show that Escherichia coli does not affect Candida albicans tolerance to amphotericin or caspofungin in an E. coli/C. albicans biofilm. In contrast, ofloxacin-tolerance of E. coli is significantly increased in a polymicrobial E. coli/C. albicans biofilm as compared to an axenic E. coli biofilm. The increased ofloxacin-tolerance of E. coli is mainly biofilm-specific as ofloxacin-tolerance of E. coli is less pronounced in polymicrobial E. coli/C. albicans planktonic cultures. Moreover, we found that ofloxacin-tolerance of E. coli decreased significantly when E. coli/C. albicans biofilms were treated with matrix-degrading enzymes such as the β-1,3-glucan-degrading enzyme lyticase. In lin...
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