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- Ballo, Ahmed, 1978, et al.
(författare)
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Nanostructured model implants for in vivo studies: influence of well-defined nanotopography on de novo bone formation on titanium implants
- 2011
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Ingår i: International Journal of Nanomedicine. - 1178-2013 .- 1176-9114. ; 6, s. 3415-28
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Tidskriftsartikel (refereegranskat)abstract
- An implantable model system was developed to investigate the effects of nanoscale surface properties on the osseointegration of titanium implants in rat tibia. Topographical nanostructures with a well-defined shape (semispherical protrusions) and variable size (60 nm, 120 nm and 220 nm) were produced by colloidal lithography on the machined implants. Furthermore, the implants were sputter-coated with titanium to ensure a uniform surface chemical composition. The histological evaluation of bone around the implants at 7 days and 28 days after implantation was performed on the ground sections using optical and scanning electron microscopy. Differences between groups were found mainly in the new bone formation process in the endosteal and marrow bone compartments after 28 days of implantation. Implant surfaces with 60 nm features demonstrated significantly higher bone-implant contact (BIC, 76%) compared with the 120 nm (45%) and control (57%) surfaces. This effect was correlated to the higher density and curvature of the 60 nm protrusions. Within the developed model system, nanoscale protrusions could be applied and systematically varied in size in the presence of microscale background roughness on complex screw-shaped implants. Moreover, the model can be adapted for the systematic variation of surface nanofeature density and chemistry, which opens up new possibilities for in vivo studies of various nanoscale surface-bone interactions.
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- Briand, Elisabeth, 1979, et al.
(författare)
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Chemical Modifications of Au/SiO2 Template Substrates for Patterned Biofunctional Surfaces
- 2011
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 27:2, s. 678-685
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to create patterned surfaces for localized and specific biochemical recognition. For this purpose, we have developed a protocol for orthogonal and material-selective surface modifications of microfabricated patterned surfaces composed of SiO2 areas (100 mu m diameter) surrounded by Au. The SiO2 spots were chemically modified by a sequence of reactions (silanization using an amine-terminated silane (APTES), followed by amine coupling of a biotin analogue and biospecific recognition) to achieve efficient immobilization of streptavidin in a functional form. The surrounding Au was rendered inert to protein adsorption by modification by HS(CH2)(10)CONH-(CH2)(2)(OCH2CH2)(7)OH (thiol-OEG). The surface modification protocol was developed by testing separately homogeneous SiO2 and Au surfaces, to obtain the two following results: (i) SiO2 surfaces which allowed the grafting of streptavidin, and subsequent immobilization of biotinylated antibodies, and (ii) Au surfaces showing almost no affinity for the same streptavidin and antibody solutions. The surface interactions were monitored by quartz crystal microbalance with dissipation monitoring (QCM-D), and chemical analyses were performed by polarization modulation-reflexion absorption infrared spectroscopy (PM-RAIRS) and X-ray photoelectron spectroscopy (XPS) to assess the validity of the initial orthogonal assembly of APTES and thiol-OEG. Eventually, microscopy imaging of the modified Au/SiO2 patterned substrates validated the specific binding of streptavidin on the SiO2/APTES areas, as well as the subsequent binding of biotinylated anti-rIgG and further detection of fluorescent rIgG on the functionalized SiO2 areas. These results demonstrate a successful protocol for the preparation of patterned biofunctional surfaces, based on microfabricated Au/SiO2 templates and supported by careful surface analysis. The strong immobilization of the biomolecules resulting from the described protocol is advantageous in particular for micropatterned substrates for cell-surface interactions.
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- Briand, Elisabeth, 1979, et al.
(författare)
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Combined QCM-D and EIS study of supported lipid bilayer formation and interaction with pore-forming peptides
- 2010
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Ingår i: The Analyst. - : Royal Society of Chemistry (RSC). - 0003-2654 .- 1364-5528. ; 135:2, s. 343-350
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Tidskriftsartikel (refereegranskat)abstract
- A novel set-up combining the quartz crystal microbalance with dissipation monitoring technique (QCM-D) and electrochemical impedance spectroscopy (EIS) under flow conditions was successfully used to follow supported lipid bilayer (SLB) formation on SiO(2). This study demonstrates the simultaneous detection, in real time, of both the electrical and the structural properties of the SLB. The combination of the two techniques provided novel insights regarding the mechanism of SLB formation: we found indications for an annealing process of the lipid alkyl chains after the mass corresponding to complete bilayer coverage had been deposited. Moreover, the interaction of the SLB with the pore-forming toxin, gramicidin D (grD) was studied for grD concentrations ranging from 0.05 to 40 mg L(-1). Membrane properties were altered depending on the toxin concentration. For low grD concentrations, the electrical properties of the SLB changed upon insertion of active ion channels. For higher concentrations, the QCM-D data showed dramatic changes in the viscoelastic properties of the membrane while the EIS spectra did not change. AFM confirmed significant structural changes of the membrane at higher grD concentrations. Thus, the application of combined QCM-D and EIS detection provides complementary information about the system under study. This information will be particularly important for the continued detailed investigation of interactions at model membrane surfaces
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- de Peppo, Giuseppe Maria, 1981, et al.
(författare)
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Osteogenic response of human mesenchymal stem cells to well-defined nanoscale topography in vitro
- 2014
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Ingår i: International journal of nanomedicine. - : Informa UK Limited. - 1176-9114 .- 1178-2013. ; 9:1, s. 2499-2515
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Tidskriftsartikel (refereegranskat)abstract
- Background: Patterning medical devices at the nanoscale level enables the manipulation of cell behavior and tissue regeneration, with topographic features recognized as playing a significant role in the osseointegration of implantable devices. Methods: In this study, we assessed the ability of titanium-coated hemisphere-like topographic nanostructures of different sizes (approximately 50, 100, and 200 nm) to influence the morphology, proliferation, and osteogenic differentiation of human mesenchymal stem cells (hMSCs). Results: We found that the proliferation and osteogenic differentiation of hMSCs was influenced by the size of the underlying structures, suggesting that size variations in topographic features at the nanoscale level, independently of chemistry, can be exploited to control hMSC behavior in a size-dependent fashion. Conclusion: Our studies demonstrate that colloidal lithography, in combination with coating technologies, can be exploited to investigate the cell response to well defined nanoscale topography and to develop next-generation surfaces that guide tissue regeneration and promote implant integration.
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- Jonsson, Magnus, 1981, et al.
(författare)
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Locally Functionalized Short-Range Ordered Nanoplasmonic Pores for Bioanalytical Sensing
- 2010
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 82:5, s. 2087-2094
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Tidskriftsartikel (refereegranskat)abstract
- Nanoplasmonic sensors based on short-range ordered nano-holes in thin metal films and discrete metal nanoparticles are known to provide similar sensing performance. However, a perforated metal film is unique in the sense that the holes can be designed to penetrate through the substrate, thereby also fulfilling the role of nanofluidic channels. This paper presents a bioanalytical sensing concept based on short-range ordered nanoplasmonic pores (diameter 150 nm) penetrating through a thin (around 250 nm) multilayer membrane composed of gold and silicon nitride (SiN) that is Supported on a Si wafer. Also, a fabrication scheme that enables parallel production of multiple (more than 50) separate sensor chips or more than 1000 separate nanoplasmonic membranes on it single wafer is presented. Together with the localization of the sensitivity to within such short-range ordered nanoholes, the structure provides it two-dimensional nanofluidic network, sized in the order of 100 x 100 mu m(2), with nanoplasmon active regions localized to each individual nanochannel. A material-specific surface-modification scheme was developed to promote specific binding of target molecules on the optically active gold regions only, while suppressing nonspecific adsorption on SiN. Using this protocol, and by monitoring the temporal variation in the plasmon resonance of the structure, we demonstrate flow-through nanoplasmonic sensing of specific biorecognition reactions with a signal-to-noise ratio of around 50 at a temporal resolution below 190 ms. With flow, the uptake was demonstrated to be at least 1 order of magnitude faster than under stagnant conditions, while still keeping the sample consumption at a minimum.
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