17 results on '"Griesser, Hans J."'
Search Results
2. Attachment of endothelial colony-forming cells onto a surface bearing immobilized anti-CD34 antibodies: Specific CD34 binding versus nonspecific binding.
- Author
-
Burzava, Anouck L. S., Jasieniak, Marek, Cockshell, Michaelia P., Voelcker, Nicolas H., Bonder, Claudine S., Griesser, Hans J., and Moore, Eli
- Subjects
SECONDARY ion mass spectrometry ,ENDOTHELIAL cells ,IMMUNOGLOBULINS ,BLOOD proteins ,CD34 antigen ,X-ray photoelectron spectroscopy ,FORMYLATION - Abstract
Cardiovascular disease is a leading cause of death worldwide; however, despite substantial advances in medical device surface modifications, no synthetic coatings have so far matched the native endothelium as the optimal hemocompatible surface for blood-contacting implants. A promising strategy for rapid restoration of the endothelium on blood-contacting biomedical devices entails attracting circulating endothelial cells or their progenitors, via immobilized cell-capture molecules; for example, anti-CD34 antibody to attract CD34+ endothelial colony-forming cells (ECFCs). Inherent is the assumption that the cells attracted to the biomaterial surface are bound exclusively via a specific CD34 binding. However, serum proteins might adsorb in-between or on the top of antibody molecules and attract ECFCs via other binding mechanisms. Here, we studied whether a surface with immobilized anti-CD34 antibodies attracts ECFCs via a specific CD34 binding or a nonspecific (non-CD34) binding. To minimize serum protein adsorption, a fouling-resistant layer of hyperbranched polyglycerol (HPG) was used as a "blank slate," onto which anti-CD34 antibodies were immobilized via aldehyde-amine coupling reaction after oxidation of terminal diols to aldehydes. An isotype antibody, mIgG1, was surface-immobilized analogously and was used as the control for antigen-binding specificity. Cell binding was also measured on the HPG hydrogel layer before and after oxidation. The surface analysis methods, x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry, were used to verify the intended surface chemistries and revealed that the surface coverage of antibodies was sparse, yet the anti-CD34 antibody grafted surface-bound ECFCs very effectively. Moreover, it still captured the ECFCs after BSA passivation. However, cells also attached to oxidized HPG and immobilized mIgG1, though in much lower amounts. While our results confirm the effectiveness of attracting ECFCs via surface-bound anti-CD34 antibodies, our observation of a nonspecific binding component highlights the importance of considering its consequences in future studies. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
3. Rational approaches for optimizing chemical functionality of plasma polymers: A case study with ethyl trimethylacetate.
- Author
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Saboohi, Solmaz, Coad, Bryan R., Short, Robert D., Michelmore, Andrew, and Griesser, Hans J.
- Subjects
SECONDARY ion mass spectrometry ,IONS ,ION energy ,PLASMA polymerization ,X-ray photoelectron spectroscopy - Abstract
Improved retention of desirable chemical structures during plasma polymerization requires rational tailoring of plasma‐phase conditions. Using ethyl trimethylacetate, we studied the effects of pressure and power on the contribution of intact molecular ions to deposition and retention of ester groups. The abundance of protonated molecular ions in plasmas varies with pressure and power, but the functionality of plasma polymers, assessed by X‐ray photoelectron spectroscopy and time‐of‐flight secondary ion mass spectrometry, is not correlated. Together with high ion flux, the ion energy distribution was found to be a key parameter and needs to be tailored to enable the soft landing of ions on the surface after traversing the sheath. The compromise between the abundance of ions and their energy distribution is optimal near the transition between the α and γ plasma phases. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
4. XPS Analysis and Antibacterial Assay of Novobiocin Coating.
- Author
-
Ys, Hardi, Semple, Susan, and Griesser, Hans J.
- Subjects
X-ray photoelectron spectroscopy ,ANTIBACTERIAL agents ,BIOLOGICAL assay ,NOVOBIOCIN ,SURFACE coatings ,ANTIBIOTICS ,BACTERIAL diseases - Abstract
Infection disease after biomedical implant surgery is often caused by unintentional contamination of micro-organism. Novobiocin is one of the most attractive antibiotic due to its high activity against gram positive bacteria and its relatively compatible to fibroblast cell line. Based on the molecular structure of novobiocin, it may be conjugated or coated onto material surfaces. The coating steps were plasma polymerisation, polymer grafting, and novobiocin conjugation. XPS analysis showed that the elements and high resolution of C 1s confirmed that the surface chemical had changed. Novobiocin, after conjugation, became more dominant in covering the surface. Antibacterial Assay to Staphylococcus epidermidis by using dead and live kit indicated the reduction of bacteria reached up to 97.27% and only 0.07% of live bacteria left. This result led to a conclusion that immobilised novobiocin may be considered as novel antibacterial coating that can prevent nosocomial infection. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
5. Deposition and XPS and FTIR Analysis of Plasma Polymer Coatings Containing Phosphorus.
- Author
-
Siow, Kim S., Britcher, Leanne, Kumar, Sunil, and Griesser, Hans J.
- Subjects
CHEMICAL vapor deposition ,X-ray photoelectron spectroscopy ,PHOTOELECTRON spectroscopy ,FOURIER transform infrared spectroscopy ,PLASMA polymerization - Abstract
Phosphate groups are part of biological molecules involved in bio-interfacial phenomena but monomers containing these groups are not volatile enough to be plasma polymerized (pp). Hence monomers with lower oxidation states of P are needed which then does not enable prediction of the oxidation state(s) of P in the pps, nor of possible aging effects. XPS and FTIR analyses of pps from triisopropyl phosphite (TIP) and diethyl phosphite (DEP) reveal the presence of phosphate and polyphosphate groups, while phosphonate and phosphate are found in pps of co-polymerized 1,7-octadiene and TIP. Post-plasma aging and electrical biasing have negligible effects on the oxidation state of P in TIP pps. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
6. Solid-state capture and real-time analysis of individual T cell activation via self-assembly of binding multimeric proteins on functionalized materials surfaces.
- Author
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Diener, Kerrilyn R., Christo, Susan N., Griesser, Stefani S., Sarvestani, Ghafar T., Vasilev, Krasimir, Griesser, Hans J., and Hayball, John D.
- Subjects
T cells ,STREPTAVIDIN ,X-ray photoelectron spectroscopy ,MAJOR histocompatibility complex ,POLYMERS ,MONOCLONAL antibodies ,PROTEINS - Abstract
Abstract: Polyfunctional T cell responses are increasingly underpinning new and improved vaccination regimens. Studies of the nature and extent of these T cell responses may be facilitated if specific T cell populations can be assessed from mixed populations by ligand-mediated capture in a solid-state assay format. Accordingly, we report here the development of a novel strategy for the solid-state capture and real-time activation analyses of individual cognate T cells which utilizes a spontaneous self-assembly process for generating multimers of biotinylated class I major histocompatibility-peptide complex (MHCp) directly on the solid-state assay surface while also ensuring stability by covalent interfacial binding. The capture surface was constructed by the fabrication of multilayer coatings onto standard slides. The first layer was a thin polymer coating with surface aldehyde groups, onto which streptavidin was covalently immobilized, followed by the docking of multimers of biotinylated MHCp or biotinylated anti-CD45.1 monoclonal antibody. The high binding strength at each step of this immobilization sequence aims to ensure that artefacts such as (partial) detachment, or displacement by proteins from solution, would not interfere with the intended biological assays. The multilayer coating steps were monitored by X-ray photoelectron spectroscopy; data indicated that the MHCp proteins self-assembled in a multimeric form onto the streptavidin surface. Immobilized multimeric MHCp demonstrated the capacity to bind and retain antigen-specific T cells from mixed populations of cells onto the solid carrier. Furthermore, real-time confocal microscopic detection and quantification of subsequent calcium flux using paired fluorescent ratiometric probes facilitated the analysis of individual T cell response profiles, as well as population analyses using a combination of individual T cell events. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
7. A ToF-SIMS and XPS study of protein adsorption and cell attachment across PEG-like plasma polymer films with lateral compositional gradients
- Author
-
Menzies, Donna J., Jasieniak, Marek, Griesser, Hans J., Forsythe, John S., Johnson, Graham, McFarland, Gail A., and Muir, Benjamin W.
- Subjects
- *
TIME-of-flight mass spectrometry , *X-ray photoelectron spectroscopy , *BLOOD protein absorption & adsorption , *POLYMER films , *PRINCIPAL components analysis , *PLASMA-enhanced chemical vapor deposition - Abstract
Abstract: In this work we report a detailed X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) study of poly(ethylene glycol) PEG-like chemical gradients deposited via plasma enhanced chemical vapour deposition (PECVD) at two different load powers using diethylene glycol dimethyl ether (DG) as a monomer. Principal component analysis (PCA) was applied to the ToF-SIMS data both before and after protein adsorption on the plasma polymer thin films. Results of the PCA loadings indicated a higher content of hydrocarbon fragments across the higher load power gradient, which adsorbed higher amounts of proteins. Gradients deposited at a lower load power retained a higher degree of monomer like functionality as did the central region directly underneath the knife edge electrode. Analysis of the adsorption of serum proteins (human serum albumin and fetal bovine serum) was monitored across the gradient films and increased with decreasing ether (PEG-like) film chemistries. The effect of protein incubation time on the levels adsorbed fetal bovine serum on the plasma polymer films was critical, with significantly more protein adsorbing after 24hour incubation times on both gradient films. The attachment of HeLa cells on the gradients appeared to be dictated not only by the surface chemistry, but also by the adsorption of serum proteins. XPS analysis revealed that at surface ether concentrations of less than 70% in the gradient films, significant increases in protein and cell attachment were observed. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
8. XPS characterization of the surface immobilization of antibacterial furanones
- Author
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Al-Bataineh, Sameer A., Britcher, Leanne G., and Griesser, Hans J.
- Subjects
- *
ANTIBACTERIAL agents , *PROTECTIVE coatings , *SURFACES (Technology) , *SPECTRUM analysis - Abstract
Abstract: Brominated furanones have attracted recent interest as antibacterial compounds. To utilize them as protective coatings in biomedical device applications, they must be covalently immobilized onto solid surfaces; however, interfacial coupling protocols developed for other biomolecules are not applicable to furanones. An azide reaction scheme has enabled covalent immobilization onto fluorinated ethylene propylene copolymer but its chemistry is less predictable, requiring detailed characterization by XPS and tapping mode AFM after each step of the immobilization sequence. XPS curve fitting resolved components in the C1s, N1s and Br3d regions. Angle dependent XPS was used to assess the depth distributions and layer thicknesses. The results indicated successful covalent immobilization of furanones; however, side reactions occurred. In addition to the expected Ctribution from bromine ion (Br−) was detected, indicating that photo-degradation of furanones took place during UV illumination, and this reaction was found to increase with illumination time. The Br− was removed by washing with water, whereas the C from immobilized furanone remained. Spectroscopic characterization will assist in elucidating the structure of furanone coatings, understanding their mode of action when covalently immobilized on surfaces, and rationally designing and optimizing an effective antibacterial coating for biomedical applications. [Copyright &y& Elsevier]
- Published
- 2006
- Full Text
- View/download PDF
9. QCM-D and XPS study of protein adsorption on plasma polymers with sulfonate and phosphonate surface groups.
- Author
-
Siow, Kim S., Britcher, Leanne, Kumar, Sunil, and Griesser, Hans J.
- Subjects
- *
PLASMA polymerization , *SULFONATES , *PHOSPHONATES , *X-ray photoelectron spectroscopy , *FIBRINOGEN - Abstract
Graphical abstract Highlights • SO 3 and PO 3 groups produced by Michael addition on heptylamine plasma polymer. • XPS analysis shows that protein adsorption saturated between 1 and 2 h. • QCM-D shows that passivation with HSA leads to reversible adsorption of lysozyme. • For fibrinogen, partial displacement occurs, regardless of surface chemistry. • Protein adsorption onto SO 3 or PO 3 surfaces is not dominated by electrostatics. Abstract As some proteins are known to interact with sulfated and phosphated biomolecules such as specific glycosaminoglycans, this study derives from the hypothesis that sulfonate and phosphonate groups on solid polymer surfaces might cause specific interfacial interactions. Such surfaces were prepared by plasma polymerization of heptylamine (HA) and subsequent grafting of sulfonate or phosphonate groups via Michael-type addition of vinylic compounds. Adsorption of the proteins fibrinogen, albumin (HSA) and lysozyme on these functionalised plasma polymer surfaces was studied by XPS and quartz crystal microbalance with dissipation (QCM-D). It was also studied whether pre-adsorption with HSA would lead to a passivated surface against further adsorption of other proteins. XPS confirmed grafting of vinyl sulfonate and vinyl phosphonate onto the amine surface and showed that the proteins adsorbed to saturation at between 1 and 2 h. QCM-D showed rapid and irreversible adsorption of albumin on all three surfaces, while lysozyme could be desorbed with PBS to substantial extents from the sulfonated and phosphonated surfaces but not from the amine surface. Fibrinogen showed rapid initial adsorption followed by slower additional mass gain over hours. Passivation with albumin led to small and largely reversible subsequent adsorption of lysozyme, whereas with fibrinogen partial displacement yielded a mixed layer, regardless of the surface chemistry. Thus, protein adsorption onto these sulfonated and phosphonated surfaces is complex, and not dominated by electrostatic charge effects. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
10. Attachment of endothelial colony-forming cells onto a surface bearing immobilized anti-CD34 antibodies: Specific CD34 binding versus nonspecific binding
- Author
-
Anouck L. S. Burzava, Marek Jasieniak, Michaelia P. Cockshell, Nicolas H. Voelcker, Claudine S. Bonder, Hans J. Griesser, Eli Moore, Burzava, Anouck LS, Jasieniak, Marek, Cockshell, Michaelia P, Voelcker, Nicolas H, Bonder, Claudine S, Griesser, Hans J, and Moore, Eli
- Subjects
surface and interface chemistry ,antifouling coating ,isotype ,Endothelial Cells ,General Physics and Astronomy ,Antigens, CD34 ,Cell Count ,x-ray photoelectron spectroscopy ,secondary ion mass spectrometry ,General Chemistry ,protein adsorption ,Antibodies ,General Biochemistry, Genetics and Molecular Biology ,Biomaterials ,antibody ,cells ,General Materials Science ,biomaterials - Abstract
Cardiovascular disease is a leading cause of death worldwide; however, despite substantial advances in medical device surface modifications, no synthetic coatings have so far matched the native endothelium as the optimal hemocompatible surface for blood-contacting implants. A promising strategy for rapid restoration of the endothelium on blood-contacting biomedical devices entails attracting circulating endothelial cells or their progenitors, via immobilized cell-capture molecules; for example, anti-CD34 antibody to attract CD34+ endothelial colony-forming cells (ECFCs). Inherent is the assumption that the cells attracted to the biomaterial surface are bound exclusively via a specific CD34 binding. However, serum proteins might adsorb in-between or on the top of antibody molecules and attract ECFCs via other binding mechanisms. Here, we studied whether a surface with immobilized anti-CD34 antibodies attracts ECFCs via a specific CD34 binding or a nonspecific (non-CD34) binding. To minimize serum protein adsorption, a fouling-resistant layer of hyperbranched polyglycerol (HPG) was used as a “blank slate,” onto which anti-CD34 antibodies were immobilized via aldehyde-amine coupling reaction after oxidation of terminal diols to aldehydes. An isotype antibody, mIgG1, was surface-immobilized analogously and was used as the control for antigen-binding specificity. Cell binding was also measured on the HPG hydrogel layer before and after oxidation. The surface analysis methods, x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry, were used to verify the intended surface chemistries and revealed that the surface coverage of antibodies was sparse, yet the anti-CD34 antibody grafted surface-bound ECFCs very effectively. Moreover, it still captured the ECFCs after BSA passivation. However, cells also attached to oxidized HPG and immobilized mIgG1, though in much lower amounts. While our results confirm the effectiveness of attracting ECFCs via surface-bound anti-CD34 antibodies, our observation of a nonspecific binding component highlights the importance of considering its consequences in future studies. Refereed/Peer-reviewed
- Published
- 2022
11. Rational approaches for optimizing chemical functionality of plasma polymers:A case study with ethyl trimethylacetate
- Author
-
Solmaz Saboohi, Andrew Michelmore, Bryan R. Coad, Hans J. Griesser, Robert D. Short, Saboohi, Solmaz, Coad, Bryan R, Short, Robert D, Michelmore, Andrew, and Griesser, Hans J
- Subjects
010302 applied physics ,chemistry.chemical_classification ,Materials science ,Polymers and Plastics ,plasma polymerization ,Protonation ,Plasma ,Polymer ,Condensed Matter Physics ,Mass spectrometry ,01 natural sciences ,Plasma polymerization ,Ion ,ethyl trimethylacetate ,Secondary ion mass spectrometry ,X-ray photoelectron spectroscopy ,Chemical engineering ,chemistry ,plasma regimes ,Physics::Plasma Physics ,0103 physical sciences ,mass spectroscopy - Abstract
Improved retention of desirable chemical structures during plasma polymerization requires rational tailoring of plasma-phase conditions. Using ethyl trimethylacetate, we studied the effects of pressure and power on the contribution of intact molecular ions to deposition and retention of ester groups. The abundance of protonated molecular ions in plasmas varies with pressure and power, but the functionality of plasma polymers, assessed by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry, is not correlated. Together with high ion flux, the ion energy distribution was found to be a key parameter and needs to be tailored to enable the soft landing of ions on the surface after traversing the sheath. The compromise between the abundance of ions and their energy distribution is optimal near the transition between the α and γ plasma phases. Refereed/Peer-reviewed
- Published
- 2021
12. Immobilization and surface characterization of NeutrAvidin biotin-binding protein on different hydrogel interlayers
- Author
-
Vermette, Patrick, Gengenbach, Thomas, Divisekera, Upulie, Kambouris, Peter A., Griesser, Hans J., and Meagher, Laurence
- Subjects
- *
SURFACE chemistry , *PHOTOELECTRON spectroscopy - Abstract
For a number of potential applications, it is desirable to immobilize avidin class molecules onto solid supports and exploit their ability to bind biotinylated molecules with high affinity. NeutrAvidin molecules were surface immobilized in various ways. In this study, NeutrAvidin was covalently attached by carbodiimide chemistry onto carboxyl groups of polyacrylic acid and carboxymethyl–dextran hydrogel interlayers. A third strategy involved the affinity “docking” of NeutrAvidin onto a biotinylated poly(ethylene glycol) interlayer. These three interlayers were selected for their low nonspecific binding of proteins, which was expected to minimize surface binding of NeutrAvidin by nonspecific interfacial adsorption. X-ray photoelectron spectroscopy (XPS) analyses allowed detailed characterization of the multilayer fabrication steps. An ELISA assay was used to measure NeutrAvidin activity, which varied with the surface immobilization route. Atomic force microcopy (AFM) force measurements showed that the hydrogel interlayer contributed to a repulsive force and verified the specific interaction between biotinylated AFM tips and the NeutrAvidin surfaces. When a solution of free biotin was injected into the AFM liquid cell, the force curve changed substantially and became identical to that recorded between surfaces carrying no NeutrAvidin, indicating that the free solution biotin had displaced NeutrAvidin proteins off the PEG–biotin layer. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
- View/download PDF
13. XPS study of sulfur and phosphorus compounds with different oxidation states
- Author
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S Siow Kim, Leanne Britcher, Hans J. Griesser, Sunil Kumar, Siow, Kim S, Britcher, Leanne, Kumar, Sunil, and Griesser, Hans J
- Subjects
Multidisciplinary ,Chemistry ,Phosphorus ,Binding energy ,Inorganic chemistry ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Sulfur ,0104 chemical sciences ,Catalysis ,Polystyrene sulfonate ,chemistry.chemical_compound ,Sodium hexametaphosphate ,X-ray photoelectron spectroscopy ,Oxidation state ,sulfur ,XPS ,oxidation state ,phosphorus ,0210 nano-technology ,binding energies - Abstract
In this report, we demonstrate that continuous improvement in XPS instruments and the calibration standards as well as analysis with standard component-fitting procedures can be used to determine the binding energies of compounds containing phosphorus and sulfur of different oxidation states with higher confidence. Based on such improved XPS analyses, the binding energies (BEs) of S2p signals for sulfur of increasing oxidation state are determined to be 166-167.5 eV for S=O in dimethyl sulfoxide, 168.1 eV for S=O2 in polysulfone, 168.4 eV for SO3 in polystyrene sulfonate and 168.8 eV for SO4 in chondroitin sulfate. The BEs of P2p signals show the following values: 132.9 eV for PO3 in triisopropyl phosphite, 133.3 eV for PO4 in glycerol phosphate, 133.5 eV for PO4 in sodium tripolyphosphate and 134.0 eV for PO4 in sodium hexametaphosphate. These results showed that there are only small increases in the binding energy when additional oxygen atoms are added to the S-O chemical group. A similar result is obtained when the fourth oxygen or poly-phosphate environment is added to the phosphorus compound. These BE values are useful to researchers involved in identifying oxidation states of phosphorus and sulfur atoms commonly observed on modified surfaces and interfaces found in applications such as biomaterials, super-capacitors and catalysis Refereed/Peer-reviewed
- Published
- 2018
14. Effects of Varying Heptylamine and Propionaldehyde Plasma Polymerization Parameters on Mesenchymal Stem Cell Attachment
- Author
-
Marek Jasieniak, Hans J. Griesser, Lisbeth Grøndahl, Anne M. Sandstrom, Justin J. Cooper-White, Sandstrom, Anne M, Jasieniak, Marek, Griesser, Hans J, Grøndahl, Lisbeth, and Cooper-White, Justin J
- Subjects
chemistry.chemical_classification ,Polymers and Plastics ,propionaldehyde ,plasma polymerization ,MSCs ,Propionaldehyde ,Polymer ,Adhesion ,Condensed Matter Physics ,Aldehyde ,Plasma polymerization ,heptylamine ,Atomic, Molecular, Nuclear, Particle and Plasma Physics ,chemistry.chemical_compound ,stem cell attachment ,Monomer ,chemistry ,X-ray photoelectron spectroscopy ,Polymer chemistry ,Fragmentation (cell biology) - Abstract
This paper investigated the impacts of two deposition times (30 s, 60 s) and discharge powers (20 W, 50 W) on the resultant chemical and physical properties of plasma polymers (pp) formed using heptylamine (HA) or propionaldehyde (PA) monomers. Pinhole-free pp films were formed on all surfaces at deposition rates that varied according to both the time and power employed. XPS and ToF-SIMS analysis showed that power has a more of an effect than time on the chemical properties of the pp, which may be attributed to differences in monomer fragmentation and cross-linking. Mesenchymal stem cell (MSC) adhesion did not vary on the four different HApp surfaces, whereas a negative correlation between cell attachment and increasing plasma energy was observed on PApp surfaces. This suggests that the presence of oxygenated groups, particularly aldehyde and carboxylic groups, may have a dominant impact on MSC adhesion to these functional polymer substrates. Refereed/Peer-reviewed
- Published
- 2012
15. Surface modification and chemical surface analysis of biomaterials
- Author
-
Peter Kingshott, Gunther G. Andersson, Sally L. McArthur, Hans J. Griesser, Kingshott, Peter, Andersson, Gunther, McArthur, Sally L, and Griesser, Hans J
- Subjects
Materials science ,Tissue Engineering ,Biocompatibility ,Polymers ,Surface Properties ,Photoelectron Spectroscopy ,Proteins ,Spectrometry, Mass, Secondary Ion ,Biocompatible Materials ,Nanotechnology ,Cell movement ,engineering.material ,Biochemistry ,Analytical Chemistry ,surface modification strategies ,X-ray photoelectron spectroscopy ,Coating ,Cell Movement ,Cell Adhesion ,Biological media ,engineering ,Humans ,Surface modification ,biomaterials surface analysis ,Thin film - Abstract
The chemical composition of the surface layers of synthetic biomaterials used for human medical devices and in biotechnology plays a key role in determining interfacial interactions between biological media (such as protein solutions, cells, tissue) and the synthetic material. Accordingly, considerable research efforts focus on improving the 'biocompatibility' of biomaterials by applying various surface modification and thin film coating approaches. Here we focus on the patterning of surface chemistries, often designed to exercise spatial control over events such as cell attachment and spreading. Secondly, we review recent developments in chemical characterisation of biomaterials surfaces, which is essential both for verifying the success of intended surface modification strategies and for reliable interpretation of observed biological responses. Biomaterials surface analysis by imaging ToF-SIMS and XPS and compositional depth profiling are discussed, as is the emerging complementary technique of Metastable Induced Electron Spectroscopy. Refereed/Peer-reviewed
- Published
- 2011
16. A ToF-SIMS and XPS study of protein adsorption and cell attachment across PEG-like plasma polymer films with lateral compositional gradients
- Author
-
Donna J. Menzies, Benjamin W. Muir, Marek Jasieniak, John S. Forsythe, Hans J. Griesser, Graham Johnson, Gail A. McFarland, Menzies, Donna J, Jasieniak, Marek, Griesser, Hans J, Forsythe, John S, Johnson, Graham, McFarland, Gail A, and Muir, Benjamin W
- Subjects
Analytical chemistry ,Diglyme ,cell attachment ,Surfaces and Interfaces ,Condensed Matter Physics ,Human serum albumin ,PEG ,plasma polymer ,protein adsorption ,Surfaces, Coatings and Films ,Secondary ion mass spectrometry ,gradient ,chemistry.chemical_compound ,Adsorption ,Monomer ,diglyme ,chemistry ,X-ray photoelectron spectroscopy ,Materials Chemistry ,medicine ,ToF-SIMS ,Ethylene glycol ,medicine.drug ,Protein adsorption - Abstract
In this work we report a detailed X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) study of poly(ethylene glycol) PEG-like chemical gradients deposited via plasma enhanced chemical vapour deposition (PECVD) at two different load powers using diethylene glycol dimethyl ether (DG) as a monomer. Principal component analysis (PCA) was applied to the ToF-SIMS data both before and after protein adsorption on the plasma polymer thin films. Results of the PCA loadings indicated a higher content of hydrocarbon fragments across the higher load power gradient, which adsorbed higher amounts of proteins. Gradients deposited at a lower load power retained a higher degree of monomer like functionality as did the central region directly underneath the knife edge electrode. Analysis of the adsorption of serum proteins (human serum albumin and fetal bovine serum) was monitored across the gradient films and increased with decreasing ether (PEG-like) film chemistries. The effect of protein incubation time on the levels adsorbed fetal bovine serum on the plasma polymer films was critical, with significantly more protein adsorbing after 24 hour incubation times on both gradient films. The attachment of HeLa cells on the gradients appeared to be dictated not only by the surface chemistry, but also by the adsorption of serum proteins. XPS analysis revealed that at surface ether concentrations of less than 70% in the gradient films, significant increases in protein and cell attachment were observed. Refereed/Peer-reviewed
- Published
- 2012
17. Uniform, adhesive, and low cytotoxic films accelerating bacterial reduction in the dark and under visible light
- Author
-
J. Kiwi, Sami Rtimi, Cesar Pulgarin, and Griesser, Hans J.
- Subjects
CFU evaluation/reduction ,Materials science ,Nanocomposite ,Kinetics ,Inorganic chemistry ,Sputtering ,Nitride ,Nitrides/Oxynitrides ,X-ray photoelectron spectroscopy ,Chemical engineering ,Silver composites ,Photocatalysis ,Chemical stability ,Nanoparticulate films ,Visible spectrum - Abstract
This study presents bacterial reduction by visible light-absorbing nanocomposite nitride and oxynitride films showing absorption in the visible spectral range and their silver (Ag) derivatives. The design, sputtering, bacterial evaluation, and surface characterization of uniform and adhesive nanoparticulate nitride and oxynitride films are described in detail. Bacterial reduction was observed by these Ag-nitrides/oxynitrides to proceed in the dark and with higher kinetics under daylight/actinic light irradiation. The special interest regarding the nitrides is their low cytotoxicity and chemical stability, which make them especially suited as supports for highly oxidative Ag nanoparticles. The Ag-TiON fast inactivation kinetics concomitant with low cytotoxicity is the essential requirement for the potential practical application of these antibacterial surfaces. The aims of this study are to show the increased kinetics of bacterial activation as a function of nitride/oxynitride composition, to report their operational long-term stability, and to characterize the film composite microstructure.
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