Falk Bernsmann - Academia.edu (original) (raw)
Papers by Falk Bernsmann
The Journal of Physical Chemistry C, May 6, 2009
It has recently been demonstrated that dopamine solutions put in contact with a variety of solid ... more It has recently been demonstrated that dopamine solutions put in contact with a variety of solid substrates allow the production of thin coatings probably made of melanin (Science 2007, 318, 426). In this article, we show that the thickness of these coatings can be ...
Berichte Der Deutschen Chemischen Gesellschaft, Dec 1, 2009
Polyoxometalates (POMs) are known since 1826 and systematically synthesized for almost a century1... more Polyoxometalates (POMs) are known since 1826 and systematically synthesized for almost a century1,2 Research on this compound class becomes an increasingly popular subdomain of supramolecular chemistry3 because they are obtained through the non-covalent ...
Eur J Inorg Chem, 2009
ABSTRACT The immobilization of polyoxometalates (POMs) into thin organized films is of major impo... more ABSTRACT The immobilization of polyoxometalates (POMs) into thin organized films is of major importance for the development of functional devices like electrochromic films and catalysts. We investigate herein two methods to incorporate the wheel-shaped tungstophosphate [H7P8W48O184]33– (P8W48) polyoxometalates (POM) into polyelectrolyte multilayer (PEM) films, which offer the advantage of controlled thickness and ease of processability. The first method, whose feasibility has been widely demonstrated, consists in the alternate deposition of a polycation and the negatively charged POM. The second method has never been used to load POMs into thin films: an exponentially grown polyelectrolyte multilayer film, made from sodium hyaluronate (HA) and poly-L-lysine (PLL), is brought in contact with the POM solution to allow its passive diffusion into the PEM film. Both methods of incorporation are compared in terms of effective POM concentration in the film. In addition it is shown that the second method leads to a maximum in the amount of incorporated POM as a function of its concentration in solution.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Clinical oral investigations, Jan 27, 2015
Biomaterial surfaces are at high risk for initial microbial colonization, persistence, and concom... more Biomaterial surfaces are at high risk for initial microbial colonization, persistence, and concomitant infection. The rationale of this study was to assess the initial adhesion on novel implant surfaces of Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans upon incubation. The tested samples were 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) samples with nitrogen-doped hydrogenated amorphous carbon (a-C:H:N) coating (A) and 3Y-TZP samples coated with ceria-stabilized zirconia-based (Ce-TZP) composite and a-C:H:N (B). Uncoated 3Y-TZP samples (C) and bovine enamel slabs (BES) served as controls. Once the surface was characterized, the adherent microorganisms were quantified by estimating the colony-forming units (CFUs). Microbial vitality was assessed by live/dead staining, and microbial-biomaterial surface topography was visualized by scanning electron microscopy (SEM). Overall, A and B presented the lowest...
The Journal of Physical Chemistry C, 2009
It has recently been demonstrated that dopamine solutions put in contact with a variety of solid ... more It has recently been demonstrated that dopamine solutions put in contact with a variety of solid substrates allow the production of thin coatings probably made of melanin (Science 2007, 318, 426). In this article, we show that the thickness of these coatings can be ...
Soft Matter, 2008
In this communication, we demonstrate that dopamine is able to undergo a polymerisation process i... more In this communication, we demonstrate that dopamine is able to undergo a polymerisation process in (PLL-HA) n polyelectrolyte multilayer films, and that this polymerisation is of the same nature as in solution at pH 8.5. This polymerisation changes the chemical ...
Materials, 2013
Bacterial adhesion to implant biomaterials constitutes a virulence factor leading to biofilm form... more Bacterial adhesion to implant biomaterials constitutes a virulence factor leading to biofilm formation, infection and treatment failure. The aim of this study was to examine the initial bacterial adhesion on different implant materials in vitro. Four implant biomaterials were incubated with Enterococcus faecalis, Staphylococcus aureus and Candida albicans for 2 h: 3 mol % yttria-stabilized tetragonal zirconia polycrystal surface (B1a), B1a with zirconium oxide (ZrO 2 ) coating (B2a), B1a with zirconia-based composite coating (B1b) and B1a with zirconia-based composite and ZrO 2 coatings (B2b). Bovine enamel slabs (BES) served as control. The adherent microorganisms were quantified and visualized using scanning electron microscopy (SEM); DAPI and live/dead staining. The lowest bacterial count of E. faecalis was detected on BES and the highest on B1a. The
Langmuir, 2011
The deposition of "polydopamine" films, from an aqueous solution containing dopamine or other cat... more The deposition of "polydopamine" films, from an aqueous solution containing dopamine or other catecholamines, constitutes a new and versatile way to functionalize solid-liquid interfaces. Indeed such films can be deposited on almost all kinds of materials. Their deposition kinetics does not depend markedly on the surface chemistry of the substrate, and the films can reach thickness of a few tens of nanometers in a single reaction step. Up to now, even if a lot is known about the oxidation mechanism of dopamine in solution, only little information is available to describe the deposition mechanism on surfaces either by oxidation in solution or by electrodeposition. The deposition kinetics of melanin was only investigated from dopamine solutions using oxygen or ammonium persulfate as an oxidant and from a tris(hydroxymethyl) aminomethane (Tris) containing buffer solutions at pH 8.5. Many other oxidants could be used, and the buffer agent containing a primary amine group may influence the deposition process. Herein we show that the deposition kinetics of melanin from dopamine containing buffers at pH 8.5 can be markedly modified using Cu 2þ instead of O 2 as an oxidant: the deposition kinetics remains linear up to thicknesses of more than 70 nm, whereas the film growth stops at 45 ( 5 nm in the presence of 0 2 . In addition, the films prepared from Cu 2þ containing solutions display an absorption spectrum with defined peaks at 320 and 370 nm, which are absent in the spectra of films prepared in oxygenated solutions. The replacement of Tris buffer by phosphate buffer also has a marked effect on the melanin deposition kinetics.
Langmuir, 2009
The buildup of polyelectrolyte multilayer films made from poly(L-lysine) (PLL) as a polycation an... more The buildup of polyelectrolyte multilayer films made from poly(L-lysine) (PLL) as a polycation and from a blend of two anionic polysaccharides, namely, beta-1,3 glycan sulfate (GlyS) and alginate (Alg), was investigated as a function of the mass fraction, x, of GlyS in the blend, at a constant total weight concentration in polyanions. We find that the film thickness, after the deposition of a given number of layer pairs, reaches a minimum for x values lower than 0.1 (the position of this minimum could not be more precisely localized) and that the film thickness at intermediate values of x is the same as that of films built at the same concentration of GlyS in the absence of Alg (pure GlyS solution). Infrared spectroscopy in the attenuated total reflection mode shows that the weight fraction of GlyS in the multilayer films is much higher than its weight fraction, x, in the blend used to build the film. This preferential incorporation of GlyS over Alg is related to preferential interactions of GlyS as compared to Alg with PLL in solution, as measured by means of isothermal titration calorimetry. We also demonstrate that GlyS is able to displace Alg almost quantitatively from (PLL/Alg)n films but that in contrast Alg is not able to exchange GlyS from (PLL/GlyS)n films. These results, which combine adsorption from blended polyanion solutions, exchange of one polyanion already present in the film by the other in solution, and thermodynamic measurements, suggest that sulfated polymers are able to interact with polycations preferentially over polymers carrying carboxylated charged groups. These results give a first structural basis to the mechanism of preferential incorporation of a given polyanion with respect to another.
Journal of Colloid and Interface Science, 2010
We recently showed the possibility to build dopamine-melanin films of controlled thickness by suc... more We recently showed the possibility to build dopamine-melanin films of controlled thickness by successive immersions of a substrate in alkaline solutions of dopamine [F. Bernsmann, A. Ponche, C. Ringwald, J. Hemmerlé, J. Raya, B. Bechinger, J.-C. Voegel, P. Schaaf, V. Ball, J. Phys. Chem. C 113 (2009) 8234-8242]. In this work the structure and properties of such films are further explored. The zeta-potential of dopamine-melanin films is measured as a function of the total immersion time to build the film. It appears that the film bears a constant zeta-potential of (-39+/-3) mV after 12 immersion steps. These data are used to calculate the surface density of charged groups of the dopamine-melanin films at pH 8.5 that are mostly catechol or quinone imine chemical groups. Furthermore the zeta-potential is used to explain the adsorption of three model proteins (lysozyme, myoglobin, alpha-lactalbumin), which is monitored by quartz crystal microbalance. We come to the conclusion that protein adsorption on dopamine-melanin is not only determined by possible covalent binding between amino groups of the proteins and catechol groups of dopamine-melanin but that electrostatic interactions contribute to protein binding. Part of the adsorbed proteins can be desorbed by sodium dodecylsulfate solutions at the critical micellar concentration. The fraction of weakly bound proteins decreases with their isoelectric point. Additionally the number of available sites for covalent binding of amino groups on melanin grains is quantified.
European Journal of Inorganic Chemistry, 2009
Polyoxometalates (POMs) are known since 1826 and systematically synthesized for almost a century1... more Polyoxometalates (POMs) are known since 1826 and systematically synthesized for almost a century1,2 Research on this compound class becomes an increasingly popular subdomain of supramolecular chemistry3 because they are obtained through the non-covalent ...
Electrochimica Acta, 2011
Different methods to prepare melanin films by dopamine oxidation are compared with respect to the... more Different methods to prepare melanin films by dopamine oxidation are compared with respect to their permeability to electrochemical probes being either neutral or carrying a positive or a negative charge. To examine charge-dependence of the permeability differently charged probes of similar size (hexaamineruthenium, ferrocenemethanol and hexacyanoferrate) are employed. We deliberately not investigated the permeability of metal cations through the melanin
Analytical and Bioanalytical Chemistry, 2008
The proteins lysozyme, amylase, and bovine serum albumin (BSA) were adsorbed on two experimental ... more The proteins lysozyme, amylase, and bovine serum albumin (BSA) were adsorbed on two experimental dental materials, made of fluoroapatite particles embedded in polymer matrices, and on silicon wafers. The protein films were prepared as single-component layers, as binary mixtures, and as double layers. These systems were investigated by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and the multivariate data analysis technique of discriminant principal-component analysis (DPCA). During adsorption of a single protein film on to the solid surfaces, the three proteins could be clearly distinguished by the scores of their mass spectra after selection of amino acidrelated peaks and DPCA. Furthermore, very similar results were obtained on the two different fluoroapatite substrates. For samples coated with binary layers of two proteins adsorbed simultaneously, it was found for both substrate types that BSA shows the strongest ability to adsorb followed by lysozyme, while amylase has the smallest ability. By contrast, the consecutive adsorption of two protein layers showed a strong influence of substrate type on the adsorption ability of the proteins.
Objective: Bacterial adhesion to implant biomaterials leads to biofilm formation and hence, to in... more Objective: Bacterial adhesion to implant biomaterials leads to biofilm formation and hence, to infection and treatment failure. The aim of this study was to examine the initial microbial colonization on different implant materials in vitro. Method: Two novel implant biomaterials were incubated with Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans for 2 h: yttria-stabilized tetragonal zirconia polycrystal surfaces (Y-TZP) with nitrogen-containing hydrogenated amorphous carbon (a-C:H:N) coating (A) and Y-TZP surfaces with zirconia-based composite (Ce-TZP) and a-C:H:N coatings (B). Bovine enamel slabs (BES) served as control. The adherent microorganisms were quantified by determination of colony-forming units (CFUs) and visualized using scanning electron microscopy (SEM), DAPI and live/dead staining. Result: A and B showed comparable CFUs sheltering greater amounts of E. coli and lower numbers of E. faecalis, S. aureus and P. a...
The Journal of Physical Chemistry C, May 6, 2009
It has recently been demonstrated that dopamine solutions put in contact with a variety of solid ... more It has recently been demonstrated that dopamine solutions put in contact with a variety of solid substrates allow the production of thin coatings probably made of melanin (Science 2007, 318, 426). In this article, we show that the thickness of these coatings can be ...
Berichte Der Deutschen Chemischen Gesellschaft, Dec 1, 2009
Polyoxometalates (POMs) are known since 1826 and systematically synthesized for almost a century1... more Polyoxometalates (POMs) are known since 1826 and systematically synthesized for almost a century1,2 Research on this compound class becomes an increasingly popular subdomain of supramolecular chemistry3 because they are obtained through the non-covalent ...
Eur J Inorg Chem, 2009
ABSTRACT The immobilization of polyoxometalates (POMs) into thin organized films is of major impo... more ABSTRACT The immobilization of polyoxometalates (POMs) into thin organized films is of major importance for the development of functional devices like electrochromic films and catalysts. We investigate herein two methods to incorporate the wheel-shaped tungstophosphate [H7P8W48O184]33– (P8W48) polyoxometalates (POM) into polyelectrolyte multilayer (PEM) films, which offer the advantage of controlled thickness and ease of processability. The first method, whose feasibility has been widely demonstrated, consists in the alternate deposition of a polycation and the negatively charged POM. The second method has never been used to load POMs into thin films: an exponentially grown polyelectrolyte multilayer film, made from sodium hyaluronate (HA) and poly-L-lysine (PLL), is brought in contact with the POM solution to allow its passive diffusion into the PEM film. Both methods of incorporation are compared in terms of effective POM concentration in the film. In addition it is shown that the second method leads to a maximum in the amount of incorporated POM as a function of its concentration in solution.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Clinical oral investigations, Jan 27, 2015
Biomaterial surfaces are at high risk for initial microbial colonization, persistence, and concom... more Biomaterial surfaces are at high risk for initial microbial colonization, persistence, and concomitant infection. The rationale of this study was to assess the initial adhesion on novel implant surfaces of Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans upon incubation. The tested samples were 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) samples with nitrogen-doped hydrogenated amorphous carbon (a-C:H:N) coating (A) and 3Y-TZP samples coated with ceria-stabilized zirconia-based (Ce-TZP) composite and a-C:H:N (B). Uncoated 3Y-TZP samples (C) and bovine enamel slabs (BES) served as controls. Once the surface was characterized, the adherent microorganisms were quantified by estimating the colony-forming units (CFUs). Microbial vitality was assessed by live/dead staining, and microbial-biomaterial surface topography was visualized by scanning electron microscopy (SEM). Overall, A and B presented the lowest...
The Journal of Physical Chemistry C, 2009
It has recently been demonstrated that dopamine solutions put in contact with a variety of solid ... more It has recently been demonstrated that dopamine solutions put in contact with a variety of solid substrates allow the production of thin coatings probably made of melanin (Science 2007, 318, 426). In this article, we show that the thickness of these coatings can be ...
Soft Matter, 2008
In this communication, we demonstrate that dopamine is able to undergo a polymerisation process i... more In this communication, we demonstrate that dopamine is able to undergo a polymerisation process in (PLL-HA) n polyelectrolyte multilayer films, and that this polymerisation is of the same nature as in solution at pH 8.5. This polymerisation changes the chemical ...
Materials, 2013
Bacterial adhesion to implant biomaterials constitutes a virulence factor leading to biofilm form... more Bacterial adhesion to implant biomaterials constitutes a virulence factor leading to biofilm formation, infection and treatment failure. The aim of this study was to examine the initial bacterial adhesion on different implant materials in vitro. Four implant biomaterials were incubated with Enterococcus faecalis, Staphylococcus aureus and Candida albicans for 2 h: 3 mol % yttria-stabilized tetragonal zirconia polycrystal surface (B1a), B1a with zirconium oxide (ZrO 2 ) coating (B2a), B1a with zirconia-based composite coating (B1b) and B1a with zirconia-based composite and ZrO 2 coatings (B2b). Bovine enamel slabs (BES) served as control. The adherent microorganisms were quantified and visualized using scanning electron microscopy (SEM); DAPI and live/dead staining. The lowest bacterial count of E. faecalis was detected on BES and the highest on B1a. The
Langmuir, 2011
The deposition of "polydopamine" films, from an aqueous solution containing dopamine or other cat... more The deposition of "polydopamine" films, from an aqueous solution containing dopamine or other catecholamines, constitutes a new and versatile way to functionalize solid-liquid interfaces. Indeed such films can be deposited on almost all kinds of materials. Their deposition kinetics does not depend markedly on the surface chemistry of the substrate, and the films can reach thickness of a few tens of nanometers in a single reaction step. Up to now, even if a lot is known about the oxidation mechanism of dopamine in solution, only little information is available to describe the deposition mechanism on surfaces either by oxidation in solution or by electrodeposition. The deposition kinetics of melanin was only investigated from dopamine solutions using oxygen or ammonium persulfate as an oxidant and from a tris(hydroxymethyl) aminomethane (Tris) containing buffer solutions at pH 8.5. Many other oxidants could be used, and the buffer agent containing a primary amine group may influence the deposition process. Herein we show that the deposition kinetics of melanin from dopamine containing buffers at pH 8.5 can be markedly modified using Cu 2þ instead of O 2 as an oxidant: the deposition kinetics remains linear up to thicknesses of more than 70 nm, whereas the film growth stops at 45 ( 5 nm in the presence of 0 2 . In addition, the films prepared from Cu 2þ containing solutions display an absorption spectrum with defined peaks at 320 and 370 nm, which are absent in the spectra of films prepared in oxygenated solutions. The replacement of Tris buffer by phosphate buffer also has a marked effect on the melanin deposition kinetics.
Langmuir, 2009
The buildup of polyelectrolyte multilayer films made from poly(L-lysine) (PLL) as a polycation an... more The buildup of polyelectrolyte multilayer films made from poly(L-lysine) (PLL) as a polycation and from a blend of two anionic polysaccharides, namely, beta-1,3 glycan sulfate (GlyS) and alginate (Alg), was investigated as a function of the mass fraction, x, of GlyS in the blend, at a constant total weight concentration in polyanions. We find that the film thickness, after the deposition of a given number of layer pairs, reaches a minimum for x values lower than 0.1 (the position of this minimum could not be more precisely localized) and that the film thickness at intermediate values of x is the same as that of films built at the same concentration of GlyS in the absence of Alg (pure GlyS solution). Infrared spectroscopy in the attenuated total reflection mode shows that the weight fraction of GlyS in the multilayer films is much higher than its weight fraction, x, in the blend used to build the film. This preferential incorporation of GlyS over Alg is related to preferential interactions of GlyS as compared to Alg with PLL in solution, as measured by means of isothermal titration calorimetry. We also demonstrate that GlyS is able to displace Alg almost quantitatively from (PLL/Alg)n films but that in contrast Alg is not able to exchange GlyS from (PLL/GlyS)n films. These results, which combine adsorption from blended polyanion solutions, exchange of one polyanion already present in the film by the other in solution, and thermodynamic measurements, suggest that sulfated polymers are able to interact with polycations preferentially over polymers carrying carboxylated charged groups. These results give a first structural basis to the mechanism of preferential incorporation of a given polyanion with respect to another.
Journal of Colloid and Interface Science, 2010
We recently showed the possibility to build dopamine-melanin films of controlled thickness by suc... more We recently showed the possibility to build dopamine-melanin films of controlled thickness by successive immersions of a substrate in alkaline solutions of dopamine [F. Bernsmann, A. Ponche, C. Ringwald, J. Hemmerlé, J. Raya, B. Bechinger, J.-C. Voegel, P. Schaaf, V. Ball, J. Phys. Chem. C 113 (2009) 8234-8242]. In this work the structure and properties of such films are further explored. The zeta-potential of dopamine-melanin films is measured as a function of the total immersion time to build the film. It appears that the film bears a constant zeta-potential of (-39+/-3) mV after 12 immersion steps. These data are used to calculate the surface density of charged groups of the dopamine-melanin films at pH 8.5 that are mostly catechol or quinone imine chemical groups. Furthermore the zeta-potential is used to explain the adsorption of three model proteins (lysozyme, myoglobin, alpha-lactalbumin), which is monitored by quartz crystal microbalance. We come to the conclusion that protein adsorption on dopamine-melanin is not only determined by possible covalent binding between amino groups of the proteins and catechol groups of dopamine-melanin but that electrostatic interactions contribute to protein binding. Part of the adsorbed proteins can be desorbed by sodium dodecylsulfate solutions at the critical micellar concentration. The fraction of weakly bound proteins decreases with their isoelectric point. Additionally the number of available sites for covalent binding of amino groups on melanin grains is quantified.
European Journal of Inorganic Chemistry, 2009
Polyoxometalates (POMs) are known since 1826 and systematically synthesized for almost a century1... more Polyoxometalates (POMs) are known since 1826 and systematically synthesized for almost a century1,2 Research on this compound class becomes an increasingly popular subdomain of supramolecular chemistry3 because they are obtained through the non-covalent ...
Electrochimica Acta, 2011
Different methods to prepare melanin films by dopamine oxidation are compared with respect to the... more Different methods to prepare melanin films by dopamine oxidation are compared with respect to their permeability to electrochemical probes being either neutral or carrying a positive or a negative charge. To examine charge-dependence of the permeability differently charged probes of similar size (hexaamineruthenium, ferrocenemethanol and hexacyanoferrate) are employed. We deliberately not investigated the permeability of metal cations through the melanin
Analytical and Bioanalytical Chemistry, 2008
The proteins lysozyme, amylase, and bovine serum albumin (BSA) were adsorbed on two experimental ... more The proteins lysozyme, amylase, and bovine serum albumin (BSA) were adsorbed on two experimental dental materials, made of fluoroapatite particles embedded in polymer matrices, and on silicon wafers. The protein films were prepared as single-component layers, as binary mixtures, and as double layers. These systems were investigated by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and the multivariate data analysis technique of discriminant principal-component analysis (DPCA). During adsorption of a single protein film on to the solid surfaces, the three proteins could be clearly distinguished by the scores of their mass spectra after selection of amino acidrelated peaks and DPCA. Furthermore, very similar results were obtained on the two different fluoroapatite substrates. For samples coated with binary layers of two proteins adsorbed simultaneously, it was found for both substrate types that BSA shows the strongest ability to adsorb followed by lysozyme, while amylase has the smallest ability. By contrast, the consecutive adsorption of two protein layers showed a strong influence of substrate type on the adsorption ability of the proteins.
Objective: Bacterial adhesion to implant biomaterials leads to biofilm formation and hence, to in... more Objective: Bacterial adhesion to implant biomaterials leads to biofilm formation and hence, to infection and treatment failure. The aim of this study was to examine the initial microbial colonization on different implant materials in vitro. Method: Two novel implant biomaterials were incubated with Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans for 2 h: yttria-stabilized tetragonal zirconia polycrystal surfaces (Y-TZP) with nitrogen-containing hydrogenated amorphous carbon (a-C:H:N) coating (A) and Y-TZP surfaces with zirconia-based composite (Ce-TZP) and a-C:H:N coatings (B). Bovine enamel slabs (BES) served as control. The adherent microorganisms were quantified by determination of colony-forming units (CFUs) and visualized using scanning electron microscopy (SEM), DAPI and live/dead staining. Result: A and B showed comparable CFUs sheltering greater amounts of E. coli and lower numbers of E. faecalis, S. aureus and P. a...