10 research outputs found
Review: the potential impact of surface crystalline states of titanium for biomedical applications
Synthèse à différentes interfaces de films bio-inspirés du byssus de la moule : Influence de la nature de l'oxydant à l'interface solide-liquide et d'ajout de polymères à l'interface air-eau
Polydopamine (PDA) materials are inspired from mussels’ byssus strong adhesion underwater. The oligomerization of dopamine in a basic medium allows forming a PDA coating on virtually any materials. In addition to the simplicity, ecofriendly and versatility of the deposition method, PDA has properties similar to those of melanin pigments and displays many outstanding properties. Thus PDAis widely used in energy, environmental and biomedical sciences. However design of PDA based new materials with tailored properties is a challenge since its structure is still unknown. In that sense one of the aims of this thesis is to gain knowledge in PDA structure-property relationship in order to design PDA materials with new properties. By choosing the appropriate oxidant we deposited thick and superhydrophylic films on any materials for the elaboration of low fouling and biocompatible surfaces. Additionally we discovered the possibility to form PDA films at the air/water interface. The investigation of this phenomenon led to the formation of stimuli responsive free standing membranes.Les matériaux à base de polydopamine (PDA) s’inspirent de la forte adhésion du byssus de la moule sous l’eau. L’oligomérisation de la dopamine dans un milieu basique permet la formation de revêtement de PDA sur n’importe quel matériau. En plus de la simplicité du procédé celui-ci est vert et versatile. La PDA a des propriétés similaires aux mélanines, d’où son utilisation dans le domaine des phénomènes de conversion d’énergie, de l’environnement et du biomédical. Cependant la structure de la PDA étant inconnue, l’élaboration de matériaux basés sur la relation structure propriétés est difficile. L’un des buts de cette thèse a été de comprendre cette relation pour élaborer de nouveaux matériaux de PDA. En choisissant l’oxydant adéquat nous avons déposé un film épais, superhydrophile et biocompatible sur n’importe quels substrats. De plus nous avons découverts la possibilité de former des films de PDA à l’interface air/eau. L’étude de ce phénomène a permis de former des membranes autosupportées et stimuli responsives
Borohydride-functionalized polydopamine-coated open cell polyurethane foam as a reusable soft structured material for reduction reactions: application to the removal of a dye
International audienceOpen cell polyurethane foams coated with mussel-inspired polydopamine can be used as support for borohydride anions through their complexation by the catechol groups of the polydopamine layer. This strong interaction prevents borohydride hydrolysis and oxidation, and based on the redox mediator properties of polydopamine, the so-functionalized polydopamine-coated open cell polyurethane foams can act as efficient and reusable soft structured materials for the reduction of methylene blue in aqueous solution without additional sodium borohydride (NaBH4). Very low amounts of released boron sub-products and very small potential of hydrogen (pH) increase are observed in comparison to previous processes using dissolved NaBH4. This considerably reduces the environmental impact of the reducing structured material on the treated wastewater compared to the latter
Stable Bioactive Enzyme-Containing Multilayer Films Based on Covalent Cross-Linking from Mussel-Inspired Adhesives
The use of immobilized
enzymes is mandatory for the easy separation
of the enzyme, the unreacted substrates, and the obtained products
to allow repeated enzymatic assays without cumbersome purification
steps. The immobilization procedure is however critical to obtain
a high fraction of active enzyme. In this article, we present an enzyme
immobilization strategy based on a catechol functionalized alginate.
We demonstrate that alkaline phosphatase (ALP) remains active in multilayered
films made with alginate modified with catechol moieties (AlgCat)
for long duration, that is, up to 7 weeks, provided the multilayered
architecture is cross-linked with sodium periodate. This cross-linking
reaction allows to create covalent bonds between the amino groups
of ALP and the quinone group carried by the modified alginate. In
the absence of cross-linking, the enzymatic activity is rapidly lost
and this reduction is mainly due to enzyme desorption. We also show
that NaIO<sub>4</sub> cross-linked (AlgCat-Alp)<sub><i>n</i></sub> films can be freeze-dried and reused at least 3 weeks later
without lost in enzymatic activity
Polydopamine Films from the Forgotten Air/Water Interface
The
formation of polydopamine under mild oxidation conditions from
dopamine solutions with mechanical agitation leads to the formation
of films that can functionalize all kinds of materials. In the absence
of stirring of the solution, we report the formation of polydopamine
films at the air/water interface (PDA A/W) and suggest that it arises
from an homogeneous nucleation process. These films grow two times
faster than in solution and can be deposited on hydrophilic or hydrophobic
substrates by the Langmuir–Schaeffer technique. Thanks to this
new method, porous and hydrophobic materials like polytetrafluoroethylene
(PTFE) membranes can be completely covered with a 35 nm thick PDA
A/W film after only 3h of reaction. Finally the oxidation of a monomer
followed by a polymerization in water is not exclusive to polydopamine
since we also transferred polyaniline functional films from the air/water
interface to solid substrates. These findings suggest that self-assembly
from a solution containing hydrophilic monomers undergoing a chemical
transformation (here oxidation and oligomerization) could be a general
method to produce films at the liquid/air interface