PRINTING AN ADHESIVE PATTERN ON AN ANTI-FOULING SUPPORT

Abstract

Process for printing an adhesive pattern on a polymer brush extending at the surface of a support (1), forming a nanometric anti-fouling layer (2), the process comprising the following steps:—placing the layer (2) in contact with a first aqueous solution (4) containing a benzophenone,—then illuminating the layer with radiation (3) at a wavelength within the absorption spectrum of benzophenone, according to the pattern and according to a surface energy.

Claims

1. A process for printing an adhesive pattern on a polymer brush extending at the surface of a support (1) forming a nanometric anti-fouling layer (2), the process comprising the following steps: placing the layer (2) in contact with a first aqueous solution (4) containing a benzophenone, then illuminating the layer with a radiation (3) at a wavelength within the absorption spectrum of the benzophenone, according to the pattern and according to a surface energy.

2. The process as claimed in claim 1, wherein the thickness of the layer (2) is between 1 nm and 20 nm.

3. The process as claimed in claim 2, wherein the wavelength is chosen between 300 nm and 400 nm.

4. The process as claimed in claim 3, wherein said polymer is a polyethylene glycol (PEG).

5. The process as claimed in claim 3, wherein said polymer is a polyNIPAM.

6. The process as claimed in claim 3, wherein said support (1) is a glass.

7. The process as claimed in claim 3, wherein said support (1) is a PolyDiMethylSiloxane (PDMS).

8. The process as claimed in claim 4, wherein the surface energy of the illumination transmitted to the PEG layer is between 10 mJ/mm.sup.2 and 1000 mJ/mm.sup.2.

9. The process as claimed in claim 5, wherein the surface energy of the illumination transmitted to the polyNIPAM layer is between 100 mJ/mm.sup.2 and 10000 mJ/mm.sup.2.

10. The process as claimed in claim 7, wherein the Young's modulus of the PDMS is less than 15 kPa.

11. The process as claimed in claim 1, for printing a pattern of a protein on the polymer brush, comprising the following additional steps: rinsing to eliminate the contact between the layer (2) and the first solution (4), then placing the layer (2) in contact with a second aqueous solution containing the protein.

12. The process as claimed in claim 1, for printing a pattern of nanoshells on the polymer brush, comprising the following additional steps: rinsing to eliminate the contact between the layer (2) and the first solution (4), placing the layer (2) in contact with a second solution containing the nanoshells.

13. The process as claimed in claim 1, for printing a pattern of DNA strands on the polymer brush, comprising the following additional steps: rinsing to eliminate the contact between the layer and the first solution (4), placing the layer (2) in contact with a second solution containing the DNA strands.

14. An application of the process as claimed in claim 1 to the production of an adhesive pattern having an adhesion gradient at the surface of the support (1), by spatial variation of the surface energy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The invention will be better understood in connection with the list of figures below, wherein:

[0038] FIG. 1 represents, in cross section, an anti-fouling substrate composed of a glass support and a layer of material that is anti-fouling, in particular for proteins, nanoshells or DNA strands, that is to say a polymer brush grafted or attached to the support. The substrate is covered with a drop of an aqueous solution containing benzophenone over all or some of the polymer brush. A zone AB of the layer, covered with benzophenone, is illuminated through the support (through the drop would also be practicable) via radiation comprising wavelengths within the absorption spectrum of benzophenone, i.e. radiation between 300 nm and 400 nm.

[0039] FIG. 2 represents the substrate rinsed of the drop from FIG. 1 and having a latent image represented in a illustrated manner by a hollow in the surface of the anti-fouling material at the zone AB. Such a material is capable of being used to print in particular a pattern of a protein, of nanoshells or of DNA or RNA strands according to a pattern corresponding to the surface of the zone AB. Specifically, the illumination of the polymer brush in the presence of benzophenone potentially renders the polymer brush adhesive in the zone AB and enables the subsequent adhesion in particular of a protein, of nanoshells or of DNA strands, by subsequently placing the polymer brush layer in contact, respectively, with in particular a solution of the protein, a solution of nanoshells or of DNA strands. An illumination according to a set of zones like AB thus enables the production of an adhesive pattern or an adhesive pattern of molecules on a polymer brush, for molecules for which the brush is normally non-adhesive.

DETAILED DESCRIPTION OF EXAMPLE(S)

[0040] In a first embodiment, disclosed with reference to FIG. 1 for the reference numbers between parentheses, are an anti-fouling substrate composed of a glass support (1) and a layer (2) of a polymer brush material which is, in this first embodiment, PEG or polyNIPAM.

[0041] In this first embodiment, radiation (3) illuminates the layer (2) over a zone AB (AB), here through a support (1) chosen to be transparent for the radiation used, a drop (4) of an aqueous benzophenone solution is deposited on the layer (2) covering the zone AB (AB). In an equivalent manner, it would be possible to illuminate the layer through the drop (4), over the same zone AB.

[0042] The radiation used comprises at least one wavelength within the absorption spectrum of benzophenone, which spectrum usefully extends in practice between 300 nm and 400 nm. Preferentially, within this range use will be made of radiation having a wavelength of less than 390 nm, in this case the exposure time of the layer to the radiation will be minimized.

[0043] The lower the absorption of benzophenone at the chosen wavelength, the greater the power of the light source will have to be or the longer the exposure time of the illuminated zone will have to be, the dose of the radiation received, equal to the product of the lighting power and the exposure time to the light, being the parameter governing the obtaining of the effect of the invention.

[0044] Since no protein to be grafted is in solution, the radiation will if necessary be of higher power than a power that gives rise to the destruction of a protein to be subsequently grafted and will only be limited by the surface density of light energy accepted by the layer, without degradation. However, the presence of benzophenone makes it possible, for PEG, to use optical powers 10 to 100 times lower than for ablation or masking techniques.

[0045] An energy density between 10 mJ/mm.sup.2 and 1000 mJ/mm.sup.2 can thus be used to obtain the appearance of an adhesive pattern on PEG. The invention may thus be satisfied with a source that produces an illumination of 2 mW over a square having sides of 400 microns for a wavelength of an ultraviolet line at 372 nm from a semiconductor laser. For polyNipam on a PDMS support, a usable energy density is between 100 mJ/mm.sup.2 and 10000 mJ/mm.sup.2. The same semiconductor laser source may again be used by simply multiplying the exposure times for PEG by 10.

[0046] In a first step of the process of this embodiment, the anti-fouling substrate is placed in contact with a drop of aqueous benzophenone solution, then in a second step a zone AB of the anti-fouling layer of the substrate is illuminated with the ultraviolet light source.

[0047] Any optical system enabling the energy of the source to be focused on the zone AB or on a set of zones at the same time can be used and such systems are known from the prior art. A microscope with a micromirror array can thus be envisaged for producing the lighting system for this embodiment. Similarly, the drop may be replaced by a film of aqueous benzophenone solution, brought into contact with the layer, then rinsed after illumination by known microfluidic means.

[0048] FIG. 2 represents the polymer brush formed as a nanometric layer, thus rinsed of the drop of the benzophenone solution and provided, in an illustrated manner, with a hollow latent pattern that is itself also nanometric with regard to its depth, in the zone AB. In order to be developed, this hollow or latent pattern needs to be subsequently brought into contact with molecules or molecular assemblies capable of adhering to the support at this hollow in a polymer brush (proteins, nanoshells, DNA strands, bacteria, etc.), the adhesion of these molecules according to the latent pattern then takes place in the presence of these molecules in aqueous solution, at the zones of the layer which have been illuminated (here AB) in the presence of benzophenone. The adhesion of molecules takes place without provision of light energy. The molecules are simply adsorbed on the polymer brush at the latent pattern or adhesive pattern. An actual pattern of molecules is thus formed on the brush. In particular if the molecules are fluorescent, it is possible to then make an image thereof by techniques known in the prior art in order to demonstrate the result of the adhesion.

[0049] However, even without bringing into contact with an aqueous solution, for example a solution of proteins, it is possible to predict, after insolation of the brush, whether the effect of the invention will be obtained, independently of the production of a subsequent actual pattern, by measuring, after illumination, whether there are hollows of nanometric depth in the brush at the illuminated locations using an atomic-force microscope (AFM), or by observing whether there are optical path variations in the brush, optically, by phase-contrast microscopy at these same locations. It is thus possible to select, without other experimentation, the polymer brushes suitable for the process of the invention, in particular as being those for which a reduction in the length of the polymer chains of the brush is observed after illumination in the presence of benzophenone.

[0050] In a second embodiment of the invention, the device from FIG. 2 is brought into contact with an aqueous solution of a protein or an aqueous solution of nanoshells. The choice of the nature of the proteins or of the nanoshells is made from the proteins and nanoshells capable of adhering to the support in order to obtain the most durable possible actual image.

[0051] It is thus possible, with the process of this second embodiment, to obtain an actual image of the zone AB for example by using a fluorescent protein, but more generally a pattern of a protein on the protein anti-fouling substrate that was used. Furthermore, the properties, under illumination, of the anti-fouling substrates make it possible to produce a fluorescence having a value that varies continuously with the illumination or the dose of optical radiation received by the zone AB and more generally a concentration of proteins, of nanoshells or of DNA strands that varies continuously with the illumination in this zone, even if this zone corresponds to the resolution limit of the optical lighting system, without recourse to densities of binary points to simulate variable concentrations of proteins.

[0052] It is thus possible to apply the invention to the production of adhesion gradients in a concentration direction for example of a protein, of nanoshells or of DNA strands, along the surface of the substrate or of the anti-fouling layer, by aligning several zones of type AB end-to-end and by varying the surface energy delivered to these zones, for example by illuminating them with variable surface zones (in J/m.sup.2), during the step of illuminating the polymer brush in the presence of benzophenone or of printing the latent image or adhesive pattern.

[0053] For example, a continuously variable adhesive effect for proteins has been obtained by variable dose illumination in the presence of benzophenone on a PEG brush, for a thickness reduction of between 0 nm reduction (no adhesion or outside-pattern zone) and 2 nm reduction (maximum adhesion) for PEG polymer brushes having a thickness estimated at 5 nm outside of the adhesion zones.

[0054] In the embodiments presented, a concentration range in millimoles of benzophenone per liter of aqueous solution (mmol/l) from 5 mmol/l to 50 mmol/l was used.

[0055] The invention is industrially applicable within the field of substrate production for printing adhesive patterns of a protein on a polymer brush.