FR3012978A1 - BIOCOMPATIBLE FILTER AND METHOD FOR MANUFACTURING BIOCOMPATIBLE FILTER - Google Patents

Abstract

Biocompatible filter (4), in particular for isolating and culturing cells contained in a liquid sample, comprising a filtration membrane (8) extending substantially in an extension plane and having a liquid inlet face, a face of liquid outlet and a plurality of through filtration pores. The filtration membrane (8) is formed of a crosslinked biocompatible composition. The filter (4) comprises a stiffening support (15) on which the filtration membrane (8) is mounted.

Description

The invention relates to the field of biocompatible filters for isolating cells contained in a liquid sample and methods for making such biocompatible filters. More specifically, the invention relates to the field of biocompatible filters, in particular for isolating and culturing cells contained in a liquid sample, comprising a filtration membrane extending substantially in an extension plane and having a liquid inlet face. and a liquid outlet face, and a plurality of through-filtering pores each connecting the liquid inlet face to the liquid outlet face by means of an inner pore surface, the filtration pores each having an opening inlet to the location of the liquid inlet face and an outlet opening at the location of the liquid outlet face, the filter further comprising a stiffening support on which the filtration membrane is mounted. The invention is especially intended to isolate and cultivate rare cells contained in a sample of biological fluid, such as blood, cerebrospinal fluid or other effusion or biological fluid. It is thus particularly applicable to the isolation of rare cells in a blood sample, for example tumor cells or fetal cells in general and trophoblastic cells in particular present in a blood sample taken from an individual. The blood sample may previously have been diluted in a suitable liquid buffer as is known from the state of the art. Because of their particular rarity, such rare cells are present in extremely small amounts in the blood samples studied, typically only a few cells per sample or single cell, despite the large volumes of the blood samples in question, ranging from one to fifty. milliliters. It is therefore desirable to be able to grow the isolated cells on the filter, especially in suitable media and in the presence of adequate growth factors, so that the cells can be studied and / or the amount of cellular material recovered can be increased. It is also desirable to minimize the measurement noise during subsequent analysis of the filter residue accumulated on the filter. By "studying said cells" is meant in particular the carrying out of routine laboratory examination as well as the observation of the cells under a microscope, for example following the application of molecular biology, cytogenetics or FISH techniques ( acronym for "Fluorescence In Situ Hybridization"), for the diagnosis of genetic abnormalities in tumor or trophoblastic cells. FR 2 883 488 discloses a porous filter for the isolation of rare cells which comprises a microporous polycarbonate membrane mounted in a rigid PVC support. This filter, however, does not allow the culture of isolated cells so that they can be studied. According to a first aspect, the subject of the invention is a biocompatible filter, in particular for isolating and cultivating cells contained in a liquid sample, comprising a filtration membrane extending substantially in an extension plane and comprising a surface of a liquid inlet and a liquid outlet face, and a plurality of through-filtering pores each connecting the liquid inlet face to the liquid outlet face by means of an inner pore surface, the filtration pores comprising each having an inlet opening at the location of the liquid inlet face and an outlet opening at the location of the liquid outlet face, the filter membrane being formed of a cross-linked biocompatible composition, and the filter comprising a stiffening support on which is mounted the filtration membrane. In one embodiment, the stiffening support is formed of a crosslinked biocompatible composition. According to one embodiment, the filtration membrane and the stiffening support are a single piece formed of a crosslinked biocompatible composition, so as to constitute a self-supporting rigid assembly. In one embodiment, the crosslinked biocompatible composition comprises at least one biocompatible component covalently photocrosslinked.

In one embodiment, the biocompatible component covalently photocrosslinked is a polyethylene glycol. In one embodiment, the crosslinked biocompatible composition comprises at least one biocompatible ionically crosslinked component.

According to one embodiment, the biocompatible ionically crosslinked component is chosen from an oligosaccharide, a polysaccharide and a crosslinked collagen. In one embodiment, the biocompatible ionically crosslinked component is selected from alginate and sucrose.

In one embodiment, the stiffening support circumferentially surrounds the filtration membrane in the extension plane. According to one embodiment, the liquid inlet face and the liquid outlet face of the filtration membrane each have a generally planar surface shape, are substantially parallel to each other and are separated by a thickness of the membrane, measured in one direction. axial axis perpendicular to the liquid inlet face and the liquid outlet face and the stiffening support has an axial size, measured in the axial direction, greater than the thickness of the membrane.

According to one embodiment, the axial size of the support is substantially between one hundred microns and one millimeter and preferably of the order of five hundred micrometers. In one embodiment, the thickness of the membrane is substantially between twenty and sixty-five microns and preferably between twenty and thirty microns.

According to one embodiment, the stiffening support has a general shape in circular or polygonal ring having an internal transverse bulk substantially between five and ten millimeters and an outer transverse bulk substantially between ten and twenty millimeters.

According to one embodiment, the liquid inlet face and the liquid outlet face of the filtration membrane each have a general disc or polygon shape having a transverse bulk substantially between five and ten millimeters. According to one embodiment, the stiffening support comprises an inactive adhesive coating, in particular a pressure-activatable adhesive or an adhesive coated with a detachable protective membrane, so as to allow a subsequent sizing of the stiffening support on an observation support .

According to one embodiment, a maximum dimension of the outlet opening of each filter pore is greater than a maximum dimension of the inlet opening of said pore.

According to a second first aspect, the subject of the invention is a filtration device, in particular for isolating cells contained in a liquid sample, comprising a filter as described above, in which the filter is mounted, by its stiffening support. in the filtration device, between a liquid supply means of the filtration device, adapted to supply liquid from a liquid sample at the location of the liquid inlet face of the filtration membrane, a part, and a liquid absorption means of the filtration device, adapted to absorb liquid from a liquid sample at the location of the liquid outlet face of the filtration membrane, on the other hand. According to a second first aspect, the subject of the invention is a method of manufacturing a biocompatible self-supporting filter in which: a transparent plane mask comprising an array of optical patterns is available; mask, - a primary mold is formed comprising recessed patterns by an inclined / rotational illumination of the photosensitive resin on the mask, - a polymer with a high permeability to the fluid gas is placed on the primary mold, - a secondary mold comprising protruding patterns by a crosslinking of the high gas permeability polymer on the primary mold, - the secondary mold is arranged in a suction chamber opposite a counter mold, - a vacuum is applied to the enclosure suction and injected into the suction chamber, between the secondary mold and the counter mold, a crosslinkable biocompatible composition, so as to have the bioco composition crosslinkable mpatible in intimate contact with the projecting patterns of the secondary mold, - is formed a filter membrane of a biocompatible filter by crosslinking the crosslinkable biocompatible composition between the secondary mold and the counter mold, and - a stiffening support is formed biocompatible filter on which is mounted the filtration membrane.

According to one embodiment, forming the filter membrane and the stiffening support of the biocompatible filter in a single piece constituting a self-supporting rigid assembly, by crosslinking the crosslinkable biocompatible composition between the secondary mold and the counter mold. According to one embodiment, the counter mold is formed by crosslinking a polymer with a high permeability to the fluid gas.

In one embodiment, the polymer with high permeability to the fluid gas is a siloxane. In one embodiment, the siloxane is polydimethylsiloxane.

In one embodiment, the crosslinkable biocompatible composition comprises at least one biocompatible component covalently photocurable. In one embodiment, the covalently photocurable biocompatible component is a polyethylene glycol. In one embodiment, the crosslinkable biocompatible composition is crosslinked by ultraviolet radiation illumination. In one embodiment, the crosslinkable biocompatible composition comprises at least one ionically crosslinkable biocompatible component. According to one embodiment, the ionically crosslinkable biocompatible component is chosen from an oligosaccharide, a polysaccharide or a crosslinked collagen.

In one embodiment, the ionically crosslinkable biocompatible component is selected from alginate and sucrose. In one embodiment, each optical pattern has a generally circular or oval shape.

In one embodiment, the optical patterns are arranged in the array in a hexagonal arrangement. In one embodiment, the optical patterns have a surface density of the order of 1 × 10 5 pattern / cm 2. According to one embodiment, the optical patterns are transparent patterns separated by opaque areas, and wherein the photosensitive resin is a positive photosensitive resin. In another embodiment, the optical patterns are opaque patterns separated by transparent areas, and wherein the photosensitive resin is a negative photosensitive resin.

According to one embodiment, the counter mold comprises a central plate surrounded by a depression, the central plate having a substantially flat extension face, the depression having an axial depth, measured in an axial direction perpendicular to the extension face, substantially between one hundred microns and one millimeter and preferably of the order of five hundred micrometers.

According to one embodiment, the depression has a generally circular or polygonal ring shape having an internal transverse bulk substantially between five and ten millimeters and an outer transverse bulk substantially between ten and twenty millimeters. The figures of the drawings are now briefly described.

Figure 1A is a diagram corresponding to a cross section of a filtration device according to the invention. Fig. 1B is a detail diagram illustrating a detail of a variant of the filter device of Fig. 1A. Figure 2A is an elevational illustration of a filter according to one embodiment of the invention. Figure 2B is a top view of the filter of Figure 2A.

Figure 2C is a cross-sectional view along the line II-II of the filter of Figure 2B. Figure 3A is a top view of a mask used in a first step of a method of manufacturing a filter according to one embodiment of the invention. Figure 3B is a cross-sectional view along the axis of the mask of Figure 3A. FIG. 4 illustrates a second step of a method of manufacturing a filter according to one embodiment of the invention.

Figure 5 illustrates a third step of a method of manufacturing a filter according to an embodiment of the invention. FIG. 6 illustrates a primary mold obtained during a third step of a method of manufacturing a filter according to one embodiment of the invention.

Figure 7 illustrates a fourth and a fifth step of a method of manufacturing a filter according to an embodiment of the invention. FIG. 8 illustrates a secondary mold obtained during a fifth step of a method of manufacturing a filter according to one embodiment of the invention. FIG. 9 illustrates a counter mold of a method of manufacturing a filter according to one embodiment of the invention, and FIG. 10 illustrates sixth, seventh and eighth steps of a method of manufacturing a filter according to an embodiment of the invention. Hereinafter a detailed discussion of several embodiments of the invention with examples and reference to the drawings. It should be noted that the drawings are not to scale and in particular that the proportions and the dimensions of the filtration pores of the filter as well as the thicknesses of the filter elements and the masks, molds and counter molds of the manufacturing process have been considerably enlarged to allow a schematic representation of the elements of the device according to the invention.

FIGS. 1A and 1B illustrate a filtration device 1, in particular intended to isolate cells 2 contained in a liquid sample 3. The liquid sample 3 can have a volume much greater than a hundred microliters, for example a few milliliters, example between one and fifty milliliters.

This device 1 comprises a filter 4, a liquid supply means 5 and a liquid absorption means 6. The filter 4 is mounted in the filtration device 1 between the liquid supply means 5 and the absorption means of liquid 6. FIG. 1A illustrates an embodiment in which the filter 4 is directly mounted between the liquid supply means 5 and the liquid absorbing means 6. FIG. 1B illustrates a variant embodiment in which the filter 4 is respectively mounted between the liquid supply means 5 and the liquid absorbing means 6 by means of two respective intermediate seals 7 for sealing the assembly. In particular, in the assembled state of the device 1, the filter 4 is kept floating between the two intermediate joints 7 in equilibrium, which ensures a smoothing of the stresses exerted on the mechanical part of the filter 4. We now also refer to FIGS. 2A, 2B and 2C, which more specifically illustrate a filter 4 according to the invention, intended in particular to isolate and cultivate rare cells 2 contained in a sample of liquid 3.

Such a filter 4 comprises a filtration membrane 8 extending substantially along an extension plane P and having a liquid inlet face 9 and a liquid outlet face 10. As illustrated in FIG. filtration 8 further comprises a plurality of filtering through pores 11 each connecting the liquid inlet face 9 to the liquid outlet face 10 by means of an inner surface of pore 12. The filtration pores 11 each comprise a inlet opening 13 at the location of the liquid inlet face 9 and an outlet opening 14 at the location of the liquid outlet face 10. Liquid of the liquid sample can thus flow through the filtration membrane 8, and in particular through the filtration pores 11 of the filtration membrane 8. The inlet opening 13 of each through pore is adapted to retain the desired rare cells 2 in the liquid sample 3. Thus, a dimension maximum of the inlet opening 13 of each through pore may advantageously be chosen so as to be less than a mean minimum dimension of the desired rare 2 cells and, as far as possible, greater than the dimensions of the constituents of the liquid sample qu it is undesirable to isolate (eg, undesired microorganisms, cells, or blood plasma elements). In addition, a maximum dimension of the outlet opening 14 of each filtering pore 11 may be greater than the maximum dimension of the inlet opening 13 of said pore through. The inner surface 12 of each filtering pore 11 through can thus have a general shape of trunk, in particular a frustoconical general shape. Throughout the description, the term "maximum dimension" of a considered element, the largest distance separating two points of the element. Thus, if the element considered is a disk, a "maximum dimension" is for example a diameter of this disk. If the element is a cube, a "maximum dimension" is for example a diagonal of this cube. In this way, since the constituents of the liquid sample 3 which it is undesirable to isolate have crossed the inlet opening 13 of the pore, the section of the latter becomes larger in size. direction of the exit aperture 14 thus greatly reducing the likelihood of said constituents becoming clogged and accumulating in the pore. More specifically, the circumference of the inlet opening 13 of each through-filtering pore 11 is, for example, able to fit between a first and a second concentric circle having a diameter of three micrometers and ten micrometers, respectively. In an advantageous embodiment, said first and second concentric circles may have a diameter of four micrometers and nine micrometers, respectively. The circumference of the outlet opening 14 of each filtering pore 11 may, for its part, fit between a first and a second concentric circle having a diameter of eight micrometers and twenty-five micrometers, respectively. and advantageously respectively having a diameter of thirteen micrometers and twenty micrometers. The inlet opening 13 of each through pore 11 has a generally circular or oval shape, so as to be adapted to the cells to be isolated and can be realized in a simple and inexpensive way. The outlet opening 14 of each through pore 11 may also have a generally circular, oval shape or a general shape of a convex polygon, in particular a hexagon for the reasons detailed below. It is thus understood that the liquid supply means 5 is thus able to supply liquid of the liquid sample 3 at the location of the liquid inlet face 9 of the filtration membrane 8 while the means liquid absorption 6 is able to absorb liquid from a liquid sample 3 at the location of the liquid outlet face 10 of the filtration membrane 8. The liquid supply means 5 may for example be a tube of liquid arrival of liquid or a storage tank of the liquid sample. The liquid absorbing means 6 may be a pump that absorbs the liquid by vacuum or evacuation or a capillary absorption device that absorbs the liquid by capillarity. The filter 4 further comprises a stiffening support 15 on which the filtration membrane 8 is mounted.

The filter 4 can in particular be mounted by its stiffening support 15, in the filtration device 1, between the liquid supply means 5 and the liquid absorption means 6 as illustrated in FIGS. 1A and 1B. The filtration membrane 8 is formed of a crosslinked biocompatible composition.

In the embodiment of the invention illustrated in FIGS. 3A, 3B and 3C, the filtration membrane 8 and the stiffening support 15 are a single piece formed of a crosslinked biocompatible composition, so as to constitute a self-supporting rigid assembly. By "biocompatible" it is meant that the biocompatible composition is capable of being in contact with biological cells without degrading said cells, in particular so as to provide support for adhesion, multiplication and cell growth. The biocompatible composition may further exhibit a low or negligible auto-fluorescence so as to allow observation of the cells 2 under a microscope by minimizing the measurement noise. A biocompatible component exhibiting a weak auto-fluorescence is, for example, polyethylene glycol (PEG) as detailed below. In the rest of the description, the terms "crosslinked" and "crosslinkable" are used, it being understood that "crosslinkable composition" or "crosslinkable component" refers to the composition or component before or after crosslinking, and "crosslinked composition" or "component crosslinked "refers to the composition or the component after crosslinking. It is also understood that a crosslinked composition, respectively a crosslinked component, is a crosslinkable composition, respectively crosslinkable component. In a first embodiment, the crosslinked biocompatible composition comprises at least one biocompatible component crosslinked covalently. In general, a polyalkylene oxide having at least one functional group capable of undergoing radical polymerization is suitable as a covalently cross-linked biocompatible component. An example of polyalkylene oxide is a polyethylene glycol modified with at least one acrylate group to make it polymerizable or crosslinkable. A polyethylene glycol acrylate, such as polyethylene glycol diacrylate, is capable of undergoing radical polymerization. Various functional groups such as acrylate groups, vinyl groups, methacrylate groups, and the like can also be used to modify the polyethylene glycol so as to make it crosslinkable.

Various ways of modifying the polyethylene glycol to make it polymerizable or crosslinkable can be implemented. One possible way is to treat it with an acryloyl halide such as acryloyl chloride. An esterification reaction between the polyethylene glycol and an acrylic acid may be conducted in an organic solvent such as toluene to render the polyethylene glycol polymerizable. Methacrylic acid, alkyl methacrylate or acryloyl halide may react similarly with PEG so as to obtain a crosslinkable derivative of PEG as described for example in Fukui, S. and Tanaka, A., 1976; FEBS. Letters 66: 179. Alternatively, a PEG alkoxide can react with an acetylene gas to produce a PEG vinyl ether to obtain a crosslinkable PEG derivative as described in Mathias, LJ, Canterberry, JB, and South, M., 1982. ; J. Polym. Sci., Polym. Lett. Ed. 23: 473. PEG can react with methacrylic anhydride to give PEG dimethacrylate. A reaction between PEG and an allyl chloride in a dry solvent catalyzed by a small amount of stannic chloride may also result in a crosslinkable PEG. In general, other techniques known in the art may be used to obtain a crosslinkable polyethylene glycol derivative. Polyethylene glycol or PEG with a wide variety of molecular weights can be modified for use in the present invention. For example crosslinkable polyethylene glycol or crosslinkable polyethylene glycol derivatives having a molecular weight of from 200 to 100,000 can be used. Cross-linkable polyethylene glycols or crosslinkable polyethylene glycol derivatives having a molecular weight in the range of from about 1,000 to about 38,000 can advantageously be used and modified with an acrylate group as described above, for example by reaction with a sodium chloride. acryloyl. In particular, the crosslinked biocompatible composition may comprise a biocompatible component covalently photocrosslinked.

Thus a polyethylene glycol can be modified so as to make it photocurable covalently, in particular by radical polymerization, by illumination with electromagnetic radiation such as visible, ultraviolet or laser light. The biocompatible component covalently photocrosslinkable is, for example, polyethylene glycol diacrylate (PEG-DA). Polyethylene glycol diacrylate (PEG-DA) is a polyethylene glycol modified with at least one acrylate group so as to make it crosslinkable or polymerizable. For photocrosslinking polyethylene glycol diacrylate, a radical initiator may be added, for example a combination of a photoinitiator such as an ethyl eosin, a cocatalyst such as triethanolamine and optionally a comonomer such as a 1-vinyl 2-pyrrolidinone . Other photoinitiators, cocatalysts and comonomers may be used to photocreat the polyethylene glycol diacrylate. Thus, for example, if PEG-DA is photocrosslinked by illumination with ultraviolet (UV) radiation, possible photoinitiators include, inter alia, 2,2-dimethoxy-2-phenyl acetophenone, benzoyl ethyl ether, 2,2-dimethoxy-2-phenyl acetophenone, dimethylphenoxyacetophenone, benzophenones. Other possible cocatalysts include, for example, triethanolamine, methyl diethanolamine, triethylamine and arginine. It should be noted that the quantity and type of comonomer used may vary. In a second embodiment of the invention, the crosslinked biocompatible composition comprises at least one ionically crosslinked biocompatible component. The second embodiment may be combined with the first embodiment in which case the crosslinked biocompatible composition may comprise at least one ionically crosslinked biocompatible component and at least one covalently crosslinked biocompatible component, in particular at least one biocompatible component photocured accordingly. covalent. The biocompatible ionically crosslinked component may be selected from an oligosaccharide, a polysaccharide and a crosslinked collagen. Thus, in particular, the ionically crosslinked biocompatible component may be chosen from alginate and sucrose. By alginate is meant here in particular salts of alginic acid. More generally, ionically suitable crosslinked biocompatible components may for example be chosen from polysaccharides such as alginate, natural polysaccharides such as chitosan, gellan gum, xanthan gum, hyaluronic acid, heparin, pectin and the like. carrageenan, oligosaccharides such as sucrose or crosslinkable collagens. Collagen is understood here to mean any peptide of collagenic nature, in particular gelatin. An example of crosslinkable collagen is for example described in the European patent application published under the number EP0575273. As illustrated in Figures 2A, 2B and 2C, the stiffening support 15 has a generally circular or polygonal ring shape. The stiffening support 15 circumferentially surrounds the filtration membrane 8 in the extension plane P.

The stiffening support 15 may for example have an external transverse size, also measured along the extension plane P, substantially between ten and twenty millimeters. The external transverse bulk defines the maximum bulk of the stiffening support 15 in the extension plane P.

The stiffening support 15 may further have an internal transverse bulk, measured along the extension plane P, substantially between five and ten millimeters. The internal transverse space defines the dimension of the inner surface circumferentially surrounded by the stiffening support 15. The internal transverse space requirement of the stiffening support 15 is thus substantially similar to the transverse space requirement of the filtration membrane 8.

The liquid inlet face 9 and the liquid outlet face 10 of the filtration membrane 8 may each have a general disk or polygon shape having a transverse bulk, measured according to the extension plane P, substantially between five and ten millimeters.

The liquid inlet face 9 and the liquid outlet face 10 of the filtration membrane 8 each have a generally flat surface shape. The liquid inlet face 9 and the liquid outlet face 10 are substantially parallel to each other and are separated by a thickness of the membrane, measured along an axial direction D perpendicular to the liquid inlet face 9 and the face liquid outlet 10.

The thickness of the membrane is for example substantially between twenty and sixty-five micrometers and preferably between thirty and fifty micrometers. Such a thickness of the membrane may in particular allow an appreciable widening of the outlet opening 14 of the pores with respect to the inlet opening 13 of the pores. The stiffening support 15 has an axial size, measured according to the direction axial D perpendicular to the plane of extension P, substantially between one hundred microns and one millimeter and preferably of the order of five hundred micrometers.

The axial size of the support is thus greater than the thickness of the membrane. The axial size of the stiffening support 15 may in particular be greater than ten times the thickness of the membrane. In this way, the stiffening support 15 is able to maintain the membrane taut avoiding that it folds on itself, and allows to form a self-supporting rigid assembly.

In an alternative embodiment of the invention, the stiffening support 15 may be reinforced by adding an external reinforcement piece not shown in the figures so as to further increase the rigidity of the filter. Such an external reinforcement piece may for example be a metal or polymer ring mounted on an axial side or on both axial sides of the stiffening support 15.

In an alternative embodiment, the stiffening support 15 may comprise an inactive adhesive coating 16, in particular a pressure-activatable adhesive or an adhesive coated with a detachable protective membrane, so as to allow subsequent sizing of the stiffening support 15 on an observation support not shown in the figures. Such an observation support may for example be introduced into an optical microscope and allow observation and examination of the cells 2 isolated on the filter 4. A method of manufacturing a filter 4 according to an embodiment of the invention will now be described. the invention with reference to FIGS. 3A, 3B and 4 to 10.

With reference to FIGS. 3A and 3B, in a first step of the method, there is a transparent plane mask 17 comprising an array 18 of optical patterns 19. This network is for example disposed on an upper surface of the mask. The mask 17 may for example be a glass slide 20 on which the array 18 of patterns is drawn by lithography of a thin layer of chromium 21. In one embodiment of the invention, each optical pattern 19 may have a shape general circular or polygonal.

In one embodiment of the invention, each optical pattern 19 may have shapes, dimensions, and features similar to those described above for the inlet openings 13 of each through pore 11. In another embodiment, each Optical pattern 19 may have shapes, dimensions, and features similar to those described above for outlet openings 14 of each through filtering pore 11.

A maximum dimension of each optical pattern 19 may be between two micrometers and ten micrometers, preferably between three micrometers and seven micrometers. In the embodiment of Figures 3A and 3B, the optical patterns 19 are disposed in the array 18 in a triangular array arrangement.

In this way it is possible to have a maximum dimension of the outlet opening 14 of each pore crossing the largest possible. In one embodiment of the invention more particularly adapted to retain rare 2 cells such as tumor cells or trophoblasts contained in a liquid sample 3, the optical patterns 19 may have a surface density of the order of 1 × 105 pattern / cm2. With reference to FIG. 4, in a second step of the method, a photoresist 22 is placed on the mask 17. In particular, the photosensitive resin is placed on the upper face of the mask.

In a first embodiment of a filter manufacturing method 4 according to the invention, the optical patterns 19 are transparent patterns 23 separated by opaque zones 24. In this embodiment, the photosensitive resin is a positive photosensitive resin. for example a resin such as AZ® 40XT resin.

In a second embodiment of a filter manufacturing method 4 according to the invention, the optical patterns 19 are opaque patterns 25 separated by transparent areas 26. In this embodiment, the photosensitive resin is a negative photoresist for example a resin such as SU-3050 resin. In a third step of the method illustrated in FIG. 5, a primary mold 27 is formed comprising recessed patterns 28 by inclined / rotational illumination of the photosensitive resin on the mask 17. FIG. 6 more particularly represents an example of a primary mold 27 formed on the mask 17 by photolithography of the photosensitive resin and having a first face 29 in contact with the mask 17 and a second face 30, free, facing the first face 29. The recessed patterns 28 extend along an axis substantially perpendicular to the first face 29 and the mask 17, between a first-face end 31 and a second-end end 32. The illumination is for example an ultraviolet radiation 33, visible or laser.

The inclined / rotational illumination of the photosensitive resin may in particular be an illumination by a rear face 34 of the transparent mask 17 opposite to the face on which the photosensitive resin, commonly called illumination by the rear face 34, is placed. By rotary illumination, it is understood that the mask 17 with the photosensitive resin on the mask 17 pivot about an axis substantially perpendicular to the first face 29 and the mask 17 during illumination. By inclined illumination, it is meant that the illumination of the photosensitive resin is carried out with a certain illumination angle 35 with respect to the axis substantially perpendicular to the first face 29 and to the mask 17. Said illumination angle 35 is by for example, an illumination angle of between ten and eighty-five degrees.

In this way, the inner surfaces of the recessed patterns 36 of the primary mold 27 may have a non-perpendicular angle with the first face 29, in particular an angle defined by the illumination angle 35. The recessed patterns 28 of the primary mold 27 may have shapes and dimensions similar to the shapes and dimensions of the pores of the filter membrane of a filter 4 according to the invention. Thus, the recessed patterns 28 of the primary mold 27 may have a maximum transverse dimension at their second face end 32 greater than a maximum transverse dimension at their first face end 31. The inner surface of the recessed patterns 28 may thus have a shape general trunk, in particular a frustoconical general shape. In a fourth step of the method illustrated in FIG. 7, a polymer with a high fluid gas permeability 37 is placed on the primary mold 27. The polymer with a high permeability for the fluid gas 37 is in particular arranged in intimate contact with the inner surfaces of the patterns. In one embodiment, the high fluid gas permeability polymer 37 is a siloxane, particularly polydimethylsiloxane (PDMS).

In a fifth step of the process, a secondary mold 38 having projecting patterns 39 is formed by a crosslinking of the high fluid gas permeability polymer 37 on the primary mold 27. The projecting patterns 39 are in particular obtained by crosslinking the polymer disposed in the recessed patterns 28 of the primary mold 27. The protruding patterns 39 of the secondary mold 38 may thus have shapes and dimensions similar and inverted with respect to the shapes and dimensions of the pores of the filter membrane of a filter 4 according to the invention. 'invention. Thus, in particular, each projecting pattern may extend along an axis substantially perpendicular to a molding face 40 of the secondary mold 38, between a molding face end 41 and a free end 42. Each projecting pattern may have a transverse dimension maximum at its molding face end 41 greater than a maximum transverse dimension at its free end 42. An outer surface of the projecting patterns 43 may thus have a generally trunk shape, in particular a generally frustoconical shape.

To achieve the crosslinking of the high gas permeability polymer, it is possible, for example, to mix the high permeability polymer with the fluid gas 37 with a crosslinking agent 44 on the primary mold 27 and then to heat said mixture on the primary mold 27. In a sixth step of the method illustrated in FIG. 10, the secondary mold 38 is placed in a suction enclosure 45 opposite a counter mold 46. In one embodiment of the method according to the invention, the counter mold 46 may be formed by crosslinking. a polymer with a high permeability to the fluid gas 37 in a manner similar to that just described for the secondary mold 38.

In another embodiment, counter mold 46 may be manufactured by mechanical action, for example by removing material from a piece of polymer, by machining methods, or by deposition of material, for example by three-dimensional printing of polymer.

FIG. 9 illustrates an embodiment of a counter mold 46 in which the counter mold 46 comprises a central plate 47 surrounded by a depression 48. The depression 48 then constitutes in particular an inverted shape of the stiffening support 15 of a filter 4 according to the invention. Thus, in particular, the central plate 47 may have a substantially flat extension face 49 and the depression 48 may have an axial depth, measured in an axial direction D perpendicular to the extension face 49, substantially between one hundred microns and one millimeter and preferably of the order of five hundred micrometers. The depression 48 may have a generally circular or polygonal ring shape having an internal transverse bulk substantially between five and ten millimeters and an external transverse bulk substantially between ten and twenty millimeters. The secondary mold 38 and the counter mold 46 may be placed facing each other and in intimate contact on at least a portion of their facing faces. The extension face 49 of the counter mold 46 and the molding face 40 of the secondary mold 38 define between them a hollow molded interior space 50. More particularly, the free end 42 of the projecting patterns 39 of the secondary mold 38 may come in intimate contact with the extension face 49 of the counter mold 46. A spacing between the extension face 49 of the counter mold 46 and the molding face 40 of the secondary mold 38 is for example substantially between twenty and sixty-five micrometers and preferably between thirty and fifty micrometers. In a seventh step of the process illustrated in FIG. 10, a vacuum of the gas contained in the suction enclosure 45 is applied and injected into the suction enclosure 45, between the secondary mold 38 and the counter mold 46, a composition biocompatible crosslinkable using injection means 51.

The suction enclosure 45 is thus in particular provided with suction means 52 able to create a depression of the gas in said enclosure. The secondary mold 38, and if necessary the counter mold 46, consisting of polymer with high gas permeability, the vacuum applied to the suction enclosure 45 is in particular adapted to have the crosslinkable biocompatible composition in contact intimate with the protruding patterns 39 of the secondary mold 38. More generally, the curable biocompatible composition can thus be disposed in intimate contact with the extension face 49 of the counter mold 46 and the molding face 40 of the secondary mold 38 and can fill the hollow mold interior space 50. The crosslinkable biocompatible composition is as described above and is not described again here. Finally, in an eighth step of the process, a filtration membrane 8 and a stiffening support 15 of a biocompatible self-supporting filter 4 are formed into a single, self-supporting rigid part by crosslinking the crosslinkable biocompatible composition between the secondary mold 38 and the against mold 46. The crosslinking of the crosslinkable biocompatible composition can be carried out in the various ways detailed above.

Thus, in particular, in one embodiment in which the crosslinkable biocompatible composition comprises at least one biocompatible component which is covalently photocrosslinkable, for example a polyethylene glycol, the crosslinkable biocompatible composition can be crosslinked by ultraviolet radiation illumination 53.45 In a subsequent step of the process, plasma oxidation of the filtration membrane (8) and / or the stiffening support (15) can be carried out. The plasma oxidation can be carried out on the liquid inlet face (9) and / or the liquid outlet face (10) of the filtration membrane (8) and / or the inner pore surface (12). filtration pores (11). Such plasma oxidation makes it possible in particular to confer a hydrophilic character to the treated faces and surfaces. In another subsequent step, a layer of poly-D-Lysine or poly-L-Lysine can be grafted onto the filtration membrane (8) and / or the stiffening support (15). For example, a graft copolymer layer of poly-L-Lysine and polyethylene glycol (PLL-g-PEG) can be obtained. The poly-D-Lysine or poly-L-Lysine graft can be performed on the liquid inlet face (9) and / or the liquid outlet face (10) of the filtration membrane (8) and / or the inner pore surface (12) of the filtration pores (11). Such a graft makes it possible in particular to increase the attachment of cells to the treated faces and surfaces. Such a graft may furthermore make it possible to improve the adsorption of serum or extracellular matrix proteins on a culture substrate.

In the description which is made above of an embodiment of a manufacturing method according to the invention, the process steps are numbered in "first step", "second step", "third step", etc. This numbering is intended to clarify the reading of the process but should not be understood as having a limiting character concerning the number and the precise position of the steps in a manufacturing method according to the invention. Thus it is understood that intermediate steps may be added to the process described above, steps may also be exchanged or conducted simultaneously in variants of the method.

Claims (35)

REVENDICATIONS1. Biocompatible filter (4), in particular for isolating and cultivating cells (2) contained in a liquid sample (3), comprising a filtration membrane (8) extending substantially in an extension plane and comprising a face of liquid inlet (9) and a liquid outlet face (10), and o a plurality of filtering pores (11) each connecting the liquid inlet face (9) to the liquid outlet face (10). ) by means of an inner pore surface (12), the filtering pores (11) each having an inlet opening (13) at the location of the liquid inlet face (9) and an opening of outlet (14) at the location of the liquid outlet face (10), characterized in that - the filtering membrane (8) is formed of a crosslinked biocompatible composition, and - the filter (4) comprises a carrier of stiffening (15) on which is mounted the filtration membrane (8). The filter (4) of claim 1, wherein the stiffening support (15) is formed of a crosslinked biocompatible composition. 3. Filter (4) according to claim 2, wherein the filtration membrane (8) and the stiffening support (15) are a single piece formed of a crosslinked biocompatible composition, so as to constitute a self-supporting rigid assembly. 4. Filter (4) according to any one of claims 1 to 3, wherein the crosslinked biocompatible composition comprises at least one biocompatible component photocured covalently. 5. Filter (4) according to claim 4, wherein the biocompatible component covalently photocrosslinked is a polyethylene glycol. The filter (4) according to any one of claims 1 to 5, wherein the crosslinked biocompatible composition comprises at least one biocompatible ionically crosslinked component. The filter (4) of claim 6 wherein the biocompatible ionically crosslinked component is selected from an oligosaccharide, a polysaccharide and a crosslinked collagen. The filter (4) of claim 7, wherein the biocompatible ionically crosslinked component is selected from alginate and sucrose. 9. Filter (4) according to any one of claims 1 to 8, wherein the stiffening support (15) circumferentially surrounds the filtration membrane (8) in the extension plane. The filter (4) according to claim any one of claims 1 to 9, wherein - the liquid inlet face (9) and the liquid outlet face (10) of the filtration membrane (8) each have a generally planar surface shape, are substantially parallel to each other and are separated by a thickness of the membrane, measured in an axial direction perpendicular to the liquid inlet face (9) and the liquid outlet face (10) and - the stiffening support (15) has an axial size, measured in the axial direction, greater than the thickness of the membrane. 11. Filter (4) according to claim 10, wherein the axial size of the support is substantially between one hundred microns and one millimeter and preferably of the order of five hundred micrometers. 12. Filter (4) according to any one of claims 10 and 11, wherein the thickness of the membrane is substantially between twenty and sixty-five microns and preferably between twenty and thirty microns. 13. Filter (4) according to any one of claims 1 to 12, wherein the stiffening support (15) has a generally circular or polygonal ring shape having an internal transverse bulk substantially between five and ten millimeters and a footprint outer transverse substantially between ten and twenty millimeters. The filter (4) according to any one of claims 1 to 13, wherein the liquid inlet face (9) and the liquid outlet face (10) of the filtration membrane (8) each have a general shape of disc or polygon having a transverse bulk substantially between five and ten millimeters The filter (4) according to any one of claims 1 to 14, wherein the stiffening support (15) comprises an inactive adhesive coating (16), in particular a pressure activatable adhesive or a membrane-covered adhesive. detachable protection, so as to allow subsequent gluing of the stiffening support (15) on an observation support. The filter (4) according to any one of claims 1 to 15, wherein a maximum dimension of the outlet opening (14) of each filter pore is greater than a maximum dimension of the inlet opening ( 13) of said pore. 17. Filtration device (1), in particular for isolating cells (2) contained in a liquid sample (3), comprising a filter (4) according to any one of claims 1 to 16, wherein the filter (4) is mounted, by its stiffening support (15), in the filtering device (1), between a liquid supply means (5) of the filtering device (1), capable of supplying liquid from a sample of liquid at the location of the liquid inlet face (9) of the filtering membrane (8), on the one hand, and liquid absorbing means (6) of the filtering device (1), suitable for absorbing liquid from a sample of liquid at the location of the liquid outlet face (10) of the filter membrane (8), on the other hand. 18. A method of manufacturing a biocompatible self-supporting filter (4) in which: - a transparent plane mask (17) having a network (18) of optical patterns (19) is present, - a fluid photosensitive resin ( 22) on the mask (17), - a primary mold (27) is formed with recessed patterns (28) by inclined / rotational illumination of the photosensitive resin on the mask (17), - is provided on the primary mold (27) a high fluid gas permeability polymer (37), a secondary mold (38) having protruding patterns (39) is formed by crosslinking the high gas permeability polymer on the primary mold (27), the secondary mold (38) is placed in a suction enclosure (45) facing a counter-mold (46); a vacuum is applied to the suction enclosure (45) and injected into the suction enclosure (45), between the secondary mold (38) and the counter mold (46), a biocompatibly crosslinkable composition e, so as to have the crosslinkable biocompatible composition in intimate contact with the protruding patterns (39) of the secondary mold (38), - a filter membrane (8) of a biocompatible filter (4) is formed by cross-linking the biocompatible composition crosslinkable between the secondary mold (38) and the mold against (46), and - a stiffening support (15) is formed of the biocompatible filter (4) on which is mounted the filtration membrane (8). 19. The method of claim 18, forming the filter membrane (8) and the stiffening support (15) of the biocompatible filter (4) in a single piece constituting a self-supporting rigid assembly, by crosslinking the crosslinkable biocompatible composition between the secondary mold (38) and counter mold (46). 20. A method according to any one of claims 18 and 19, wherein the counter mold (46) is formed by crosslinking a polymer with high permeability to the fluid gas (37). The method of claim 20, wherein the high fluid gas permeability polymer (37) is a siloxane. 22. The method of claim 21, wherein the siloxane is polydimethylsiloxane. The method of any one of claims 18 to 22, wherein the crosslinkable biocompatible composition comprises at least one biocompatible component covalently photocrosslinkable. The method of claim 23, wherein the biocompatible component covalently photocrosslinkable is a polyethylene glycol. 25. The method according to claim 23, wherein the crosslinkable biocompatible composition is crosslinked by ultraviolet radiation illumination (53). The method of any one of claims 18 to 25, wherein the crosslinkable biocompatible composition comprises at least one ionically crosslinkable biocompatible component. 27. The method of claim 26, wherein the ionically crosslinkable biocompatible component is selected from a cross-linked oligosaccharide, polysaccharide or collagen. The method of claim 27, wherein the ionically crosslinkable biocompatible component is selected from alginate and sucrose. 29. A method according to any one of claims 18 to 28, wherein each optical pattern (19) has a generally circular or oval shape. 30. A method according to any one of claims 18 to 29, wherein the optical patterns (19) are arranged in the array (18) in a hexagonal arrangement. 31. A method according to any one of claims 18 to 30, wherein the optical units (19) have a surface density of the order of 1 x 105 pattern / cm2. The method of any one of claims 18 to 31, wherein the optical patterns (19) are transparent patterns (23) separated by opaque areas (24), and wherein the photosensitive resin (22) is a resin positive photosensitive. The method of any one of claims 18 to 31, wherein the optical patterns (19) are opaque patterns (25) separated by transparent areas (26), and wherein the photosensitive resin (22) is a resin negative photosensitive. 34. A method according to any one of claims 18 to 33, wherein the counter mold (46) comprises a central plate (47) surrounded by a depression (48), the central plate (47) having an extension face (49) substantially planar, the depression (48) having an axial depth, measured in an axial direction (D) perpendicular to the extension face (49), substantially between one hundred micrometers and one millimeter and preferably of the order five hundred micrometers. 35. A method of manufacturing a filter (4) according to claim 34, wherein the depression (48) has a generally circular or polygonal ring shape having an internal transverse bulk substantially between five and ten millimeters and an external transverse bulk substantially between ten and twenty millimeters.