Catalytic membrane comprising a nucleic acid

Abstract

The present invention relates to a composition comprising a nucleic acid covalently attached to a porous solid support whereby said nucleic acid is a ligand for a catalyst, said catalyst being linked to said nucleic acid by covalent bonding or intercalation. The invention also relates to a membrane comprising said composition and to a catalytic membrane reactor comprising said membrane. The invention also relates to methods for the preparation of said composition and membrane and to the use of said composition or membrane as a catalyst.

Description

[0001] CATALYTIC MEMBRANE COMPRISING A NUCLEIC ACID

[0002] FIELD OF THE INVENTION

[0003]

[0001] The present invention relates to a composition comprising a nucleic acid covalently attached to a porous solid support whereby said nucleic acid is a ligand for a catalyst, said catalyst being linked to said nucleic acid by covalent bonding or intercalation. The invention also relates to a membrane comprising said composition and to a catalytic membrane reactor comprising said membrane. The invention also relates to methods for the preparation of said composition and membrane and to the use of said composition or membrane as a catalyst.

[0004] BACKGROUND

[0005]

[0002] Asymmetric catalysis is a powerful synthetic tool allowing for the preparation of sophisticated chemical compounds in a straightforward and sustainable manner. Intensified asymmetric catalytic processes thus represent a promising way of preparing chiral compounds and building blocks at the large scale in a reduced number of process steps, at a large scale and with minimal footprint. However, the intensification of asymmetric catalytic processes still offers a large number of challenges. A first challenge relates to the provision of suitable catalytic systems for intensified process set-ups, such as packed bed reactors, membrane reactors, whereby the chiral catalyst is provided in a form that it can be employed in a continuous manner and recycled in further process iterations. A widely used approach to this end consists in immobilizing the catalyst on a solid support. However, the immobilization of a homogeneous catalyst on a surface typically has unpredictable outcomes. For instance, for polymer-supported catalysts, the catalytically active site may be buried or hindered by polymer chains of the solid support and / or the polymer may not swell sufficiently in the solvent system of the reaction. This may cause loss of catalytic efficiency, which can translate in lower conversion and / or induction of enantioselectivity.

[0006]

[0003] Different types of asymmetric catalysts may be immobilized on solid support for the purposes of process intensification, including organometallic complexes or organocatalysts, as reviewed for instance by Rodriguez-Escrich C. et al. in Chem. Rec. 2018, 18, 1 - 20 in the context of process intensification using packed bed reactors. Examples of immobilized chiral catalysts for membrane reactors have also been reported but are less frequent.

[0007]

[0004] While some efforts have been dedicated to immobilize organometallic catalysts and organocatalysts on solid support, the immobilization of macromolecular ligands or catalysts for the development of intensified process still remains under study. In this regard, several catalytic systems employing a nucleic acid such as deoxyribonucleic acid (DNA) as a chiral ligand have been disclosed in the art. Such systems are typically based on the formation of a complex between, on the one hand, a catalytically active organometallic complex comprising a metal cation and a ligand, and on the other hand, a molecule of DNA. The ligand in the organometallic complex may be chosen so as to intercalate between DNA bases via n-n stacking interactions. Alternatively, in other systems known in the art, the cation is suitable for coordinating with some nitrogen atoms located on the nitrogenated bases of the DNA. In all cases, the catalytically active site, i.e. the metal cation, is located close to the DNA molecule, whose helicity creates a chiral environment around the metal cation, thus providing for induction of enantioselectivity in the metal-catalyzed reactions.

[0008]

[0005] Several examples of such homogeneous systems have been reported. For instance, Roelfes G. et al. disclose in Angew. Chem. Int. Ed. 2005, 44, 3230-3232 a copper (II) complex of a 2-(aminomethyl)pyridine derivative bearing an acridine moiety able to intercalate into a double stranded DNA molecule, thus forming a supramolecular complex whereby the copper (II) active site is located in the vicinity of the DNA molecular. The resulting complex was successfully used as catalyst in the [2+4] cycloaddition reaction of cyclopentadiene with a pyridin-2-yl chaicone derivative to produce an enantiomerically enriched product. This document teaches that the combination of the three components (metal cation, ligand and DNA) is required to allow for the production of a chiral product. Ligand design may further be employed to improve the regioselectivity of the reaction. The same research groups disclosed a few years later in Chem. Commun. 2006, 635-637 that the acridine moiety in the ligand, which was promoting intercalation of the ligand in the DNA structure, is not essential to produce a chiral compound and that bidentate aromatic nitrogenated ligands such as bipyridil derivatives provide good results in terms of product enantioselectivity. It was found in particular that 4,4’-dimethyl-2,2’-bipyridine (dmpby) is the ligand which provides the highest enantiomeric excess. To date, the catalyst system comprising salmon sperm DNA, Cu(ll) and dmbpy as ligand is the privileged system for the model cycloaddition reaction of cyclopentadiene with the aforementioned pyridin-2-yl chaicone derivative, as it provides the best results in terms of regioselectivity and enantioselectivity. Such a system is reported to yield in Diels-Alder reactions at best a conversion of in between 80%-99% and an enantiomeric excess (ee) of in between 82%-99% (Mansot, J., Chemistry - A European Journal, Volume26, Issue16, 2020, Pages 3519-3523; Boersma AJ, J Am Chem Soc. 2008 Sep 3; 130(35): 11783-90). Significantly less conversion rates and enantiomeric excess values are also reported for such systems (Dong, X. et al. Angew Chem Int Ed Engl. 2024 Aug 19;63(34):e202407838; Rosati, F. et al., Chem. - A Eur. J. 2009, 15, 9596-9605), revealing the significant lack of reproducibility that these reactions currently face under conventional operating conditions.

[0009]

[0006] The aforementioned cycloaddition reaction is of particular interest in the preparation of fine chemicals, such as pharmaceutical ingredients, agrochemicals, flavours an fragrances, or intermediates thereof, as illustrated by Funel, J. A. in Angewandte Chem Int. Ed. 2013, 52, 3822-3863. In such compounds, the presence of a chiral center in the molecular structure can significantly affect the properties of the compound.

[0010]

[0007] The aforementionned catalytic system has also been applied as catalyst for the 1 ,4-addition reaction of malonate to Michael acceptors by Zhao, H. et al. in RSC Adv., 2014, 4, 54051 , thus showing the versatility of this approach.

[0011]

[0008] Attempts to immobilize such catalyst systems have been disclosed in the art. In a first approach, Park, S. et al. disclose in Biomater. Sci., 2013, 1 , 103 a system consisting of solid supported DNA comprising salmon testes DNA and silica gel functionalized with quaternary ammonium groups. In said system, the DNA is immobilized on the solid support by the means of electrostatic interactions between the negative charge of the phosphodiester groups of the DNA backbone and the positive charges of the quaternary ammonium groups of the silica gel. The prepared heterogeneous system was then tested as a catalyst in the same model reaction as disclosed above, employing the catalyst as a suspension. Nevertheless, in this case, the authors observed that, while the exo / endo regioselectivity of the reaction was preserved in the heterogeneous system with respect to the homogeneous system, the enantiomeric excess of the cycloadduct product suffers a decrease of 5% for the immobilized catalyst if compared with the homogeneous version of the catalyst. In this document, the authors are further silent on how the cycloaddition process could be intensified.

[0012]

[0009] In a different approach Benedetti et al. report in Chem. Commun. 2015, 51 , 6076- 6079 an immobilized catalyst comprising ctDNA immobilized by the means of covalent anchoring on cellulose. The catalyst composition further comprises an organometallic complex of copper with dmbpy. The authors are however silent about the porosity of the solid support. The resulting solid catalyst was employed in a packed bed reactor operated under flow conditions. While the system proves to be robust and can be operated for long periods of time due to its reusability, the packed bed reactor configuration suffers from the fact that the residence time, and consequently the flow rate, must be sufficient to allow for completion of the reaction, which results in a low productivity of the process when operated under flow conditions.

[0013]

[0010] From what is disclosed in the art, it derives that there is still a need for improved catalytically active heterogeneous compositions comprising immobilized nucleic acid suitable for intensified processes, such as cycloaddition processes, whereby said nucleic acid provides a chiral environment to a catalyst.

[0014] SUMMARY OF THE INVENTION

[0015]

[0011] After exhaustive research, the inventors have developed an immobilized catalyst comprising a nucleic acid immobilized on a porous solid support as chiral ligand and a catalyst suitable for binding or intercalating with said nucleic acid. The inventors have particularly found that binding the nucleic acid to a porous solid support by the means of covalent linking surprisingly allows maintaining the enantioselectivity induced by the catalyst in the studied cycloaddition reaction, unlike the systems described in the art for that purpose. In addition, the inventors have found that the developed immobilized catalyst is suitable as a catalytic membrane in a catalytic membrane reactor. The resulting catalytic membrane surprisingly preserves its structural integrity and no loss of nucleic acid or catalyst is observed when the catalyst is used as catalytic membrane in a membrane reactor during prolonged operation, whereby the membrane is placed at the interface of a first phase for providing the substrates of the catalytic reaction and a second phase for extracting the product(s) of the catalytic reaction. Even more surprisingly, no loss of the intercalated or bound catalyst is observed in such conditions. When used in a catalytic membrane reactor, the inventors have found that the mass transfer conditions at the catalytic site are improved significantly with respect to the homogeneous version of the catalyst.

[0016]

[0012] Without being bound to theory, it is believed that the poor solvation of the nucleic acid in the homogeneous system causes random agglomerations of the nucleic acid, which causes ill-defined and poorly reproducible mass transfer conditions. In addition, the high viscosity of a solution of nucleic acid prevents the reaction substrates and products from diffusing at high rate from and to the catalytic site. The inventors further hypothesize that immobilizing the nucleic acid on a solid support provides a liquid phase having higher mass transport rates of reactants and products than the situation where the nucleic acid is present in the solution (i.e. homogeneous approach), in which case the catalytic turnover frequency is mainly driven by the rate of diffusion of reactants / products, such that the system of the invention provides for a process suffering from fewer mass transport issues.

[0017]

[0013] Thus, a first aspect of the invention relates to a composition comprising:

[0018] - a nucleic acid covalently attached to a porous solid support; and

[0019] - a catalyst suitable for binding with or intercalating into said nucleic acid.

[0020]

[0014] The invention also relates to a process for the preparation of a composition according to the first aspect of the invention. Thus, the second aspect of the invention relates to a process for the preparation of a composition according the first aspect of the invention comprising the steps of: (i) providing a nucleic acid covalently attached to a porous solid support;

[0021] (ii) providing a catalyst suitable for binding with or intercalating into said nucleic acid; and

[0022] (iii) contacting the catalyst suitable for binding with or intercalating into said nucleic acid with the porous solid support bearing said nucleic acid.

[0023]

[0015] Alternatively, the second aspect of the invention relates to a process for the preparation of a membrane according to the fifth aspect of the invention comprising the steps of:

[0024] (i’) providing a porous solid support for forming a membrane;

[0025] (ii’) providing a nucleic acid;

[0026] (iii’) contacting a catalyst suitable for binding with or intercalating into the nucleic acid provided in (ii’) to produce a nucleic acid based catalyst;

[0027] (iv’) covalently binding the nucleic acid based catalyst produced in step (iii) on the solid support provided in (i’).

[0028]

[0016] The third aspect of the invention relates to the use of the composition according to the first aspect of the invention as a catalyst. Depending on the catalyst intercalated or bound to the nucleic acid, a large range of catalytic reactions is covered by the third aspect of the invention. The skilled person will readily identify reactions susceptible of being catalysed by said catalyst upon reduction to practice of the invention on the basis of common general knowledge. Such reactions are for instance described in Applied Homogeneous Catalysis with Organometallic Compounds: A Comprehensive Handbook in Four Volumes, 3rd Edition, 2017, Wiley, ISBN: 978-3-527-65175-7.

[0029]

[0017] The inventors have found that the composition of the first aspect of the invention is particularly useful as a membrane. Thus, the fourth aspect of the invention relates to a membrane comprising the composition according to the first aspect of the invention.

[0030]

[0018] A fifth aspect of the invention relates to the use of a membrane according to the fourth aspect of the invention as a catalyst. The skilled person will readily identify reactions susceptible of being catalysed by said catalyst upon reduction to practice of the invention on the basis of common general knowledge.

[0031]

[0019] A sixth aspect of the invention relates to a process for the preparation of a membrane according to the fifth aspect of the invention comprising the steps of:

[0032] (i) providing a porous solid support for forming a membrane;

[0033] (ii) covalently binding a nucleic acid on the solid support provided in (i);

[0034] (iii) providing a catalyst suitable for binding with or intercalating into said nucleic acid;

[0035] (iv) contacting the catalyst suitable for binding with or intercalating into said nucleic acid with the porous solid support bearing said nucleic acid produced in (ii); and

[0036] (v) forming a membrane.

[0020] Alternatively, the sixth aspect of the invention relates to a process for the preparation of a membrane according to the fifth aspect of the invention comprising the steps of:

[0037] (i) providing a porous solid support for forming a membrane;

[0038] (ii’) providing a nucleic acid;

[0039] (iii’) contacting a catalyst suitable for binding with or intercalating into the nucleic acid provided in (ii’) to produce a nucleic acid based catalyst;

[0040] (iv’) covalently binding the nucleic acid based catalyst produced in step (iii’) on the solid support provided in (i);

[0041] (v) forming a membrane.

[0042]

[0021] The seventh aspect of the invention relates to a membrane reactor comprising a membrane according to the fifth aspect of the invention.

[0043] BRIEF DESCRIPTION OF THE DRAWINGS

[0044]

[0022] Fig. 1 describes the bioconjugation of DNA onto an alumina coated sensor as measured with a quartz crystal microbalance with dissipation monitoring, showing the evolution of the measured frequency (in Hertz) over time (in seconds) when salmon testes DNA was injected in the buffer medium comprising a non-porous alumina support (arrow 1) till the end of the conjugation reaction (arrow 2).

[0045]

[0023] Fig. 2 shows a membrane reactor comprising a membrane (2) arranged for being in chemical contact with an upstream current (A) flowing through a feed chamber (1) and a downstream current (B) flowing through a receiving chamber (3).

[0046]

[0024] Fig. 3 shows an exploded lateral side cut view of a membrane reactor according to the seventh aspect of the invention comprising a first chamber arranged for being in chemical contact with a membrane (3) via microfluidic channels (4) suitable for feeding a solution of reagents to said membrane (3) via inlet (1) and outlet (T) and a second chamber arranged for being in chemical contact with said membrane (3) via microfluidic channels (4) suitable for circulating a solution of the product of the reaction produced at said membrane (3) via inlet (2) and outlet (2’).

[0047]

[0025] Fig. 4 shows the evolution in function of time (expressed in hours) of the fraction of equilibrium concentration of a dye in the receiving phase in Example 3 of the comparative example (dashed lined) and membrane reactor (plain line).

[0048]

[0026] Fig. 5 shows the evolution of the concentration of DNA in the feed phase (filled circles) and receiving phase (hollow circles) over time (expressed in hours) of a membrane reactor comprising a catalytic membrane according to the invention.

[0049]

[0027] Fig. 6 shows the evolution of the conversion, expressed as a percentage, over time, expressed in hours of the reference reaction of Example 6, whereby the DNA is suspended in the feed reaction chamber.

[0028] Fig. 7 shows the evolution of the conversion, expressed as a percentage, over time, expressed in hours of the reaction of Example 6, whereby the DNA is immobilized on the membrane of the membrane reactor.

[0050] DETAILED DESCRIPTION

[0051]

[0029] All terms as used herein in this application, unless otherwise stated, shall be understood in their ordinary meaning as known in the art. Other more specific definitions for certain terms as used in the present application are as set forth below and are intended to apply uniformly throughout the specification and claims unless an otherwise expressly set out definition provides a broader definition.

[0052]

[0030] For the purposes of the invention, any ranges given include both the lower and the upper end-points of the range. Ranges given, such as temperatures, times, molar ratio, volume ratio and the like, should be considered approximate (i.e. with a 5% margin of variation around indicated point), unless specifically stated.

[0053]

[0031] In the context of the present invention, the term “covalently attached”, when related to a nucleic acid molecule and a solid support, refers to the fact that the nucleic acid is attached to the solid support via a covalent bond between an atom comprised in the nucleic acid and an atom comprised in the solid support. Said atom comprised in the nucleic acid is preferably an atom located at the 5’ or 3’ end of the nucleic acid and is optionally linked to the carbohydrate ring of said 5’ or 3’ end of the nucleic acid via a linker. Said atom comprised in the solid support is preferably an atom that is attached to the solid support via a linker.

[0054]

[0032] In the context of the present invention, a compound is “suitable for binding with a nucleic acid” when said compound may form a complex with said nucleic acid by the means of covalent and non-covalent interactions. Such binding preferably occurs between heteroatoms found on the nitrogenated bases of the nucleic acid and said compound, and preferably takes the form of metal-heteroatom bonds.

[0055]

[0033] In the context of the present invention, a compound is “suitable for intercalating a nucleic acid” when said compound comprises a group suitable for forming a complex between with flat aromatic group of the nucleic acid formed by pairing of nucleotide bases involving TT-TT interactions.

[0056]

[0034] In the context of the present invention, the term “pore size” refers to the largest dimension of the transversal section of a pore. For instance, for a pore of substantially cyclindrical shape, “pore size” refers to the diameter of the circle representing the transversal section of said pore. Such parameter may be measured according to well- established methods, such as microscopy.

[0057]

[0035] In the context of the present invention, a material is “substantially isoporous” when said material comprises of pores of substantially the same size and substantially the same shape. Without prejudice to the common understanding and ordinary meaning of this term as known in the art, for example, a material is “substantially isoporous” when said material comprises a population of pores representing at least 50% v / v of the pores of the material, said pores having the same size value ± 10%; more preferably, a material is “substantially isoporous” when said material comprises a population of pores representing at least 75% v / v of the pores of the material; said pores having the same size value ± 10%.

[0058]

[0036] In the context of the invention, the term “alkyl” refers to an aliphatic saturated hydrocarbon chain that is linear or branched and having the number of carbon atoms defined in the claims and the description. Non-limiting examples of alkyl groups include, for instance, methyl, ethyl, n-propyl, i-propyl, n-butyl, / -butyl, t-butyl, n-pentyl, neo-pentyl, and hexyl.

[0059]

[0037] In the context of the invention, the term “haloalkyl” refers to an alkyl group as defined above and having the number of carbon atoms defined in the claims and the description whereby at least one of the hydrogen atoms is replaced with a halo atom.

[0060] The term “halo” group or atom refers to a group selected from fluoro, chloro, bromo and iodo. Thus, non-limiting examples of haloalkyl groups include, among others, chloromethyl, fluoromethyl, perfluoroalkyl groups such as trifluoromethyl, tetrafluoroethyl, and bromomethyl.

[0061]

[0038] In the context of the invention, the term “halo” refers to a substituting group deriving from a halogen atom, such as bromo, chloro, fluoro and iodo. Preferred halo atoms are chloro and fluoro.

[0062]

[0039] In the context of the invention, the term “alkyloxycarbonyl” refers to a saturated linear or branched hydrocarbon group having the number of carbon atoms indicated in the description or in the claims which is attached to the remainder of the molecular formula through a carboxyl group (-O(O)C-) and wherein the alkyl chain is attached to the oxygen atom of the carboxyl group.

[0063]

[0040] In the context of the invention, the term “alkenyl” refers to an aliphatic unsaturated hydrocarbon chain that is linear or branched and having the number of carbon atoms defined in the claims and the description wherein at least two carbon atoms are linked through a double carbon-carbon bond. Non-limiting examples of alkenyl groups include, among others, vinyl, propen-1 -yl, propen-2-yl, butenyl, and iso-butenyl.

[0064]

[0041] In the context of the invention, the term “alkyloxy” refers to a saturated linear or branched hydrocarbon group having the number of carbon atoms indicated in the description or in the claims which is attached to the remainder of the molecular formula through an oxy group (-O-).

[0065]

[0042] In the context of the present invention, within a ring system comprising at least two rings, a ring is said to be "isolated" when the ring is connected by a single covalent bond connecting a member of said ring with a member of a second ring. Thus, a ring system comprising two isolated rings embraces the case where a first ring is a substituent of a second ring, such as, for instance the case where a phenyl ring is a substituent of a further phenyl group -thereby forming a biphenylyl group.

[0066]

[0043] In the context of the present invention, within a ring system comprising at least two rings, two rings are said to be "fused" when they have at least two adjacent atoms in common in their cyclic structure.

[0067]

[0044] In the context of the present invention, the term "aryl" or “aromatic” refers to a molecular fragment consisting of a conjugated planar ring system made of the number of carbon atoms defined in the description and in the claims, wherein the number of delocalized electrons is 4m+2, being m an integer number, being said system connected to the remainder parts of the compound comprising an aromatic ring system through any available position. Aromatic ring systems known in the art include, for instance, benzene (phenyl), naphthalene, phenanthrene, indene, anthracene and tetracene; especially phenyl.

[0068]

[0045] In the context of the present invention, the term "heteroaryl" or “heteroaromatic” refers to a molecular fragment consisting of a conjugated planar ring system made of the number of carbon atoms defined in the description and in the claims and heteroatoms such as O, S, NH and N wherein the number of delocalized electrons is 4m+2, being m an integer number, being said system connected to the remainder parts of the compound comprising an aromatic ring system through any available position. Heteroaromatic ring systems known in the art include, for instance, furan, thiophene, pyridine, pyrazine, pyrimidine, pyrrole, imidazole, pyrazole, oxazole, isoxazole, thiazole, pyridazine, triazine, benzofuran, iso benzofuran, indole, isoindole, benzothiophene, benzo[c]thiophene, benzimidazole, purine, indazole, benzoxazole, benzisoxazole, benzothiazole, quinoline, isoquinoline, quinoxaline, acridine, quinazoline, cinnoline, and phthalazine.

[0069]

[0046] As defined above, a first aspect of the invention relates to a composition comprising:

[0070] - a nucleic acid covalently attached to a porous solid support; and

[0071] - a catalyst suitable for binding with or intercalating into said nucleic acid.

[0072] Nucleic acid

[0073]

[0047] In a preferred embodiment of the first aspect of the invention, the nucleic acid is one of deoxyribonucleic acid (DNA) or ribonucleic acid. As they are easier to obtain, naturally occurring nucleic acids are preferred.

[0074]

[0048] In a further preferred embodiment of the first aspect of the invention, the nucleic acid is a double stranded nucleic acid.

[0075]

[0049] Thus, in preferred embodiments of the first aspect of the invention, the nucleic acid is a naturally occurring double stranded DNA molecule.

[0050] The number of nitrogenated bases, i.e. the length of the DNA molecule is not particularly limited. However, the nucleic acid must comprise a sufficient number of nitrogenated bases so as to create a chiral environment around the catalyst. Thus, in particular embodiments, the nucleic acid comprises at least 6 nitrogenated bases. In more particular embodiments, the nucleic acid comprises at least 10 nitrogenated bases; more particularly of at least 50, 100 or 200 nitrogenated bases.

[0076]

[0051] In further embodiments, the nucleic acid comprises no more than 2000 nitrogenated bases. The nucleic acid may also be an oligonucleotide, i.e. a nucleotide having less than 150 nitrogenated bases.

[0077]

[0052] In a more particular embodiment of the first aspect the invention, the nucleic acid is double stranded salmon testes DNA; more particularly, it is a double stranded salmon testes DNA oligomer.

[0078]

[0053] The amount of nucleic acid in the composition of the first aspect of the invention must be sufficiently high for allowing each molecule of catalyst to bind or intercalate said nucleic acid. Thus, in a particular embodiment, the amount of nucleic acid is higher than the amount whereby the composition of the first aspect of the invention comprises one mole of catalyst per each six moles of nitrogenated bases in the sequence of the nucleic acid. In another embodiment, the amount of nucleic acid is lower than the amount whereby the composition of the first aspect of the invention comprises one mole of catalyst per each mole of said nucleic acid.

[0079] Solid support

[0080]

[0054] The solid support of the composition of the first aspect of the invention is not particularly limited as long as it is a porous solid material suitable for being covalently linked to a nucleic acid molecule as further defined below and it consists of a material that neither reacts nor gets solubilized in the targeted catalytic reaction.

[0081]

[0055] In a particular embodiment of the first aspect of the invention, the solid support comprises pores having a size of between 1 and 500 nm; preferably of between 1 and 50 nm.

[0082]

[0056] In a particular embodiment of the first aspect of the invention, the solid support is substantially isoporous.

[0083]

[0057] The use of a porous solid support is particularly advantageous as it allows for: (i) confining catalytic sites within the cavities of the pores and / or (ii) improving the transport of reaction substrates and products from and to the catalytic site. This enables the implementation of these catalytic systems in membrane reactors (e.g. contactor configuration), which provide improved mass transfers with respect to the processes known in the art. As a result, the catalytic process is faster than in reactor configurations disclosed in the art (e.g. homogeneous system or packed bed reactor). Thus, it is preferred in some embodiments that the nucleic acid is essentially located within the pores of the porous solid support.

[0084]

[0058] Suitable porous solid supports for catalytic membrane reactors are known in the art and include ceramic materials, polymer materials, metal organic frameworks and covalent organic frameworks. Examples of such materials are known in the art and will become apparent to the skilled person upon reduction to practice of the invention using common general knowledge. Particularly, examples of isoporous polymer materials have been disclosed in Yu, H., Qiu, X., Nunes, S.P. and Peinemann, K.-V. (2014), Self- Assembled Isoporous Block Copolymer Membranes with Tuned Pore Sizes. Angew. Chem. Int. Ed., 53: 10072-10076, the content of which is incorporated herein by reference.

[0085]

[0059] Preferred solid supports of the composition of the first aspect of the invention include porous ceramic materials, such as alumina or silica.

[0086]

[0060] In particular embodiments, the solid support has a porosity comprised between 25% and 90%. This means that between 25% and 90% of the surface of the material is occupied by pores. Such porosity values advantageously warrant a good coverage of the surface of the material with nucleic acid, while maintaining a sufficient permeability.

[0061] In a more particular embodiment, the porous solid support consists of anodic aluminium oxide. More particularly, the porous solid support consists of anodic aluminium oxide having a pore size of between 1 and 50 nm; more particularly of about 20 nm. More particularly, the porous solid support consists of anodic aluminium oxide having a porosity higher than 50%.

[0087] Covalent attachment of the nucleic acid to the solid support

[0088]

[0062] In an embodiment, the nucleic acid is covalently attached to said porous solid support via a covalent bond involving a functional group FGi comprised at the 5’ or 3’ termination of said nucleic acid. In some embodiments, said nucleic acid preferably comprises a moiety of formula (A) wherein Oarepresents an oxygen atom comprised in an ether or phosphodiester group, the wavy line represents the attachment point of the moiety of formula (A) to the 5’ or 3’ termination of said nucleic acid,

[0089] L is a bivalent group deriving from the abstraction of a hydrogen atom born by a terminal carbon atom in a radical selected from the group consisting of (Ci-Ci2)alkyl, (C2- Ci2)alkenyl, a group of formula (Ci-Ci2)alkyl-X-(Ci-Ci2)alkyl wherein -X- is selected from -O-, -S-, -COO-, -OCO-, -NR - wherein R’ is hydrogen or (Ci-Ce)alkyl, -CONR- wherein R’ is hydrogen or (Ci-Ce)alkyl, -NR’CO- wherein R’ is hydrogen or (Ci-Ce)alkyl, and a group of formula (Ci-Ci2)alkyl-(O-(Ci-Ci2)alkyl)n-O wherein n is an integer of from 1 to 10;

[0090] FGi is a functional group selected from the group consisting of -NH2, -OH, -SH, -COOR being R hydrogen or a (Ci-Ce)alkyl group, an azide group, an alkene group, an alkyne group and -CHO. In said embodiment, the functional group FG1 is suitable for reacting with a functional group comprised in the porous solid support or with a cross-linking reagent suitable for reacting with both FG1 and a functional group comprised in the porous solid support, thus producing the covalent bonding of the nucleic acid to the porous solid support.

[0091]

[0063] In a preferred embodiment, in the moiety of formula (A), FG1 is a NH2 group.

[0092]

[0064] In a preferred embodiment, in the moiety of formula (A), Oais an oxygen atom comprised in a phosphodiester group.

[0093]

[0065] In a preferred embodiment, in the moiety of formula (A), L is a bivalent group deriving from the abstraction of a hydrogen atom born by a terminal carbon atom in a (Ci-Ci2)alkyl group.

[0094]

[0066] In a more preferred embodiment, the moiety of formula (A) is one wherein:

[0095] (i) Oa is an oxygen atom comprised in a phosphodiester group;

[0096] (ii) L is a bivalent group deriving from the abstraction of a hydrogen atom born by a terminal carbon atom in a (Ci-Ci2)alkyl group; and

[0097] (iii) FG1 is NH2.

[0098]

[0067] In a further embodiment, the nucleic acid is covalently attached to said porous solid support via a covalent bond involving a functional group FG2 comprised in the porous solid support.

[0099]

[0068] In a further embodiment, the nucleic acid is covalently attached to said porous solid support via a covalent bond involving a functional group FG2 comprised in the porous solid support wherein FG2 is a functional group selected from the group consisting of -NH2, -OH, -SH, -COOR being R hydrogen or a (Ci-C6)alkyl group an azide group, an alkene group, an alkyne group and -CHO. Preferably, FG2 is -NH2 or -SH.

[0100]

[0069] In a further embodiment, the porous solid support comprises a functional group FG2 as defined above that is attached to the porous solid support through a linker that is a bivalent group deriving from the abstraction of a hydrogen atom born by a terminal carbon atom in a radical selected from the group consisting of (Ci-Ci2)alkyl, (C2- Ci2)alkenyl, a group of formula (Ci-Ci2)alkyl-X-(Ci-Ci2)alkyl wherein -X- is selected from -O-, -S-, -COO-, -OCO-, -NR - wherein R’ is hydrogen or (Ci-Ce)alkyl, -CONR - wherein R’ is hydrogen or (Ci-Ce)alkyl, -NR’CO- wherein R’ is hydrogen or (Ci-Ce)alkyl, and a group of formula (Ci-Ci2)alkyl-(O-(Ci-Ci2)alkyl)n-O wherein n is an integer of from 1 to 10. Preferably, the porous solid support comprises a functional group FG2 as defined above that is attached to the porous solid support through a linker that is a bivalent group deriving from the abstraction of a hydrogen atom born by a terminal carbon atom in a (Ci-Ci2)alkyl group; more preferably from a propyl group.

[0101]

[0070] Thus, in a particular embodiment, the porous solid support comprises an amino group or a thiol group that is attached to the porous solid support through a linker that is a bivalent group deriving from the abstraction of a hydrogen atom born by a terminal carbon atom in a (Ci-Ci2)alkyl group; more preferably from a propyl group.

[0102]

[0071] As will be obvious to the skilled person, FG1 and FG2 are selected in a manner that they can react with each other or with a cross-linking agent so as to form a group forming a covalent bonding between the nucleic acid and the porous solid support. Suitable combinations of such functional groups will become apparent to the skilled person upon reduction to practice of the invention on the basis of common general knowledge. For example, when the covalent bonding between the nucleic acid and the solid support is the result of a direct reaction between FG1 and FG2, one of FG1 and FG2 may be -COOR or -CHO, being R hydrogen or a (Ci-C6)alkyl group, and the other of FG1 or FG2 may be selected from -NH2, -OH and -SH. Also, for example, when the covalent bonding between the nucleic acid and the solid support is the result of a direct reaction between FG1 and FG2, both FG1 and FG2 may be -SH. In addition, when the covalent bonding between the nucleic acid and the solid support is the result of a crosslinking reaction, FG1 and FG2 may be the same group, such as, for instance -NH2. This is particularly the case when the cross-linking agent comprises in its molecular formula a plurality of aldehyde groups; preferably two. Suitable cross-linking agents comprising a plurality of aldehyde groups in their molecular formula will become apparent to the skilled person upon reduction to practice of the invention. Those include, for instance, glutaraldehyde. Thus, any reactivity known in the art for reacting FG1 and FG2, optionally with a cross-linking agent, may be used to conjugate the nucleic acid with the solid support, so that the covalent binding involves one or more bivalent functional groups selected from the group consisting of a thioether, a disulphide, an amide, an ester, an ether, a thioester, a triazolyl group, a urea group and an imine group. Alternatively, when FG1 is an amino group and FG2 is a thiol group, suitable cross-linking agents comprise in their molecular formula groups for reacting with FG2, such as maleimide, and groups for reacting with FG1, such as a N-succinimidyl ester group or the like.

[0103]

[0072] In an embodiment, a cross-linking agent that contains a plurality of aldehyde groups in its molecular formula is a cross-linking agent that contains between 2 and 10 aldehyde groups in its molecular formula. In a particular embodiment, the cross-linking agent that contains a plurality of aldehyde groups in its molecular formula is a crosslinking agent that contains 2 aldehyde groups in its molecular formula.

[0104]

[0073] In a more preferred embodiment, the nucleic acid is covalently attached to said porous solid support via a covalent bond involving:

[0105] (1) a functional group FGi comprised at the 5’ or 3’ termination of said nucleic acid that is NH2; and

[0106] (2) a cross-linking agent that comprises in its molecular a plurality of aldehyde groups, such as glutaraldehyde.

[0107]

[0074] In a more preferred embodiment, the nucleic acid is covalently attached to said porous solid support via a covalent bond involving:

[0108] (1) an amino group comprised in the porous solid support; and

[0109] (2) a cross-linking agent that comprises in its molecular a plurality of aldehyde groups, such as glutaraldehyde.

[0110]

[0075] In a more preferred embodiment, the nucleic acid is covalently attached to said porous solid support via a covalent bond involving:

[0111] (1) a functional group FG1 comprised at the 5’ or 3’ termination of said nucleic acid that is NH2;

[0112] (2) an amino group comprised in the porous solid support; and

[0113] (3) a cross-linking agent that comprises in its molecular a plurality of aldehyde groups, such as glutaraldehyde. Thus, in said embodiment, the nucleic acid is covalently attached to said porous solid support via covalent bonding involving an amino group comprised at the 5’ or 3’ end of said nucleic acid and via covalent bonding involving an amino group comprised in said solid support; preferably, the nucleic acid is covalently attached to said porous solid support via an amino group comprised at the 5’ end of said nucleic acid and via an amino group comprised in said solid support by cross-linking, more preferably by cross-linking mediated by glutaraldehyde.

[0114]

[0076] In more preferred embodiments, the nucleic acid is covalently attached to said porous solid support via a covalent bond involving:

[0115] (1) a functional group FG1 comprised at the 5’ or 3’ termination of said nucleic acid wherein the nucleic acid comprises a moiety of formula (A) as defined above wherein:

[0116] (i) Oais an oxygen atom comprised in a phosphodiester group;

[0117] (ii) FG1 is NH2;

[0118] (2) an amino group comprised in the porous solid support that is attached to the porous solid support through a linker that is a bivalent group as defined above; and

[0119] (3) a cross-linking agent that comprises in its molecular a plurality of aldehyde groups, such as glutaraldehyde.

[0120]

[0077] In more preferred embodiments, the nucleic acid is covalently attached to said porous solid support via a covalent bond involving: (1) a functional group FGi comprised at the 5’ or 3’ termination of said nucleic acid wherein the nucleic acid comprises a moiety of formula (A) as defined above wherein:

[0121] (i) Oais an oxygen atom comprised in a phosphodiester group;

[0122] (ii) L is a bivalent group deriving from the abstraction of a hydrogen atom born by a terminal carbon atom in a (Ci-Ci2)alkyl group;

[0123] (iii) FGi is NH2;

[0124] (2) an amino group comprised in the porous solid support that is attached to the porous solid support through a linker that is a bivalent group deriving from a (Ci-Ci2)alkyl group; preferably from a propyl group; and

[0125] (3) a cross-linking agent that comprises in its molecular a plurality of aldehyde groups, such as glutaraldehyde.

[0126]

[0078] In more preferred embodiments, the nucleic acid is covalently attached to said porous solid support via a covalent bond involving a thiol group comprised in the porous solid support that is attached to the porous solid support through a linker that is a bivalent group deriving from a (Ci-Ci2)alkyl group; preferably from a propyl group; and a crosslinking agent that comprises in its molecular formula a maleimide group for reacting with said thiol group, such as N-y-maleimidobutyryl-oxysulfosuccinimide ester.

[0127]

[0079] In more preferred embodiments, the nucleic acid is covalently attached to said porous solid support via a covalent bond involving:

[0128] (1) a functional group FGi comprised at the 5’ or 3’ termination of said nucleic acid wherein the nucleic acid comprises a moiety of formula (A) as defined above wherein:

[0129] (i) Oa is an oxygen atom comprised in a phosphodiester group;

[0130] (ii) L is a bivalent group deriving from the abstraction of a hydrogen atom born by a terminal carbon atom in a (Ci-Ci2)alkyl group;

[0131] (iii) FGi is NH2;

[0132] (2) a thiol group comprised in the porous solid support that is attached to the porous solid support through a linker that is a bivalent group deriving from a (Ci-Ci2)alkyl group; preferably from a propyl group; and

[0133] (3) a cross-linking agent that comprises in its molecular a maleimide group for reacting with said thiol group and a, such as N-y-maleimidobutyryl-oxysulfosuccinimide ester.

[0134]

[0080] In a more preferred embodiment of the first aspect of the invention, the surface density of the nucleic acid is comprised between 1010molecules of nucleic acid per cm2of the surface of the solid support and 1016molecules of nucleic acid per cm2; preferably, it is comprised between 5 1012and 9 1013molecules of nucleic acid per cm2. The surface density of the nucleic acid may be determined by measuring the resonance frequency of a quartz crystal sensor modified with the material forming the membrane of a known surface and employing quartz crystal microbalance with dissipation as disclosed in the Examples. When the quartz crystal sensor is modified with a non-porous material identical to the one comprised in the composition of the first aspect of the invention, the measured surface density does not take into account the presence of pores in the material, that it that the obtained value needs to be corrected with the average surface density of the pores of the material.

[0135] Catalyst suitable for binding or intercalating the nucleic acid

[0136]

[0081] As mentioned above, the composition of the first aspect of the invention comprises a catalyst suitable for binding or intercalating the nucleic acid.

[0137]

[0082] In preferred embodiments of the first aspect of the invention, said catalyst is an organometallic complex comprising a catalytically active metal and a ligand.

[0138]

[0083] In further preferred embodiments of the first aspect of the invention, the catalyst is suitable for binding to the nucleic acid. More particularly, the composition of the first aspect of the invention is one wherein the catalyst is bound to the nucleic acid.

[0139]

[0084] In preferred embodiments of the first aspect of the invention, said catalyst is an organometallic complex comprising a catalytically active metal and a ligand that is suitable for binding to the nucleic acid. Said binding particularly takes place between the catalytically active metal and the nucleic acid. It is particularly preferred that the binding of the catalyst to the nucleic acid is between the catalytically active metal and at least one nitrogen atom, preferably two nitrogen atoms, each of said nitrogen atoms being in particular comprised in an adenine and / or guanine nitrogenated base comprised in said nucleic acid.

[0140]

[0085] In preferred embodiments, the nucleic acid is one which comprises adenine and / or guanine nitrogenated base arranged in the sequence of such nucleic acid in a manner suitable for one atom of the catalytically active metal being bound to two nitrogen atoms comprised in adenine and / or guanine nitrogenated base comprised in said nucleic acid.

[0141]

[0086] While any catalytically active metal may be used, in preferred embodiments, the catalyst is an organometallic complex comprising a catalytically active metal that is copper. In the present invention, it is contemplated that “copper” refers to copper in any of its known catalytically active oxidation states, including copper (0), copper (II) or copper(l); preferably, it is copper (II).

[0142]

[0087] In preferred embodiments, the catalyst is an organometallic complex comprising a ligand that is a bidentate ligand. Said bidentate ligand may be:

[0143] (i) a N,N-bidentate ligand, which is a ligand that binds to a metal cation by formation of a bond between two N atoms comprised in the ligand and the metal cation;

[0144] (ii) a N,P bidentate ligand which is a ligand that binds to a metal cation by formation of a bond between one N atom and one P atom comprised in the ligand and the metal cation; (iii) a P,P bidentate ligand, which is a ligand that binds to a metal cation by formation of a bond between two P atoms comprised in the ligand and the metal cation;

[0145] (iv) a N,0 bidentate ligand, which is a ligand that binds to a metal cation by formation of a bond between one N atom and one O atom comprised in the ligand and the metal cation; and

[0146] (v) a 0,0 bidentate ligand which is a ligand that binds to a metal cation by formation of a bond between two O atoms comprised in the ligand and the metal cation.

[0147]

[0088] In more preferred embodiments, the catalyst is an organometallic complex comprising a ligand that is a N,N bidentate ligand.

[0148]

[0089] In more preferred embodiments, the catalyst is an organometallic complex comprising a ligand that comprises in its molecular formula a moiety of formula (B) wherein each double dashed bond represents a single or double bond and each single dashed bond represents the absence or presence of a single covalent bond and wherein each wavy line represents the connection points of the moiety of formula (B) to the remainder part of the ligand, said moiety of formula (B) being optionally substituted at any available position with one or more radicals selected from the group consisting of.

[0149] - (Ci-Ce)alkyl optionally substituted with a (Ce-C2o)aryl ring or a (Cs-C2o)heteroaryl ring that is optionally substituted at any available position by one or more groups selected from the group consisting of (Ci-Ce)alkyl, (Ci-Ce)alkyloxy, (Ci-Ce)haloalkyl, (Ci- C6)alkyloxycarbonyl, halo, nitro, and cyano ,

[0150] - a radical of formula -X-Y wherein X is N, O, CH or S and Y is a planar aromatic group suitable for intercalating a nucleic acid such as a ring system comprising 3 aromatic 6- membered fused rings, one of said rings being a pyridine ring,

[0151] -(Ci-Ce)alkyloxy, (Ci-Ce)haloalkyl, (Ci-C6)alkyloxycarbonyl, halo, nitro, and cyano or, alternatively, said moiety of formula (B) being comprised in a ring system comprising from 2 to 5 aromatic rings, said rings being isolated or fused, and being further optionally substituted at any available position by one or more groups selected from the group consisting of (Ci-Ce)alkyl optionally substituted with a radical of formula -X-Y as defined above, (Ci- Ce)alkyloxy, (Ci-Ce)haloalkyl, (Ci-C6)alkyloxycarbonyl, halo, nitro, and cyano.

[0090] When the ligand comprises a radical of formula -X-Y, it is preferred that the ring system comprising 3 aromatic 6-membered fused rings is an acridine ring system. It is also preferred that X is N. In such cases, the ligand is particularly suitable for intercalating the nucleic acid.

[0152]

[0091] In such embodiments, it is preferred that the ligand is selected from the group consisting of the compounds of formula (B1) wherein m is an integer of from 2 to 5 and Rais (Ci-Ce)alkyl optionally substituted with a (Ce-C2o)aryl ring that is optionally substituted at any available position by one or more groups selected from the group consisting of (Ci-Ce)alkyl, (Ci-Ce)alkyloxy, (Ci- Ce)haloalkyl, (Ci-C6)alkyloxycarbonyl, halo, nitro, and cyano.

[0153]

[0092] In further preferred embodiments, the catalyst is an organometallic complex comprising a ligand that is a heteroaromatic compound comprising a moiety of formula (I) comprised in a ring system comprising from 2 to 5 aromatic rings, said rings being isolated or fused, and being further optionally substituted at any available position by one or more groups selected from the group consisting of (Ci-Ce)alkyl, (Ci-Ce)alkyloxy, (Ci- Ce)haloalkyl, (Ci-C6)alkyloxycarbonyl, halo, nitro, and cyano wherein each wavy line represents the connection points of the moiety of formula (I) to the remainder part of the heteroaromatic compound. Said ring systems are preferably selected from the group consisting of: and are optionally substituted at any available position as defined above.

[0093] In preferred embodiments, the catalyst is an organometallic complex comprising a ligand that is a heteroaromatic compound comprising a moiety of formula (I) comprised in a ring system comprising from 2 to 5 aromatic rings comprising from 2 to 3 rings, said rings being isolated or fused, and being further optionally substituted at any available position by one or more groups selected from the group consisting of (Ci-Ce)alkyl, (Ci- Ce)alkyloxy, (Ci-Ce)haloalkyl, (Ci-C6)alkyloxycarbonyl, halo, nitro and cyano.

[0154]

[0094] In more particular embodiments, the catalyst is an organometallic complex comprising a ligand that is a heteroaromatic compound comprising a moiety of formula (I) comprised in a ring system selected from 2 ,2’-bipyridine and phenanthroline; said ring system being further optionally substituted at any available position by one or more (Ci- Ce)alkyl groups.

[0155]

[0095] In even more preferred embodiments, the catalyst is an organometallic complex comprising a ligand selected from the group consisting of 4,4’-dimethyl-2,2’-bipyridine and 2,2’-bipyridine.

[0156]

[0096] In even more preferred embodiments, the catalyst is an organometallic complex of copper with a ligand selected from the group consisting of 4,4’-dimethyl-2,2’-bipyridine and 2,2’-bipyridine.

[0157] Preferred compositions

[0158]

[0097] In preferred embodiments of the first aspect of the invention, the composition is one wherein:

[0159] (i) the nucleic acid is a naturally occurring double stranded DNA, such as salmon testes DNA or salmon testes DNA oligomer;

[0160] (ii) the porous solid support consists of anodic aluminium oxide having a pore size of between 1 and 50 nm; preferably of about 20 nm;

[0161] (iii) the nucleic acid is covalently attached to said porous solid support via covalent bonding involving an amino group comprised at the 5’ end of said nucleic acid and via covalent bonding involving an amino group comprised in said solid support by crosslinking mediated by glutaraldehyde; and / or

[0162] (iv) the catalyst is an organometallic complex of copper and a heteroaromatic compound as defined above; preferably said heteroaromatic comprises a moiety of formula (I) comprised in a ring system selected from 2,2’-bipyridine and phenanthroline; said ring system being further optionally substituted at any available position by one or more (Ci- Ce)alkyl groups; more preferably, said heteroaromatic compound is selected from the group consisting of 4,4’-dimethyl-2,2’-bipyridine and 2,2’-bipyridine.

[0163]

[0098] As mentioned above, the second aspect of the invention relates to a process for the preparation of a composition according to the first aspect of the invention, and comprising the steps of (i) providing a nucleic acid covalently attached to a porous solid support;

[0164] (ii) providing a catalyst suitable for binding with or intercalating into said nucleic acid; and

[0165] (iii) contacting the catalyst suitable for binding with or intercalating into said nucleic acid with the porous solid support bearing said nucleic acid.

[0166]

[0099] Alternatively, the second aspect of the invention relates to a process for the preparation of a membrane according to the fifth aspect of the invention comprising the steps of:

[0167] (i’) providing a porous solid support for forming a membrane;

[0168] (ii’) providing a nucleic acid;

[0169] (iii’) contacting a catalyst suitable for binding with or intercalating into the nucleic acid provided in (ii’) to produce a nucleic acid based catalyst;

[0170] (iv’) covalently binding the nucleic acid based catalyst produced in step (iii) on the solid support provided in (i’).

[0171]

[0100] Methods for carrying out step (i) or (iv’) are well known in the art and will become apparent to the skilled person upon reduction to practice of the invention. In particular, methods for conjugating a nucleic acid to a solid support are well known in the art and are disclosed for instance in Bioconjugate Techniques, Greg T. Hermanson, Academic Press 2013, 3rd Edition, ISBN 9780123822390, 9780123822406, the content of which is incorporated herein by reference - any of such methods is suitable for carrying out step (i) or (iv’).

[0172]

[0101] In particular embodiments of the process of the second aspect of the invention, the nucleic acid is covalently attached to the solid support via covalent bonding involving functional groups as defined above in the first aspect of the invention.

[0173]

[0102] In more particular embodiments of the process of the second aspect of the invention, the covalently attached nucleic acid is obtainable by reaction of a porous solid support comprising a functional group FG2 as defined above in the first aspect of the invention, and a nucleic acid bearing a functional group FG1 as defined above in the first aspect of the invention, optionally in the presence of a cross-linking agent as defined above. As mentioned above, it is contemplated that both FG1 and FG2 are an amino group which react with a cross-linking agent comprising a plurality of aldehyde groups in its molecular formula, such as glutaraldehyde, thus providing a nucleic acid covalently attached to a porous solid support. It is also contemplated that FG2 is a thiol group, FG1 is an amino group and the cross-linking agent comprises a maleimide group for reacting with said thiol group and a N-succinimidyl ester group for reacting with said N-amino group, such as N-y-maleimidobutyryl-oxysulfosuccinimide ester.

[0174]

[0103] Both the nucleic acid and the porous solid support are preferably as defined in any of the preferred and particular embodiments of the first aspect invention described above.

[0104] In particular embodiments of the process of the second aspect of the invention, the catalyst provided in step (ii) or (iii’) is as defined in any of the preferred and particular embodiments of the first aspect invention described above. Methods for carrying out step (ii) or (iii’) will become apparent to the skilled person upon reduction to practice of the invention on the basis of common general knowledge. When the catalyst is an organometallic complex of a catalytically active metal cation or a precursor thereof with a ligand, step (ii) or (iii’) may comprise contacting a source of said catalytically active metal cation or a precursor thereof with a ligand. Suitable conditions for carrying out such preparation are well known in the art and will become apparent to the skilled person upon reduction to practice of the invention. For instance, a nitrate salt of the catalytically active metal, e.g. copper (II), may be contacted with a ligand as defined above to produce a catalyst suitable for binding with or intercalating a nucleic acid.

[0175]

[0105] Step (iii) or (iii’) of the process of the second aspect is preferably carried out in a solvent suitable for solubilizing the catalyst and providing a dispersion of the solid support bearing the nucleic acid. Conditions for step (iii) or (iii’) must be suitable for allowing the binding of the catalyst to the nucleic acid and / or the intercalation of the catalyst in the nucleic acid.

[0176]

[0106] The third aspect of the invention relates to the use of the composition of the first aspect of the invention as a catalyst.

[0177]

[0107] In preferred embodiments, the third aspect of the invention relates to the use of the composition as defined in any of the particular and preferred embodiments of the first aspect of the invention described above as a catalyst.

[0178]

[0108] Any chemical reaction susceptible of being promoted by the catalyst comprised in the composition of the first aspect of the invention may be carried out by the composition of the first aspect of the invention, including, in a non-limiting way, cycloaddition reactions (click chemistry, Diels-Alder reactions), C-H activation reactions, oxidation reactions, and coupling reactions. Preferably, the use of the composition of the first aspect of the invention is as a catalyst for the Diels-Alder reaction.

[0179]

[0109] In preferred embodiments of the third aspect of the invention, said use is for the production of an enantiomerically enriched chiral product.

[0180]

[0110] The inventors have found in particular that the use of an immobilized catalyst whereby the nucleic acid is covalently linked to a solid support advantageously allows maintaining the enantiomeric enrichment of the product produced by the reaction when it is catalysed with the non-supported nucleic acid based catalyst.

[0181]

[0111] As mentioned above, the fourth aspect of the invention relates to a membrane comprising the composition according to the first aspect of the invention.

[0112] In preferred embodiments, the membrane of the fourth aspect of the invention comprises a composition as defined in any of the particular and preferred embodiments of the first aspect of the invention described above.

[0182]

[0113] In further preferred embodiments, the membrane of the fourth aspect of the invention consists essentially of a composition as defined in any of the particular and preferred embodiments of the first aspect of the invention described above.

[0183]

[0114] In more preferred embodiments, the membrane of the fourth aspect of the invention consists of a composition as defined in any of the particular and preferred embodiments of the first aspect of the invention described above.

[0184]

[0115] In preferred embodiments, the membrane of the fourth aspect of the invention has a thickness of between 1 pm and 1 mm; preferably of between 1 pm and 500 pm; more preferably, of between 100 pm and 500 pm; and even more preferably of about 300 pm.

[0185]

[0116] The membrane of the fourth aspect of the invention is particularly useful as a catalyst. The fifth aspect of the invention thus relates to the use of the membrane of the fourth aspect of the invention as a catalyst.

[0186]

[0117] In preferred embodiments, the fifth aspect of the invention relates to the use of the membrane as defined in any of the particular and preferred embodiments of the fourth aspect of the invention described above as a catalyst.

[0187]

[0118] Any chemical reaction susceptible of being promoted by the catalyst comprised in the composition of the first aspect of the invention may be carried out by the membrane of the fourth aspect of the invention, including, in a non-limiting way, cycloaddition reactions (click chemistry, Diels-Alder reactions), C-H activation reactions, oxidation reactions, and coupling reactions. Preferably, the use of the membrane of the fourth aspect of the invention is as a catalyst for the Diels-Alder reaction.

[0188]

[0119] In preferred embodiments of the fifth aspect of the invention, said use is for the production of an enantiomerically enriched chiral product.

[0189]

[0120] The inventors have found in particular that the use of a membrane comprising an immobilized catalyst as defined herein advantageously allows performing the catalysed reaction in a catalytic membrane reactor, whereby the reaction substrates react with the catalyst immobilized on the membrane to form the reaction product which permeates through the membrane, thus allowing for the simultaneous chemical transformation and product separation.

[0190]

[0121] The sixth aspect of the invention relates to a process for the preparation of a membrane according to the fifth aspect of the invention comprising the steps of:

[0191] (i) providing a porous solid support for forming a membrane;

[0192] (ii) covalently binding a nucleic acid on the solid support provided in (i); (iii) providing a catalyst suitable for binding with or intercalating into said nucleic acid;

[0193] (iv) contacting the catalyst suitable for binding with or intercalating into said nucleic acid with the porous solid support bearing said nucleic acid produced in (ii); and

[0194] (v) forming a membrane.

[0195]

[0122] Alternatively, the sixth aspect of the invention relates to a process for the preparation of a membrane according to the fifth aspect of the invention comprising the steps of:

[0196] (i) providing a porous solid support for forming a membrane;

[0197] (ii’) providing a nucleic acid;

[0198] (iii’) contacting a catalyst suitable for binding with or intercalating into the nucleic acid provided in (ii) to produce a nucleic acid based catalyst;

[0199] (iv’) covalently binding the nucleic acid based catalyst produced in step (iii) on the solid support provided in (i);

[0200] (v) forming a membrane.

[0201]

[0123] The porous solid support of step (i) must be suitable for forming a membrane and is preferably provided in the form of a membrane, that is, step (v) may be performed prior to step (ii) or (iv’). Said support is preferably as defined in any of the particular and preferred embodiments of the first aspect of the invention.

[0202]

[0124] In a preferred embodiment, the solid support of step (i) is preferably provided as a membrane and comprises a functional group of formula FG2 as defined in any of the preferred and particular embodiments described above for the first aspect of the invention.

[0203]

[0125] Step (ii) or (iv’) of the process of the sixth aspect of the invention relates to the covalent binding of the nucleic acid to the solid support provided in (i). As will be apparent to the skilled person, step (ii) or (iv’) of the process of the sixth aspect of the invention preferably involves the covalent binding of the nucleic acid to the solid support as defined in any of the particular and preferred embodiments described above in the first aspect of the invention.

[0204]

[0126] In particular, step (ii) or (iv’) may be carried out by reaction of a porous solid support comprising a functional group FG2 as defined above, and a nucleic acid bearing a functional group FG1 as defined above in the first aspect of the invention, optionally in the presence of a cross-linking agent. As mentioned above, it is contemplated that both FG1 and FG2 are an amino group which react with a cross-linking agent comprising a plurality of aldehyde groups in its molecular formula, such as glutaraldehyde, thus providing a nucleic acid covalently attached to a porous solid support.

[0127] Steps (iii) and (iv) of the process of the sixth aspect of the invention are preferably carried out as defined above for steps (ii) and (iii) of the process of the second aspect of the invention. Likewise, steps (iii’) and (iv’) of the process of the sixth aspect of the invention are preferably carried out as defined above for steps (iii’) and (iv’) of the process of the second aspect of the invention.

[0205]

[0128] As mentioned above, the seventh aspect of the invention relates to a membrane reactor comprising a membrane according to the sixth aspect of the invention. Such membrane reactor is particularly a catalytic membrane reactor, whereby the catalyst is comprised in the membrane such that the reaction takes place at the membrane. Since the membrane comprises a porous solid support, the product of the reaction permeates through the membrane, allowing for simultaneous production and separation of the product. This represents a clear advantage over the non-supported system whereby the nucleic acid molecules tend to aggregate, thus causing emulsions in the biphasic mixtures employed for product recovery from the reaction mixture.

[0206]

[0129] In a preferred embodiment of the seventh aspect of the invention, the membrane reactor comprises (i) a first chamber arranged for being in chemical contact with said membrane and suitable for receiving a solution of reagents suitable for reacting with the catalytically active metal comprised in said membrane, and (ii) a second chamber arranged for being in chemical contact with said membrane and suitable for receiving a solution of the one or more product of the reaction of the reagents of said first chamber with said catalytically active metal.

[0207]

[0130] In said embodiment, the solutions of the first and second chambers flow through said chambers. The inventors have found that the catalyst surprisingly remains in contact with the nucleic acid and no relevant leakage of catalyst is observed when a solution is flowed in one or both of the chambers being in chemical contact with the membrane. Preferably, the solution of the second chamber flows in counter current to the solution of the first chamber. This advantageously provides for improved mass transfer conditions over the systems disclosed in the art and, hence, an improved reaction rate and higher catalytic turnover.

[0208]

[0131] The use of a substantially planar membrane in a membrane reactor configuration provides for an improved control over the flow hydrodynamic, in contrast with particles or spiral-wound membranes.

[0209]

[0132] In further particular embodiments, membrane shapes providing the highest surface to volume ratio are preferred. Such shapes include, for instance, hollow fibers or spiral wound.

[0210]

[0133] Throughout the description and claims the word “comprises" and variations of the word, are not intended to exclude other technical features, additives, components or steps. Furthermore, the word “comprise” encompasses the cases of “consist of” and “consists essentially of”. Additional objects, advantages and features of the invention will become apparent to those skilled in the art upon examination of the description or may be learned by practice of the invention. The following examples are provided by way of illustration, and they are not intended to be limiting of the present invention.

[0211] EXAMPLES

[0212] AAO: anodic aluminium oxide

[0213] DNA: deoxyribonucleic acid

[0214] QCM-D: Quartz Crystal Microbalance with Dissipation

[0215] PBS: phosphate buffered saline

[0216] DCM : dichloromethane

[0217] DNA oligomers (21-mers) bearing an amino group at the 5’ end (“oligomer 1”) and their complementary strand (“oligomer 2”) were purchased from Biomers (Germany).

[0218] Preparative example 1 : Preparation of a membrane and sensor comprising a nucleic acid immobilized on a solid support

[0219]

[0134] Procedure A: AAO membranes were cleaned using piranha base solution, rinsed with ethanol and repeatedly washed with ultrapure water. The anodic aluminum oxide (AAO) membranes with diameter 25 mm and measured average pore size of 35 nm were purchased from Whatman. Then, the membranes were placed in a buffer solution containing (3-aminopropyl)trimethoxysilane (APS, 97%). As buffer, Phosphate Buffered Saline (PBS) was used comprising 10 mM phosphate buffered saline, 1 M NaCI, 2.7 mM KCI, 5 mM of MgCh and adjusted to pH 7.4 at 25 °C. The membranes were than washed with ultrapure water, thoroughly dried and subsequently placed in (glutaraldehyde buffer solution (25% in H2O) for several hours. After another rinsing step followed by drying, the sensors and membranes were bioconjugated with the 5’ amine-modified DNA (oligomer 1) for immobilization at a concentration of 50 pM in PBS buffer. Subsequently, the duplex was formed by adding oligomer 2 in the same buffer.

[0220]

[0135] Procedure In another method, the membrane was placed in 20 ml of 95% ethanol containing 1 mM acetic acid and 3% (w / w) of (3-Mercaptopropyl)triethoxysilane and were stirred for 30 min at room temperature, followed by three-fold washing with ethanol. The membrane was then placed in PBS 5M buffer (0.01 M phosphate buffered saline; NaCI-0.138 M; KCI-0.0027 M; pH 7.4; 5 mM MgCl2) overnight and used for coupling with amino-modified DNA (100 pM, oligomer 1) using 2 mg / ml sulfo-GMBS (Sulfo-N-succinimidyl 4-maleimidobutyrate) as cross-linking agent. Subsequently, the duplex was formed by adding oligomer 2 in the same buffer.

[0136] Procedures A and B described above were used to prepare AAO-coated QCM- D sensors. Said sensors were coated with non-porous AAO. In all cases, sensors and membranes were finally rinsed with abundant PBS buffer.

[0221] QCM-D characterization

[0222]

[0137] QCM-D measurement were made using a Q-Sense E4 System (Biolin Scientific I Q-Sense AB, Vastra Frdlunda, Sweden). Standard gold and Aluminium Oxide (AI2O3) sensor chips (QSX301 and QSX309 respectively, Q-Sense, Vastra Frdlunda, Sweden) were employed with the following specifications: frequency 4.95 MHz ± 50 kHz, diameter 14 mm, thickness 0.3 mm, RMS surface roughness of electrode <3 nm. Before modification, the sensors were cleaned 1. with an UV cleaner for 10 min; 2. with basic Piranha (1 :1 :5 ratio of H2O2, 25% ammonia solution, and ultra-pure water, respectively) at 80 °C for 5 minutes; 3. again with UV cleaner for 10 minutes. All QCM-D measurements were done under temperature control at 23 °C and a flow rate of 35pL / min. Before each experiment, the baseline was assumed stable when AF<0,1 Hz during one minute.

[0223]

[0138] Fig. 1 describes the bioconjugation of DNA onto an alumina coated sensor as measured with a quartz crystal microbalance with dissipation monitoring, showing the evolution of the measured frequency (in Hertz) over time (in seconds) when salmon testes DNA was injected in the buffer medium comprising a non-porous alumina support (arrow 1) till the end of the conjugation reaction (arrow 2).

[0224]

[0139] The results of Figure 1 show that the surface density of DNA was of about 890 ng of DNA per cm2of the non-porous alumina surface, which corresponds to about one molecule of DNA per each 3 nm2of the surface.

[0225] Characterization of membrane by confocal microscopy

[0226]

[0140] The experiments were performed on a Leica SP2 AOBS confocal microscopy with lens that has 63x zoom and a numerical aperture of 1.4. The excitation wavelength was at 488 nm and the emission spectra were taken from 505 to 535 nm (Atto 488 marked DNA was used as a fluorophore). The voltage 477 V was applied to obtain fluorescence intensity of the surface. Two different pictures were obtained in the same time: the fluorescence and the reflection mode of the laser. With the reflection mode, the width of the membrane was measured. The fluorescence image shows a full and uniform coverage of the surface of aluminium oxide.

[0227] Example 2: Preparation of a membrane comprising an immobilized nucleic acid based catalyst

[0228]

[0141] Preparation of Cu(ll) complex'. In a vial, one equivalent of dimethylbipyrimidine (200 mg) was dissolved in 10 mL of EtOH, sonicating the solution (Solution A). On the other hand, 1.1 equivalents of the Cu(NOa)2 salt (224 mg) were dissolved in 1 mL of EtOH (Solution B). Solution B was added to Solution A and kept stirring for 48 hours. Finally, the mixture was filtered, resulting in a solid, which was washed with cold EtOH and dried under vacuum. The final product (catalytic complex) may be purified by recrystallization from EtOH.

[0229]

[0142] Preparation of 20 mM MOPS Solution (MOPS Solution): In a media bottle, add 4.18 g of 3-(N-morpholino)propane sulfonic acid (MOPS), 1 L of Milli-Q water, and 375 pL of 10 M NaOH to obtain a 20 mM MOPS solution with a pH of 6.5.

[0230]

[0143] Preparation of st-DNA 2 mg / mL Solution (Solution C): In a 100 mL bottle, add 40 mg of st-DNA and 80 mL of the previously prepared MOPS solution. The resulting solution is kept in the refrigerator at 5°C for 24 hours without stirring.

[0231]

[0144] Preparation of 0.9 mM catalytic complex solution (Solution D) : To obtain a 0.9 mM catalytic complex solution, weigh 3.34 mg of the preformed catalytic complex (see above) into a vial and dissolve it in 10 mL of the previously prepared solution C.

[0232]

[0145] Solution D was used to prepare a membrane according to the invention following the procedure of Example 1 by replacing the solution of the 5’ amine-modified DNA (oligomer 1) for immobilization at a concentration of 50 pM in PBS buffer by solution D.

[0233] Example 3: Membrane reactor

[0234]

[0146] The membrane of Example 1 was then placed in a membrane reactor as described in Figure 2 or 3.

[0235]

[0147] No catalyst gets detached from the surface during reactor operation:

[0236] No DNA leakage: For proving that no catalyst was detached from the DNA even under prolonged operation, a DNA-catalyst modified nanoporous alumina membrane as prepared in Example 1 was placed between two flow channels in a membrane contactor configuration (see Fig.2). This configuration allowed the membrane to be the solid interface between two moving liquids, the upstream feed flow and the downstream receiving flow. As shown in Figure 5, the concentration of the DNA-based catalyst in the feed phase during operation up to almost 10 days is above 92% and is in fact stable over the whole duration of operation, while the concentration of the DNA in the receiving chamber is below detection limit (0%) at all times. These results show that no DNA is extracted during the operation of the membrane reactor, such that the catalyst can be advantageously re-used in further reaction runs.

[0237] No Catalyst leakage: In the configuration depicted in Figure 2, MIFI -Cu(ll) (MIF1 = copper-(2-(pyridin-2-yl)imidazo[1 ,2-a]pyridine)dinitrate) was recirculated at a concentration of 0,39 mM in the feed phase over a nanoporous alumina membrane during 20 hours. Concurrently, a receiving phase consisting of dicholoromethane / hexane (1 :1 v / v) was recirculated. Concentration of the MIF1 -ligand in the feed and receiving phases over time was monitored by UV-Vis spectrometry by measuring the absorbance at different points in time at 320 nm of the feed and receiving phases. It was observed that, in the absence of DNA, the catalytic complex permeated across the membrane due to its concentration gradient across the membrane. Surprisingly, when the ligand interacted with dsDNA in the feed phase under otherwise identical operation conditions, no permeation of ligand was observed during almost 20 hours. It furthermore proves that the membrane reactor can be operated in a prolonged manner without loss of any part of the DNA-based catalyst.

[0238]

[0148] Membrane reactors provide for improved mass transport conditions: As a first comparative example (diffusion controlled transport), permeation experiments were performed using a side-by-side diffusion cell (PermeGear Inc., Hellertown, PA). Viton gaskets between the membrane and each cell prevented leaking. The volume of the receptor chamber (RC) and the donor chamber (DC) was equal and amounted to 7 mL. The stirring speed in the donor and receptor chambers was 1200 rpm and two small PTFE stirring bars were used in each side. The active membrane area was 0.28 cm2. Both chambers were magnetically stirred. Dye transport (erioglaucine disodium salt, also known as brilliant blue410 (Merck, Catalogue N° 861146)) was monitored by observing the rate of increase of the UV absorbance at 630 nm in RC (NanoDrop 2000c Spectrophotometer, Thermo Fisher Scientific). Calibration curves were used to convert the UV absorbance into concentration of the dye. DC was filled with 7 mL of 0.0028 mM coloring dye in the same buffer which was used in QCM-D measurements, while the RC contained only buffer. Solutions of the dye of a concentration of 500 ppm (v / v) in dichlormethane / hexane (1 :1 v / v) were used.

[0239]

[0149] As an example, a similar experiment was performed in a membrane flow reactor in the contactor configuration as shown in Figure 2 or 3. Said reactor comprises an upstream (feed) recirculation of the dye solution and a downstream receiving chamber for the dye extraction. Flow conditions in both chambers were 1 ml / min. The active membrane area was approximately 0,4 cm2. The flow was in opposite directions to increase the transfer of matter and recirculated using a peristaltic tubing pump in case of aqueous solutions (Ismatec, Wertheim, Germany). While using organic solvents, the flow was recirculated with a ReaXus LD Class piston pump (Teledyne Isco, Lincoln, USA). The permeation of the dye (as above) was monitored inserting a cuvette (Hellma GmbH, Mullheim, Germany) in the circuit of the receiving channel and using the spectrophotometer.

[0240]

[0150] Fig. 4 shows the evolution in function of time (expressed in hours) of the fraction of equilibrium concentration of a dye in the receiving phase in Example 3 of the comparative example (dashed lined) and membrane reactor (plain line). The results of Figure 4 show that the equilibrium phase distribution of the dye between the donor and receiving phases is reached much faster in the membrane reactor configuration than in the stirred tanks configuration of the side-by-side diffusion cells. Thus, the membrane reactor configuration advantageously provides for an improved mass transport of the reactants and products in the chambers of said reactor.

[0241] Example 4: Diels-Alder reaction

[0242]

[0151] The Diels-Alder reactions were done in aqueous solution containing 20 mM MOPS (3-(N-morpholino)propanesulfonic acid) and at a pH of 6.5. The DNA bound catalyst was prepared by mixing an aqueous solution of salmon-sperm DNA with an aqueous solution of catalyst [Cu(ligand)(NO3)2] 24 hours in advance. Then, an aliquot of a stock solution (0.5 M) of dienophile was added and the MOPS buffer was added achieving a final concentration of 20 mM MOPS, 1.3 mg / mL DNA, 0.39 mM of ligand (2,2’-bipyridine or dmbpy), 0.3 mM of metal (copper(ll) nitrate^) and 1 mM of dienophile. The mixture was cooled to 5 °C. The reaction started by addition of freshly refluxed cyclopentadiene (final concentration 15 mM) and the resulting solution was recirculated in a membrane reactor as disclosed in Figure 2 comprising an AAO membrane and a receiving phase consisting of dichloromethane. Flow conditions in both chambers were 1 ml / min. The active membrane area was approximately 0,4 cm2.

[0243]

[0152] For analysis and after extracting the product, the DCM was evaporated and 2 mL of ethyl acetate were added to each sample. Then, the ethyl acetate solutions were sonicated, filtered and analysed by HPLC using a Daicel Chiralcel-ODH column (heptane / iPrOH 98:2, 0.5 ml / min). The configuration employed was also adapted such as to allow an on-line monitoring of the product formation in the receiving phase.

[0244]

[0153] The endo percentage and the enantiomeric excess percentage of the endo isomer were calculated with the areas of each product obtained at a wavelength of 266 nm. The calibration curves for the dienophile and products were generated in each HPLC measurement round. The yield and conversion were determined by measuring the total area of products (=10-16’) or dienophile (=16-2T) at 313 and 266 nm, respectively.

[0245]

[0154] As a result, an enantiomeric excess of 99.0 ± 0.1 in the case of ligand 2,2’- biypridine and 99.6 ± 0.6 in the case of dmbpy as a ligand was determined. The conversion was 93% and 96%, respectively.

[0246]

[0155] This experiment shows that performing the reaction in a membrane reactor does not modify the results of the reaction carried out in the literature (see for instance Roelfes, G. et al. Chem. Commun., 2006, 635-637). Example 5: Diels -Alder reaction using a membrane catalyst

[0247]

[0156] The same reaction as Example 4 was carried out using as catalyst a membrane comprising immobilized DNA according to Example 2. All other experimental conditions were exactly as described in Example 4. As a result, an enantiomeric excess of 95.0 ± 2.0 was determined. The conversion was 92%. This shows that the DNA-ligand-Cu2+catalyst immobilized on the membrane surface performs as in the best results reported from conducting the reaction in solution.

[0248] Example 6: Kinetics of Diels Alder reaction

[0249]

[0157] Reference reaction’. The procedure of Example 4 has been repeated at 25 °C. Figure 6 shows an evolution of the conversion of the starting material over time. After 6h, the reaction has reached its maximum conversion of 91 %. The respective ee was >95%. The efficiency of the catalytic reaction can be described by the turnover number (TON) and the turnover frequency (TOF) according to and with n: number of moles; t: time.

[0250] According to the experimental conditions (Example 4), the average TON for this reaction was determined to be 3 and the TOF yielded 1.4- 10’4s’1.

[0251]

[0158] In a separate approach, a DNA membrane reactor in which the support membrane was alumina was prepared. The overall membrane area was 4 cm2. DNA oligonucleotides with a molecular weight of approximately 6700 Da were immobilized on the alumina surface according to the procedure of Preparative Example 1. The resulting surface density determined by QCM-D (see Preparative Example 1) yielded a DNA concentration about 1200 times lower than in the reference reaction. All other parameters were identical to the reference reaction described above with the exception that the reaction solution was recirculated over the membrane surface and that the DNA was immobilized on the membrane rather than suspended in solution. As shown in Figure 7, the reaction ceased at about 52h with an average conversion of 95%. The average ee was determined to be >95%. Owing to the overall concentration of DNA being about three orders of magnitude lower while maintaining all other concentrations equal to the reference reaction, a significantly higher TON of about 3800 was found. In comparison to the reference reaction, this is three orders of magnitude higher. Also, the resulting TOF was 2 10-2 s’1, two orders of magnitude higher than in the reference reaction and in the range of an industrially relevant value. This shows the superior performance of the membrane of the invention in comparison to methods known in the art. This superior performance is entirely due to enhanced mass transport conditions in the vicinity of the immobilized DNA-based catalyst.

[0252]

[0159] In addition, the immobilized DNA can be re-used for subsequent reactions, thus increasing TON and TOF even further.

Claims

32CLAIMS1. Membrane comprising a composition comprising:- a nucleic acid covalently attached to a porous solid support; and- a catalyst suitable for binding with or intercalating into said nucleic acid, wherein:(a) said catalyst is an organometallic complex comprising a catalytically active metal and a bidentate ligand selected from the group consisting of:(i) a N,N-bidentate ligand, which is a ligand that binds to a metal cation by formation of a bond between two N atoms comprised in the ligand and the metal cation;(ii) a N,P bidentate ligand which is a ligand that binds to a metal cation by formation of a bond between one N atom and one P atom comprised in the ligand and the metal cation;(iii) a P,P bidentate ligand, which is a ligand that binds to a metal cation by formation of a bond between two P atoms comprised in the ligand and the metal cation;(iv) a N,0 bidentate ligand, which is a ligand that binds to a metal cation by formation of a bond between one N atom and one O atom comprised in the ligand and the metal cation; and(v) a 0,0 bidentate ligand which is a ligand that binds to a metal cation by formation of a bond between two O atoms comprised in the ligand and the metal cation.

2. Membrane according to claim 1 wherein the nucleic acid is a double stranded deoxyribonucleic acid.

3. Membrane according to any one of claims 1 to 2 wherein the porous solid support is substantially isoporous.

4. Membrane according to any one of claims 1 to 3 wherein the porous solid support has a pore size of between 1 and 500 nm; preferably of between 1 and 50 nm.

5. Membrane according to any one of claims 1 to 4 wherein the porous solid support is selected from the group consisting of ceramic materials, polymer materials, metal organic frameworks and covalent organic frameworks; preferably it is a porous ceramic material such as silica and alumina.

336. Membrane according to any one of claims 1 to 5 wherein the catalyst is bound to said nucleic acid.

7. Membrane according to any one of claims 1 to 6 wherein the catalyst is an organometallic complex of copper and a bidentate nitrogenated ligand that is preferably a heteroaromatic compound comprising a moiety of formula (I) comprised in a ring system comprising from 2 to 5 aromatic rings, said rings being isolated or fused, and being further optionally substituted at any available position by one or more groups selected from the group consisting of (Ci-Ce)alkyl, (Ci-Ce)alkyloxy, (Ci-Ce)haloalkyl, (Ci- C6)alkyloxycarbonyl, halo, nitro and cyanowherein each wavy line represents the connection points of the moiety of formula (I) to the remainder part of the heteroaromatic compound; more preferably the ligand is 4,4’- dimethyl-2,2’-bipyridine or 2 ,2’-bipyridine.

8. Membrane according to any one of claims 1 to 7 wherein the nucleic acid is covalently attached to said porous solid support via covalent bonding involving an amino group comprised at the 5’ or 3’ end of said nucleic acid and / or via covalent bonding involving an amino group comprised in said solid support.

9. Membrane according to any one of claims 1 to 8 wherein the nucleic acid is covalently attached to said porous solid support via a covalent bond involving:(1) a functional group FGi comprised at the 5’ or 3’ termination of said nucleic acid wherein the nucleic acid comprises a moiety of formula (A)wherein:(i) Oais an oxygen atom comprised in a phosphodiester group;(ii) FGi is NH2;(iii) L is a bivalent group deriving from the abstraction of a hydrogen atom born by a terminal carbon atom in a (Ci-Ci2)alkyl group;(2) an amino group comprised in the porous solid support that is attached to the porous solid support through a linker that is a bivalent group deriving from the abstraction of a hydrogen atom born by a terminal carbon atom in a (Ci-Ci2)alkyl group; and(3) a cross-linking agent that comprises in its molecular a plurality of aldehyde groups, such as glutaraldehyde.

10. Membrane according to any one of claims 1 to 9 wherein the nucleic acid is covalently attached to said porous solid support via an amino group comprised at the 5’ or 3’ end of said nucleic acid and via an amino group comprised in said solid support by cross-linking, more preferably by cross-linking mediated by glutaraldehyde.11 . Membrane according to any one of claims 1 to 10 wherein:(i) the nucleic acid is a salmon testes DNA oligomer; and(ii) the porous solid support is alumina having an average pore size of about 20 nm;(iii) the nucleic acid is covalently attached to said porous solid support via covalent bonding involving an amino group comprised at the 5’ end of said nucleic acid and via covalent bonding involving an amino group comprised in said solid support by cross-linking mediated by glutaraldehyde; and / or(iv) the catalyst is an organometallic complex of copper and a heteroaromatic compound as defined in claim 7.

12. Process for the preparation of a membrane according to any one of claims 1 to 11 comprising the steps of:(i) providing a porous solid support for forming a membrane;(ii) covalently binding a nucleic acid on the solid support provided in (i);(iii) providing a catalyst suitable for binding with or intercalating into said nucleic acid;(iv) contacting the catalyst suitable for binding with or intercalating into said nucleic acid with the porous solid support bearing said nucleic acid produced in (ii); and(v) forming a membrane; or, alternatively, comprising the steps of:(i) providing a porous solid support for forming a membrane;(ii’) providing a nucleic acid;(iii’) contacting a catalyst suitable for binding with or intercalating into the nucleic acid provided in (ii’) to produce a nucleic acid based catalyst;(iv’) covalently binding the nucleic acid based catalyst produced in step (iii’) on the solid support provided in (i); and(v) forming a membrane.

13. Use of the membrane according to any one of claims 1 to 11 as a catalyst.

14. Membrane reactor comprising a membrane according to any one of claims 1 to 11 ; wherein said reactor further comprises (i) a first chamber arranged for being in chemical contact with said membrane and suitable for receiving a solution of reagents suitable for reacting with the catalytically active metal comprised in said membrane, and (ii) a second chamber arranged for being in chemical contact with said membrane and suitable for receiving a solution of the one or more product of the reaction of the reagents of said first chamber with said catalytically active metal.

15. Composition comprising:- a nucleic acid covalently attached to a porous solid support; and- a catalyst suitable for binding with or intercalating into said nucleic acid; wherein each of the nucleic acid, the porous solid support and the catalyst is as defined in any one of the claims 1 to 11.

16. Use of the composition according to claim 15 as a catalyst.

17. Process for the preparation of a composition according to claim 15 comprising the steps of:(i) providing a porous solid support for forming a membrane;(ii) covalently binding a nucleic acid on the solid support provided in (i);(iii) providing a catalyst suitable for binding with or intercalating into said nucleic acid;(iv) contacting the catalyst suitable for binding with or intercalating into said nucleic acid with the porous solid support bearing said nucleic acid produced in (ii).

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