EP3028334A1

EP3028334A1 - Fuel biocell

Info

Publication number: EP3028334A1
Application number: EP14777811.2A
Authority: EP
Inventors: Aurélien AUGER; Raoudha HADDAD
Original assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 2013-07-31
Filing date: 2014-07-30
Publication date: 2016-06-08
Also published as: FR3009209A1; FR3009209B1; JP6373377B2; JP2016536253A; WO2015015440A1; US20160181648A1

Abstract

The invention relates to nanoparticles, preferably metal oxides, at least partially coated on the surface by a silylated polymer, and functionalised by at least one molecule of an oxidation-reduction mediating agent, characterised in that the immobilisation of said molecule(s) of said mediating agent on the surface of said nanoparticles is enabled by non-covalent bonds, preferable π-π type interactions, established between ethylenic, acetylenic and/or aromatic patterns, respectively present in the region of said silylated polymer and said molecule(s) of the oxidation-reduction mediating agent.

Description

Biopile fuel

The present invention relates to the field of fuel cells. More particularly, the present invention relates to nanoparticles functionalized on the surface with at least one redox-mediating agent, their preparation process, and their implementation for the electrode preparation, in particular for fuel cells, as well as the preparation of biopile, in particular glucose biopile.

A fuel biopile, or enzymatic biopile, is a battery in which at least one of the two catalysts is enzymatic. The advantage of using enzymatic catalysts lies in their ability to oxidize or reduce organic molecules in a specific manner. The second advantage of enzymatic catalysts is to exploit their catalytic performance in physiological electrolytic media.

As examples of fuel biopiles, mention may be made of the biopiles described in WO 2011/117357 and WO 2005/096430.

Many problems remain to be solved in the realization of enzymatic biopiles to allow the development of these energy sources. In particular, it is necessary to increase the power of current biopiles. Different approaches have been tried with respect to this aspect, such as improving enzyme immobilization techniques, modifying the chemical structure of enzymes, or even improving electron transfer between the active center. of the enzyme and the surface of the electrode.

In recent years, numerous studies have been conducted on the development of new energy conversion systems. Although several fuels, such as methanol, ethanol, hydrogen, have been studied extensively, glucose remains the ideal fuel for medical applications. The battery, or biopile, with glucose / oxygen fuel is a very promising way to allow energy supply of implantable devices in a living being, in particular medical devices, without the need for an external fuel charge. Glucose is a constituent of physiological fluid in mammals (5 mM in the blood in humans), and is nontoxic. The development of such a battery technology in which the fuel is glucose and oxidant, molecular oxygen, would allow a major advance in the development of implantable devices, particularly in the medical field, such as those dedicated to the detection of diabetes, or for the supply of pacemakers or hearing aids or eye. Glucose oxidase (GOx), a homodimeric enzyme, is undoubtedly the most used in the design of glucose / oxygen biocells, particularly with the craze observed for the development of metabolic glucose biosensors. Each of its subunits has a redox cofactor responsible for its enzymatic activity vis-à-vis D-glucose: Flavin Adenine Dinucleotide (FAD). GOx has a very high selectivity towards glucose. Indeed, it preferentially oxidizes only D-glucose. In addition, it exhibits remarkable activity and stability in the conditions of temperature and physiological pH (37 ° C, ~ 7.4). These two characteristics make this protein a preferred candidate for the development of implantable glucose biopiles.

As indicated above, the development of a biopile involves the ability to efficiently transfer the electrons from the catalytic site of the enzyme in question to the electrode of the biopile. Concerning the GOx, its redox FAD center is deeply buried in the protein cage of the enzyme. Although this location confers good stability to the enzyme, it makes it difficult to exploit the direct electron transfer of FAD to the electrode. Thus, under normal conditions, the transfer of electrons between the active site of the GOx and an electrode is a very slow or non-existent process. This phenomenon is due to the large distance between the active site of the enzyme and the electrode. However, the transfer of electrons between the active site and the electrode can be facilitated if an electron acceptor is used as a mediator.

The problem of improving electron transfer between the active center of an enzyme and a surface of the electrode is also encountered in the field of biosensors and biosensors.

Wilson et al. (Biosensors & Bioelectronics, 1992,7: 165) review the biosensors using Glucose Oxidase (GOX).

Teng et al. (Biosensors & Bioelectronics, 2011, 266: 4661) describe ZnO nanotubes surface-modified with ferrocene. ZnO nanotubes are surface modified with tetraethylorthosilicate (TEOS) in the presence of ammonia. On these modified nanotubes is grafted covalently a monocarboxylic acid ferrocene. The nanotubes are also conjugated to an antibody and are implemented in an electrochemical immunoassay method for the detection of antigen.

Qiu et al. (Biosensors & Bioelectronics, 2009, 24: 2920) describe a chitosan / ferrocene / nanoparticle Au / glucose oxidase composite film in which ferrocene is covalently bound to chitosan which is then adsorbed onto the gold nanoparticles. The film is deposited on an electrode for the detection of glucose. Liang et al. (Electrochimica Acta, 2012, 69: 167) describe nanoparticles of Fe2C> 3 covalently modified at the surface by ferrocene using a chemistry-click method resulting from the reaction between thiol functions introduced at the surface of the nanoparticles and a vinyl group carried by ferrocene. The nanoparticles obtained are used on an electrode in the presence of glucose oxidase for the detection of glucose.

Qiu et al. (Biosensors & Bioelectronics, 2009, 24: 2649) disclose gold-coated Fe2C> 3 nanoparticles (Fe2C> 3 @ Au), covalently surface-modified with ferrocene (Fc), obtained by reaction of Fe ₂ O ₃ nanoparticles. Au with HS (CH ₂ ) 6Fc. The nanoparticles obtained are used on an electrode for detecting dopamine.

Hu et al. (J Mol Catal B-Enzym, 2011, 72: 298) describe an electrode comprising on its surface, deposited by adsorption or by electroplating, in particular, multi-layered carbon nanotubes, nanoparticles of ZnO and GOx. The electrode is used for the detection of glucose.

However, there is still a need to improve the electron transfer between an enzyme capable of catalyzing an oxidation reaction, and in particular to oxidize glucose, and an electrode in order to obtain a satisfactory yield for the development of a fuel biopile, and in particular a glucose biopile.

There is still a need for modified nanoparticles, which can be used for the preparation of an electrode of a fuel biopile, and improving the transfer of electrons from the active center of an enzyme to the electrode.

There is still a need for functionalized nanoparticles with a redox mediating agent.

There is still a need for a process for the simple and effective preparation of such nanoparticles.

There is still a need for a simple, efficient method for the preparation with good performance of functionalized nanoparticles with a redox mediating agent.

There is still a need for electrodes formed, in particular, by means of an enzyme capable of catalyzing an oxidation reaction, and in particular of oxidizing glucose, in which the transfer of electrons between the catalytic site of the enzyme and the electrode is improved. There is still a need for modified nanoparticles that can be used for the preparation of a fuel cell electrode, which are stable over time, which can be stored in a dry form and can be quickly and simply dissolved in the preparation of the electrode.

There is still a need for fuel biocells whose energy efficiency is improved.

There is still a need for fuel biocells whose various elements can be easily recycled, in particular the various elements constituting an enzymatic catalyst electrode.

The object of the present invention is to satisfy these needs.

Thus according to one of its first objects, the present invention relates to nanoparticles, preferably metal oxides, coated at least partially at the surface with a silylated polymer, and functionalized with one or more molecules of at least one mediating agent. oxy-reductant, characterized in that the immobilization of said molecule (s) of said mediator agent at the surface of said nanoparticles is non-co-valent bonds, preferably π-π interactions, established between patterns ethylenic, acetylenic, and / or aromatic, respectively present at said silylated polymer and said oxy-reducing agent molecule (s) molecule (s).

Unexpectedly, and as detailed in the examples presented below, the inventors have observed that such nanoparticles, when they are implemented on an electrode, in the presence of an enzyme capable of carrying out an oxidation reaction, and in particular capable of oxidizing glucose, and more particularly glucose oxidase (GOx), promote the transfer of electrons to the electrode.

As also shown in the examples below, the implementation of an electrode comprising these nanoparticles, preferably adsorbed on multi-layer carbon nanotubes in the presence of an enzyme capable of catalyzing an oxidation reaction, such as a GOx, in a fuel biopile can substantially improve the energy efficiency of this biopile.

Finally, as the examples detailed below show, the nanoparticles, the electrodes and the biopiles comprising them prove to be, in particular, simple to produce, stable over time, and can be easily recycled.

According to another of its objects, the present invention relates to agglomerates of nanoparticles of the invention, and preferably comprising on the surface at least one water-soluble polymer, as described below. According to another of its objects, the present invention relates to a support material on the surface of which is adsorbed at least one nanoparticle of the invention.

According to another of its objects, the present invention relates to an ink comprising at least nanoparticles of the invention or a support material of the invention.

According to another of its objects, the present invention relates to an electrode formed in whole or in part of nanoparticles of the invention or a support material of the invention.

According to another of its objects, the present invention relates to a fuel biopile comprising, as anode, nanoparticles of the invention, a support material of the invention, an ink of the invention, said ink being dried, or at least one electrode of the invention.

According to another of its objects, the present invention relates to a method for preparing nanoparticles of the invention, comprising at least the steps of:

a- arranging nanoparticles, preferably metal oxide, in dispersion in an organic solvent,

b- bringing said nanoparticles into contact with at least one silylated polymer precursor comprising at least one ethylenic, acetylenic and / or aromatic unit, under conditions conducive to the formation of a silylated polymer having an ethylenic unit (s); ), acetylenic (s), and / or aromatic reactive (s), and its deposition at least partially on the surface of said nanoparticles,

c- bringing into contact the nanoparticles obtained in step b- and at least one molecule of a redox-mediating agent provided with at least one ethylenic, acetylenic and / or aromatic unit, under conditions appropriate to the immobilizing the molecule (s) of said surface-mediating agent of said nanoparticles via the establishment of non-valent bonds, preferably of π-π type interactions, established between the ethylenic, acetylenic and / or aromatic units respectively present in the level of said silylated polymer and the oxidative reducing agent molecule (s).

Within the meaning of the invention, the term "reactive (s)" is intended to refer to (s) ethylene, acetylenic and / or aromatic unit (s) of a silylated polymer. on the surface of a nanoparticle, one or more ethylenic (s), acetylenic (s), and / or aromatic unit (s) arranged so as to enable them to form non-cellular bonds, preference for π-π-type interactions, with ethylenic, acetylenic and / or aromatic unit (s) present at the level of a redox-mediating agent used to functionalize a nanoparticle . According to another of its objects, the present invention relates to a method for preparing an agglomerate of the invention, comprising at least the steps of:

- Having a nanoparticle dispersion of the invention, and preferably comprising on the surface at least one water-soluble polymer, as described below,

- Dipping of said dispersion in liquid nitrogen, to obtain a solid material,

- recover by filtration the solid material thus obtained, and where appropriate

lyophilize the solid material thus recovered.

According to another of its objects, the present invention relates to a process for preparing an electrode of the invention, comprising at least one step of depositing on a support, in particular a glassy carbon support or an anionic membrane and / or cationic, preferably a membrane of a fluoropolymer based on sulfonated tetrafluoroethylene copolymer, an ink of the invention.

The present invention advantageously makes it possible to prepare, in a simple and reproducible manner, nanoparticles that can be used for the preparation of an electrode of a fuel biopile, and that improves the transfer of electrons from the active center of an enzyme to the electrode.

The present invention advantageously makes it possible to have nanoparticles functionalized on the surface by at least one oxido-reducing mediating agent configured to allow an electronic transfer between the catalytic site of an enzyme and an electrode.

The present invention advantageously makes it possible to prepare fuel biocells with improved energy efficiency, which can be used to supply energy to devices, particularly medical devices, in particular for therapeutic or diagnostic purposes, intended to be implanted in an animal, in particular an animal. mammal, especially a human being.

LEGENDS OF FIGURES

Figure 1 ; illustrates the interactions of a functionalized ZnO nanoparticle according to the invention with a glucose oxidase (GOx) enzyme.

Figure 2; illustrates the structure of GOx and the principle of glucose oxidation.

Figures 3A, 3B and 3C; represent (3A) non-modified ZnO nanoparticles, (3B) silylated surface-modified znO nanoparticles, dried and milled, and (3C) polymer-modified ZnO nanoparticles silylated and functionalized with oxy-reductant agent mediator molecules. The bar represents 30 nm. The observations are made by Transmission Electron Microscopy (TEM).

Figure 4; represents the schematic diagram of the surface modification of a nanoparticle of the invention, ZnO nanoparticle, with a silylated polymer and its functionalization by non-covalent bonding with oxy-reductant mediating agent molecules (ferrocene, Fc ) (nanoparticle ZnO-Fc), and lyophilization of these nanoparticles in the presence of a water-soluble polymer (polyvinyl alcohol, PVA).

Figure 5; illustrates the flow diagram of a glucose / oxygen biopile of the invention using glucose oxidase at the anode.

Figures 6A and 6B; illustrate cyclic voltammetric curves of a functionalized vitreous carbon (A) by nanoparticles of ZnO-Fc alone and (B) by nanoparticles of ZnO-Fc alone (curve (a)) or nanoparticles of ZnO-Fc adsorbed on multilayer carbon nanotubes (multiwalls carbon nanotubes, MWCNT) (MWCNT / ZnO-Fc) (curve (b)) in phosphate buffer (100 mM) at pH 7. Scanning rate: 50 mV / s.

Figures 7A and 7B; illustrate (A) a voltage linear polarization curve at 2 mV / s and (B) a corresponding power curve of a biofuel cell whose anode comprises (a) nanoparticles of ZnO-Fc adsorbed onto nanotubes of carbon in the presence of GOx (CNTs / ZnO-Fc / GOx) or (b) carbon nanotubes in the presence of ferrocene and GOx (CNTs / Fc / GOx), and whose cathode is platinum-based (C-Pt) ).

Figure 8; illustrates a discharge curve of a biofuel cell of the invention whose anode comprises nanoparticles of ZnO-Fc adsorbed on carbon nanotubes in the presence of GOx (CNTs / ZnO-Fc / GOx) subjected to a voltage of 200 mV.

Figure 8; illustrates the possible interactions of functionalized ZnO nanoparticles according to the invention with GOx molecules.

nanoparticles

The nanoparticles of the invention are coated, or modified, at least partially at the surface, with a silylated polymer, and functionalized with one or more molecules of at least one redox mediator. The immobilization of the nanoparticle surface-mediating agent molecule (s) is based on non-covalent bonds, established between ethylenic, acetylenic and / or aromatic units, respectively present at the level of the silylated polymer and the oxy-donor reducing agent molecule (s).

As specified above, the immobilization of the molecule (s) of the mediator on the surface of the nanoparticles is advantageously of π-π type interactions.

According to one embodiment, the nanoparticles of the invention may be metal oxides.

According to one embodiment, the nanoparticles that are suitable for the invention may be semiconductor nanoparticles.

Preferably, the nanoparticles that are suitable for the invention may be nanoparticles chosen from nanoparticles of SiO 2, MgO, Al ₂ O ₃ , ZnO, CeO ₂ , TiO ₂ , ZrO ₂ , and mixtures thereof. More preferably, the nanoparticles of the invention may be ZnO nanoparticles.

The nanoparticles that are suitable for the invention may have a mean diameter in size ranging from 2 to 50 nm, preferably ranging from 10 to 50 nm, preferably ranging from 15 to 40 nm, and more preferably still ranging from 20 to 30 nm.

Measuring the average diameter in size of the nanoparticles of the invention can be achieved by any method known to those skilled in the art. In particular, the average size diameter of the nanoparticles can be determined by photon correlation spectroscopy (PCS; Photon Correlation Spectroscopy), or can be directly measured in photographs taken by transmission electron microscopy (or TEM). Such methods are known to those skilled in the art and do not need to be further detailed in this text.

The nanoparticles that are suitable for the invention can be obtained by any technique known in the art, and especially as illustrated in the examples of the invention.

By way of example, ZnO nanoparticles that are suitable for the invention can be obtained by co-precipitation from hydrated zinc nitrate and sodium carbonate, both in aqueous solution. The zinc nitrate solution is added dropwise into the sodium carbonate solution with stirring and at room temperature. The solution obtained can then be stirred, preferably at least for 2 hours, at room temperature. The precipitate obtained can be filtered. The powder thus recovered may be dried, for example in an oven, in particular at 100 ° C. The solid is then calcined. The calcination may be carried out under air at 400 ° C. for 4 hours. Silicon alkoxide

The nanoparticles of the invention are coated, or modified, at least partially at the surface, with a silylated polymer.

According to one embodiment of the invention, the silylated polymer may form nanoparticles at the surface of a monomolecular layer.

The silylated polymer at the surface of the nanoparticles may be obtained by polymerization of at least one precursor of the silylated polymer comprising at least one ethylenic, acetylenic and / or aromatic unit. The polymerization of this precursor of the silylated polymer can be carried out so that the silylated polymer forms a monomolecular layer on the surface of the nanoparticles.

The presence of a monomolecular layer of silylated polymer at the surface of the nanoparticles can be validated, for example, by a determination of the zeta potential.

According to one embodiment, the precursor of the silylated polymer may be a silicon alkylalkoxide of general formula (I):

in which :

- R ¹ , R ² and R ³ , identical or different, may represent a group OR ⁵ with R ⁵ may represent a saturated alkyl group, linear or branched C 1 -C 4; or a halogen, in particular chosen from Cl or F, and

R ⁴ may represent a linear, branched or cyclic C ₂ to C ₁₀ hydrocarbon group comprising at least one ethylenic, acetylenic and / or aromatic unit and, where appropriate, interrupted by one or more heteroatoms, such as oxygen or nitrogen, and preferably oxygen, and / or carrying an oxo function.

According to a preferred embodiment, R ¹ , R ² and R ³ , which may be identical or different, and preferably identical, may represent a group OR ⁵ , with R ⁵ being as defined above or hereinafter; or a halogen selected from Cl or F.

Preferably, R ¹ , R ² and R ³ , which are identical or different, and preferably identical, may represent a halogen selected from Cl or an F.

More preferably, R ¹ , R ² and R ³ , which are identical or different, and preferably identical, may represent a group OR ⁵ , with R ⁵ being as defined above or hereinafter.

According to a preferred embodiment, R ⁵ may represent an alkyl group chosen from a methyl, an ethyl or a propyl, and preferably selected from a methyl or an ethyl. Preferably, R ¹ , R ² , R ³ are the same, and may be selected from OR ⁵ , with R ⁵ being methyl or ethyl.

According to one embodiment, R ⁴ may be a C2 to C ₁₀ hydrocarbon group comprising a radical chosen from an aryl radical, in particular a phenyl or naphthyl radical, a vinyl (or ethenyl) radical, or a propenyl or isopropenyl radical, and where appropriate, being interrupted by one or more heteroatoms, such as oxygen or nitrogen, and preferably oxygen, and / or carrying an oxo function.

According to one embodiment, R ⁴ may be a hydrocarbon group Ce -C _lo comprising a cyclic radical selected from aryl phenyl or naphthyl.

According to one embodiment, R ⁴ can be a linear or branched C 2 to C 8 hydrocarbon group comprising at least one ethylenic or acetylenic unsaturation, and optionally being interrupted by an oxygen atom and / or carrying an oxo function.

Preferably, R ⁴ may be optionally interrupted by an oxygen atom and carry an oxo function. More preferably, the oxygen interrupting the hydrocarbon chain and the oxo group can be conjugated.

According to a preferred embodiment, R ⁴ can be chosen from a vinyl radical, a propenyl or isopropenyl radical, and a C ₇ branched hydrocarbon radical, comprising at least one ethylenic unsaturation, the chain being interrupted by an oxygen atom and carrying an oxo function, the oxygen atom and the oxo function being conjugated _.

According to a preferred embodiment, R ⁴ can be chosen from a phenyl group, a vinyl radical, a propenyl radical, an isopropenyl radical, and a radical - (CH ₂ ) ₃ OC (O) C (CH ₃ ) = CH ₂

More preferably, R ⁴ may be chosen from a phenyl radical, a vinyl radical, a propenyl radical, and a radical - (CH ₂ ) ₃ 0C (O) C (CH ₃ ) = CH _2.

More preferably, R ⁴ may be chosen from a phenyl radical, a vinyl radical, and a radical - (CH ₂ ) ₃ OC (O) C (CH ₃ ) = CH _2.

A silicon alkoxide suitable for the invention may be chosen from trimethoxyvinylsilane (CAS No. 2768-02-7), triethoxyvinylsilane (CAS number 78-08-0) and triethoxyphenylsilane (CAS No. 780-69-8). ), trimethoxyphenylsilane (CAS number, 2996-92-1), and the ester of 2-methylpropen-2-oyl and 3- (trimethoxysilyl) propyl (CAS number, 2530-85-0), or a mixture of them.

Preferably, a silicon alkoxide suitable for the invention may be chosen from trimethoxyvinylsilane, triethoxyvinylsilane, triethoxyphenylsilane, trimethoxyphenylsilane, or a mixture thereof. Preferably, a silicon alkoxide suitable for the invention is trimethoxy vinyl silane.

Redox-reducing mediator molecules

The nanoparticles coated or modified, at least partially at the surface, with a silylated polymer, are functionalized with one or more molecules of at least one oxidizing reducing agent.

A molecule of oxido-reducing mediating agent that is suitable for the invention may be chosen from ferrocenes; methylene green; the Blue Nile; macrocyclic organometallic complexes, such as porphyrins and phthalocyanines; quinones; phenoxazines, such as blue methylene or toluidine blue; tetrathiafulvalene; tetracyanoquinodimethane; benzylviologen; tris (2,2'-bipyridine) cobalt (III) perchloride; indophenols, such as dichlorophenolindophenol; and preferably is selected from ferrocenes.

Preferably, a molecule of redox mediator agent suitable for the invention is a ferrocene molecule.

A molecule of oxido-reducing mediating agent that is suitable for the invention is present in a form functionalized by at least one radical comprising at least one ethylenic, acetylenic and / or aromatic unit.

A radical comprising at least one ethylenic, acetylenic and / or aromatic unit that is suitable for the invention may be a C ₂ -C ₁₀ hydrocarbon group comprising a radical chosen from an aryl radical, in particular a phenyl or naphthyl radical, a vinyl radical. or a propenyl or isopropenyl radical, and where appropriate, interrupted by one or more heteroatoms, such as oxygen or nitrogen, and preferably oxygen, and / or carrying an oxo function.

In particular, such a radical can satisfy the definitions of the radical R ⁴ given previously.

A radical comprising at least one ethylenic, acetylenic and / or aromatic unit may be bonded directly or via a spacer to the oxidoreducing agent molecule.

A spacer suitable for the invention may be a C ₁ -C ₁₀ carbon chain, optionally substituted with alkyls, in particular C ₁ -C ₄ , and / or halogen units, in particular chosen from Cl or F, and or optionally interrupted by heteroatoms, in particular O or N, and / or amide, ester or ether functional groups. The choice of presence and nature of a spacer arm is a general knowledge of the skilled person. In particular, the choice of the nature of the spacer between a molecule of redox-mediating agent and a radical comprising at least one ethylenic, acetylenic and / or aromatic unit is operated on the basis of the general knowledge of the one skilled in the art, considering that this spacer should not affect, at least substantially, the ability of ethylenic (s), acetylenic (s), and / or aromatic (s), to bind in a manner non-covalent, and especially by π-π type interactions, ethylenic (s), acetylenic (s), and / or aromatic (s) present at the level of the silylated polymer.

It is a matter of general knowledge of those skilled in the art, depending on the nature of the oxidoreducing agent molecule and the nature of the radical comprising at least one ethylenic and / or aromatic unit to be grafted onto the latter, to implement the appropriate operating conditions. These do not need to be detailed further here.

Molecules of oxy-reducing mediator agents that are suitable for the invention thus modified are commercially available. As oxy-reducing mediator agents thus modified and suitable for the invention, there may be mentioned, in a nonlimiting manner, vinyl ferrocene (CAS No. 1271-51-8) and ferrocenylmethyl methacrylate (CAS No. 31566). - 61-7). Water-soluble polymer

The nanoparticles of the invention may further comprise, on the surface, at least one water-soluble polymer. Such a polymer can be adsorbed on the surface of the nanoparticles. The use of a water-soluble polymer advantageously makes it possible to obtain a homogeneous dispersion in a liquid of the molecules of oxidoreducing mediating agents located on the surface of the nanoparticles of the invention. In particular, such a polymer can make it possible to promote the formulation of mediators which are insoluble and indispersible.

A water-soluble polymer that is suitable for the invention may be chosen from polyvinyl alcohol, polyethylene stearate, polyvinylidene chloride (co-vinyl chloride), poly (styrene-co-maleic anhydride), polyvinylpyrrolidone, poly (vinyl butyral-co-vinyl-alcohol-co-vinyl acetate), poly (maleic anhydride-alt-1-octadecene), polyvinyl chloride, PEOX (poly- (2-ethyl-2- oxazoline), PLGA (poly (lactic acid-co-acid-glycan), and mixtures thereof. Preferably, a water-soluble polymer that is suitable for the invention is polyvinyl alcohol (PVA).

Process for preparing nanoparticles

A process for preparing nanoparticles of the invention may comprise at least the steps of:

b- bringing said nanoparticles into contact with at least one silylated polymer precursor comprising at least one ethylenic, acetylenic and / or aromatic unit, under conditions conducive to the formation of a silylated polymer with ethylenic unit (s) ( s), acetylenic (s), and / or aromatic (s) reagent (s) (that is to say capable of reacting with the redox mediator), and its deposition at least partially on the surface of said nanoparticles,

c- bringing together the nanoparticles obtained in step b- and at least one oxidoreducing agent molecule with at least one ethylenic, acetylenic and / or aromatic unit, under conditions suitable for immobilization of molecule (s) of said mediator agent at the surface of said nanoparticles via the establishment of non-covalent bonds, preferably π-π type interactions, established between the ethylenic, acetylenic and / or aromatic units respectively present at said silylated polymer and said at least one redox mediator molecule (s).

The nanoparticles to be used in a method of the invention may be, in particular, as defined above.

In step a- of a process of the invention, the nanoparticles may be dispersed in an organic solvent, in a concentration ranging from 0.02 to 20 g / l, preferably ranging from 0.1 to 15 g / l. L, more preferably varying from 0.5 to 10 g / l, more preferably varying from 1 to 5 g / l, and more preferably still at a concentration of approximately 2 g / l.

An organic solvent that is suitable for the invention may be chosen in particular from isopropanol, tetrahydrofuran (THF), butanol or cyclohexanol.

Preferably, an organic solvent suitable for the invention is isopropanol. Step b- of a process of the invention advantageously makes it possible to obtain surface-modified nanoparticles by means of a sylated polymer, preferably a monomolecular layer.

The surface modification of the nanoparticles, in step b- of a process of the invention, can be carried out using a silicon alkoxide, in particular, as defined above.

Such a silicon alkoxide may be used in a reaction solvent at a rate of 0.01 and 10 g / l, preferably from 0.05 to 8 g / l, preferably from 0.1 to 6 g / l, preferably from 0.2 to 4 g / l, more preferably from 0.4 to 2 g / l, even from 0.6 to 1 g / l, and more advantageously still at the rate of 0.6 g / l.

A reaction solvent that is suitable for the invention may be a solvent, or an organic phase, in particular be chosen from isopropanol, tetrahydrofuran (THF), butanol, or cyclohexanol.

Preferably, a reaction solvent suitable for the invention is isopropanol. According to one embodiment, in a process of the invention, step b- can be carried out in the presence of a hydrolyzing agent. Such an agent may be, in particular, selected from ammonia, sodium hydroxide or potassium hydroxide.

Preferably, a hydrolyzing agent that is suitable for the invention is ammonia. A hydrolysing agent can be used in amounts of 5 to 50%, or even 6 to 40%, or even 7 to 30%, or even 8 to 20%, or even advantageously in a proportion of about 10% by weight, by relative to the weight of the solvent.

Step b- of a process of the invention may be carried out at room temperature, ranging from about 20 to 24 ° C, and may last from about 20 to 3 hours, and preferably about 24 hours.

Preferably this step can be carried out with stirring, according to the means usually implemented by those skilled in the art.

Step c- of a process of the invention advantageously makes it possible to obtain nanoparticles functionalized on the surface by one or more molecules of an oxy-reducing agent-reducing agent.

This step c- can be carried out by means of oxy-reducing agent mediator molecules, especially as defined above.

In step c) of a process of the invention, an oxy-reducing agent may be used in a reaction solvent in a proportion of 0.25 to 25% by weight, relative to the weight of the solvent. even from 0.5 to 20%, even from 1 to 15%, even from 2 to 10%, even from 3 to 8%, from 4 to 6%, and still more preferably 5% by weight, based on the weight of the solvent.

For the implementation of a step c- of a process of the invention, the nanoparticles from step b- can be recovered, isolated, and dispersed in a reaction solvent, in particular an aqueous solvent, in particular water, or organic, especially as defined above, at a rate of 0.25 to 25%, or even 0.5 to 20%, or even 1 to 15%, or even 2 to 10%, or even 3 to 8%, or even 4 to 6%, and more advantageously still, at 5% by weight, relative to the weight of the solvent.

A reaction solvent which is suitable for the invention for step c may in particular be chosen from an aqueous phase, in particular water, or an organic phase, for example as defined above. Preferably, a reaction solvent suitable for the invention is an aqueous phase, and more preferably is water.

According to one embodiment, in a method of the invention, step c- can be carried out at room temperature, and especially at a temperature ranging from about 20 to 24 ° C. Step c- may be carried out for example for a period of time of about 2 to 6 days, or even 3 to 5 days, and preferably about 4 days.

Step c- may preferably be carried out with stirring, according to the means usually employed by those skilled in the art.

According to one embodiment, a method of the invention may further comprise bringing into contact with the nanoparticles obtained in step c- with at least one water-soluble polymer, under conditions favorable to the immobilization, in particular by adsorption, of this polymer at the surface of the functionalized nanoparticles.

According to a preferred embodiment, step c- can be carried out in the presence of at least one water-soluble polymer, under conditions conducive to the immobilization, in particular by adsorption, of this polymer at the surface of the functionalized nanoparticles.

A water-soluble polymer that is suitable for the invention may, in particular, be as defined above.

A water-soluble polymer may be used in a solvent in a proportion of 2 to 40% by weight relative to the weight of the solvent, or even 3 to 30%, or even 4 to 25%, or even 5 to 20%, or even 5 to 15%, or even 6 to 12%, or even 8 to 10%, and more preferably 10% by weight relative to the weight of the solvent.

A solvent suitable for the invention for the water-soluble polymer may in particular be as defined above, and preferably may be water. According to one embodiment, a process of the invention may further comprise an intermediate step between steps b- and c-, consisting in isolating the nanoparticles obtained at the end of step b-, in particular by centrifugation, and optionally a step of drying said isolated nanoparticles.

Such an isolation step of the nanoparticles can be carried out by centrifugation at ambient temperature, and at a speed of between 4000 and 12000 rpm, and in particular of the order of 8000 rpm (ie 8000 ± 500 rpm), for a period of time between 1 min and 1 h, in particular between 2 min and 30 min and, in particular for 10 min.

Following the isolation step, the nanoparticles thus obtained can be subjected to a drying step and then a grinding step. The drying and milling steps can be performed by any technique usually employed by those skilled in the art.

According to one embodiment, a method of the invention may further comprise at least one additional step, at the end of step c-, of crystallizing the nanoparticles. Such a step can be performed by dipping the dispersion of nanoparticles obtained in step c- into liquid nitrogen (N ₂ ), drop by drop. The precipitate thus obtained can be filtered by any technique usually used by those skilled in the art.

According to one embodiment, a method of the invention may further comprise at least one additional step of lyophilizing the nanoparticles. The lyophilization step can be carried out by any technique usually used by those skilled in the art.

The nanoparticles thus obtained may be in the form of self-dispersible agglomerates in an aqueous or organic solvent, especially as defined above.

A method of the invention advantageously makes it possible to obtain surface-coated or surface-modified nanoparticles by means of a sylile polymer, preferably in monomolecular layer, and functionalised on the surface by means of oxydo-reducing mediating agent molecules, the latter being being immobilized at the surface by means of non-covalent bonds, preferably π-π type interactions, established between ethylenic units. acetylenic, and / or aromatic respectively present at said silylated polymer and said at least one oxy-reducing agent molecule (s).

The present invention also relates to nanoparticles that can be obtained according to a process as defined above.

agglomerate

The nanoparticles described above, and preferably the nanoparticles comprising on the surface at least one water-soluble polymer, can be formulated in the form of agglomerates.

Such an agglomerate may be in the form of a ball (s), preferably having an average diameter of about 2 to 3 mm.

According to one embodiment, an agglomerate of the invention may be self-dispersible in a hydrophilic solvent, preferably in an aqueous solvent, and more preferably in water.

The dispersion of an agglomeration of nanoparticles of the invention may advantageously be carried out in an aqueous phase, and preferably in water, during the formulation of an ink.

The homogeneous nature of a solution or dispersion of an agglomeration of nanoparticles of the invention in a solvent can be evaluated by any method known in the field, for example, macroscopically, visually.

Process for preparing an agglomerate

An agglomerate of the invention may be more particularly prepared according to a method as detailed below.

A method for preparing an agglomerate of the invention may comprise at least the steps of:

- Having a nanoparticle dispersion of the invention, especially as defined above, and preferably comprising at least one water-soluble polymer, especially as defined above,

- Dipping of said dispersion in liquid nitrogen, to obtain a solid material,

- recover by filtration the solid material thus obtained, and where appropriate

lyophilize the solid material thus recovered. Support material

Material

According to a preferred embodiment, the nanoparticles of the invention can be adsorbed on the surface of a support material.

A support material that is suitable for the invention may be chosen from a multi-layer carbon nanotube, a single-layer carbon nanotube, graphene, graphite, carbon fibers, and fullerenes.

Preferably, a support material that is suitable for the invention may be a multi-layer carbon nanotube.

Carbon nanotubes that may be suitable for the invention may have a diameter of about 9.5 nm, and a purity of at least 95% or more.

Multi-sheet carbon nanotubes suitable for the invention comprise at least two sheets.

Preferably, a support material that is suitable for the invention consists of multi-layer carbon nanotubes. Such nanotubes advantageously have a role of conducting electrons, thus promoting the transfer of electrons from the catalytic site of an enzyme to an electrode, when the nanoparticles of the invention are used in a fuel cell.

According to one embodiment, on the surface of this support material, can be further adsorbed at least one enzyme. According to this embodiment, a support material of the invention may comprise, co-adsorbed on the surface, at least nanoparticles of the invention and at least one enzyme.

Enzyme

An enzyme suitable for the invention may be an enzyme capable of catalyzing an electron generating reaction, and preferably an oxidation reaction.

Preferably, an enzyme suitable for the invention may be able to catalyze the oxidation of glucose. Such an enzyme may be selected from glucose oxidase, cellobiose dehydrogenase, or glucose dehydrogenase.

More preferably, an enzyme suitable for the invention may be glucose oxidase (GOx).

An enzyme suitable for the invention may be obtained by any method known in the art, such as extraction from microorganisms, and especially bacteria or yeasts such as Aspergillus niger, producing them naturally or after modification by genetic engineering. Such methods are known to those skilled in the art and do not need to be detailed further here.

Process for the preparation of a support material

A support material of the invention may be more particularly prepared according to a method as detailed below.

A method of preparing a carrier material of the invention may comprise at least the steps of:

- Having a dispersion of a carrier material in a physiologically acceptable solvent, preferably an aqueous solution, and more preferably still water,

- Having a dispersion of nanoparticles functionalized with one or more molecules of an oxy-reducting mediator as defined above, and preferably comprising on the surface at least one water-soluble polymer, especially as defined above, in a a physiologically acceptable solvent, preferably an aqueous solution, and even more preferably water,

- Mixing the dispersion of the support material with the dispersion of nanoparticles under conditions conducive to the adsorption of the nanoparticles on the surface of the support material.

For the purposes of the invention, the term "physiologically acceptable" is intended to mean a solvent which can be administered, for example orally, topically, or by injection, to an animal, preferably a mammal, and preferably still to a human being.

A support material that is suitable for the invention may in particular be as defined above.

Advantageously, the mixture of the dispersion of the support material with the dispersion of nanoparticles can be subjected to different means of agitation, mechanical, thermal or sound. Preferably, a stirring means that is suitable for the invention may be sound agitation, in particular by ultrasound. Such agitation advantageously promotes the adsorption of the nanoparticles on the surface of the support material, such as the walls of the carbon nanotubes. The duration of an ultrasound bath can be, for example, approximately 30 minutes.

A process for preparing a carrier material of the invention may further comprise at least one additional step of adding to the dispersion mixture of the carrier material and the nanoparticle dispersion a solution or dispersion of at least one enzyme, preferably as defined above. The solution or the dispersion of enzyme (s) can be carried out in a physiologically acceptable solvent, preferably an aqueous solution, and more preferably still water.

The mixture containing at least one support material, at least nanoparticles of the invention, and at least one enzyme may be further subjected to a stirring step as defined above. Such agitation advantageously promotes the adsorption of the nanoparticles and the enzyme on the surface of the support material, such as the walls of the carbon nanotubes. The duration of an ultrasound bath can be, for example, approximately 30 minutes.

According to a preferred variant embodiment, the mixture of the support material, the nanoparticles of the invention and at least one enzyme can be produced during the same step. The mixture thus obtained may also be subjected to a stirring step as defined above.

According to an alternative embodiment, a method for preparing a support material of the invention may further comprise at least one step of adding to the dispersion or suspension obtained at least one fluorinated sulfonic acid copolymer. This step is advantageously carried out prior to the stirring step.

According to one embodiment, the suspension or dispersion of a support material thus obtained can be used as an ink.

Ink

According to one embodiment, the nanoparticles of the invention can be formulated in the form of an ink.

An ink of the invention may comprise at least nanoparticles of the invention or at least one support material according to the invention.

The dispersant or solvent phase of an ink of the invention may be a hydrophilic solvent, preferably an aqueous or organic liquid phase, and more preferably be water.

Preferably, a hydrophilic solvent that is suitable for the invention is a physiologically acceptable solvent.

According to one embodiment, an ink according to the invention may further comprise at least one fluoropolymer based on sulfonated tetrafluoroethylene copolymer. A copolymer-based sulfonated fluoropolymer tétrafluoroéhtylène suitable for the invention may in particular be of NAFION ^®.

Process for preparing an ink

An ink of the invention may be more particularly prepared according to a method as detailed below.

A process for preparing an ink of the invention may comprise at least the steps of:

- Having nanoparticles of the invention or a support material of the invention,

dispersing or suspending the nanoparticles or the support material in a hydrophilic solvent.

The ink thus obtained can be subjected to different means of agitation, mechanical, thermal or sound. Preferably, a stirring means that is suitable for the invention may be sound agitation, in particular by ultrasound. The duration of an ultrasound bath can be, for example, approximately 30 minutes.

According to an alternative embodiment, a method for preparing an ink of the invention may further comprise at least one step of adding to the dispersion or suspension obtained at least one fluoropolymer based on sulfonated tetrafluoroethylene copolymer. This step is advantageously carried out prior to the stirring step.

Electrode

An electrode of the invention may be formed in all or part of the nanoparticles of the invention or a support material of the invention, especially as defined above.

According to one embodiment, the nanoparticles or the support material is / are deposited on a vitreous carbon support or an anionic and / or cationic membrane, preferably a membrane of a fluoropolymer based on a sulfonated tetrafluoroethylene copolymer.

The choice of a material for an electrode of the invention may depend on a number of factors, including, in particular, the pH at which the reaction catalyzed by the enzyme or the nature of the oxidizing reducing agent is to be carried out. Those skilled in the art can on the basis of their general knowledge operate the appropriate choice of material to remember. For example, when the enzyme catalyzed reaction is to be carried out, preferably, at a pH of 7, or close to 7, as is the case for GOx, a material suitable for an electrode of the invention can be a fluoropolymer membrane based on sulfonated tetrafluoroethylene copolymer, and preferably a membrane of NAFION ^® .

Preferably a support suitable for an electrode of the invention may be a membrane of a fluoropolymer based on sulfonated tetrafluoroethylene copolymer. A membrane of a copolymer of fluorinated sulphonic acid suitable for the invention may be a membrane of NAFION ^®.

Method of preparing an electrode

An electrode of the invention may be more particularly prepared according to a method as detailed below.

A method for preparing an electrode of the invention may comprise at least one step of depositing on a support, in particular a glassy carbon support or an anionic and / or cationic membrane, preferably a membrane of a fluoropolymer with base of sulfonated tetrafluoroethylene copolymer, an ink of the invention, especially as defined above.

The deposition of the ink can be performed by any technique known to those skilled in the art, including drop-casting.

Biopile fuel

A biopile consists of two electrodes. The anode transports the flow of electrons resulting from the oxidation of glucose. These electrons are found at the end of the electric circuit at the cathode and are captured by a catalyst that ensures the reduction of oxygen in water. This flow of electrons, from the negative to the positive electrode, induces at the same time the circulation of an electric current in the external circuit.

A fuel biopile of the invention may comprise, as anode or anode compartment, nanoparticles of the invention, a support material of the invention, an ink of the invention, the ink being dried, or at least one electrode of the invention.

An ink of the invention may be deposited and dried on a support, for example a NAFION ^® membrane. The anode compartment of a biopile of the invention can be served by a continuous flow, with the aid of a peristaltic pump, of a solution of glucose (for example 50 mM) prepared in a buffer, for example a phosphate buffer (100 mM, pH 7). According to one embodiment, a biopile of the invention may comprise a cathode, or a cathode compartment, consisting of an electrode comprising at the surface a metal chosen from platinum, gold or silver, especially in the form of metal nanoparticles. These nanoparticles may in particular be present in a form immobilized on the surface of carbon nanoparticles.

Preferably, the metal may be platinum. Advantageously, platinum makes it possible to maintain the biocompatibility of the biopile and also advantageously enables the reduction of oxygen in the air to a relatively high potential.

According to one embodiment, the metal may be deposited on the surface of a membrane of a fluoropolymer based on sulfonated tetrafluoroethylene copolymer.

According to one embodiment, the cathode of a biopile of the invention may also be covered with a porous metal layer, and in particular a porous layer of gold, silver, platinum or titanium.

The cathode compartment of a biopile of the invention can be obtained, for example, as follows. An ink based on carbon particles, for example VULCAN XC-72-R, coated with platinum nanoparticles, for example 60% Pt, may be used. The catalyst based on platinum nanoparticles can be sprayed on a membrane of

NAFION ^® with a coverage of 600 μg / cm ² . A porous gold layer deposited by PVD

(Physical Vapor Deposition) allows the collection of electrons.

The cathode compartment of the battery can be exposed to the air and can operate under "air breathing" conditions.

Throughout the text, namely the description presented above and the examples presented hereinafter, the expression "between ... and ..." relating to a range of values must be understood as including the limits of this beach.

The examples given below are presented by way of illustration of the subject of the invention and should not be interpreted as limiting its scope. EXAMPLES

Example 1

Synthesis of ZnO Nanoparticles Functionalized to Ferrocene

The scheme for the synthesis of ZnO nanoparticles functionalized with ferrocene according to the invention is presented in FIG. 3. The synthesis and analysis of ZnO nanoparticles

The synthesis of pure ZnO nanoparticles was carried out by co-precipitation.

The initial reagents are hydrated zinc nitrate and sodium carbonate. To prepare 10 g of a sample of pure ZnO, a 0.2 mol / L solution of Zn (NO ₃ ) 2.6H ₂ O is prepared, i.e., 36.5 g in 615 mL of 'distilled water. A 0.5 mol / l solution of sodium carbonate was made by dissolving 13.78 g of sodium carbonate in 246 ml of distilled water.

The zinc nitrate solution is added dropwise into the sodium carbonate solution under vigorous mechanical stirring at room temperature. The solution is then stirred for 2 hours at room temperature. The precipitate is filtered on a Buchner funnel. The powder thus recovered is dried overnight in an oven at 100.degree. The solid is then calcined under air (100 L / h) at 400 ° C for 4 h. The nanoparticles obtained are 20 to 30 nm in diameter, and are crystallized. Elemental analysis reveals the presence of zinc in the sample. Measurements of particle diameter and the presence of Zn in the sample can be performed as described by Bellat et al. (Eng Eng Chem Res, 2011, 50 (9), 5714-5722). lb - Surface modification of ZnO nanoparticles

The nanometric ZnO (1 g) is dispersed in isopropanol (500 mL) in a 1 L flask with vigorous stirring and at room temperature. The hydrolyzing agent, ammonia (30%, 61 mL) is then added to the reaction mixture with vigorous stirring. A solution of triethoxyvinylsilane (0.323 g, 1.7 mmol, CAS # 78-08-0) in isopropanol (250 mL) is added to the basic reaction mixture, and the resulting solution is stirred at room temperature for 24 h. The solution is then centrifuged (8000 rpm, 10 min), and the supernatant is discarded. The solid obtained is dispersed in ethanol (100 mL) and then centrifuged again (8000 rpm, 10 min). The functionalized ZnO is oven dried (50 ° C, 4 h), then milled and used as obtained for the next step. Preparation of Ferrocene Functionalized ZnO Nanoparticles A 100 mL aqueous solution containing polyvinyl alcohol PVA (CAS No. 9002-89-5) (10 g at 10% w in deionized water) was stirred at room temperature. ambient temperature. Surface-functionalized ZnO (0.5 g, 5% w) is added with vigorous stirring followed by ferrocenylmethyl methacrylate (0.5 g, 1.76 mmol, 5% w, CAS No. 31566-61-7).

The reaction medium is stirred for 4 days at ambient temperature in order to obtain a homogeneous dispersion of the reaction medium. The dispersion obtained is soaked in liquid nitrogen (N ₂ ) dropwise, filtered and lyophilized for 48 h. The resulting material (11 g, 100%) is in the form of a ball of about 2-3 mm, self-dispersible in water.

Example 2

Realization of a biopile based on ZnO nanoparticles functionalized by ferrocene

2a- Principle

The stack consists of two electrodes (Figure 4). The anode transports the flow of electrons resulting from the oxidation of glucose. These electrons are found at the end of the electric circuit at the cathode and are captured by a catalyst that ensures the reduction of oxygen in water. This flow of electrons, from the negative to the positive electrode, induces at the same time the circulation of an electric current in the external circuit.

In a battery according to the invention, the enzymatic catalyst for the oxidation of glucose is glucose oxidase. The material used to form the cathode of the biopile is platinum, which has the advantage of maintaining the biocompatibility of the application. Platinum advantageously allows the reduction of oxygen in the air at a relatively high potential.

In general, the oxidation of glucose leads to the formation of gluconic acid according to the following reaction:

CgH sÛg · CeH-ioOg + 2H * + 2Θ

The reaction taking place at the cathode of the cell is the reduction of oxygen to H ₂ O according to the following equation: 1/2 0 ₂ + 2 H '+ 2 e ^ H ₂ 0

2b- Electrochemical characterization of ZnO nanoparticles functionalized with ferrocene (ZnO-Fc)

We started with the electrochemical characterization of ZnO nanoparticles functionalized to ferrocene alone. For that we prepare a solution of concentration 60 mg / mL of these nanoparticles in water. It should be noted that ferrocene is known to be insoluble in water.

The functionalization method of the invention allows a perfect dispersion of the nanoparticles in the water just after one hour in an ultrasonic bath.

10 μL of the prepared ZnO solution is deposited by "drop casting" on a vitreous carbon electrode (radiometer analytical A35T090) having a diameter of 3 mm and then dried in air, then under vacuum. This electrode is our working electrode. The cyclic voltammetric characterization of this compound is carried out using a three-electrode system: a platinum counter electrode, a saturated calomel electrode as reference electrode (Radiometer analytical XM110 and REF621) and the functionalized vitreous carbon electrode. as working electrode. The characterization is carried out in a solution of phosphate buffer (100 mM) at pH 7. The scanning speed is 50 mV / s.

In order to improve the active and specific surface, we used multi-layer carbon nanotubes (MWCNT) (NANOCYL NC7000) supplied by NANOCYL. These carbon nanotubes are 9.5 nm in diameter and have a purity> 95%. These carbon nanotubes are used without any additional purification step. For this, a dispersion in water consisting of 60 mg / ml of ZnO-Fc and 2.5 mg / ml of MWCNTs was prepared. 10 μl of this dispersion were deposited on a glassy carbon electrode and treated as previously mentioned.

We have indeed observed the peak of oxidation of ferrocene on the vitreous carbon electrode, thus confirming the presence of the redox mediator on the surface of the electrode (FIG. 5A). This anodic oxidation peak increases considerably in the presence of carbon nanotubes (FIG. 5B).

This shows the role that MWCNTs play in terms of surface area increase and electrical conductivity. In addition, we observed a shift of the oxidation peak towards the positive potentials (Ea = 300 mV) during the use of nanotubes of carbon, which shows an improvement in electron transfer favored by the three-dimensional structure offered by the CNTs.

2c- Glucose biocomile design based on ZnO nanoparticles functionalized with ferrocene (ZnO-Fc)

The ferrocene functionalized ZnO nanoparticle ink was prepared as follows: a mixture of 60 mg / mL ZnO-Fc and 2.5 mg / mL MWCNT was sonicated for 1 hour. To this mixture was added 7 mg / ml glucose oxidase (GOX) from Aspergillus Niger and 80 .mu.l of NAFION ^®. The suspension is then passed for 30 minutes in an ultrasonic bath in order to homogenize the mixture and to allow adsorption of the nanoparticles and the enzyme on the walls of the carbon nanotubes.

For the preparation of the stack, the catalyst ink based on ZnO-Fc is deposited on the anodic portion of a NAFION ^® membrane. For the anodic cathode compartment of the cell, an ink based on carbon particles (VULCAN XC-72-R) coated with platinum nanoparticles (60% Pt) is used. The catalyst based on platinum nanoparticles is sprayed on the NAFION ^® membrane with a coverage of 600 μg / cm ² .

A porous layer of gold deposited by PVD (Physical Vapor Deposition) allows the collection of electrons.

The anode compartment is served by a continuous flow using a peristaltic pump of a glucose solution (50 mM) prepared in phosphate buffer (100 mM, pH 7). The cathode compartment of the battery is exposed to the air and operates under "air breathing" conditions.

The performance of the battery is tested under ambient conditions. For this, positive potentials are applied between the anode and the cathode at a rate of 2 mV / s and a current has been measured indicating an electron flow between the anode and the cathode as shown by the polarization curve. A comparative study of the performance of nonfunctionalized ferrocene-based batteries has been carried out and has clearly shown the role played by ZnO nanoparticles in the catalysis process (FIGS. 6A & 6B).

Finally, a constant potential discharge of 200 mV was undertaken for the CNTs / ZnO-Fc / GOX battery. At this potential, the current begins to drop to 460 μΑ after a period of 15 minutes (Figure 7). BIBLIOGRAPHY

- WO 201 1/1 17357

- WO 2005/096430

- Bellat et al., Ind. Eng. Chem. Res., 2011, 50 (9): 5714-5722

- Hu et al, Mol Mol B-Enzym, 2011, 72: 298

- Liang et al, Electrochimica Acta, 2012, 69: 167

- Qiu et al, Biosensors & Bioelectronics, 2009, 24: 2649

- Qiu et al, Biosensors & Bioelectronics, 2009, 24: 2920 - Teng et al, Biosensors & Bioelectronics, 2011, 26: 4661

Wilson et al, Biosensors & Bioelectronics, 1992, 7: 165

Claims

1. Nanoparticles, preferably of metal oxides, coated at least partially at the surface with a silylated polymer, and functionalized with one or more molecules of a redox-mediating agent, characterized in that the immobilization of said or said molecule (s) of said mediator at the surface of said nanoparticles are non-covalently bonded, preferably π-π-type interactions, established between ethylenic, acetylenic, and / or aromatic units respectively present at said silylated polymer and said at least one redox mediator molecule (s).

2. Nanoparticles according to claim 1, wherein the silylated polymer is obtained by polymerization of at least one precursor of said silylated polymer comprising at least one ethylenic, acetylenic and / or aromatic unit.

3. Nanoparticles according to the preceding claim, wherein said precursor is a silicon alkylalkoxide of general formula (I):

in which :

R ¹ , R ² and R ³ , which are identical or different, represent a group OR ⁵ , with R ⁵ representing a saturated, linear or branched C 1 -C 4 alkyl group; or a halogen, in particular chosen from Cl or F, and

R ⁴ represents a linear, branched or cyclic C ₂ -C ₁₀ hydrocarbon-based group comprising at least one ethylenic, acetylenic and / or aromatic unit and, where appropriate, interrupted by one or more heteroatoms, such as oxygen; or nitrogen, and preferably oxygen, and / or carrying an oxo function.

4. Nanoparticles according to any one of the preceding claims, said nanoparticles being semiconductive.

Nanoparticles according to any one of the preceding claims, wherein the at least one redox mediator molecule (s) are selected from ferrocenes; methylene green; the Blue Nile; macrocyclic organometallic complexes, such as porphyrins and phthalocyanines; quinones; phenoxazines, such as blue methylene or toluidine blue; tetrathiafulvalene; tetracyanoquinodimethane; benzylviologen; tris (2,2'-bipyridine) cobalt (III) perchloride; indophenols, such as dichlorophenolindophenol; and preferably is selected from ferrocenes.

6. Nanoparticles according to the preceding claim, wherein said molecule (s) of the mediator agent is / are present (s) in a functionalized form with at least one radical comprising at least one ethylenic unit, acetylenic, and / or aromatic.

7. Nanoparticles according to any one of the preceding claims, further comprising at the surface at least one water-soluble polymer, in particular chosen from polyvinyl alcohol, polyethylene stearate, polyvinylidene chloride-vinyl chloride, poly (styrene-co-maleic anhydride), polyvinylpyrrolidone, poly (vinyl butyral-co-vinyl-alcohol-co-vinyl acetate), poly (maleic anhydride-alt-1-octadecene), poly (chloride of vinyl), PEOX (poly- (2-ethyl-2-oxazoline), PLGA (poly (lactic-co-acid-glycolic acid), and mixtures thereof.

Agglomerate of nanoparticles as defined in claim 7.

9. Support material on the surface of which is adsorbed at least one nanoparticle according to any one of claims 1 to 7.

10. Material according to the preceding claim, on the surface of which is further adsorbed at least one enzyme, said enzyme (s) being (s) capable (s) to catalyze an oxidation reaction.

An ink comprising at least nanoparticles as defined in any one of claims 1 to 7 or a material according to claims 9 or 10.

12. An electrode formed in whole or in part of nanoparticles as defined in any one of claims 1 to 7 or a material according to claims 9 or 10.

13. Fuel biopile comprising, as anode, nanoparticles as defined in any one of claims 1 to 7, a material according to claims 9 or 10, an ink as defined in claim 11, said ink being dried, or at least one electrode as defined in claim 12.

14. Process for preparing nanoparticles as defined in any one of claims 1 to 7, comprising at least the steps of:

b- bringing said nanoparticles into contact with at least one silylated polymer precursor comprising at least one ethylenic, acetylenic and / or aromatic unit, under conditions conducive to the formation of a silylated polymer with ethylenic unit (s) ( s), acetylenic (s), and / or aromatic (s) reactive (s) and its deposition at least partially at the surface of said nanoparticles, c- bringing into contact the nanoparticles obtained in step b- and at least one molecule of a redox-mediating agent provided with at least one ethylenic, acetylenic and / or aromatic unit, under conditions appropriate to the immobilizing said molecule (s) of said mediator agent at the surface of said nanoparticles by establishing non-covalent bonds, preferably π-π type interactions, established between the ethylenic, acetylenic and / or aromatic units, respectively present at said silylated polymer and said at least one redox mediator molecule (s).

15. Method according to the preceding claim, wherein step b- is carried out in the presence of a hydrolyzing agent, especially selected from ammonia, sodium hydroxide or potassium hydroxide.

16. The method of claim 14 or 15, wherein step c- is carried out in the presence of at least one water-soluble polymer, under conditions conducive to the immobilization of this polymer on the surface of said nanoparticles.

17. Nanoparticles obtainable by the process as defined in any one of claims 14 to 16.

18. A process for preparing an agglomerate as defined in claim 8, comprising at least the steps of:

- Have a dispersion of nanoparticles according to claim 7,

- Dipping of said dispersion in liquid nitrogen, to obtain a solid material,

- recover by filtration the solid material thus obtained, and where appropriate

lyophilize the solid material thus recovered.

19. A method for preparing an electrode as defined in claim 12, comprising at least one step of depositing on a support, in particular a glassy carbon support or an anionic and / or cationic membrane, preferably a membrane of a fluoropolymer based on a sulfonated tetrafluoroethylene copolymer, an ink as defined in claim 11.