Process for the preparation of a suspension of nanosized synthetic zeolite materials, suspensions of nanosized synthetic zeolite materials obtained by said process and their uses in therapy and diagnosis

Abstract

The present invention relates to a method for the preparation of a colloidal aqueous suspension of stable zeolite nanocrystals having framework structures comprising at least one cation selected from Gd, Fe, Cu and Ce, said structures being loaded with a gas selected from O.sub.2, CO.sub.2 and mixtures thereof, to the colloidal aqueous suspension of zeolite nanocrystals obtained by such a process, and to the use of said suspension in therapy, more particularly in cancer therapy and hypoxia-related diseases and/or in diagnosis.

Claims

1. A method for the preparation of a colloidal aqueous suspension of stable zeolite single nanocrystals with monodisperse particle size distribution ranging from 5 to 200 nm, said stable zeolite single nanocrystals having a three-dimensional framework comprising silicon or silicon and aluminum, said framework comprising channels and cavities at least partially filled with at least one gas of O.sub.2 or CO.sub.2 and at least one cation C of Gd, Fe, Cu, or Ce in an amount ranging from about 0.1 to about 10 weight % with respect to the total mass of said nanocrystals, wherein said method comprises the following steps: 1) subjecting a colloidal suspension CS1 of at least one type of stable zeolite single nanocrystals with monodisperse particle size distribution ranging from about 5 to 200 nm, said stable zeolite single nanocrystals having a three-dimensional framework comprising at least one of silicon or aluminum, said framework comprising channels and cavities and alkali metal cations M, to an ion exchange of at least a part of the alkali metal cations M with at least one cation C of Fe, Gd, Cu, or Ce, to obtain a colloidal suspension in water CS2 of zeolite single nanocrystals having a three-dimensional framework comprising channels and cavities, and at least one cation C of Fe, Gd, Cu, or Ce in an amount ranging from 0.1 to 10 weight % with respect to the total mass of the zeolite single nanocrystals; wherein step 1) is carried out by adding to the colloidal suspension CS1, a solution containing at least one salt of a cation C of Fe, Gd, Cu, or Ce; 2) purifying the colloidal suspension CS2 of zeolite single nanocrystals obtained in step 1) with water until a pH ranging from 6.5 to 7.5 is reached; and 3) contacting the purified colloidal suspension of zeolite single nanocrystals obtained in step 2) with at least one gas of O.sub.2 or CO.sub.2.

2. The method according to claim 1, wherein the amount of cation C ranges from 1 to 5 weight % with respect to the total amount of the zeolite single nanocrystals.

3. The method according to claim 1, wherein the concentration of the salt of cation C in the solution that is added into the suspension CS1 ranges from 1 to 10 mM.

4. The method according to claim 1, wherein the salt of the cation C comprises C(NO.sub.3).sub.3.Math.nH.sub.2O, wherein C=Gd, Fe, Ce or Cu.

5. The method according to claim 1, wherein the zeolite single nanocrystals present in the colloidal suspension CS1 comprise: zeolite single nanocrystals having a FAU- or an EMT-three-dimensional framework of SiO.sub.2 and Al.sub.2O.sub.3 tetrahedra; zeolite single nanocrystals having an MFI-three-dimensional framework of SiO.sub.2 tetrahedra; or zeolite single nanocrystals having an LTL-three-dimensional framework of SiO.sub.2 and Al.sub.2O.sub.3 tetrahedra.

6. The method according to claim 5, wherein the zeolite single nanocrystals present in the colloidal suspension CS1 used in step 1) has a FAU-type or an EMT-type three-dimensional framework.

7. The method according to claim 1, wherein step 2) is a washing step by double distilled water and is repeated until the pH of the colloidal suspension CS2 reaches a value of 7±0.2.

8. The method according to claim 1, wherein step 3) is performed by bubbling the colloidal suspension CS2 with pure O.sub.2, pure CO.sub.2, or with a mixture composed of about 95% by volume of O.sub.2 and of about 5% by volume of CO.sub.2.

9. A colloidal aqueous suspension of a zeolite material prepared according to the method as defined in claim 1, wherein: said zeolite material is the form of stable zeolite single nanocrystals with monodisperse particle size distribution ranging from 5 to 200 nm, said stable zeolite single nanocrystals has a three-dimensional framework comprising silicon or silicon and aluminum, said framework comprising channels and cavities at least partially filled with at least one gas of O.sub.2 and CO.sub.2, and said framework comprises at least one cation C of Fe, Gd, Cu, or Ce in an amount ranging from 0.1 to 10 weight % with respect to the total mass of said nanocrystals.

10. The colloidal aqueous suspension according to claim 9, wherein the amount of cation C ranges from 1 to 5 weight % with respect to the total mass of said nanocrystals.

11. The colloidal aqueous suspension according to claim 9, wherein the cation C comprises at least one of Gd or Fe.

12. The colloidal aqueous suspension according to claim 9, wherein said cation C is Gd and the amount of Gd ranges from 1.2 to 1.9% by mass with respect to the total mass of the zeolite material.

13. The colloidal aqueous suspension according to claim 9, wherein said cation C is Fe, and the amount of Fe ranges from 0.9 to 2% by mass with respect to the total mass of the zeolite material.

14. The colloidal aqueous suspension according to claim 9, wherein said zeolite material comprises a mixture of cations Gd and Fe, the amount of Gd ranges from 1 to 5% by mass with respect to the total mass of the synthetic zeolite material and the amount of Fe ranges from 0.9 to 2% by mass with respect to the total mass of the zeolite material.

15. A composition for at least one of therapy or diagnosis comprising a colloidal aqueous suspension of a zeolite material in the form of stable zeolite single nanocrystals as defined in claim 9.

16. A composition for cancer therapy or treatment of hypoxia-related diseases composition comprising the composition according to claim 15.

17. A composition for diagnosis of brain tumors comprising the composition according to claim 15.

18. A contrast agent in imaging comprising the colloidal aqueous suspension of a zeolite material in the form of stable zeolite single nanocrystals as defined in claim 9, wherein the cation C comprises at least one of Gd or Fe.

19. A pharmaceutical composition comprising: a colloidal aqueous suspension of a zeolite material in the form of stable zeolite single nanocrystals as defined in claim 9, and a pharmaceutical carrier.

20. The pharmaceutical composition according to claim 19, wherein said composition is an injectable composition.

21. A diagnosis composition comprising: a colloidal aqueous suspension of a zeolite material in the form of stable zeolite single nanocrystals as defined in claim 9, wherein cation C comprises at least one of Gd or Fe, and a biocompatible carrier.

22. The diagnosis composition according to claim 21, wherein said composition is an MRI diagnosis composition.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 represents (A) the results of quantification of astrocytes, neurons, U87-MG, HEK 293 and bEnd.3 cells viability following a 48 h exposure to increasing concentrations of FAU-Na, FAU-Gd or FAU-Fe; (B) the result of effect of nanosized zeolites on the cell cycle on U87-MG and HEK 293 cells, assessed using flow cytometry after exposure to 100 μg/ml of FAU-Na, FAU-Gd, FAU-Fe or water as a control for 14 h and 48 h.

(2) FIG. 2 represents the results of genotoxicity assays. A) γH2AX staining (left panel) and corresponding quantification (right panel) on U87-MG and HEK293 cells after exposure to FAU-Na, FAU-Fe and FAU-Gd at 100 μg/ml for 14 h0, 24 h or 72 h.B) Micronucleus detection after Hoechst 33342 staining (left panel) and corresponding quantification (right panel) on U87-MG and HEK293 cells after exposure to FAU-Na, FAU-Fe and FAU-Gd at 100 μg/ml for 14 h0, 24 h or 72 h.

(3) FIG. 3 (A) represents CBV and SatO.sub.2MRI maps, obtained before and 15 min after intravenous injection of FAU-Gd carrying CO.sub.2 or carbogen solution, T2-w anatomic image of the corresponding tumor and a map of the differences of signal between the two maps (ΔCBV and ΔSatO.sub.2 respectively); (Control consisted of an injection of H.sub.2O saturated with CO.sub.2 or Carbogen); (B, C) gives the quantification of the ΔCBV and ΔSatO.sub.2 in the healthy relative to the tumor tissue. Mean±SEM, n=5 for control groups; n=8 for FAU-Gd—CO.sub.2 group; n=5 for FAU-Gd-Carbogen group (*p<0.02; **p<0.0001, following an ANOVA); (D, E) reports the evolution over the time of the pCO.sub.2 and the pH respectively in the blood of healthy Wistar rats following injection of a solution of FAU-Gd carrying CO.sub.2 or H.sub.2O saturated with CO.sub.2 as a control. Mean±SEM, n=5 per group (*p<0.05, following a two-way ANOVA); (F) represents the T2* MRI signal (reflecting the BOLD effect) measured in the venous sinus of healthy Wistar rats 4 min following an intravenous injection of CO.sub.2 loaded FAU-Gd compared to FAU-Gd not loaded with CO.sub.2, to water saturated with CO.sub.2 and to the simple breathing of CO.sub.2. Mean±SEM, n=5.

(4) FIG. 4 represents (A) relaxivity in vitro measurements at room temperature at 7 teslas. The calculated r1 parameter of the FAU-Gd nanosized zeolites was 74.2 mM−1.s−1; (B) from left to right respectively T2w anatomic image of the tumor, T1-w images acquired before (top left) or 5 min after (top right) intravenous injection of 300 μl of a FAU-Gd solution (1%); (lower left) and a map of the differences of signal between the two T1-w images; (C) the results of the quantification over the time of the T1-w signal intensity in the healthy and the tumor tissue following an intravenous injection of 300 μl of a FAU-Gd solution (1%). The arrow indicates the time of injection. Mean±SEM; n=5. Two-way ANOVA (*p<0.0001, tissue effect and time effect).

(5) FIG. 5 represents (A) Experimental set-up used to load nanozeolites with gases (CO2 and/or O2). The flowrate was 1 l/min and the duration was fixed at 30 minutes; (B) Experimental set-up used to assess the ability of nanozeolites to release their oxygen payload. 12 ml of buffer (phosphate buffered saline) solution is kept in a closed tube linked to an oxygen sensor. Then, zeolites loaded with oxygen are injected into the buffer solution through a needle and the reoxygenation of the buffer is continuously monitored. Of note, this experimental set-up can be used in an hypoxic chamber so as to strictly control the oxygenation of the buffer before injection of nanozeolites; (C) Representation of the reoxygenation ability of nanozeolites as a function of the initial buffer oxygenation (21%; 5%; 1% and 0.1%) and as a function of time. Oxygen concentration was measured 30 minutes before nanozeolites injection in the system and 60 minutes after; (D) The more the initial oxygenation is low, the more nanozeolite release oxygen. The similar experimental set-up was used as described in (B); (D) Quantification of oxygen released from zeolites in a buffer solution (phosphate buffered saline, pH=7.2, 37° C., initial oxygen concentration 0.1%) as a function of the charge balancing cation and as a function of time. The similar experimental set-up was used as described in (B).

(6) FIG. 6 represents (A) physisorbed O.sub.2 measured at −196° C. on nanosized FAU-Na—X, FAU-Gd, and FAU-Fe zeolites; (B) the quantification of oxygen released from zeolites in a buffer solution (phosphate buffered saline, pH=7.2, 37° C. as a function of the charge balancing cation(*p<0.05; ANOVA). Mean±s.d., n=3/condition. The result show the absolute quantification of oxygen release and the value of saturated water alone was deducted.

EXAMPLES

(7) The starting materials used in the examples which follow, are listed below: sodium aluminate (NaAlO.sub.2) (Strem-chemicals, 56.7% Al.sub.2O.sub.3, 39.5% Na.sub.2O); sodium hydroxide (NaOH): Sigma Aldrich; colloidal silica (Ludox-HS 30, 30 wt % SiO.sub.2, pH=9.8): Aldrich; iron nitrate (Fe(NO.sub.3).sub.3.9H.sub.2O) (Aldrich, 99.9%); gadolinium nitrate hexahydrate (Gd(NO.sub.3).sub.3.6H.sub.2O); sodium silicate (Na.sub.2SiO.sub.3) (Prolabo, 29% SiO.sub.2, 8% Na.sub.2O) aluminum powder (325 mesh, 99.5% purity): Alfa Aesar;

(8) These starting materials were used as received from the manufacturers, without additional purification.

(9) The various zeolite material obtained in the examples were characterized over various scales of sizes.

(10) Transmission Electron Microscopy (TEM):

(11) Diluted colloidal suspensions of zeolite material obtained after step 3) were sonicated for 15 min and then 2-3 drops of fine particle suspensions were dried on carbon-film-covered 300-mesh copper electron microscope grids. The crystal size, morphology and crystallinity of solids were determined by a transmission electron microscopy (TEM) using a JEOL 2010 FEG operating at 200 kV.

(12) Dynamic Light Scattering (DLS) Analysis:

(13) The hydrodynamic diameters of the zeolite material in the various suspensions were determined with a Malvern Zetasizer Nano. The analyses were performed on samples after purification with a solid concentration of 10 wt % and pH=8. The back-scattering geometry (scattering angle 173°, HeNe laser with 3 mW output power at 632.8 nm wavelength) allows measurements at high sample concentration, since a complete penetration of the incident light through the sample is not required.

Example 1: Preparation of a Colloidal Aqueous Suspension of Single Nanocrystals Having a FAU Type Tetrahedral Framework Comprising Fe as Cation C

(14) A colloidal aqueous suspension CS1-1 was first prepared according to the following steps i) to iv′):

(15) Step i)

(16) A clear aqueous aluminate suspension A was prepared by dissolving 0.92 g of sodium aluminate in 3 g of double-distilled (dd) H.sub.2O (water clear within 2-3 min).

(17) A clear aqueous silicate suspension B was prepared by mixing 10 g of colloidal silica with 3.37 g of NaOH, and 1 g of dd H.sub.2O. As a result, a turbid suspension was obtained. In order to transform the turbid suspension into a clear suspension, the turbid suspension was stirred well for 1-2 min, or placed on a shaker for 1 min.

(18) Step ii):

(19) Solution A was added spontaneously under stirring to the solution B; during the mixing, solution B was kept in ice, as a result semi-transparent viscous precursor suspension was obtained, and transformed to a water clear suspension during the first 1-2 hours of aging time.

(20) The resulting clear suspension had the following molar composition: 8.5Na.sub.2O: 1.1Al.sub.2O.sub.3: 10SiO.sub.2: 122H.sub.2O.

(21) Step iii):

(22) The resulting clear suspension was then aged 24 h at room temperature (i.e. 25° C.), dehydrated under vacuum, and the water content was adjusted to the following molar composition.

(23) 8.5Na.sub.2O: 1.1Al.sub.2O.sub.3: 10SiO.sub.2: 50H.sub.2O.

(24) Step iv):

(25) Then, the hydrothermal crystallization was conducted at 50° C. for 1 day to obtain monodisperse nanoparticles of a synthetic faujasite material dispersed in mother liquor, said nanoparticles having a particle size of 10 nm.

(26) Steps iv′):

(27) Single nanocrystals of the synthetic faujasite material were purified by three steps centrifugation (25.000 rpm for 4 h) followed by redispersion in water until reached pH=8.5 and with a content of 5 wt. % of zeolite with respect to the total mass of the dispersion.

(28) The Si/Al molar ratio of the obtained synthetic faujasite material was 1.03, with a Si concentration of 71.43 mg/l, an Al concentration of 67.56 mg/l, and a Na concentration of 60.32 mg/l.

(29) The resulting colloidal aqueous suspension CS1-1 obtained after step iv′) above, was then used in the following steps 1 to 3).

(30) Step 1)

(31) 20 ml Fe(NO.sub.3).sub.3.9H.sub.2O with a concentration in the range of 5.0-5.1.10.sup.−5M was added to 20 ml of the zeolite suspension obtained in step iv′) (5 wt. % zeolite) and kept for 1 h.

(32) Step 2)

(33) The zeolite was purified by one cycle centrifugation and redispersion in distilled water. The procedure was repeated two or three times. The final ion-exchanged samples were purified three times with distilled H.sub.2O by consecutive high-speed centrifugation and redispersion in distilled water until the pH value reached 7.

(34) Step 3)

(35) The purified colloidal aqueous suspension obtained in step 2) was then bubbled with O.sub.2 or CO.sub.2 or carbogen at a flow rate of 80 mL/min for 30 minutes.

(36) Characterizations

(37) The as synthesized FAU nanocrystals comprising Fe as cation C (FAU-Fe) obtained at the end of step 2) have then been characterized. The main characteristics of the FAU-Fe material thus obtained, including the dynamic diameter obtained by DLS analysis of the suspension prior step 3) are given in Table 1 below:

(38) TABLE-US-00001 TABLE 1 Zeta Chemical composition (wt. %) Diameter Potential Si Al Na Fe (nm) (mV) 46.07 39.05 13.18 1.71 10-30 −37.7

(39) As a reference for comparative purpose in the following example, FAU nanocrystals not forming part of the present invention, i.e. not comprising any cation C have also been prepared according to the same process until step iv′), i.e. the step 1) of ion-exchange was not performed (FAU-Na).

(40) These FAU-Na nanocrystals had the characteristics given in Table 2 below:

(41) TABLE-US-00002 TABLE 2 Chemical composition (wt. %) Diameter Zeta Potential Si Al Na Fe Gd (nm) (mV) 40.05 32.66 27.21 0.0 0.0 10-30 −37.7

Example 2: Preparation of a Colloidal Aqueous Suspension of Single Nanocrystals Having a FAU Type Tetrahedral Framework Comprising Gd as Cation C

(42) A colloidal aqueous suspension CS2-2 of single nanocrystals having a FAU type tetrahedral framework comprising Gd as cation C was prepared according to the same process as detailed in example 1 above until step iv′) included.

(43) The colloidal aqueous suspension CS1-1 obtained after step iv′) above, was used in the following steps 1 to 3).

(44) Step 1)

(45) The as-prepared zeolite suspension CS1-1 obtained in step iv′) of example 1 was ion-exchanged by gadolinium (III) nitrate hexahydrate (Gd(NO.sub.3).sub.3.6H.sub.2O).

(46) 25 mL of Gd(NO.sub.3).sub.3.6H.sub.2O (3 mM) were added on 5 mL of said suspension (2.5%). The suspension was then kept under stirring at room temperature for 1 h.

(47) Step 2)

(48) The suspension was washed by double distilled water. This procedure was repeating three times to obtain finally a suspension CS2-2 of FAU-Gd zeolite having a pH of 7.

(49) Step 3)

(50) The purified colloidal aqueous suspension obtained in step 2) was then bubbled with O.sub.2 or CO.sub.2 or carbogen at a flow rate of 80 mL/min for 30 minutes.

(51) Characterizations

(52) The as synthesized FAU nanocrystals comprising Gd as cation C (FAU-Gd) obtained at the end of step 2) have then been characterized. The main characteristics of the FAU-Gd material thus obtained, including the dynamic diameter of zeolite nanocrystals obtained by DLS analysis of the suspension prior to step 3) and chemical analysis by ICP are given in Table 3 below:

(53) TABLE-US-00003 TABLE 3 Zeta Chemical composition (wt. %) Diameter Potential Si Al Na Gd (nm) (mV) 44.70 33.85 18.06 3.33 10-30 −37.7

Example 3: Preparation of a Colloidal Aqueous Suspension of Single Nanocrystals Having an EMT Type Tetrahedral Framework Comprising Fe as Cation C

(54) A colloidal aqueous suspension CS2-3 of single nanocrystals having an EMT type tetrahedral framework comprising Fe as cation C has been prepared according to the same process as in example 1 above until step iv′), except that during step iii) the aging was performed at 23° C. for 14 h and during step iv), the hydrothermal crystallization was conducted at 30° C. for 36 hours.

(55) The precursor suspension had the following molar composition: 5SiO.sub.2:1Al.sub.2O.sub.3:17.48Na.sub.2O:340.3H.sub.2O (9.074 g NaAlO.sub.2, 65.610 g NaOH, 57.693 g Na.sub.2SiO.sub.3, 180 g H.sub.2O).

(56) The colloidal aqueous suspension CS1-3 obtained after step iv′) above, was used in the following steps 1 to 3).

(57) Step 1)

(58) 20 ml Fe(NO.sub.3).sub.3.9H.sub.2O with a concentration in the range of 5.0-5.1.10.sup.−5M was added to 20 ml of the EMT zeolite suspension obtained in step 4′) (5 wt. % zeolite) and kept for 1 h.

(59) Step 2)

(60) The zeolite was purified by one cycle centrifugation and redispersion in distilled water. The procedure was repeated two or three times. The final ion-exchanged samples were purified three times with distilled H.sub.2O by consecutive high-speed centrifugation and redispersion in distilled water until the pH value reached 7.

(61) Step 3)

(62) The purified colloidal aqueous suspension obtained in step 2) was then bubbled with O.sub.2 or CO.sub.2 or carbogen at a flow rate of 80 mL/min for 30 minutes.

(63) Characterizations

(64) The as synthesized EMT nanocrystals comprising Fe as cation C (EMT-Fe) obtained at the end of step 2) have then been characterized. The main characteristics of the EMT-Fe material thus obtained, including the dynamic diameter obtained by DLS analysis of the suspension prior to step 3) are given in Table 4 below:

(65) TABLE-US-00004 TABLE 4 Zeta Chemical composition (wt. %) Diameter Potential Si Al Na Fe (nm) (mV) 35.9 34.7 11.5 2.8 15-50 −37.0

Example 4: Preparation of a Colloidal Aqueous Suspension of Single Nanocrystals Having an EMT Type Tetrahedral Framework Comprising Gd as Cation C

(66) A colloidal aqueous suspension CS2-4 of single nanocrystals having an EMT type tetrahedral framework comprising Gd as cation C was prepared according to the same process as detailed in example 3 above until step iv′) included.

(67) The colloidal aqueous suspension CS1-3 obtained after step iv′) above, was used in the following steps 1 to 3).

(68) Step 1)

(69) The as-prepared zeolite suspension CS1-3 obtained in step iv′) of example 3 was ion-exchanged by gadolinium (III) nitrate hexahydrate (Gd(NO.sub.3).sub.3.6H.sub.2O).

(70) 25 mL of Gd(NO.sub.3).sub.3.6H.sub.2O (3 mM) were added on 5 mL of said suspension (2.5%). The solution was then kept under stirring at room temperature for 1 h.

(71) Step 2)

(72) The zeolite was then washed by double distilled water. This procedure was repeating three times to obtain finally the suspension of EMT-Gd zeolite at a pH 7.

(73) Step 3)

(74) The purified colloidal aqueous suspension obtained in step 2) was then bubbled with O.sub.2 or CO.sub.2 or carbogen at a flow rate of 80 mL/min for 30 minutes.

(75) Characterizations

(76) The as synthesized EMT nanocrystals comprising Gd as cation C (EMT-Gd) obtained at the end of step 2) have then been characterized. The main characteristics of the EMT-Gd material thus obtained, including the dynamic diameter obtained by DLS analysis of the suspension prior to step 2) are given in Table 5 below:

(77) TABLE-US-00005 TABLE 5 Zeta Chemical composition (wt. %) Diameter Potential Si Al Na Gd (nm) (mV) 35.8 34.3 10.9 1.8 15-50 −36.6

Example 5: In Vitro Verification of the Innocuity of the Nanosized Zeolite Material of the Invention

(78) 5.1. Materials and Methods

(79) Multiple cell types originating from various organs were exposed to nanosized zeolites. Both pathological and healthy brain cells were used: mouse brain endothelial cells (bEnd.3 cell line), mouse astrocytes and neurons (primary culture), and human glioma cells (U87-MG) and a cell type derived from the kidney (HEK 293 cell line), as follows:

(80) Cell Lines

(81) A human glioblastoma cell lines, U87-MG purchased from American Type Culture Collections (ATCC, Manassas, Va., USA) and HEK 293 cells (Human Embryonic Kidney cells) were used. Cells were cultured in DMEM (Sigma-Aldrich, France) supplemented with 10% fetal bovine serum (Eurobio, France), 2 mM glutamine (Sigma-Aldrich, France) and penicillin (1000 U/ml)/streptomycin (100 μg/ml)(Sigma-Aldrich, France).

(82) bEnd.3 mouse brain endothelial cells were purchased from ATCC and cultured in high glucose (4500 mg/I) DMEM (Sigma-Aldrich, France) supplemented with 10% fetal bovine serum (Eurobio, France), 2 mM glutamine (Sigma-Aldrich, France) and penicillin (1000 U/ml)/streptomycin (100 μg/ml) (Sigma-Aldrich, France). Cells were maintained in culture at 37° C. with 5% CO.sub.2 and 95% humidity.

(83) Primary Culture of Astrocytes

(84) Cerebral cortices were isolated from neonatal (1 to 3-day-old) mice (Swiss, CURB, France) carefully stripped of the meninges and dissociated to generate a single-cell suspension. Cultures were allowed to grow in a humidified 5% CO.sub.2 incubator at 37° C. to confluency (15-20 days) prior to use in DMEM supplemented with 10% fetal bovine serum (Eurobio, France), 10% horse serum (Eurobio, France), 2 mM glutamine (Sigma-Aldrich, France) and penicillin (1000 U/ml)/streptomycin (100 μg/ml) (Sigma-Aldrich, France). At about 80% confluence, the growth medium was replaced by the same medium.

(85) Primary Cultures of Cortical Neurons/Astrocytes

(86) Cultures were prepared from E15-E16 mouse embryos (Swiss mice; CURB, France). Microdissection of cortices was followed by a dissociation of the tissue in a 37° C. DMEM (Sigma-Aldrich, France). Cells grew on plates coated with poly-d-lysine (0.1 mg/ml) and laminin (0.02 mg/ml) in DMEM supplemented with 5% fetal bovine serum, 5% horse serum (Eurobio, France), and 2 mm glutamine (Sigma-Aldrich, France). Cells were maintained in a humidified 5% CO.sub.2 atmosphere at 37° C. Neurons were used after 12 d in vitro.

(87) Cells Exposure to Nanosized Zeolites

(88) Cells were exposed to zeolites (FAU-Na as prepared in example 1 used as a reference not forming part of the present invention, FAU-Fe and FAU-Gd as prepared also according to example 1 but forming part of the present invention) for various times. Zeolites were diluted in culture medium at a concentration of 1, 10, 50 or 100 μg/ml and added directly into the wells. The control condition consisted of an addition of pure water only into the wells with the same volume as for zeolites solutions.

(89) Cells Viability

(90) Cells were seeded in 24-wells plates to achieve 80% confluency for the control on the day of the analysis. Cell viability was assessed 48 h following exposure to zeolites with the WST-1 assay (Roche, France) according to manufacturer's instructions.

(91) Cell Cycle Analysis

(92) At various time points following cell exposure to 100 μg/ml of nanosized zeolites, cell cycle of U87-MG and HEK 293 cells was studied by flow cytometry with Coulter DNA Prep Reagents kit according to manufacturer's instructions (Beckman Coulter SAS, France). Propidium iodide staining was analyzed using the Beckman Coulter's Gallios flow cytometer (Beckman Coulter SAS, France) with 10 000 events per determination. Analysis and determination of cell distribution in each phase of cell cycle was performed using the Kaluza software (Beckman Coulter SAS, France).

(93) DNA Double Strands Breakdown and Micronuclei Formation Analysis by Immunocytochemistry

(94) Cells were plated in 24-well plates on coverslips and one day later were exposed to 100 μg/ml of zeolites for 14, 24 or 48 h. The positive controls consisted of cells 30 min after irradiation with a dose of 4Gy (XRad225Cx, PXi, CYCERON platform). Cells were then fixed for 1 h at 4° C. with 4% PFA. Non-specific bindings were blocked with a solution of 3% bovine serum albumin (BSA) (Sigma-Aldrich, France)-PBS-0.1% Tween (Sigma-Aldrich, France) for 1 hour at room temperature. Then, cells were incubated overnight at 4° C. with a primary antibody. The following primary antibodies was used: phospho-histone H2AX (ser139) (1/200; Cell Signaling Technology, D175, 2577S) in 1% BSA-PBS-0.1% Tween. The revelation was achieved by an Alexa-555-conjugated anti-rabbit secondary antibody (1/200; Molecular Probes, A21429). Cells were counterstained with Hoechst 33342 (10 μg/ml; Sigma-Aldrich, France) for nuclear staining. All immunocytochemistry markers were observed on a Leica DMi8 microscope with a 40× objective. For each condition, at least 3 coverslips were analyzed and images from 5 representative fields per slide were acquired.

(95) 5.2. Results

(96) The results of cell survival are reported on FIG. 1 annexed.

(97) FIG. 1A gives the results of quantification of astrocytes, neurons, U87-MG, HEK 293 and bEnd.3 cells viability following a 48 h exposure to increasing concentrations of FAU-Na, FAU-Gd or FAU-Fe. On this figure, the cell viability is given in % of control for each tested concentration. A slight dose-dependent decrease in cell viability following exposure to concentrations exceeding 10 μg/ml for all cell types was observed, except for U87-MG cells for which no change in cell viability was observed whatever the concentration used. Neurons appeared to be the most sensitive cell type since the maximum loss in cell viability (65.8±2.1%) was achieved when exposed to 100 μg/ml of FAU-Na. The presence of gadolinium (FAU-Gd) or the presence of iron (FAU-Fe) did not induce any further toxicity relative to Na whatever the cell type and the concentration used. These data strongly support that a dramatic effect of nanosized zeolites on the cell viability can be excluded.

(98) The result of effect of nanosized zeolites on the cell cycle on U87-MG and HEK 293 cells, assessed using flow cytometry after exposure to 100 μg/ml of FAU-Na, FAU-Gd, FAU-Fe or water as a control for 14 h and 48 h are provided on FIG. 1B annexed. No difference of the cell distribution in the different phases of cell cycle between the control group and cells exposed to nanosized zeolites was noticed (FAU-Na, FAU-Fe or FAU-Gd) for both cell types and for the two exposure times.

(99) The results of the potential genotoxic effect of nanosized zeolites using immunofluorescent labeling of γH2AX as a marker of DNA double strand breaks and the micronucleus formation assay as a marker of mitotic death are given by FIG. 2 annexed. U87-MG cells showed almost no γH2AX positive cells for control conditions or after exposure to zeolite materials FAU-Na, FAU-Gd or FAU-Fe. A slight decrease in the marker was observed after 24 h of experiment for all conditions. HEK 293 cells exhibited a higher proportion of γH2AX positive cells compared to U87-MG cells and the percentage of γH2AX positive cells slightly increased after 24 and 72 h of experiment. However, no change in the proportion of γH2AX positive cells after exposure to FAU-Na, FAU-Gd or FAU-Fe as compared to the control condition were detected (FIG. 2A). These results are also supported by the micronuclei formation assay. Both for U87-MG and HEK 293 cells, the number of cells forming micronucleus was low (below 10%) whatever the duration of the experiment (FIG. 2B). Furthermore, compared to the control, there is no significant increase in the formation of micronuclei after exposure to FAU-Na and FAU-Gd. As a whole, in term of DNA damages, these results allow to conclude, that FAU-Na, FAU-Fe and FAU-Gd do not have a genotoxic effect.

(100) Overall, these data support for absence of adverse effects of FAU-Na (reference not forming part of the present invention), FAU-Gd and FAU-Fe (nanosized zeolite material according to the invention) in vitro on a wide range of cells type originating from the tumor, the healthy brain, the kidney and the endothelium.

Example 6: Study of the Vasoactive Effect of Nanosized Zeolite Material According to the Invention Carrying CO.SUB.2

(101) In this example, the vasoactive effect of nanosized zeolite material Gd-FAU as prepared in example 1, carrying CO.sub.2 or Carbogen, was studied.

(102) To study the functional benefit of this material as gas carrier, a multiparametric MRI in a rat orthotopic model of glioblastoma was used.

(103) 6.1. Materials and Methods

(104) Ethical Approval and Animal Issues

(105) Animal investigations were performed under the current European directive (2010/63/EU) as incorporated in national legislation and in authorized laboratories (B14118001). The animals were obtained from an inhouse breeding stock at the Centre Universitaire de Ressources Biologiques (CURB, A14118015). The male athymic nude rats (250-300 g, three to four months) were maintained in specific pathogen free housing and were fed with γ-irradiated laboratory food and given water ad libitum

(106) Animals were manipulated under deep anesthesia (5% isoflurane for induction, 2% for maintenance in 70% N.sub.2O/30% O.sub.2). Body temperature was monitored and maintained at 37.5±0.5° C. with a feedback-controlled heating pad connected to a rectal probe.

(107) Orthotopic Glioma Cells Implantations

(108) U87-MG (ATCC, LGC Standards Molsheim, France) cells were stereotactically injected into the caudatoputamen of rats. Briefly, animals were anesthetized, body temperature was monitored and maintained around 37.5° C. Rats were placed in a stereotactic head holder and a scalp incision was performed along the sagittal suture. A 1 mm diameter burr hole was drilled in the skull. U87-MG cells (5.10.sup.4 cells in 3μ|PBS-glutamine 2 mM) were injected over 6 min via a fine needle (30G) connected to a Hamilton syringe. The injection site was the right caudatoputamen with stereotactic coordinates: AP=0, L=3 and D=6 mm. The needle was then slowly removed and the craniotomy sealed.

(109) Imaging Experiments

(110) For characterization of tumor, Magnetic Resonance Imaging (MRI) experiments were done once a week. MRI was performed on a 7 teslas horizontal magnet (Pharmascan, Bruker, Ettlingen). A cross coil configuration was used (volume/surface coil, Bruker, Ettlingen). The tumor was detected using an accelerated T2w sequence (RARE, acceleration factor of 8; TR/TEeff=5000/62.5 msec; number of experiments (NEX=2; 20 contiguous slices; resolution=0.15×0.15×0.50 mm3; acquisition time=4 min). Tumor volumes were delineated manually with ImageJ software.

(111) Detection of FAU-Gd with MRI

(112) Experiments were performed on tumor bearing rats on a 7 teslas horizontal magnet (Pharmascan, Bruker, Ettlingen). After a scout view and a T2w-RARE8 scan, 300 μl of a 1% solution of FAU-Gd was administered intravenously and T2*w-EPI (TR/TE=20,000/12 ms, Number of EXcitation: NEX=3, 50 contiguous slices, resolution=0.3×0.3×0.3 mm) or T1w-FLASH images (TR/TEeff=500/10.32 ms; NEX=1; 10 slices; resolution=0.15×0.15×1.5 mm3; acquisition time=2 min) were obtained prior to and every 2 min following the injection.

(113) Relaxometry

(114) FAU-Gd nanocrystals were dissolved in distilled water in concentration ranging from 0.127 to 0.3175 mM in Gd. Solutions were placed in vials placed in a polystyrene support. MRI images of the phantoms were acquired at room temperature. MRI was performed on a 7 teslas horizontal magnet (Pharmascan, Bruker, Ettlingen). A cross coil configuration was used (volume/surface coil, Bruker, Ettlingen). For T1-weighted (T1w) images, a flow sensitive alternating inversion recovery and rapid acquisition with relaxation enhancement (FAIR-RARE) sequence was used (TR: 780 ms, TE: 4.73 ms, TI: increasing from 6.16 ms to 750 ms following a geometrical function, RARE factor of 4, image matrix: 128×128, 1 slice with a thickness of 3 mm and total acquisition time of 16 min 38 sec). Image analysis was carried out with Bruker software Paravision (version 6.0.1), MATLAB R2012b software and imageJ (version 1.50f) software. The R1 value (inverse of the calculated T1 value) was plotted as a function of the Gd concentration for each experimental point, and the slope of the line corresponded to the compound relaxivity (s.sup.−1 mM.sup.−1).

(115) Fractional Cerebral Blood Volume Maps Before and after Intravenous Injection of Gas-Loaded FAU-Gd

(116) For the imaging protocol, after a scout view and a T2w-RARE8 scan, fractional cerebral blood volume (fCBV) was measured at equilibrium as previously described (Valable S et al., 2016, J Cereb Blood Flow Metab. 2017 July; 37(7):2584-2597. doi: 10.1177/0271678X16671965. Epub 2016 Jan. 1). Five T2*w (TR=20,000 ms, Number of EXcitation: NEX=3, 50 contiguous slices, resolution=0.3×0.3×0.3 mm) and four T2w (TR=20,000 ms, NEX=3) images (echo planar imaging: EPI) were acquired with various echo times (TE for T2*=12, 15, 18, 21, and 24 ms and for T2w=40, 60, 80, and 100 ms, respectively). An intravenous administration of a contrast agent (iron oxide nanoparticles P904® (200 mmol.Math.kg−1, Guerbet Research) was then performed and a T2*w images (TE=12 ms) was acquired so as to measure cerebral blood volume (CBV) maps at rest conditions. Then, 300 μl of CO.sub.2 or Carbogen loaded FAU-Gd (1%) were intravenously injected and CBV maps were measured every 5 minutes until 1 hour post-injection. Consequently, for each animal, fCBV maps were obtained under two conditions: baseline and after administration of gas loaded FAU-Gd. Image analysis was performed with in-house developed macros based on the ImageJ software (http://rsb.info.nih.gov/ij/, 1997-2014) as previously described.

(117) Oxygen Saturation Maps Before and after Intravenous Injection of Gas-Loaded FAU-Gd

(118) Oxygen saturation (SatO.sub.2MRI) maps were derived from the equation published by Christen et al (J. Cereb Blood Flow Metab. 2014 September; 34(9):1550-7. doi: 10.1038/jcbfm.2014.116. Epub 2014 Jul. 9). Briefly, SatO.sub.2MRI maps were calculated as a function of the T2*w signal after correction of inhomogeneities of magnetic field (B0), blood volume fraction, and T2 effects. SatO.sub.2MRI maps were generated at rest conditions and after administration of gas loaded FAU-Gd.

(119) Statistical Analyses

(120) Data are presented as mean±SD or SEM. Statistical analyses were obtained with JMP programs (SAS Institute).

(121) 6.2. Results

(122) The results of measurement of the percentage of change in cerebral blood volume (CBV) following the IV injection of FAU-Gd carrying CO.sub.2 or carbogen, are reported on FIG. 3 annexed. On this FIG. 3, FIG. 3(A) represents CBV and SatO.sub.2MRI maps, obtained before and 15 min after intravenous injection of FAU-Gd carrying CO.sub.2 or carbogen solution, T2-w anatomic image of the corresponding tumor and a map of the differences of signal between the two maps (ΔCBV and ΔSatO.sub.2 respectively). Control consisted of an injection of H.sub.2O saturated with CO.sub.2 or Carbogen. FIG. 3 (B, C) gives the quantification of the ΔCBV and ΔSatO.sub.2 in the healthy relative to the tumor tissue. Mean±SEM, n=5 for control groups; n=8 for FAU-Gd—CO.sub.2 group; n=5 for FAU-Gd-Carbogen group (*p<0.02; **p<0.0001, following an ANOVA). FIG. 3 (D, E) reports the evolution over the time of the pCO.sub.2 and the pH respectively in the blood of healthy Wistar rats following injection of a solution of FAU-Gd carrying CO.sub.2 or H.sub.2O saturated with CO.sub.2 as a control. Mean±SEM, n=5 per group (*p<0.05, following a two-way ANOVA). FIG. 3 (F) represents the T2* MRI signal (reflecting the BOLD effect) measured in the venous sinus of healthy Wistar rats 4 min following an intravenous injection of CO.sub.2 loaded FAU-Gd compared to FAU-Gd not loaded with CO.sub.2, to water saturated with CO.sub.2 and to the simple breathing of CO.sub.2. Mean±SEM, n=5.

(123) These results show that after 15 min, the injection of CO.sub.2 loaded FAU-Gd, induces an increase in CBV inside the tumor tissue whereas it induced a decrease in the healthy tissue (FIG. 3 A, B) with a significant difference of 9.91% between the two tissues. No changes between healthy and tumor tissues were observed following injection of water saturated with CO.sub.2 but also following injection of FAU-Gd unloaded with CO.sub.2.

(124) Similar results, although slightly attenuated, were observed with FAU-Gd loaded with Carbogen with a difference of 5.95% between the healthy and tumor tissue (FIG. 3 A, C).

(125) The measurements of tissue saturation in oxygen (SatO.sub.2) before and after injection of FAU-Gd carrying CO.sub.2 or Carbogen were carried out to determine if the increase in CBV led to a reoxygenation of the tumor (FIGS. 3A, B and C). The results show that with FAU-Gd carrying CO.sub.2, the ΔSatO.sub.2 remained unchanged in the tumor whereas it induced a decrease in the healthy tissue with a significant difference of 4.53% between the two compartments. The opposite situation was observed with Carbogen, resulting in an increase in the ΔSatO.sub.2 in the tumor and not in the healthy tissue resulting in a difference of 2.79% between the two compartments.

(126) These results suggest a specific functional effect of nanosized zeolites of the invention carrying gas in the tumor. However, following intravenous injection, zeolite will experience two compartments before reaching the tumor.

(127) The release of gas in the blood was further investigated by following the arterial partial pressure of CO.sub.2 (paCO.sub.2) following injection of FAU-Gd carrying CO.sub.2 (FIG. 3F). An increase in the paCO.sub.2 of 4 mmHg was observed reaching a peak at 10 min, paralleled by a slight acidification (FIG. 3 D, E). These changes were not observed with water saturated with CO.sub.2 and FAU-Gd unloaded with CO.sub.2.

(128) While the breathing of 5% of CO.sub.2 (used as a control) induced an increased in the BOLD signal of 7.06±2.25%, the intravenous injection of nanosized zeolites CO.sub.2-loaded FAU-Gd resulted in an increase in the BOLD signal of 5.05±2.65%. Injection of water saturated with CO.sub.2 or nanosized zeolites without CO.sub.2 failed to modify the BOLD signal

(129) These data allow to postulate that a release of gas occurs into the systemic circulation but the specific accumulation of nanosized zeolites into the tumor tissue may be sufficient to successfully deliver gas within the tumor which in turn increases blood volume and oxygenation. These data also suggest that nanosized zeolites accumulate specifically within the tumoral tissue and not in the healthy brain.

(130) The results of the distribution of FAU-Gd in the brain following an intravenous injection are given on FIG. 4.

(131) FIG. 4A represents relaxivity in vitro measurements at room temperature at 7 teslas. The calculated r1 parameter of the FAU-Gd nanosized zeolites was 74.2 mM−1.Math.s−1.

(132) FIG. 4B represents from left to right respectively T2w anatomic image of the tumor, T1-w images acquired before (top left) or 5 min after (top right) intravenous injection of 300 μl of a FAU-Gd solution (1%); (lower left) and a map of the differences of signal between the two T1-w images. FIG. 4C gives the results of the quantification over the time of the T1-w signal intensity in the healthy and the tumor tissue following an intravenous injection of 300 μl of a FAU-Gd solution (1%). The arrow indicates the time of injection. Mean±SEM; n=5. Two-way ANOVA (*p<0.0001, tissue effect and time effect).

(133) These results show that nanosized zeolites according to the present invention are likely to extravasate and accumulate in the tumor tissue but not to cross the blood brain barrier. This hypothesis has been verified, thanks to the presence of gadolinium in the zeolite, by dynamic T1-weighted MRI to detect FAU-Gd after an IV injection (FIG. 4 B,C). The results clearly show that a hyper-signal appears following the injection that is circumscribed inside the tumor. The difference between the T1-w images acquired after and before the injection (FIG. 4B, right image) demonstrates that FAU-Gd efficiently reached the tumor and not the surrounding healthy tissue. The quantification of the signal over the time show that the increase is slightly delayed and occurs about 30 s following the injection of FAU-Gd with a maximum increase of 3.67±1.36% of the baseline obtained after about 1 min40 s (FIG. 4C). These data strongly suggest the capacity of the nanosized FAU-Gd to specifically target brain tumors.

(134) It is interesting to note that despite gadolinium accounts for only 3.33% of the zeolite weight, it is possible to detect it with MRI. The quantity of gadolinium that has to be injected to obtain signal is therefore low for FAU-Gd, probably due to a good access of water molecules to gadolinium atoms. This is of great importance in a context of concerns that are now being raised about the stability of gadolinium chelates complex currently in use and a link with suspected adverse effects as well as accumulation of gadolinium in various tissues including the brain.

(135) Overall, these data show the ability of the nanosized FAU-Gd according to the invention to carry CO.sub.2 or Carbogen resulting in functional effects on blood volume and oxygenation between the healthy and the tumor tissue.

Example 7: Study of the Release of Oxygen by Zeolites in Aqueous and Hypoxic Conditions

(136) 7.1. Materials and Methods

(137) A hypoxia chamber (IN VIVO2 500™, 3M) was used to get a stable and precisely controlled gas composition of the atmosphere with a precision of 0.1% O.sub.2 by adapting the amount of N.sub.2. PBS (Phosphate buffered saline, Sigma-Aldrich) solution was equilibrated with the gas mixture contained in the hypoxia chamber for 1 h prior to the experiment. A closed reaction vessel containing 12 ml of equilibrated PBS at 37° C., and a dissolved oxygen sensor (SevenGo (Duo) Pro™/OptiOx™, Mettler Toledo) was used inside the hypoxia chamber. Prior to the experiment, baseline was established by measuring the oxygen saturation in the system for 30 min. Oxygen-loaded nanozeolites (FIG. 5A) were then added to the system and dissolved oxygen in the PBS solution was measured continuously for 1 h (FIG. 5B). The oxygen release capacity of FAU nanosized zeolites with different cations composition (FAU-Na as prepared in example 1 used as a reference not forming part of the present invention, FAU-Fe and FAU-Gd as prepared also according to example 1 but forming part of the present invention) was compared to pure water saturated with oxygen as a control. The oxygen release capacity of FAU-Na nanozeolites was compared for decreasing levels of oxygen in the atmosphere (21, 5, 1 and 0.1% of 02).

(138) 7.2. Results

(139) Experiments were performed at various percentage of oxygen by replacing oxygen by nitrogen in the incubator so as to mimic hypoxic conditions that could be observed in tumor situations.

(140) When experiments were performed at 21% (normoxic condition), almost no release of oxygen occurred in the medium when O.sub.2 loaded FAU-Na were delivered (FIG. 5C). When 5% or 1% of oxygen was used, the oxygen release became more prominent and reached a maximum when oxygen concentration was 0.1%.

(141) The release of oxygen depending on the nature of the carrier was analyzed too. The results show that the control, consisting of water saturated with oxygen, is by itself able to provide oxygen in the system. The amount of oxygen increases by 2.82±0.13 times from the baseline after saturated water injection.

(142) However, when O.sub.2 loaded FAU-Na nanocrystals were injected, the amount of oxygen in the system is significantly higher compared to the control as the concentration increases up to 3.13±0.14 times from the baseline.

(143) The zeolite nanocrystals containing gadolinium and iron were also evaluated. The results show that the addition of gadolinium does not significantly change the amount of O.sub.2 released compared to FAU-Na zeolites. On the other hand, the addition of iron in zeolites strongly increases their ability to release oxygen. The oxygen concentration increases to a maximum of 4.76±0, 38 times for FAU-Fe compared to the baseline.

(144) Regarding the kinetics of gas release, the profile is substantially the same for the four conditions. Gas release occurs very quickly, the maximum is reached about 2 min after the injection into the system.

Example 8: Comparison of O.SUB.2 .Release Capacity of FAU-Na, FAU-Gd and FAU-Fe Zeolite Samples

(145) In the following, FAU-Na is prepared as in example 1 and used as a reference, not forming part of the present invention.

(146) FAU-Fe and FAU-Gd are prepared according to example 1 and are part of the present invention.

(147) In-situ adsorption of CO.sub.2 and O.sub.2 on nanosizedzeolites: Powder samples of as prepared and ion-exchanged zeolites were pressed (˜10.sup.7 Pa) into self-supported disks (2 cm.sup.2 area, 20 mg.Math.cm.sup.−2). Fourier-transform infrared (FTIR) spectra were recorded using a Nicolet 6700 IR spectrometer equipped with a mercury cadmium telluride (MCT) detector and an extended KBr beam splitter. Spectra were recorded in the 400-5500 cm.sup.−1 range at 4 cm.sup.−1 with 128 scans. The in situ was evacuated or flooded with different gases and also heated up to 577° C. was used. The samples were activated at 225° C. for 2 h under vacuum. Various amounts of CO.sub.2 (at 25° C.) or O.sub.2 (at −196° C.) were introduced into the cell and kept in equilibrium for 5 minutes at the corresponding temperatures before recording each spectrum. All the spectra were normalized to the sample's mass and plotted as absorbance per gram over the wavelength.

(148) The physisorbed O.sub.2 and physi- or chemisorbed CO.sub.2 were also evaluated by in-situ IR spectroscopy following the introduction of controlled quantities of the desired gas into the zeolite samples. The CO.sub.2 loading capacity of zeolites samples follows the trend FAU-Fe>FAU-Na>FAU-Gd. Despite the lower quadrupole moment of oxygen compared to CO.sub.2 which renders it less efficient for adsorption on zeolites, small amount of iron (1.7 wt. %, measured with ICP-AES, see table 1) introduced in the zeolite (Fe—X) substantially improved the O.sub.2 adsorption capacity in comparison to the FAU-Na and FAU-Gd zeolite samples (FIGS. 6A and 6B).

(149) The O.sub.2 release capacity of FAU-Na, FAU-Gd and FAU-Fe zeolite samples was then compared at 0.1% of O.sub.2. To differentiate the quantity of oxygen provided by the zeolites from the oxygen provided by the dispersing solution (pure water), the values were deducted from the value of saturated water alone. Samples FAU-Na, FAU-Gd and FAU-Fe deliver to the system 0.26, 0.49 and 0.54 mg of oxygen per ml, respectively, as shown in FIG. 6B. These results clearly show that the FAU-Gd and FAU-Fe zeolites deliver more oxygen than the FAU-Na zeolite. Thus, FAU-Na, FAU-Gd and FAU-Fe zeolites transport 19, 37 and 41 mmol of O.sub.2/g respectively, which is higher than the values recorded for HEMOXYCarrier®, a natural giant extracellular haemoglobin from polychaete annelids and Polymer Hollow Microparticles (PHM).