JPS6323158B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to porous materials, and in particular, but not exclusively, to the production of porous particles suitable for selectively retaining molecules from a fluid material containing them. Concerning what to do.

According to one aspect of the invention, (i) providing an intermediate material, the intermediate material comprising substantially insoluble, sorptive, finely divided inorganic material particles;
A slurry containing an additive convertible to an insoluble form and a solvent for the additive is treated to convert the additive to an insoluble form, whereby the insoluble form of the additive binds the particles of the inorganic material. (ii) heating said intermediate material to dissolve at least some amount of said insoluble additive; A method of making a porous material is provided, comprising: burning out the porous material, thereby creating a porous material.

According to another aspect, the present invention processes a slurry comprising substantially insoluble, sorptive, finely divided inorganic material particles, an additive that can be converted to an insoluble form, and a solvent for the additive to remove the additive. converting to an insoluble form, thereby creating an intermediate material containing particles of said inorganic material bound together by an additive in said insoluble form, and heating said intermediate material to form said insoluble form; A method of making a porous material is provided which includes burning out at least some amount of an additive in the form of a porous material, thereby creating a porous material.

As used herein with respect to inorganic materials capable of forming porous materials, the term "sorptive" refers to whether the inorganic material is inherently sorptive and capable of sorption of molecules, or whether the inorganic material is inherently sorptive and capable of sorption of molecules. By doing so, it becomes a sorptive property and can adsorb molecules. Furthermore, it is to be understood that sorption methods in connection with the present invention may include absorption and adsorption (including physical sorption and chemical sorption) and combinations thereof.

As used herein, the term "substantially insoluble" means that the inorganic material comes into contact with the porous material in making the porous material in accordance with the present invention and in using the porous material for its intended purpose. means that the inorganic material is substantially insoluble in the substance.

The slurry may be treated to precipitate the insoluble additive, thereby creating an intermediate material containing particles of the inorganic material bound together by the precipitated insoluble additive. can.

We have found that after converting the additive to an insoluble form to create the intermediate material, it is generally advantageous to at least partially dry the intermediate material to facilitate handling and/or storage. I discovered something. Drying is carried out, for example, in air or methanol.

According to the present invention, the slurry is preferably reduced into droplets and contacted with a reagent capable of precipitating the insoluble form of the additive, such that after removal of the precipitated insoluble form of the slurry, substantially spherical particles are formed. The intermediate material is a substantially spherical discrete particle such that discrete porous particles are created. It will be appreciated that it is advantageous to separate this intermediate material from the precipitation reagent prior to heating to remove the additive in precipitated form.

In carrying out the process of the invention, the intermediate material is heated to a temperature at which the insoluble additive burns off leaving a porous material (i.e., the insoluble additive serves as a temporary additive). It is preferable to remove the insoluble form of the additive. In addition to the additive, additional pore-forming fugitive materials can also be incorporated into the intermediate material and then used to create more pores in the porous material. This additional pore-forming fugitive material then serves to increase or modify the porosity created by the removal of the insoluble additive.

GB 1421531 discloses, inter alia, a method for producing discrete porous particles having interconnected internal pores for selectively retaining macromolecules from a fluid material containing them. are doing.
The method of the invention can be used to produce discrete porous particles for such purposes.

If the porous material is to be used to selectively retain molecules (e.g. polymers) from a fluid material containing them, the porous material will It will be appreciated that the pore structure should be such that it is permeable and sorbed by the sorptive inorganic material.

Regarding the size of the pores and their relationship to the size of molecules that can or cannot be sorbed, see GB 1421531.

The size of the pores of a porous material, and therefore the size of the molecules that cannot or can pass through the pores, can be controlled by varying the amount of additive or fugitive material, or by adding a suitable additive or fugitive material. can be changed by adding at the manufacturing stage.

The aforementioned British Patent No. 1421531 describes the enhancement of molecular separation using "molecular sieving action" and the production of materials with sorption and molecular sieving properties. By appropriate selection of additives or fugitive materials, the properties of such molecular sieves can be controlled.
can be introduced into porous materials made in accordance with the present invention by adjusting the size of the pores.

In some cases, inorganic ions can be incorporated into the intermediate material (e.g., by interacting with additives to form complexes) and create impurities in the porous material after heating. .

If these impurities are soluble, they can be removed by treating the porous material with a suitable solvent to elute the impurities.

Examples of additives that can be converted into insoluble form that can be used in the present invention are polymeric substances such as algylates, algylates, pectins, polygalacturonic acids and proteins.

Although the abovementioned additives are preferred from an economic point of view, other, more expensive additives which can be converted into insoluble forms [e.g. carboxymethyl derivatives of cellulose, rubbers, derivatives of polyacrylic acid, polymers of styrene-maleic anhydride and nucleic acids] can also be used.

"Insoluble form" with respect to additives refers to materials used during the production of intermediate materials according to the present invention (e.g., reagents used to cause precipitation) and subsequent processing of the intermediate materials. means a form that is substantially insoluble in the substances used in the process (eg, drying reagents).

Examples of additional pore-forming fugitive materials that can be incorporated into the intermediate material in addition to additives that can be converted into insoluble form are hemoglobin and soluble starch. Furthermore, powdered insoluble polymers can also be used as temporary materials for this type of pore formation.

Certain other materials such as casein, gelatin and vegetable proteins can also be used as temporary materials for this additional porosity formation. It is also possible to use the "temporary additives" disclosed in GB 1421531, such as ammonium carbonate, polyvinyl alcohol, dextran, bovine serum albumin and ovalbumin.

When selecting a temporary material for this additional porosity formation, it is generally preferred to choose a material that does not readily diffuse or disperse from the slurry during conversion of the additive to an insoluble form. Of course.

Also, when attempting to form particles, it is highly preferred to avoid additional pore-forming fugitive materials that can cause premature precipitation (ie, before droplet formation). For example, if alginate is an additive, it is highly preferred to avoid certain casein formulations that contain calcium ions as impurities, since calcium ions cause premature precipitation of calcium alginate.

Additives that can be converted into insoluble form and additional pore-forming fugitive materials (if used) contribute to the formation of interconnected internal pores (porous network) in the porous material. do.

Examples of inorganic materials that can be formed into porous materials according to the present invention are natural earths such as titania, calcium phosphate, bentonite and celite, and other inorganic materials (i.e. aluminum oxide) as disclosed in British Patent No. 1,421,531. , barium sulfate, zinc oxide and calcium sulfate).

In one preferred embodiment of the invention,
The discrete porous particles are formed by mixing a substantially insoluble, sorptive, finely divided inorganic material with an aqueous solution of a soluble alginate (e.g., sodium alginate) into a slurry, forming the slurry into droplets, and forming the droplets into droplets.
contacting a reagent capable of precipitating the soluble alginate as an insoluble alginate, such as an aqueous solution of calcium chloride, thereby containing particles of the inorganic material bound together by the precipitated alginate. It is made by a method that includes forming intermediate particles and heating the intermediate particles to burn off at least some of the alginate, thereby creating discrete porous particles.

In another preferred embodiment of the invention, the discrete porous particles are prepared by mixing a substantially insoluble, sorbent, finely divided inorganic material into a slurry with an aqueous solution of a soluble alginate (e.g., ammonium alginate). Forming the slurry into droplets and contacting the droplets with an acidic reagent that precipitates alginic acid, thereby creating intermediate particles containing the inorganic material particles bound together by the precipitated alginic acid. , and heating the intermediate particles to burn off at least some of the alginic acid, thereby creating discrete porous particles.

In any of the preferred embodiments described above,
If desired, the slurry can further contain additional pore-forming fugitive materials as described above to increase or modify the amount of porosity in the discrete porous particles.

Discrete porous particles capable of selectively retaining macromolecules from a fluid material containing them are
It is made from titania, celite, bentonite, and calcium phosphate in the 200-500 micron diameter range with pores of suitable size for macromolecules to pass through and be sorbed. The particles can be sized to suit a particular application, and can be sized outside the above ranges if desired. Therefore, depending on the intended use of the particles, the particles may be made, for example, with a diameter of 50 μm.
It can be made in a size range of -5 mm.

An example of a macromolecular species selectively retained by the discrete porous particles made in accordance with the present invention is hemoglobin selectively retained from an aqueous solution containing hemoglobin and bovine serum albumin. Other macromolecules, such as those disclosed in GB 1421531, may also be selectively retained by the porous particles of the present invention.

The invention also provides porous materials made by the method of the invention.

Preferably, the porous material is in the form of discrete porous particles.

It has been discovered that a number of factors influence the particle size of discrete porous particles made in accordance with the present invention. That is,
The particle size depends on the inorganic material content of the slurry, the size of the slurry droplets before the conversion (eg, precipitation) step, and the porosity of the particles. The size of the droplet is
the viscosity of the slurry and, if a nozzle is used to create droplets, the diameter of the nozzle orifice;
It depends on the type of nozzle (eg, needle nozzle, swirl nozzle, or atomizing nozzle) and the rate of injection of the slurry from the orifice.

By varying the above factors, particles of a particular desired size can be created.

GB 1421531 also describes uses of the invention disclosed therein, and it is to be understood that these uses also apply to the porous material of the present invention.

For example, the discrete porous particles of the invention can be used in chromatographic separations. Also, for example,
The porous material of the present invention may be a biological material such as an enzyme [according to the invention disclosed, for example, in British patent application no. It can be used as a support material on which biologically active substances can be immobilized.

Amyloglucosidase was thus immobilized on discrete porous particles of TiO ₂ (made according to the invention) as well as Celite using the invention disclosed in the above-mentioned UK Patent Application No. 28212/74.

The invention will be further explained below by way of examples.

Example 1 200g by ball milling for 5 hours
of TiO ₂ was added to sodium alginate [Wellgum.
Alginate. Industries. 1 made by Welgum Alginate lndustries Ltd.
% aqueous solution to obtain a slurry of suitable viscosity for droplet formation. This slurry was dripped into a 0.1 M solution of calcium chloride through a pipette nozzle (1 mm diameter) to create a discrete particle intermediate material containing TiO ₂ particles bound together by their precipitated calcium alginate.

The particles were sufficiently durable for handling. The particles were transferred to methanol in which they were dehydrated to 25% of their original volume. The particles are then heated to 100°C in a furnace for 1-2 hours and finally heated to 900°C.
Discrete porous particles of titania (diameter
500μ) was obtained.

Example 2 200 g of Celite was converted into sodium alginate [Wellgum.
Alginate. Inda street. The mixture was slurried in a 2% aqueous solution 1 (manufactured by MITSUDO LIMITED). In a manner similar to Example 1, this slurry is added dropwise to a 0.1 M solution of calcium chloride to produce a discrete particle intermediate material containing Celite particles bound together by their precipitated calcium alginate. Ivy. The particles are then placed in the air and then in a furnace.
It was dried at 100°C and finally sintered at 1150°C to produce discrete porous particles of Celite (500μ in diameter).

Example 3 200 g of TiO ₂ was prepared by treating with a homogenizer for 20 minutes to prepare ammonium alginate [Colatex A/RK Extra, alginate. Industries, Limited (Collatex A/RK EXTRA, Alginate
The sample was slurried in a 2% aqueous solution 1 (manufactured by Industries Ltd.). This slurry was added dropwise to 0.1 M HCl through a pipette nozzle (1 mm diameter) to dissolve TiO ₂
A discrete particle intermediate material was created containing particles bound together by alginic acid.

This was dried in air and heated to obtain discrete porous particles of titania.

Example 4 A sample of slurry made according to Example 1 was
10% (w/w) hemoglobin was added as a temporary material for additional pore formation.

The slurry was formed into droplets and processed in the same manner as in Example 1 to obtain discrete porous particles.

Example 5 Discrete porous particles were obtained in the same manner as in Example 4 except that 10% soluble starch was used as an additional pore-forming material.

Example 6 600 g of Celite [kotsuholite. Laboratories. (Koch-Light Laboratories Ltd.)
[manufactured by BDH Ltd.] and 10 g of soluble starch (additional pore-forming material) [manufactured by BDH Ltd.] were mixed with sodium alginate [Wellgum. Alginate. Industries. It was made into a slurry in 1% aqueous solution 6 (manufactured by MITSUDO LIMITED).

The resulting slurry was added dropwise to a 0.1M aqueous solution of CaCl ₂ to create a discrete particle intermediate material containing Celite particles and starch bound together by calcium alginate.

The discrete particles were dried in methanol and then in air at 80°C and then heated to 1150°C to obtain discrete porous particles of Celite (diameter 500μ).

Example 7 20 g of TiO ₂ and 5 g of the commercially available polymer resin Amberlite CG50, 100-200 meshes (additional pore-forming material) were mixed with 1.5 g of sodium alginate (manufactured by Wellgum Alginate Industries Limited). slurried in 100 ml of % aqueous solution. The generated slurry
A discrete particle intermediate material containing TiO ₂ particles and polymeric resin particles bound together by calcium alginate was created by dropping into a CaCl ₂ 0.1M solution.

The discrete particles were dried in methanol and then heated to create discrete porous particles.

Example 8 20 g of calcium orthophosphate was added to 1% of sodium alginate (of the type used in Example 1).
The resulting slurry was stirred in 100 ml of aqueous solution and without delay was added dropwise to a 0.1 M CaCl ₂ solution to create a discrete particle intermediate material containing calcium phosphate bound together by the precipitated calcium alginate. .

It has been found that this particle intermediate material can be dried in air or methanol to yield particles that are tough enough to handle.

The particles were heated to obtain discrete porous particles of calcium phosphate.

Example 9 This example demonstrates the retention of selectivity of macromolecular species by discrete porous particles made according to Example 1.

Porous titania particles prepared in the same manner as in Example 1 were packed into a column with a length of 5 cm and a diameter of 0.5 cm.
I made the floor.

The bed was equilibrated with 20mM Tris buffer (PH 6.8) and then 2ml of an aqueous solution containing 2.5mg bovine serum albumin and 2.5mg hemoglomin was passed through the bed.

Bovine serum albumin was not sorbed by the particles and appeared in the eluate from the bed. This was quantified by trichloroacetic acid precipitation.

Hemoglobin was sorbed and retained by the particles, and then hemoglobin was eluted from the particles using 0.1 M potassium pyrophosphate (PH 9.6) and quantified spectrophotometrically.

Example 10 This example demonstrates the retention of selectivity of polymeric species by discrete porous particles made according to Example 2.

The method of Example 9 was carried out using porous Celite particles prepared according to Example 2 as the bed in place of the titania particles.

Once again, it was found that bovine serum albumin was not sorbed by the particles and, as in Example 9, hemoglobin was sorbed and then removed.

Example 11 In this example, a biologically active substance, in this case the papain enzyme, was immobilized onto discrete porous particles made in accordance with the present invention.

5 ml of discrete porous particles of celite (prepared as in Example 6) were thoroughly mixed on ice with 1.5 ml of Pasol ("Pasol" is from Powell and Schiofield).
It is a papain preparation in solution form available from Schofield).

A 4% solution of Tannia (a synthetic polyphenol manufactured by Harshaw Chemicals) in 2:1 water:acetone was prepared and the pH was adjusted to 7 with NaOH. 2.25ml of this solution
0.6 ml of formaldehyde was added to the solution.

The resulting solution was added to the Celite particles and Pasol and the whole was left on ice for 1 1/4 hours.

The Celite particles on which the papain enzyme was thus immobilized were washed with demineralized water and benzoyl. Arginine. Efficacy was assayed for enzymatic activity by measuring esterase activity using ethyl ester as a substrate.

Insoluble activity was 10% of soluble activity.

Claims (1)

[Claims] 1. (i) Processing of a slurry comprising substantially insoluble, sorptive, finely divided inorganic material particles, an additive capable of being converted to an insoluble form, and a solvent for the additive to render the additive insoluble. (ii) heating this intermediate material to form an intermediate material in which the additive in insoluble form binds together particles of the inorganic material; Burning out at least some amount of the additive in insoluble form, thereby creating a porous material having continuous internal porosity, where the porous material allows the predetermined polymeric material to pass through the porous material. determining the amount of the inorganic material, the additive, and the additive so as to have a porous structure that is suitable for selectively retaining a given polymeric material from a fluid containing said polymeric material. A method for producing a porous material or a porous material suitable for immobilizing a biologically active substance on a porous material. 2. The method of claim 1, wherein additional pore-forming fugitive materials are incorporated into the intermediate material.