AU682391B2 - Composite biological-molecule-accretion material - Google Patents

Description

C-II1I~L I WO 95105240 PCT/US94/09187 1 COMPOSITE BIOLOGICAL-MOLECULE-ACCRETION MATERIAL This is a continuation-in-part of priority U.S. Patent Application Serial No. 08/106,415 filed 13 August 1993.

Background and Summary of the Invention The present invention relates generally to filters and other devices for removing undesired chemicals from solution, and more particularly to a composite biological-molecule-accretion material for extracting desired target biological molecules from aqueous solution and substantially permanently binding to those molecules.

There have been several conventional proposals for dealing with removal of unwanted chemicals from solution. However, none has proven adequate for dealing with removal and ultimate disposal of certain chemically labeled molecules regularly used in connection with basic and applied biological research. Those molecules will be referred to in the present application as target molecules, and a list of them is provided below: Target Biological Molecules 1. peptides; 2. polypeptides; 3. RNA; 4. DNA; enzymes; 6. nucleic acids; 7. proteins; o. biopolymers; and 9. amino acids.

The essential problem for laboratories performing research with such molecules is that present environmental regulations no longer allow for simply pouring them down the drain after they are chemically labeled according to known procedures. Examples of such labeling involve using radioactivity or fluorescence to label a desired molecule. While radio-labeled molecules, sometimes referred to as probes, will be referred to throughout, it should be understood that the to-be-described invention is usable for removing any SUBSTITUTE SHEET (RULE 26) pi I

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WO 95/05240 PCTIUS94/09187 2 chemically labeled target molecule from aqueous solution and substantially permanently binding to it.

Basic and applied biological research can also result in waste products characterizable as mixtures of toxic organic solutions and radio labeled target molecules in aqueous solutions. Such mixtures of solutions will be referred to herein as "mixed waste". The to-be-described invention is also usable for removing such radio labeled target molecules from such mixed waste.

Nowhere has there been shown or suggested to provide a composite biological-molecule-accretion material for extracting desired target biological molecules from either aqueous solution or mixed waste, and substantially permanently binding to those molecules. Accordingly, it is a principal object of the present invention to provide such a material that overcomes the drawbacks of prior-art materials.

Another object is to provide such a material that provides for such removal and binding to a relatively wide variety of molecules such as the target molecules listed above.

Yet another object is to provide such a material that has a relatively long working life.

Another important object of the invention is to provide such a material that can be readily and easily disposed of after its working life -s over.

It is also an object of the invention to provide such a material that can be easily and cost-effectively manufactured.

In brief summary, one aspect of the invention includes a composite biological-molecule-accretion material for extracting (or removing) desired target biological molecules from aqueous solution and substantially permanently binding to those molecules. The material includes a first component designed with a yck, hlrW binding affinity for proteins and peptides in such solution, and .second s 6 component -designed with a binding affinity for nucleic acids in such solution. The material is capable of being formed in a body for passing such solution through it, and such passing has the effect of removing the proteins, peptides and nucleic acids from such solution and binding them to the body. That binding is substantially permanent so that subsequent passage of additional aqueous solution -1- 2/1 will not unbind substantially the accreted proteins, peptides and nucleic acids from the body.

Preferably the first component consists essentially of dextran-coated activated charcoal particles, the second component consists essentially of an anion-exchange resin and the third component consists essentially of a cationexchange resin. The preferred relative volumes of activated charcoal to the exchange resins is 1:1, and the preferred relative volumes of the two ionexchange resins is 1:1. As a result, relative volumes for the composition of the preferred version of the material is 2 parts dextran-coated charcoal particles to 1 10 part anion-exchange resin to 1 part cation-exchange resin.

C° oo° v I NNW WO 95/05240 PCT/US94/09187 3 will not unbind substantially the accreted proteins, peptides and nucleic s from the body.

Preferably the first component consists es ally of dextran-coated activated charcoal particles, and the second ponent consists essentially of an anion-exchange resin and a cation- ange resin. The preferred relative volumes of both components ar ,and the relative volumes of the two ion-exchange resins is 1:1. a result, relative volumes for the composition of the preferred ve of the material is 2 parts dextran-coated charcoal particles to 1 part anionexchange resin to 1 part cation-exchange resin.

Another aspect of the present invention includes a method of filtering target biological molecules out of water. The method includes the step of forming a filter bed by soaking a mixture of dextran-coated, activated charcoal in water for a preselected time period, adding to the mixture an ion-exchange resin with a preselected charge-sensitivity, drying the mixture, and rehydrating the mixture. The method also includes the step of placing the filter bed into a waterfiltration apparatus with an input and an output, and passing water containing the target biological molecules through the filtration apparatus to capture substantially the target biological molecules in the filter bed.

These and other objects and advantages of the invention will be more clearly understood from a consideration of the accompanying drawings and the following description of the preferred embodiment.

Brief Description of the Drawings Fig. 1 is an isometric view of the accretion material of the present invention after being formed in a body .(or filter bed) and being placed into conventional water-filtration apparatus.

Fig. 2 is a side-sectional view through line 2-2 of Fig. 1 with the accretion material being formed in a body, and with solid lines indicating an unswelled condition of the material, and dashed lines indicating a swelled condition of the same.

Fig. 3 is a fragmentary, greatly enlarged, schematic view of the unswelled body of accretion material shown in Fig. 2.

I -r I-1 WO 95/05240 PCT/US94/09187 4 Fig. 4 is a fragmentary, greatly enlarged, schematic view of the swelled body of accretion material shown in Fig. 2.

Fig. 5 is a greatly enlarged view of unswelled charcoal particles forming part of the accretion material.

Fig. 6 shows the charcoal particles of Fig. 5 after swelling.

Fig. 7 shows the charcoal particles of Fig. 6 after being coated with dextran substance.

Fig. 8 shows the charcoal particles of Fig. 7 being mixed with anionand cation-exchange resins, with the resins being indicated schematically by encircled and Fig. 9 shows the charcoal particles of Fig. 8 after being mixed with the resins.

Fig. 10 is like Fig. 2 only that it shows the swelled condition of the body of accretion material in solid lines, and shows introduction into the conventional water-filtration apparatus of aqueous solution containing desired target biological molecules, with the solution passing through the body.

Detailed Description of the Preferred Embodiment Referring generally to Figs. 1-4 and 10, applicant will describe generally how he proposes using the invented composite biological-moleculeaccretion material, which material is indicated at 10 being made in accordance with its to-be-described preferred embodiment. After describing how the invented material is used, applicant will discuss details of its composition. Material 10 is formed in a body 12, with body 12 being placed in a conventional water-filtration apparatus 14. In its place in apparatus 14, body 12 will allow a to-be-described aqueous solution to pass through it, with such passing having the effect of removing certain target molecules such as proteins, peptides and nucleic acids from such solution and binding them to body 12. The binding is substantially permanent in that subsequent passage of additional aqueous solution will not unbind substantially the accreted proteins, peptides and nucleic acids from the body. As will be shown, material 10 does not unbind substantially from the acc:.eted proteins, peptides and nucleic acids even when subsequent passage of 4 1 i ~e WO 95/05240 PCTIUS94/09187 additional aqueous solution includes relatively harsh components such as detergents.

Still referring to Figs. 1-4 and 10, conventional water-filtration apparatus 14 is constructed with an input 16 and an output 18, and includes a receptacle 20 for receiving effluent from output 18. Receptacle 20 is formed with a suitable port 22, which may be an aspiration port, for dispensing effluent from the receptacle. The port may be fitted with the usual control valve (undepicted).

It should also be understood that a suitable support screen (undepicted) may be provided within apparatus 14 and around body 12 to hold material 10 in place so that the to-be-described aqueous solution must pass through body 12 after being poured through input 16.

While undepicted, it should be understood that multiple stages of filtration are possible, if desired, to perform a backup function as a way of removing even more chemically-labeled target molecules from waste solutions.

In other words, the invention may include an arrangement of two or more apparatuses, like apparatus 14, with each such apparatus having a body of material, an input, and output, each like those described above. -Preferably, such arrangement would include a vertical stacking of such apparatuses, with the bottom apparatus being placed over a receptacle like receptacle 20. As used herein, a one-stage filtration system is one like that depicted in Fig. 1. A twostage filtration system is one that has a vertical stack of two apparatuses, like apparatus 14, with the bottom apparatus being placed over a receptacle like receptacle 20. To stack such apparatuses, it is presently proposed to use suitable support structure for stabilizing the stack.

Refocusing on material 10, certain physical characteristics of accretion material 10 will also be described before describing its composition.

Referring to Fig. 2, body 12 is shown in an unswelled condition with solid lines between bracketed area A, and in a swelled condition up to a dashed line between bracketed area B. The significance of the unswelled/swelled condition will be described. The unswelled condition of body 12 is also shown in a greatly enlarged, schematic view in Fig. 4. Similarly, Fig. 5 shows the swelled condition in a greatly enlarged, schematic view.

i I C 1 Referring to Figs. 5-9, a schematic presentation of a method of forming material 10 is shown, As will be described, material 10 includes a first component 10a (Fig. 7) designed with a binding affinity for proteins and peptides in aqueous solution such as solution 24 shown in to-be-described Fig.

10. Material 10 also includes second and third components (collectively shown as lOb) (Figs. 8-9) designed with a bi-ding affinity for nucleic acids in such solution.

From an overview, Figs. 5-7 show formation of first component 10a, and Figs. 8-9 show introduction and then mixing of second and third components 10 lOb with first component lOa. The first component includes, and preferably consists essentially of, dextran-coated activated charcoal particles, which exhibit the requisite binding affinity for proteins and peptides. The second component consists essentially of an anion-exchange resin and the third component consists essentially of an anion-exchange resin and the third component consists essentially of a cation-exchxange resin. Those resins exhibit 15 the requisite binding affinity for nucleic acids. Material 10 is preferably formed of 1 part by volume of first component 10a and 1 part by volume of second and third components lo0b. lob is preferably formed of 1 part by volume anionexchange resin and 1 part by volume cation-exchange resin. Therefore, the preferred formulation of material 10, by volume, is 2 parts first component to 1 part anion-exchange resin and 1 part cation-exchange resin. The total volume of ion exchange resin (both anion- and cation-exchange resins) in the preferred embodiment is about one-third to one-half of the volume of the dextran-coated activated charcoal. Also, suitable filler material, such as coarse sand, may be added to increase flow rate through material With material 10 being formed into body 12, it may also be characterized as a target-biological-substance-retaining filter for use in a filter system to remove substantially and selectively desired target biological substances from an aqueous solution (eg. solution 24 of Fig. 10). First component 10a may also 6/1 be thought of as a filter-matrix component formed from first and second subcomponents. The first subcomponent is preferably activated charcoal particles, and the second component is a water soluble, high molecular-weight substance such as dextran. Second and third components 10b may also be thought of as a charge-carrier component distributed substantially in the filtermatrix component to V*9 99 *9 e

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WO 95/05240 PCT/US94/09187 7 provide a plurality of charged sites therein. The filter-matrix component (first component 10a) and the charge-carrier component (seconr d compone 10b) are usable in a desired thickness (as body 12) in a filter system (apparatus 14) to provide a filter that defines paths through its thickness for allowing the aqueous solution solution 24 of Fig. 10) to pass, and removes substantially the target biological substances by binding them to the charged sites.

Material 10 being formed as body 12 may also be characterized in yet another way as a filter bed for use in a filter system to remove target biological substances contained in an aqueous solution solution 24 of Fig.

10). First component 10a may be characterized as means for forming a filter matrix that is porous substantially only to that portion of such solution that does not include the target biological substances. The filter-matrix-forming means includes first and second subcomponents, activated charcoal particles and a watersoluble, high-molecular-weight substance, respectively. The high-molecular-weight substance is preferably dextran, and it is mixed with the charcoal particles to coat a\ck Ibcrd them. Second components 10b may be characterized as a charge-carrier component distributed substantially in the filter-matrix-forming means to provide a plurality of charged sites therein. The filter-matrix-forming means and the charge-carrier component are usable in a desired thickness body 12) in a filter system apparatus 14) to provide a filter bed that defines paths through its thickness for allowing the aqueous solution (solution 24 of Fig. 10) to pass, and removes substantially the target biological substances by binding them to the charged sites.

Referring to Figs. 5-7, preparation of material 10 is shown schematically with first component 10a being formed by soaking a mixture of activated charcoal 10al and dextran 10a 2 in water (undepicted) for a preselected time period. Figs. 5-6 show the swelling of charcoal 10al in water prior to addition of dextran 10a2. The presently preferred time period is about one hour.

Next, referring to Figs. 8-9, second componentOh, taking the form of preselected anion- and cation-exchange resins (shown schematically as encircled and is mixed with first component 1Oa. The resins forming second component have a preselected charge-sensitivity, and preferred ones will be described below

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WO 95/05240 PCT/US94/09187 8 vid hl-cdl in connection with example formulations. After mixing the first )a second components, the mixture is aspirated to remove residual water and allowed to dry, and then rehydrated with a suitable amount of water so that it swells. Applicant has found that such rehydration promotes formation of the above-described filter matrix within body 12, and lessens the possibility that some target molecules will be missed when the first amount of the aqueous solution solution 24 of Fig.

is passed through body 12.

EXAMPLE I Material 10 was prepared using 45% activated charcoal such as that marketed under the trademark "NORIT 25% Whatman DE52 pre-swollen microgranular anion exchanger (diethylaminoethyl cellulose, catalog number 4057 050), 25% Rolm Haas Co. Amberlite CG-50 (weakly acidic cation exchanger, carboxylic type, hydrogen form, wet mesh 100-200), and 5% coarse sand. An amount of that material having a wet volume of 100 ml was formed in a body like body 12 and placed in a filter structure like apparatus 14. 20/uCi of 3 sS-ATP in 800ml of Tris/Borate EDTA buffer was passed through the body of material After subsequently passing 800ml of aqueous solution containing no radio-labeled biomolecules through the mjaterial, the total effluent contained only .37/Ci of radioactive isotope, indicating a permanent binding efficiency of approximately 98% for ATP.

EXAMPLE II Material 10 was prepared as in example I and placed in a filter structure like apparatus 14. Solutions containing 24 1 uCi of 32 P-CTP DNA probe in 0.1% sodium dodecyl sulfate solution were passed through material Despite the harsh character of a detergent like the sodium dodecyl sulfate solution; only .2/zCi of the 32 P-CTP DNA probe passed through the material, indicating a permanent binding efficiency of greater than 99%.

EXAMPLE III Material 10 was prepared as in example I and placed in a filter structure like apparatus 14. 49 1 uCi of 32 P-labeled, 1450 base-pair DNA fragment in a 50% formamide solution was passed through the material. Analysis of the WO 95/05240 PCT/US94/09187 9 effluent from apparatus 14 revealed .3pCi of radio-isotope passed through the material, indicating a permanent binding efficiency of greater than 99%.

EXAMPLE IV Material 10 was prepared as in example I and placed in a filter structure like apparatus 14. A mixed waste solution of HPLC waste water by volume) containing radiolabeled peptide was passed through the material. Specifically, 300-mL of the solution containing approximately 4.5#/Ci '2I-PEP (-endorphine) was passed through the material.

Analysis of the effluent from apparatus 14 revealed less than 0.0004 zCi of radioisotope passed through the material, indicating a permanent binding efficiency of greater than 99.99%. Over a 48-hour time period, water was intermittently passed through the material, and analysis of the effluent after such time period indicated no change in the 99.99+% permanent binding efficiency.

A prolonged use of material 10 in a one-stage filtration system was run over an 8-month period to remove SS radioactive nucleotides. Specifically, an amount of material 10 having a wet volume of 100 ml was formed in a body like body 12 and placed in a filter structure like apparatus 14. 58 units of aqueous solutions containing sS radioactive nucleotides were passed through the amount of material 10, and the average of radioactive material absorbed by the amount of that material was 91.3%.

Additional, similar experiments involving radiolabeled proteins, peptides and nucleic acids revealed similar results, with approximately 98-99% or such molecules becoming substantially permanently bound to the accretion material as the aqueous solution containing such molecules was passed through an amount of the material formed into a body such as a filter bed. The additional experiments have involved solutions with 'SI-labeled peptides, 3Slabeled amino-acid monomers. When using a body of material 10 having a wet volume of 100 ml, the time for passage through the body of aqueous solution containing target molecules ranged from about 10 minutes with aspiration, to overnight under gravity feed.

Material 10 worked as described above with acidic or basic aqueous solutions. It has also indicated a relatively long working life, i.e. an amount of t? WO 95/05240 PCTIUS94/09187 material 10 with a wet volume of 100 ml continues to )it the above binding efficiency of 98-99% after weekly use in a biological laboratory for approximately six months.

For situations where it is important to control the pH of solutions that are passed through material 10, buffer-like components may be added to material 10. It is presently proposed to use solid forms of acid- or base-leaching substances. For example, solid masses or nuggets of NaOH may be uniformly distributed in the material, using suitable mixing apparatus, to act as a buffer when acidic solutions are passed through material 10. Likewise, suitable weak acids may be used, in solid masses/nuggets, to act as a buffer when basic solutions are passed through material Operation and Preferred Method of Practicing Using the above-described biological-molecule-accretion material which is a solid, a method may be practiced for extracting desired target biological molecules from aqueous solution and substantially permanently binding them to that solid. The method includes the step of forming a solid with a binding affinity for such molecules. The forming step is preferably practiced by making the above-described biological-molecule-accretion material 10. The method also includes the steps of shaping the solid into a body and placing the body into a water-filtration apparatus with an input and an output, and passing aqueous solution containing such molecules through the filtration apparatus to remove them substantially from such solution, and substantially permanently bind them to the solid. Next, there is a step of repeating the passing step with additional aqueous solution and maintaining binding of the accreted proteins, peptides and nucleic acids to the solid.

Use of material 10 also involves a method of filtering target biological molecules out of water. That method includes a step of forming a filter bed by the substeps of soaking a mixture of dextran and activated charcoal in water for a preselected time period, adding to the mixture an ion-exchange resin with a preselected charge-sensitivity, drying the mixture, and then rehydrating the mixture. The second step involves placing the filter bed into a water-filtration apparatus with an input and an output, and the third step involves passing water

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WO 95/05240 PCT/US94/09187 11 containing the target biological molecules through the filtration apparatus to capture substantially the target biological molecules in the filter bed.

It is presently proposed to maintain material 10 in a wet condition throughout its working life, although if the material were to dry out, a simple rehydration step could be performed as described above. Such rehydration was performed in connection with Example IV above and that amount of material exhibited 99.99 permanent binding efficiency.

When material 10 has exceeded its working life, it is dried by aspiration, removed from water-filtration apparatus 14, and disposed of as solid radioactive waste. Any effluent from aspirating may be poured down a drain if sufficiently low radioactivity is detected. It is presently contemplated that state and federal regulations do, or may soon, require extremely low or no radioactivity for effluent poured down a drain to a public water supply. With those regulations in mind, multiple-stage filtration systems utilizing material 10 may be used until a sufficiently low radioactivity is detected.

It should also be understood that material 10 could be tailored to be selective to certain types of molecules as opposed to being designed for removal of the entire class of target molecules listed above. For example, if one wanted to remove only those molecules with negative charges in aqueous solution (such as DNA compounds), then only a cation-exchange resin would be used as 4 11 O3 The present invention achieves the above objects by providing a composite biological-molecule-accretion material for extracting desired target biological molecules from aqueous solution and substantially permanently binding to those molecules. That material overcomes the drawbacks of prior-art materials, and provides for such extraction/removal and binding to a relatively wide variety of molecules such as the target molecules listed above. The invented material has presently shown to have a relatively long working life, and when its working life is over the material can be disposed of readily and easily. Based on its preferred embodiment, the material can also be easily and cost-effectively manufactured.

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WO 95/05240 PCT/US94/09187 Accordingly, while a preferred embodiment of the invention has been described herein, it is appreciated that modifications are possible that are within the scope of the invention.

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Claims (17)

1. A composite biological-molecule-accretion material for extracting target biological molecules from both basic and acidic aqueous solutions and substantially permanently binding to those molecules comprising: a first component comprising activated charcoal which is coated with a water soluble, high molecular weight substance; a second component comprising an anionic exchange resin; and, a third component comprising a cationic exchange resin; wherein the material is capable of being formed into a body for passing such solution through it, with such passing having the effect of removing target biological molecules comprising proteins, peptides and nucleic acids from such solution and binding them to the body, and with the binding being substantially permanent so that subsequent passage of additional aqueous solutions at both 15 acidic and basic pHs will not substantially unbind the accreted proteins, peptides and nucleic acids.

2. The material of claim 1 wherein the first component includes activated charcoal which is coated with dextran.

3. The material of claim 1 which further comprises sand as a filler.

4. The material of claim 1 wherein the anion exchange resin comprises, or is derived from, cellulose. The material of claim 1 being formed of two parts by volume of the first component, one part by volume anion-exchange resin, and one part by volume cation-exchange resin.

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6. The material of claim 1 wherein the body is capable of binding to DNA molecules contained in such solution and maintaining such binding to at least of those molecules after subsequent passage of additional aqueous solution containing a detergent.

7. The material of claim 1 wherein the body is capable of binding to DNA molecules contained in such solution and maintaining such binding to at least of those molecules after subsequent passage of additional aqueous solution 10 containing 0.1% sodium dodecyl sulfate. O

8. The material of claim 1 wherein the body is capable of binding to DNA molecules contained in such solution and maintaining such binding to at least 95% of those molecules after subsequent passage of additional aqueous solution 15 containing 50% formamide solution.

9. The material of claim 1 wherein the body is capable of binding to peptides contained in mixed waste that includes a toxic organic solution and a radiolabeled peptide in aqueous solution, and maintaining such binding to at least 95% of those peptides after subsequent passage of aqueous solution. The material of claim 1 wherein the body is capable of binding to an amount of 125 -P-endorphine (1 25 1-sEP) contained in mixed waste that includes acetonitrile/60% water by volume, and maintaining such binding to at least 95% of the amount of 1 25 1I/EP after subsequent passage of aqueous solution.

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11. A target-biological-substance-retaining filter mnaterial for use in a filter system to remove target biological substances from both acidic and basic aqueous solutions comprising: a first component comprising activated charcoal which is coated with a water soluble, high molecular weight substance; a second component comprising an anionic exchange resin; and, a third component comprising a cationic exchange resin; wherein the material is capable of being formed into a body for passing such solution through it, with such passing having the effect of removing target 10 biological molecules from such solution and binding them to the material, and with the binding being substantially permanent so that subsequent passage of additional aqueous solutions at both acidic and basic pHs will not substantially unbind the molecules, with the components being useable in a desired thickness in a filter system to provide a filter body that defines paths through such thickness for allowing the aqueous solution to pass, and removes substantially the target biological molecules by binding them to the material.

12. A target-biological-substance-retaining filter system for removing target biological substances from both acidic and basic aqueous solutions said system comprising: a hollow housing having an inlet and outlet and (ii) a filter material contained within the housing said material comprising: a first component comprising activated charcoal which is coated with a water soluble, high molecular weight substance; a second component comprising an anionic exchange resin; and, a third component comprising a cationic exchange resin; wherein the filter material is capable of being formed into a body for passing such solution through it, with such passing having the effect of I removing target biological molecules from such solution and binding them to the body, and with the binding being substantially permanent so that subsequent passage of additional aqueous solutions both at acidic and basic pHs will not substantially unbind the accreted molecules with the filter materials being useable in a desired thickness in the filter system to provide a filter body that defines paths through such thickness for allowing the aqueous solution to pass, and removes substantially the target biological molecules by binding them to the material. eeoete S 10

13. A method for extracting target biological molecules from multiple basic and acidic aqueous solutions and substantially permanently binding to those molecules, the method comprising the step of: contacting the aqueous solutions having biological molecules therein with a solid material comprising: 15 a first component comprising activated charcoal coated with a water soluble, high molecular weight polymer, a second component comprising an anionic exchange resin; and a third component comprising a cationic exchange resin, with the second •and third components mixed with the first component to provide a plurality of positively and negatively charged sites therein; whereby the amount of material is sufficient to bind more than 95% of the target biological materials in the aqueous solutions and the binding is substantially permanent so that the subsequent passage of additional aqueous solutions at both acidic and basic pHs will not substantially unbind the accreted target biological molecules

14. The method of claim 13 further comprising the steps of: shaping the solid material into a filter body by placing the solid into a water-filtration apparatus with an input and an output; and R"C0C KET O' passing aqueous solutions containing target biological molecules through the filtration apparatus to substantially remove target molecules comprising proteins, peptides and nucleic acids from such solutions.

15. The method of claim 13 or 14 further comprising the step of repeating the passing step with additional aq{iaous solutions having acidic and basic pHs.

16. The method of anyone of claims 13 to 15 wherein the water soluble, high molecular weight polymer is dextran.

17. A method for extracting target biological molecules from multiple acidic and basic aqueous solutions by forming a filter bed of accretion material comprising: a first component comprising activated charcoal coated with a water 15 soluble, high molecular weight polymer; and a second component comprising an anionic exchange resin; and a third component comprising a cationic exchange resin, with the second and third components mixed with the first component to provide a plurality of positively and negatively charged sites therein; wherein the method comprises the steps of: placing the accretion material into a water-filtration apparatus to form a filter bed said apparatus having an input and an out. and passing acidic and basic aqueous solutions containing the target biological molecules through the inlets of the filtration apparatus, with such passing having the effect of removing target biological molecules comprising proteins, peptides, and nucleic acids from such solutions and binding them to the filter bed; whereby the subsequent passage of additional aqueous solutions at both -lu P M acidic and basic pHs will not substantially unbind the accreted target biological molecules. Dated this seventeenth day of June 1997. OREGON HEALTH SCIENCES UNIVERSITY Patent Attorneys for the Applicant: F.B. RICE CO. a LI II II