Redox controlled electrosorption and decomposition device for the purification of blood and other fluids

Abstract

Device for removing substances from blood and other fluids such as water, wastewater, chemicals and other biofluids, includes i) an electrocatalytic decomposition filter including a DC power source, a set of electrodes with a catalytic surface or in direct contact with sorbents offering catalytic activity, ii) an electrosorption filter including a DC power source, a set of electrodes, nanostructured sorption material and/or a porous polymer matrix, iii) an inlet for entry of blood or blood plasma or dialysate fluid into the device, iv) an outlet for the removal of purified blood, blood plasma, ultrafiltrate or dialysate fluid from the device, and v) a conduit connecting the inlet with the outlet and holding the electrosorption filter such that the blood, blood plasma, ultrafiltrate or dialysate fluid is forced through the electrosorption and electrocatalytic decomposition filter, and vi) a sensor and control system to safeguard the device from producing oxidative stress.

Claims

1. A device for the removal of toxic substances from dialysate fluid, blood, blood plasma or ultra filtrate, comprising: i) a housing having an inlet for entry of dialysate fluid, blood, blood plasma or ultrafiltrate into said housing, an outlet for the removal of purified dialysate fluid, blood, blood plasma or ultrafiltrate and excess fluid from said housing, and a conduit connecting said inlet with said outlet ii) an electrocatalytic decomposition filter for removing toxins, toxic solutes, toxic small and middle-sized molecules and protein bound toxins from the dialysate fluid, blood, bloodplasma or ultrafiltrate, said electrocatalytic decomposition filter being contained in said conduit such that said dialysate fluid, blood, blood plasma or ultrafiltrate must pass through said electrocatalytic decomposition filter when flowing from said inlet to said outlet and said electrocatalytic decomposition filter comprising: a) a set of electrodes with an electrocatalytic surface for decomposition and gasification of toxins via electro-oxidation b) or a set of electrodes that are in direct electrical contact with porous materials that have been coated with electrocatalytic material c) power source to provide the electrodes with an electrical charge in order to activate the electrocatalytic electrode surface or the electrocatalytic material d) an electronic means to control and switch the electrical charge on the electrodes in view of resorbing and release of toxins and to prevent built-up of deposits on the electrodes, iii) an electrosorption filter for removing toxins, toxic solutes, toxic small and middle-sized molecules and protein bound toxins from the dialysate fluid, blood, blood plasma or ultrafiltrate, said electrosorption filter being contained in said conduit such that said dialysate fluid, blood, blood plasma or ultrafiltrate must pass through said electrosorption filter when flowing from said inlet to said outlet and said electrosorption filter comprising: a) a nanostructured sorption material; b) a set of electrodes coated with or in electrical contact with the sorption material; c) a power source to provide the electrodes with an electrical charge and generate an electrical field strength in the sorption medium; d) a sensor unit for monitoring the quality of the cleansed dialysate fluid, blood, blood plasma or ultrafiltrate and a control system to correct and adjust the quality of the cleansed dialysate fluid, blood, blood plasma or ultrafiltrate, wherein the sensor unit is configured for monitoring the redox state and the electrocatalytic decomposition rate of the cleansed dialysate fluid, blood, blood plasma or ultrafiltrate and the control system is configured for controlling infusion of a reducing agent to correct and adjust the cleansed dialysate fluid, blood, blood plasma or ultrafiltrate to prevent oxidative stress wherein the electrodes are made from carbonaceous material.

2. Device according to claim 1, wherein the electrosorption filter and electrocatalytic decomposition filter are combined into one filter compartment wherein the sorption material is contained in between the electrocatalytic electrodes.

3. Device according to claim 2, wherein said electrocatalytic decomposition and electrosorption filter is provided in the form of a cartridge with said electrodes coated with said sorption material or with said electrodes surrounded by a porous envelop containing said sorption material.

4. Device according to claim 2, wherein said electrocatalytic decomposition and electrosorption filter is combined with a permeable envelop to form a filter pad comprising an envelop surrounding a filter pad contents, wherein the envelop of said pad comprises a permeable membrane and the contents of said pad comprise said sorption material.

5. Device according to claim 4, further comprising a hemofilter for separating patient ultrafiltrate from patient blood cells or to allow blood-dialysate toxin exchange in a dialysis setup, and a plasmafilter and said electrosorption filter are combined to form a filter pad wherein a permeable membrane is formed by said plasmafilter.

6. Device according to claim 2, wherein said device further comprises a plasmafilter for separating patient blood plasma from patient blood cells.

7. Device according to claim 2, wherein said device further comprises a hemofilter for separating patient ultrafiltrate from patient blood cells or to allow blood-dialysate toxin exchange in a dialysis setup.

8. Device according to claim 2, wherein said device further comprises an electrosorption filter for removing toxins, small and middle-sized molecules from the patient blood plasma.

9. Device according to claim 2, wherein said device further comprises means for supplementing said dialysate fluid and/or said (purified) blood plasma with at least one substance selected from the group consisting of vitamins, minerals, anticoagulants, anti microbial agents and other medicaments.

10. Device according to claim 2, wherein said device further comprises ion exchange systems.

11. Device according to claim 2, wherein the sorption materials are being regenerated with a regeneration fluid in combination with a reversed voltage mode on the electrodes, and that optionally the voltage of the external source is electronically regulated depending on the reading of the sensor system and/or can be reversed into opposite values in order to repel and to release toxins, unwanted deposits and to regenerate the sorption materials.

12. Device according to claim 1, wherein said device further comprises a plasmafilter for separating patient blood plasma from patient blood cells.

13. Device according to claim 12, further comprising an electrosorption filter for removing toxins, small and middle-sized molecules from the patient blood plasma, said hemofilter and a electrosorption filter being combined to form a filter pad wherein a permeable membrane is formed by said hemofilter.

14. Device according to claim 1, wherein said device further comprises a hemofilter for separating patient ultrafiltrate from patient blood cells or to allow blood-dialysate toxin exchange in a dialysis setup.

15. Device according to claim 1, wherein said device further comprises an electrosorption filter for removing toxins, small and middle-sized molecules from the patient blood plasma.

16. Device according to claim 1, wherein said device further comprises means for supplementing said dialysate fluid and/or said (purified) blood plasma with at least one substance selected from the group consisting of vitamins, minerals, anticoagulants, anti microbial agents and other medicaments.

17. Device according to claim 1, wherein said device further comprises ion exchange systems.

18. Device according to claim 1, wherein the sorption materials are being regenerated with a regeneration fluid in combination with a reversed voltage mode on the electrodes, and that optionally the voltage of the external source is electronically regulated depending on the reading of the sensor system and/or can be reversed into opposite values in order to repel and to release toxins, unwanted deposits and to regenerate the sorption materials.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic setup of the fluidic system for a hemodialysis application. Blood of a patient is being purified via a dialysis procedure using a hemofilter and a dialysate circuit. The dialysate in the circuit is being continuously purified by a sorbent unit equipped with sorbents and electrodes for electrosorption and electrocatalytical decomposition. Dimensions of the sorbent unit are in the range of 100-1000 ml, typically around 200 ml. The volume of the dialysate is in the range of 50-500 ml, typically 100 ml. The weight of the dialysate and sorbent unit together are in the range of 150-1500 grams, typically 300 grams. After saturation with toxins, the sorbent unit can be regenerated by flushing with a saline or other sodium salt solution in order to remove the toxins. The frequency hereof depends on the size of the patient and the size of the sorbent unit, typically 1-4 times a day. A sensor and control system is provided in order to secure the quality of the dialysate. In order to safeguard the patient from oxidative stress, the redox state of the dialysate is continuously measured and based here on the intensity of the electrochemical decomposition is being adjusted. As a second safety measure, an injector system with a reducing agent such as vitamin C can be activated in case of an emergency. This injector system can also be used to infuse medicine or compounds such as bicarbonate to correct the acidose of the patient.

(2) FIG. 2 shows a prototype version of a wearable hemodialysis device based upon the invention. It contains a hemofilter, blood pump, dialysate pump, various sensors to monitor the quality of the dialysate (temperature, pressure, conductivity, pH and redox), the sorbent unit with electrosorption and electrocatalytic decomposition and a degaser.

(3) FIG. 3-6 are experimental results obtained with a prototype of the invention and indicate the typical performance in terms of clearance of toxins.

(4) FIG. 7 shows a typical example of a coulometric redox state sensor which can be used to measure the oxidation-reduction potential of the cleansed fluid

(5) FIG. 8 shows the response of such a sensor upon the presence of chloramines as a byproduct from electrocatalytic decomposition. In order to stay on the safe side for biocompatibility the level of chloramines must be kept below 0.1 mg/1, this corresponds to a redox value of <20 mV for this sensor.

(6) FIG. 9 shows the amount of vitamin C that is needed to neutralize the presence of chloramines in case of a breakout. The anti-oxidant vitamin C will react (reduce) with the chloramines to form harmless chloride ions and amines.

(7) FIGS. 10 and 11 show experimental results with respect to the prevention of oxidative stress measured with a MDA test (lipid oxidation) and AOPP test (protein oxidation)

DETAILED DESCRIPTION OF THE INVENTION

(8) The term sorption as used herein, refers to both adsorption and absorption. Adsorption is a process that occurs when a gas or liquid or solute (called adsorbate) accumulates on the surface of a solid or more rarely a liquid (adsorbent), forming a molecular or atomic film (adsorbate). It is different from absorption, where a substance diffuses into a liquid or solid to form a solution. The term sorption encompasses both processes, while desorption is the reverse process.

(9) The term small-sized molecules, as used herein, refers to molecules with a molecular weight lower than 500 Da, such as uric acid, urea, guanidine, ADMA, creatinine.

(10) The term middle-sized molecules, as used herein, refers to molecules with a molecular weight between 500 Da and 5000 Da, such as end products from peptides and lipids, amines, amino acids, protein bound compounds, cytokines, leptins, microglobulins and some hormones.

(11) The term nanoporous materials refers to materials having pores that are by definition roughly in the nanometer range, that is between 1?10.sup.?7 and 0.2?10.sup.?9 m and includes reference to the 3 categories set out by IUPAC of microporous materials (such as zeolites) having pore sizes of 0.2-2 nm; mesoporous materials having pore sizes of 2-50 nm; and macroporous materials having pore sizes of 50-1000 nm.

(12) The term ionic solutes, as used herein, refers to components such as phosphates, sulphates, carbon hydrates, chlorides, ammonia, potassium, calcium, sodium.

(13) Nano sized as used herein, refers to a size of approximately 1-1000 nm, more preferably 1-100 nm.

(14) The term electrosorption refers to a process where ionic solutes and charged molecules in a solution are being adsorpted onto the surface of a sorbent with the help of an additional electrical surface charge on the sorbent provided by an electrical power source.

(15) The term electrosorption filter refers to a filter system comprising a sorbent that can be electrically charged or discharged with an external power source via electrodes connected to the sorbent material.

(16) The term catalytic as used herein, refers to a process that specific chemical reactions are being promoted when in contact with another material due to specific inter-molecular interactions.

(17) The term electrocatalytic as used herein refers to a catalytic chemical reaction that is being initiated via electrical activation.

(18) The term decomposition as used herein refers to a chemical reaction where a component is broken down to its smaller constituents.

(19) The term gasification as used herein refers to a chemical reaction where the component is being gasified and released from the system.

(20) The term electrocatalytic decomposition as used herein refers to a process where a chemical component is being broken down into smaller chemical species, preferrably gaseous species, via electrocatalytic oxidation.

(21) The term electrocatalytic decomposition filter as used herein refers to a filter system comprising electrodes that remove toxins via electrocatalytic activated decomposition of these toxins and subsequent gasification.

(22) The term electrosorption-decomposition filter as used herein refers to a filter system that combines an electrosorption filter and an electrocatalytic decomposition filter.

(23) The Purification Device Holding an Electrosorption and Decomposition Filter Package

(24) A device of the present invention can take the form of an electrosorption and decomposition filter package that is placed in the dialysis fluid system of a hemodialysis or peritoneal dialysis system, enabling the removal of toxins from the dialysis fluid. The electrosorption and decomposition filter continuously purifies the dialysate fluid, keeping the toxin concentration in the dialysis fluid low, resulting in an improvement of the hemodialysis and peritoneal dialysis efficiency, typically with 100%, and reduces the consumption of dialysis fluid needed dramatically, ideally down to 0.1-1 liters. An additional and optional function of the sorption filter is to release ingredients for supplementing of the blood such as calcium, vitamin A, C and B12, anti-coagulation agents, anti microbial agents, minerals, specific medicaments etc. This option will simplify the operation of existing hemodialysis and peritoneal dialysis systems and will reduce the chance on occurring infections in the peritoneal dialysis system. Infusion of ingredients, supplements or medicaments can also be delivered by the injector system which is part of the redox state control system.

(25) A device of the present invention can take the form of wearable peritoneal dialysis system wherein the electrosorption and decomposition filter package is placed in a wearable peritoneal dialysis system. Due to the continuous filtering of the electrosorption and decomposition filter, the volume of dialysate fluid can be reduced to typically 1-2 liters. The wearable peritoneal dialysis device comprises a tubular access system to the abdominal cavity and a unit comprising a fluid pump, power, sensors, electronic control, a facility to place and replace said electrosorption and decomposition filter package, typically on a daily basis and a system to dispose off excess water. The injector system of the redox control unit can be used to infuse continuously glucose in the peritoneal fluid in order to maintain osmotic pressure for extracting fluid from the patient. This may lower the overall glucose concentration needed and this in turn may enfavour the condition and lifetime of the patients peritoneal membrane.

(26) A device of the present invention can take the form of wearable hemodialysis system wherein the electrosorption and decomposition filter system is placed in a wearable hemodialysis system. Thanks to the continuous filtering of the electrosorption and decomposition filter, the volume of dialysate fluid can be reduced to typically 50-500 ml. The wearable hemodialysis device comprises a vascular access tubing system and a unit comprising a small hemofilter system, fluid pump, power, sensors, electronic control, a facility to place and replace said electrosorption and decomposition filter package, typically on a daily-to-weekly basis, and a system to dispose off excess water. An additional and optional function of the device is to release ingredients for supplementing the blood such as calcium, vitamin A, anti-coagulation agents, anti microbial agents, minerals, specific medicaments etc. This option will simplify the operation of the hemodialysis system and will reduce the chance on occurring infections.

(27) d) A device of the present invention can take the form of a wearable or desktop sized artificial kidney based on blood plasmafiltration or blood ultrafiltration combined with electrosorption and decomposition filtering. In such an embodiment, the blood plasma filtration step will performed by a special plasma filter, or the ultrafiltrate will be extracted via a special hemofilter, with a relative large pore size, that separates blood from plasma or the ultrafiltrate, allowing toxic solutes, small/middle molecules and protein bound toxins to pass with the plasma or ultrafiltrate into the compartment with the electrosorption-decomposition filter package for cleansing. Via an additional hemofilter with a smaller pore size, excess water can be removed from the blood plasma or ultrafiltrate preventing loss of albumin. The cleansed blood plasma or ultrafiltrate is then re-entered into the bloodstream. It will be understood that in such an embodiment, the device further comprises the necessary tubing, vascular access and feedback systems, pumping, electronics, sensors, power packs and other requirements. However, these are not essential to the present invention. An advantage of the artificial kidney device is that no dialysis fluid will be needed. In a preferred embodiment of this device, the plasma, ultrafiltrate or hemofilter and the electrosorption and decomposition filter are being combined to form a filter package, said filter package comprising an envelop, made from a hemofilter material, surrounding a filter material and electrodes.

(28) The fluidic scheme of such a device for hemodialysis treatment is depicted in FIG. 1. Blood from a patient is fed via blood lines 11 to a hemofilter at a flow rate of 100-200 ml/min (typically 125 ml/min). Toxins are transferred by the dialyzer membrane 13 (e.g. a high flux filter) to the dialysate circuit. In the dialysate circuit 15, the dialysate is passed through a sorbent unit 17 where the dialysate is being cleansed from toxins via electrosorption and electrocatalytic decomposition.

(29) Here urea, urate, ammonia, creatinine and other toxins with amine-groups are being decomposed and degased. The voltage over each pair of electrodes can be as high as 20 V but in order to limit hydrolysis, the voltage difference should be kept low, typically below 4 V. Other toxins such as the small solutes potassium and phosphate as well as toxic middle molecules as beta2microglobulin and the protein bound toxins such as p-cresol, indoxylsulphate and hyppuric acid are adsorbed in the electrosorption section.

(30) The nanostructured sorption materials herein offer a very large surface area and chemical activity to bind a high load of toxins, typically in the range of 10-50% on weight basis. This purification mode can be operated until the sorption material is saturated with toxins. This depends on the amount of sorbent used. A representative embodiment will comprise 100-500 grams (typically around 150-200 grams) of sorbent, allowing a continuous purification mode to last 6-24 hours. The device can be set into reverse mode by switching the external voltage into its opposite sign in combination with a regeneration fluid. With the reversed voltage, the sorption function changes into a repellent function and the toxins are enforced to unbind and to leave sorbent surface. Hereby the sorbent is being cleaned and regenerated. The released toxins in the compartment are removed by disposing the regeneration fluid.

(31) The quality of the dialysate is being monitored by a control unit 19. This control unit is provided with sensors 21, typically for temperature, conductivity, pH and redox state. The redox sensor 21 is used to safeguard the system for producing oxidative stress. Upon reading, the electrocatalytic decomposition is regulated and if needed the injector system 23 is activated for infusion of a reducing or oxidizing agent.

(32) In order to prevent fluidic overload, excess fluid can be withdrawn from the patient via a seperate line that removes ultrafiltrate from the patient. This can be done continuously (as a drain, typical flow rate 1 ml/min) or discontinuously a few times a day (e.g. 20 ml/min for 20 minutes).

(33) The volume of the disposed ultrafiltrate is typically around 1-2 L per day, the normal amount of excess fluid to be released by a human. The blood circuit 11 further comprises a temperature sensor 25, a blood pump 27 and a temperature pressure air bubble detector 29. The dialysate ciruit further comprises two valves 31, 32, a dyalysate pump 33 and a degasser 35.

(34) In FIG. 2 a picture is shown of a prototype version that is used for experimental verification. It comprises a hemofilter 41 in order to exchange toxins from the blood to the dialysate and to extract ultrafiltrate. The electrosorption and decomposition unit 43 continuously removes the toxins from the dialysate. Other components such as pumping units 45, 47, degas-unit 55, sensors 49-53 and fluidic valves and injector 57 are indicated in picture 2.

(35) The hemofilter in a device of the present invention is preferably a commercially available hemofilter (e.g. such as produced by Gambro GmbH, Hechingen, Germany or Membrana GmbH, Wuppertal, Germany).

(36) In an alternative embodiment the electrosorption and decomposition filter in a device of the invention may comprise an inlet 59 for receiving patient blood plasma or ultrafiltrate exiting said plasmafilter or hemofilter, and at least one outlet 61, 63 for recovery of purified blood plasma or ultrafiltrate.

(37) A device of the present invention may, in any embodiment, further comprise means for supplementing the (purified) blood plasma or dialysate fluid with at least one substance selected from the group consisting of vitamins such as vitamins A, C, E and B12; minerals such as calcium, sodium and potassium; anticoagulants; bicarbonate to restore the acidose of a patient, anti microbial agents and other medicaments.

(38) Optionally, the device or filter pad may comprise ion exchange systems.

(39) In another aspect, the present invention provides a method for removing toxic substances from blood, comprising using a device according to the present invention.

(40) In another aspect, the present invention provides a method for removing toxic substances from hemodialysis or peritoneal dialysis fluids, comprising using a device according to the present invention.

(41) In another aspect, the present invention provides a method for removing substances from other fluids such as water, e.g. for making drinking water or purifying aquarium water, and for purifying chemicals used in industrial processes as well as removing substances from other biofluids such as urine, milk, bio-analytical fluids, comprising using a device according to the present invention.

(42) The electrosorption and decomposition filter in a device of the present invention may take the form of a filter cartridge, consisting of a rigid or flexible container comprising a set of built-in electrodes and a replaceble filter pad with sorption materials.

(43) This, in another aspect, the present invention may take the form of a device with built-in electrodes connected to a power supply such as a battery or a rectifier, holding an electrosorption and decomposition filter cartridge in contact with these electrodes and comprising a blood plasma separator or hemofilter and a sorption filter pad with sorption materials for extracting ionic solutes and small and middle sized molecules from the blood plasm, ultrafiltrate or dialysate.

(44) In a preferred embodiment therefore, the device for the removal of toxic substances from blood from a patient, comprises a hemofilter and an electrosorption filter, wherein the electrosorption filter removes toxic solutes, small and middle-sized molecules from the blood based, and includes such functions as selective sorption, controlled release and anti-microbial control.

(45) In a most preferred embodiment, the plasmafilter of hemofilter, and electrosorption filter are separate parts. For instance, the plasmafilter or hemofilter may consist of an existing, commercially available plasmafilter or (high flux) hemofilter and the electrosorption filter may consist of a cartridge with built in electrodes. In this cartridge also the sorption material is contained. The sorption material can be held in a porous envelop to form a filter pad.

(46) The device of the present invention can be used for filtering or purification of blood of patients with a (developing) renal failure. In a preferred embodiment, the device takes the form of a wearable artificial kidney device, but can also be embodied in desktop sized equipment or in adapted hemodialysis or peritoneal dialysis equipment.

(47) The artificial kidney is able to perform some of the functions which normally will be done by a properly functioning human or animal kidney, in particular filtering of blood and regulation and control of the content of substances in the blood.

(48) Redox Control and Prevention Chloramines

(49) Chloramines are being formed as a byproduct from the electrocatalytic decomposition. In a solution where next to urea and organic toxins also chloride ions are present, the electrocatalytic decomposition will also interact with the chloride ions leading to oxidation and the formation of chorine (Cl2) and hypochlorite (HOCL) according to the following reactions.
2Cl.sup.?>Cl.sub.2+2e
Cl2+H.sub.2O>HOCl+HCl

(50) Hypochlorite in turn may react with ammonia or amines to form chloramines, predominantly monochloramine NH.sub.2Cl:
NH.sub.3+HOCl.fwdarw.NH.sub.2Cl+H.sub.2O

(51) Chloramines provide oxidative stress and this may harm e.g. red blood cells leading to hemolysis. This must be prevented at all times. The safety limit for chloramines is set to max. 0.1 mg/l (ANSI/AMI RD5 standard).

(52) One way of preventing chloramines is to make sure that sufficient sorbent material is present in the sorbent unit itself that is capable of absorbing or eliminating chloramines. Especially activated carbon is very useful in this respect since activated carbon can entrap chloramines and can break down chloramines by catalytic reduction. This is well known in the industry of water purification. It has been found that for a wearable hemodialysis device, a carbon trap of 50-100 grams is sufficient to eliminate all chloramines residues. Other types of carbon within the carbonaceous family such as nanotubes and graphene might show similar or even better capabilities.

(53) Also important in this respect is the choice and size of the electrocatalytic electrodes. It has been found that members of the carbonaceous family such as carbon and graphite tend to produce less chloramines than metal electrodes such as Pt. However the catalytic decomposition of urea and related toxins is also less efficient compared to Pt. This in turn effects the overall design of the system.

(54) In order safeguard the system from producing oxidative stress, a three level safety approach is followed:

(55) (1) depending on the capacity of the electrocatalytic decomposition system and the related production of chloramines, a carbon trap is employed with sufficient capacity to entrap and decompose the formed chloramines. For safety this carbon trap should be overdesigned e.g. with a factor two.

(56) (2) to control the efficiency of the carbon trap over time, the redox state is continuously monitored by means of redox sensor. The redox state is a measure for the level of chloramines. In case the redox state rises and tends to reach the limit value, the intensity of the electrocatalytic decomposition is reduced. This will lower the redox state. A redox state sensor measures the oxidation-reduction potential (ORP) of a fluid. Such a sensor can be a commercially available ORP sensor (usually comprising a Pt-electrode, Ag/AgCl reference electrode and a salt-bridge, see e.g. Mettler Toledo or Vernier) or a flow-through coulometric sensor as depicted in FIG. 7. In FIG. 7 three Pt wires are used for both the reference, working and counter electrode, but other materials such as Au, Ag or Ag/AgCl can also be used. In FIG. 8 the response is shown of such a sensor upon the presence of chloramines (oxidizing agent).

(57) (3) in case of a sudden, unexpected rise in redox state (e.g. due to a break through of chloramines) an injector is activated for the infusion of reducing agent such as vitamin C (ascorbic acid) or similar anti-oxidant. The antioxidant reduces the choramine back to ammonia and chloride ions:
C.sub.5H.sub.5O.sub.5CH.sub.2OH+NH.sub.2Cl>C.sub.5H.sub.3O.sub.5CH.sub.2OH+NH.sub.3+HCl

EXPERIMENTAL RESULTS

Example 1: Hemodialysis Performance

(58) A prototype has been built as depicted in FIG. 2. This setup has been tested in a dynamic test using 1.5 L of animal blood passing a high flux filter at 120 ml/min for dialysis treatment. The dialysate circuit contained 100 ml of dialysate. The electrosorption and decomposition unit was filled with 110 grams of an ion-exchange resin (ps-pvb), 50 grams of a nanostructured FeOOH sorbent and 50 grams of activated carbon. Graphite electrodes were used for the decomposition of urea and related toxins at a voltage of 3.6 V per electrode pair. The total electrode surface amounted to 585 cm.sup.2. The dialysate flow was set to 45 ml/min. Concentrations in the animal blood were measured every hour. After each hour the blood was spiked with new toxins (urea 10 mmol, potassium 1.5 mmol, phosphate 0.75 mmol, creatinine 0.5 mmol) in order to maintain a representative toxin level. The concentration profiles are depicted in FIG. 3-6, in which:

(59) FIG. 3 shows a diagram of Urea removal from 1.5 L animal blood (cow) with a sorbent unit with 160 g sorbents and 585 cm2 electrodes in a dialysis setup (Gambro 2H filter). Every hour the blood was spiked with 10 mmol urea. Total removed in 6 hours: 60 mmol urea;

(60) FIG. 4 shows a diagram of Creatinine removal from 1.5 L animal blood (cow) with a sorbent unit with 160 g sorbents and 585 cm2 electrodes in a dialysis setup (Gambro 2H filter). Every hour the blood was spiked with 0.5 mmol creatinine. Total removed in 6 hours: 3.7 mmol creatinine;

(61) FIG. 5 shows a diagram of Potassium removal from 1.5 L animal blood (cow) with a sorbent unit with 160 g sorbents and 585 cm2 electrodes in a dialysis setup (Gambro 2H filter). Every hour the blood was spiked with 1.5 mmol potassium. Total removed in 6 hours: 9 mmol potassium; and

(62) FIG. 6 shows a diagram of Phosphate removal from 1.5 L animal blood (cow) with a sorbent unit with 160 g sorbents and 585 cm2 electrodes in a dialysis setup (Gambro 2H filter). Every hour the blood was spiked with 0.75 mmol phosphate. Total removed in 6 hours: 5 mmol phosphate.

(63) The overall results are given in the table below.

(64) TABLE-US-00001 TABLE Hemodialysis experiment: 6 hours dialysis of animal blood Toxin Total removed in 6 hours (mmol) Urea 60 Creatinine 3.7 Potassium 9 Phosphate 5

(65) FIG. 7 shows an example of a coulometric flow through redox state sensor. It comprises three electrodes: a reference electrode, a working electrode where molecules are being oxidized or reduced and a counter electrode for measuring the amount of molecules that have been oxidized or reduced. In this setup the electrodes are Pt wires, but other geometries and metals (such as Au, Ag, AgCl) are also feasible.

(66) FIG. 8 shows a diagram of Chloramines and redox state versus electrocatalytic potential. As a first safety measure chloramine level is controlled below 0.1 mg/l by means of a redox sensor and a control system that regulates the electrocatalytic decomposition. The threshold value for chloramines is 0.1 mg/l (ANSI/AAMI RD5:2003). In this example (see experiment 1) it means that the voltage of the electrocatalytic decomposition should be kept below 4.1 V.

(67) FIG. 9 shows a diagram of Neutralization of chloramines with vitamin C. As a second safety measure infusion of vitamin C (or similar anti-oxidants such as sodium-ascorbate, vitamin E, glutathion) is initiated in case the voltage control mechanism fails to keep the chloramine level below 0.1 mg/l. This figure shows the amount of vitamin C that is needed to fully neutralize the presence of chloramines.

Example 2: Prevention of Oxidative Stress

(68) The prototype as described in example 1 was also used to verify the prevention of oxidative stress. Two oxidative stress tests have been performed: (1) MDA test: Lipid peroxidation is a well-defined mechanism of cellular damage in animals and plants. Lipid peroxides are unstable indicators of oxidative stress in cells that decompose to form more complex and reactive compounds such as Malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), natural byproducts of lipid peroxidation. Oxidative modification of lipids can be induced in vitro by a wide array of pro-oxidant agents and occurs in vivo during aging and in certain disease conditions. Measuring the end products of lipid peroxidation is one of the most widely accepted assays for oxidative damage. These aldehydic secondary products of lipid peroxidation are generally accepted markers of oxidative stress. (2) AOPP test: Advanced Oxidation Protein Products (AOPP) are uremic toxins created during oxidative stress through the reaction of chlorinated oxidants, such as chloramines and hypochlorous acid, with plasma proteins. AOPPs are structurally similar to Advanced Glycation End-Product (AGE) proteins and exert similar biological activities. AOPPs are elevated in patients with renal complications, atherosclerosis, diabetes mellitus, systemic sclerosis, as well as HIV-positive patients. Human Serum Albumin (HSA) treated with HOCl and AOPP generated in vivo can ignite oxidative reactions in both neutrophils and monocytes, which indicates both can be used as true mediators of inflammation

(69) The results of these tests are depicted in FIGS. 10 (MDA test) and 11 (AOPP test) in which:

(70) FIG. 10 shows a diagram of the effect of electrocatalytic decomposition on oxidative stress in which the Oxidative stress is measured according to the MDA test (lipid oxidation, formation of malondialdehyde adduct) at conditions as described in experiment 1. Electrocatalytic decomposition does not produce oxidative stress. Tendency is even to lower the oxidative stress (probably due to the presence of carbon in the dialysate circuit); and

(71) FIG. 11 shows a diagram of the effect of electrocatalytic decomposition on oxidative stress in which the Oxidative stress is measured according to the AOPP test (advanced protein oxidation formation) at conditions as described in experiment 1. Electrocatalytic decomposition does not produce oxidative stress.

(72) As is evident from these figures, the measures that were taken to prevent oxidative stress (carbon trap and voltage control on the electrocatalytic decomposition) appeared to be successful. No oxidative stress due to electrocatalytical decomposition could be detected.