Details for Patent: 5,505,932

Title:	Method for the preparation of fluorocarbon-containing polymeric shells for medical imaging
Abstract:	In accordance with the present invention, compositions comprising imaging agent(s) contained within polymeric shells are provided. Invention compositions are useful, for example, as contrast agents for magnetic resonance imaging (MRI), ultrasonography, and X-ray computer tomography. The polymeric shell diameter is typically approximately 2 microns in diameter. Consequently, these materials have organ specificity due to rapid scavenging by the reticuloendothial system (RES) or the mononuclear phagocyte (MNP) system upon intravenous injection. Furthermore, polymeric shells of the invention can be used to measure and monitor local oxygen and temperature. Exemplary contrast agents contemplated for use in the practice of the present invention include fluorinated compounds. Fluorinated compounds in general are hydrophobic and as such have limited water solubility. The invention method permits preparation of such compounds in a biocompatible form suitable for ready delivery.
Inventor(s):	Grinstaff; Mark W. (Pasadena, CA), Desai; Neil P. (Los Angeles, CA), Suslick; Kenneth S. (Champaign, IL), Soon-Shiong; Patrick (Los Angeles, CA), Sandford; Paul A. (Los Angeles, CA), Merideth; Noma R. (Pacific Palisades, CA)
Assignee:	Vivorx Pharmaceuticals, Inc. (Santa Monica, CA)
Filing Date:	Jun 06, 1995
Application Number:	08/478,986
Claims:	1. A method for the preparation of imaging agent(s) for in vivo delivery, said method comprising subjecting biocompatible polymer capable of being crosslinked by disulfide bonds and said imaging agent(s) in suitable media to ultrasonic irradiation conditions for a time sufficient to promote crosslinking of said biocompatible polymer by disulfide bonds; said crosslinking occuring directly, that is, without a crosslinking agent being used; wherein said agent is substantially completely contained within a polymeric shell, wherein the largest cross-sectional dimension of said shell is no greater than about 10 microns, and wherein said polymeric shell containing agent therein is suspended in a biocompatible aqueous liquid for in vivo delivery. 2. A method according to claim 1 wherein said crosslinking occurs under static conditions of ultrasonic irradiation. 3. A method according to claim 1 wherein said crosslinking occurs under continuous flow conditions of ultrasonic irradiation. 4. The method according to claim 1, wherein said imaging agent is a fluorine-containing magnetic imaging agent selected from: (a) C.sub.x F.sub.2x+y-z A.sub.z, wherein: x=1-30, y=2; or 0 or -2, when x.gtoreq.2; or -4 when x.gtoreq.4, z=any whole number from 0 up to (2x+y-1), and A is selected from H, halogens other than F, -CN, -OR, wherein R is H, alkyl, fluoroalkyl, alkenyl, fluoroalkenyl, alkynyl, fluoroalkynl, aryl, fluoroaryl, alkanoyl, fluoroalkanoyl, alkenoyl, fluoroalkenoyl, alkynoyl, fluoroalkynoyl, (b) [C.sub.x F.sub.2x+y,-z A.sub.z ].sub.a JR.sub.b-a, wherein: x, z, A and R are as defined above, y'=+1; or -1 or -3, when x.gtoreq.2; or -5 when x.gtoreq.4, J=O, S, N, P, Al or Si, a=1, 2, 3, or 4, and b=2 for a divalent J, or 3 for a trivalent J, or 4 for a tetravalent J, (c) A'-[(CF.sub.2).sub.x -O].sub.c -A", wherein: x is as defined above, A' is selected from H, halogens, -CN, -OR, wherein R is H, alkyl, fluoroalkyl, alkenyl, fluoroalkenyl, alkynyl, fluoroalkynyl, aryl, fluoroaryl, alkanoyl, fluoroalkanoyl, alkenoyl, fluoroalkenoyl, alkynoyl, fluoroalkynoyl, A" is selected from H or R, wherein R is as defined above, c=1-300, or ##STR2## wherein: x is as defined above, and c'=2-20, as well as mixtures of any two or more thereof. 5. The method according to claim 1, wherein said biocompatible polymer and imaging agent(s) are subjected to ultrasonic irradiation conditions comprising acoustic power in the range of about 1 up to 1000 watts/cm.sup.2. 6. The method according to claim 1, wherein said biocompatible polymer and imaging agent(s) are subjected to ultrasonic irradiation conditions comprising acoustic power in the range of about 50 up to 200 watts/cm.sup.2. 7. The method according to claim 1, wherein said biocompatible polymer and imaging agent(s) are subjected to ultrasonic irradiation conditions for less than 5 minutes. 8. The method according to claim 1, wherein said biocompatible polymer and imaging agent(s) are subjected to ultrasonic irradiation conditions for a time ranging from about 15 seconds up to 60 seconds. 9. The method according to claim 1, wherein said imaging agent(s) is (are) initially dissolved or suspended in a dispersing agent. 10. The method according to claim 1, wherein said dispersing agent is selected from vegetable oil, aliphatic, cycloaliphatic, or aromatic hydrocarbons having 4-30 carbon atoms; aliphatic or aromatic alcohols having 2-30 carbon atoms; aliphatic or aromatic esters having 2-30 carbon atoms; alkyl, aryl, or cyclic ethers having 2-30 carbon atoms; alkyl or aryl halides having 1-30 carbon atoms; ketones having 3-30 carbon atoms; polyalkylene glycols; or combinations of any two or more. 11. The method according to claim 10, wherein said vegetable oil is selected from soybean oil, mineral oil, corn oil, rapeseed oil, coconut oil, olive oil, safflower oil, or cotton seed oil. 12. The method according to claim 1, wherein said imaging agent(s) is (are) dissolved in a volatile organic solvent prior to being subjected to ultrasonic irradiation conditions. 13. The method according to claim 8, further comprising evaporating the volatile organic solvent under vacuum prior to suspending said polymeric shells in a biocompatible aqueous liquid. 14. The method according to claim 1, wherein said biocompatible aqueous liquid is selected from water, saline, a solution containing appropriate buffers, or a solution containing nutritional agents. 15. The method according to claim 14, wherein said nutritional agent is selected from amino acids, sugars, proteins, carbohydrates, vitamins, or fats. 16. The method according to claim 1, wherein said polymeric shell comprises polyethylene glycol covalently linked thereto. 17. The method according to claim 1, wherein said imaging agent(s) is (are) useful for the in vivo determination of local oxygen concentrations. 18. The method according to claim 1, wherein said imaging agent(s) is (are) capable of undergoing a phase transition. 19. The method according to claim 1, wherein said biocompatible polymer is selected from naturally occurring or synthetic polymers. 20. The method according to claim 19, wherein said naturally occurring polymers are selected from proteins containing sulfhydryl groups and/or disulfide groups, polypeptides containing sulfhydryl groups and/or disulfide groups, lipids containing sulfhydryl groups and/or disulfide groups, polynucleic acids containing sulfhydryl groups and/or disulfide groups, or polysaccharides containing sulfhydryl groups and/or disulfide groups. 21. The method according to claim 19, wherein said synthetic polymers are selected from synthetic polypeptides containing sulfhydryl groups and/or disulfide groups, polyvinyl alcohol modified to contain free sulfhydryl groups and/or disulfide groups, polyhydroxyethyl methacrylate modified to contain free sulfhydryl groups and/or disulfide groups, polyacrylic acid modified to contain free sulfhydryl groups and/or disulfide groups, polyethyloxazoline modified to contain free sulfhydryl groups and/or disulfide groups, polyacrylamide modified to contain free sulfhydryl groups and/or disulfide groups, polyvinyl pyrrolidone modified to contain free sulfhydryl groups and/or disulfide groups, polyalkylene glycols modified to contain free sulfhydryl groups and/or disulfide groups, as well as mixtures of any two or more thereof. 22. The method according to claim 1, wherein crosslinking of said biocompatible polymer by disulfide bonds occurs by reaction with free radicals. 23. The method according to claim 1, wherein said biocompatible polymer is albumin. 24. The method according to claim 20, wherein said biocompatible, naturally occurring polymer is hemoglobin. 25. The method according to claim 20, wherein said biocompatible, naturally occurring polymer is gluten. 26. The method according to claim 20, wherein said biocompatible, naturally occurring polymer is lipase. 27. The method according to claim 1, wherein said imaging agent is selected from superparamagnetic or paramagnetic metal particles suspended in a biocompatible medium. 28. The method according to claim 27, wherein said metal particle is iron, iron oxide, manganese or manganese oxide. 29. The method according to claim 27, wherein said particles are suspended in a biocompatible fluorocarbon medium selected from: (a) C.sub.x F.sub.2x+y-z A.sub.z, wherein: x=1-30, y=2; or 0 or -2, when x.gtoreq.2; or -4 when x.gtoreq.4, z=any whole number from 0 up to (2x+y-1), and A is selected from H, halogens other than F, -CN, -OR, wherein R is H, alkyl, fluoroalkyl, alkenyl, fluoroalkenyl, alkynyl, fluoroalkynl, aryl, fluoroaryl, alkanoyl, fluoroalkanoyl, alkenoyl, fluoroalkenoyl, alkynoyl, fluoroalkynoyl, (b) [C.sub.x F.sub.2x+y,-z A.sub.z ].sub.a JR.sub.b-a, wherein: x, z, A and R are as defined above, y'=+1; or -1 or -3, when x.gtoreq.2; or -5 when x.gtoreq.4, J=O, S, N, P, Al or Si, a=1, 2, 3, or 4, and b=2 for a divalent J, or 3 for a trivalent J, or 4 for a tetravalent J, (c) A'-[(CF.sub.2).sub.x -O].sub.c -A", wherein: x is as defined above, A' is selected from H, halogens, -CN, -OR, wherein R is H, alkyl, fluoroalkyl, alkenyl, fluoroalkenyl, alkynyl, fluoroalkynyl, aryl, fluoroaryl, alkanoyl, fluoroalkanoyl, alkenoyl, fluoroalkenoyl, alkynoyl, fluoroalkynoyl, A" is selected from H or R, wherein R is as defined above, c=1-300, or ##STR3## wherein: x is as defined above, and c'=2-20, as well as mixtures of any two or more thereof. 30. The method according to claim 1, wherein said magnetic resonance imaging agent is selected from gadolinium, dysprosium, or manganese metal complexes that are encapsulated within the polymeric shell. 31. The method according to claim 1, wherein said polymeric shell containing agent therein is suspended in a biocompatible aqueous liquid. 32. The method according to claim 31, wherein said biocompatible aqueous liquid is selected from water, buffered aqueous media, saline, buffered saline, solutions of amino acids, solutions of sugars, solutions of vitamins, solutions of carbohydrates, or combinations of any two or more thereof. 33. The method according to claim 1, wherein said agent is contained within said shell neat. 34. The method according to claim 1, wherein said agent within said shell is dissolved or suspended in a biocompatible dispersing agent. 35. The method according to claim 33, wherein said biocompatible dispersing agent is selected from soybean oil, mineral oil, corn oil, rapeseed oil, coconut oil, olive oil, safflower oil, cotton seed oil, aliphatic, cycloaliphatic or aromatic hydrocarbons having 4-30 carbon atoms, aliphatic or aromatic alcohols having 2-30 carbon atoms, aliphatic or aromatic esters having 2-30 carbon atoms, alkyl, aryl, or cyclic ethers having 2-30 carbon atoms, alkyl or aryl halides having 1-30 carbon atoms, optionally having more than one halogen substituent, ketones having 3-30 carbon atoms, 36. A method for the preparation of imaging agent(s) for in vivo delivery, said method comprising subjecting biocompatible polymer capable of being crosslinked by disulfide bonds and said imaging agent(s) to conditions suitable to disperse said imaging agent(s) into said biocompatible polymer, and to conditions suitable to promote crosslinking of said biocompatible polymer by disulfide bonds; said crosslinking occuring directly, that is, without a crosslinking agent being used; wherein said agent is substantially completely contained within a polymeric shell, wherein the largest cross-sectional dimension of said shell is no greater than about 10 microns, and wherein said polymeric shell containing agent therein is suspended in a biocompatible aqueous liquid for in vivo delivery.