Nanoparticulate probe for in vivo monitoring of tissue oxygenation

Abstract

A new class of micro- and nano-particulate paramagnetic spin probes especially useful for magnetic resonance imaging techniques, including electron paramagnetic resonance (EPR) and magnetic resonance imaging (MRI). The probes are lithium phthalocyanine derivative compounds. Also provided are suspensions and emulsions comprising lithium phthalocyanine derivative probes. Also provided are noninvasive methods for measuring noninvasive methods of measuring oxygen concentration, oxygen partial pressure, oxygen metabolism, and nitric oxide concentration in a specific tissue, organ, or cell in vivo or in vitro.

1 . A particulate probe comprising a lithium phthalocyanine derivative or a radical thereof selected from the group consisting of: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
       wherein R is selected from the group consisting of O(CH 2 ) n CH 3 , S(CH 2 ) n CH 3 , O(CH 2 ) n CH 2 OH, O(CH 2 ) n CH 2 NH 2 , O(CH 2 ) n CH 2 SH, and combinations thereof; and, wherein n is from 1 to 6. 
     
     
         2 . The particulate probe of  claim 1 , wherein the particulate probe has a size of up to 10 microns. 
     
     
         3 . The particulate probe of  claim 2 , wherein the particulate probe has a size of less than 0.22 microns. 
     
     
         4 . The particulate probe of  claim 1 , wherein the particulate probe has been derivatized to be a magnetic resonance imaging (MRI) probe, an electron spin resonance (ESR) probe, an electron paramagnetic resonance (EPR) probe, an electron paramagnetic resonance imaging (EPRI) probe, or a proton electron double resonance imaging (PEDRI) probe. 
     
     
         5 . The particulate probe of  claim 1 , wherein the probe comprises a compound of Formula 1 or a radical thereof: 
       
         
           
           
               
               
           
         
       
       wherein R is selected from the group consisting of O(CH 2 ) n CH 3 , S(CH 2 ) n CH 3 , O(CH 2 ) n CH 2 OH, O(CH 2 ) n CH 2 NH 2 , O(CH 2 ) n CH 2  SH, and combinations thereof; and, wherein n is from 1 to 6. 
     
     
         6 . The particulate probe of  claim 1 , wherein the probe comprises a compound of Formula 2 or a radical thereof: 
       
         
           
           
               
               
           
         
       
       wherein R is selected from the group consisting of O(CH 2 ) n CH 3 , S(CH 2 )nCH 3 , O(CH 2 ) n CH 2 OH, O(CH 2 ) n CH 2 NH 2 , O(CH 2 ) n CH 2 SH, and combinations thereof; and, wherein n is from 1 to 6. 
     
     
         7 . The particulate probe of  claim 1 , wherein the probe comprises a compound of Formula 5 or a radical thereof: 
       
         
           
           
               
               
           
         
       
       wherein R is selected from the group consisting of O(CH 2 ) n CH 3 , S(CH 2 ) n CH 3 , O(CH 2 ) n CH 2 0H, O(CH 2 ) n CH 2 NH 2 , O(CH 2 ) n CH 2 SH, and combinations thereof; and, wherein n is from 1 to 6. 
     
     
         8 . The particulate probe of  claim 1 , wherein the probe comprises a compound of Formula 6 or a radical thereof: 
       
         
           
           
               
               
           
         
       
       wherein R is selected from the group consisting of O(CH 2 ) n CH 3 , S(CH 2 ) n CH 3 , O(CH 2 ) n CH 2 0H, O(CH 2 ) n CH 2 NH 2 , O(CH 2 ) n CH 2 SH, and combinations thereof; and, wherein n is from 1 to 6. 
     
     
         9 . A suspension comprising a particulate probe for MR imaging, the probe having oxygen active centers, wherein the probe is a radical of a lithium phthalocyanine derivative, and wherein the suspension is in a medium selected from the group consisting of nonphysiological media, physiological media, buffers, and combinations thereof. 
     
     
         10 . The suspension of  claim 9 , wherein the particulate probe is selected from the group consisting of: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
       wherein R is selected from the group consisting of O(CH 2 ) n CH 3 , S(CH 2 ) n CH 3 , O(CH 2 ) n CH 2 OH, O(CH 2 ) n CH 2 NH 2 , O(CH 2 ) n CH 2 SH, and combinations thereof; and, wherein n is from 1 to 6. 
     
     
         11 . The suspension of  claim 9 , further comprising a stabilizing agent, wherein the stabilizing agent is selected from the group consisting of amino acids, synthetic peptides, peptides of natural origin, proteins, sugars, carbohydrates, nucleic acid homopolymers, amino acid homopolymers, DNA, RNA, and combinations thereof; and wherein the stabilizing agent adheres to the radical probe without blocking the oxygen active centers. 
     
     
         12 . The suspension of  claim 9 , further comprising a stabilizing medium, wherein the stabilizing medium is selected from the group consisting of emulsions containing saturated fatty acids; emulsions containing unsaturated fatty acids; emulsions containing saturated and unsaturated fatty acids; salts of emulsions containing saturated fatty acids; salts of emulsions containing unsaturated fatty acids; salts of emulsions containing saturated and unsaturated fatty acids; diglycerides; triglycerides; bile salts; and combinations thereof. 
     
     
         13 . The suspension of  claim 9 , further comprising a phospholipid, wherein the phospholipid encapsulates the radical probe without blocking the oxygen active centers. 
     
     
         14 . The suspension of  claim 13 , wherein the phospholipid forms phospholipid liposomes which encapsulate the radical probe without blocking the oxygen active centers. 
     
     
         15 . The suspension of  claim 14 , wherein the phospholipid is selected from the group consisting of cholesterol, phosphatidyl choline, phosphatidylethanolamine, phosphatidylserine, cardiolipin, and combinations thereof; and wherein the phospholipid is in the form of unilamellar or multilamellar liposomes or vesicles. 
     
     
         16 . A method of measuring oxygen concentration, oxygen partial pressure, or oxygen metabolism in a specific tissue or organ in a subject, the method comprising the steps of:
 (a) administering at least one particulate probe according to  claim 1  to the subject;   and   (b) applying a magnetic resonance (MR) spectroscopy or imaging technique for measuring O 2  concentration in tissues or organs of the subject.   
     
     
         17 . The method of  claim 16 , wherein the MR technique is selected from the group consisting of MRI, ESR, EPR, ERPI, and PEDRI. 
     
     
         18 . The method of  claim 16 , wherein the particulate probe or radical thereof remains in the subject for at least 180 days. 
     
     
         19 . The method of  claim 16 , wherein the subject is a human subject. 
     
     
         20 . A method of measuring nitric oxide (NO), separately or in combination with oxygen, in a specific tissue or organ of a subject, the method comprising the steps of:
 (a) administering at least one particulate probe according to  claim 1  to the subject;   and   (b) applying a magnetic resonance (MR) spectroscopy technique for measuring NO concentration in tissues or organs of the subject.