Method of monitoring the release from liposomes of a product of interest using superparamagnetic nanoparticles

Abstract

The present application relates to a method of monitoring the membrane permeabilization of liposome and the incidental release of a compound of interest.

1 - 13 . (canceled) 
     
     
         14 . A liposome comprising a thermosensitive lipidic membrane encapsulating superparamagnetic nanoparticles the electrostatic surface charge of which is below −20 mV or above +20 mV when measured in an aqueous medium between pH 6 and 8, for use in a method of monitoring the liposome membrane permeabilization and the incidental release of a product of interest, the method comprising:
 a) measuring T2*, 
 b) heating the liposome at Tm or above Tm, 
 c) measuring T2* after step b), 
 d) obtaining the r 2*  values from the T2* values obtained from step a) and step c), 
 e) determining the ratio of r 2*  before the heating step at Tm or above Tm/r 2*  after the heating step at Tm or above Tin, a ratio above 1.5 being indicative of the liposome membrane permeabilization and of the incidental release of the product of interest, thereby monitoring the liposome membrane permeabilization. 
 
     
     
         15 . A liposome comprising a thermosensitive lipidic membrane encapsulating superparamagnetic nanoparticles the electrostatic surface charge of which is below −20 mV or above +20 mV measured in an aqueous medium between pH 6 and 8, for use in a method of monitoring the liposome membrane permeabilization and the incidental release of a product of interest, the method comprising:
 a) measuring T2* and T1, 
 b) heating the liposome at Tm or above Tm, 
 c) measuring T2* and T1 after step b), 
 d) obtaining r 2*  and r 1  values from the T2* and T1 values obtained from steps a) and c), 
 e) determining the ratio of r 2* /r 1  before and after the heating step at Tm or above Tm, a ratio of r 2* /r 1  before the heating step b) and of r 2* /r 1  after the heating step b) above 2 being indicative of the liposome membrane permeabilization and of the incidental release of the product of interest, thereby monitoring the liposome membrane permeabilization. 
 
     
     
         16 . The liposome according to  claim 14 , wherein the liposome is for use in a method as defined in  claim 14  further comprising at least one step of measuring T2*, or T2 and T2*, during the heating step b). 
     
     
         17 . The liposome according to  claim 15 , wherein the liposome is for use in a method as defined in  claim 15  further comprising at least one step of measuring T2* and T1, and optionally T2, during the heating step b). 
     
     
         18 . The liposome according to  claim 14 , wherein Tm is between 39° C. and 45° C. 
     
     
         19 . The liposome according to  claim 14 , wherein the thermosensitive lipidic membrane comprises at least a phosphatidylcholine. 
     
     
         20 . The liposome according to  claim 18 , wherein the thermosensitive lipidic membrane further comprises cholesterol. 
     
     
         21 . The liposome according to  claim 19 , wherein the thermosensitive lipidic membrane further comprises distearylphosphatidylethanolamine-methoxypolyethylene glycol. 
     
     
         22 . The liposome according to  claim 20 , wherein the thermosensitive lipidic membrane further comprises distearylphosphatidylethanolamine-methoxypolyethylene glycol. 
     
     
         23 . The liposome according to  claim 14 , wherein the largest size of the liposome is between 50 and 500 nm or between 50 and 250 nm. 
     
     
         24 . The liposome according to  claim 14 , wherein the nanoparticles are covalently or electrostatically fully coated with an agent selected from a carboxylic acid, a phosphate and an amine agent. 
     
     
         25 . The liposome according to  claim 14 , wherein the nanoparticles are prepared from iron oxide such magnetite and/or maghemite. 
     
     
         26 . The liposome according to  claim 14 , wherein the nanoparticle largest size is between 2 and 30 nm or between 2 and 20 nm. 
     
     
         27 . The liposome according to  claim 14 , wherein the product of interest is selected from a therapeutic nucleic acid, a cytostatic compound, and a cytotoxic compound.