Supercritical fluids processing: preparation of protein microparticles and their stabilisation

Abstract

A coprecipitate of protein or polypeptide and stabiliser obtained by a process for the co-precipitation of a substance with a stabiliser therefor, by a gas anti solvent process comprising introducing into a particle formation vessel a supercritical fluid pure or mixed with a modifier; and a solution comprising said substance and said stabiliser dissolved in a solvent; so as said solvent is extracted from the solution by said supercritical fluid and co-precipitation of the substance and stabiliser occurs. The process may be carried out using an apparatus comprising a particle formation vessel and a nozzle having a central orifice serving to introduce a solution of the substance and a plurality of outer orifices serving to carry a flow of supercritical fluid into the particle formation vessel, such that the solvent is extracted from the solution by the supercritical fluid and precipitation of micron sized particles of the substance/stabiliser occurs.

1 . A coprecipitate of protein or polypeptide and stabiliser obtained by a gas anti solvent process comprising introducing into a particle formation vessel a supercritical fluid pure or mixed with a modifier; and 
 a. a solution comprising said protein or polypeptide and said stabiliser dissolved in a solvent;    b. so as said solvent is extracted from the solution by said supercritical fluid and co-precipitation of said protein or polypeptide and stabiliser occurs, wherein said stabiliser is a sugar.    
   
   
       2 . A coprecipitate as claimed in  claim 1  wherein the solution comprises a protein and coprecipitation of the protein and stabiliser occurs.  
   
   
       3 . A coprecipitate according to  claim 1  wherein said solution and said supercritical fluid are introduced into said particle formation vessel via separate inlet nozzles.  
   
   
       4 . A coprecipitate according to  claim 3  wherein said supercritical fluid is introduced into said particle formation vessel via a plurality of inlet nozzles.  
   
   
       5 . A coprecipitate as claimed in  claim 4  wherein said nozzles are present on a disk, the solution inlet nozzle being in the centre of said disk surrounded by a plurality of supercritical fluid inlet nozzles evenly spaced along the circumference thereof.  
   
   
       6 . A coprecipitate according to  claim 1 , wherein the solution is introduced into the particle formation vessel mixed with a modifier.  
   
   
       7 . A coprecipitate according to  claim 1 , wherein the supercritical fluid is introduced into the particle formation vessel mixed with a modifier.  
   
   
       8 . A coprecipitate according to  claim 1 , wherein said supercritical fluid is selected from carbon dioxide, ethane, ethylene, propane, sulfur hexafluoride, nitrous oxide, chlorotrifluoromethane, monofluoromethane, xenon and mixtures thereof.  
   
   
       9 . A coprecipitate according to  claim 1 , wherein said solvent is selected from water, ethanol, methanol, DMSO, isopropanol, acetone, THF, acetic acid, ethylene glycol, polyethylene glycol, and N,N-dimethylaniline and mixtures thereof.  
   
   
       10 . A coprecipitate according to  claim 1 , wherein said modifier, which is different from said solvent, is selected from water, ethanol, methanol, DMSO, isopropanol, acetone, THF, acetic acid, ethylene glycol, polyethylene glycol, and N,N-dimethylaniline and mixtures thereof.  
   
   
       11 . A coprecipitate according to  claim 1 , wherein the supercritical fluid is carbon dioxide, the solvent is water, and the modifier is ethanol.  
   
   
       12 . A coprecipitate according to  claim 1 , wherein the stabiliser is a trehalose.  
   
   
       13 . A coprecipitate according to  claim 1 , wherein the ratio of protein or polypeptide to stabiliser in the solution is 1:1 to 10 w/w.  
   
   
       14 . A coprecipitate according to  claim 13 , wherein the ratio of protein or polypeptide to stabiliser in the solution is 1:2 w/w.  
   
   
       15 . A coprecipitate as claimed in  claim 1 , wherein the supercritical fluid enters the particle formation vessel at the speed of sound in the fluid or greater.  
   
   
       16 . A coprecipitate as claimed in  claim 1 , wherein a modifier is used and the ratio between fluid flow rate and modifier flow rate range 4:1 to 8:1 w/w. supercritical is within the  
   
   
       17 . A coprecipitate as claimed in  claim 1 , wherein a modifier is used and the ratio between modifier flow rate and solution flow rate is within the range 15:1 to 25:1 w/w.  
   
   
       18 . A coprecipitate according to  claim 13 , wherein the ratio of protein or polypeptide to stabiliser in the solution is 1:2 to 4:1 w/w.