Continuous sonication method for preparing protein encapsulated microbubbles

Claim 1

The method of producing an imaging agent for diagnostic use in the human circulatory system in which an aqueous solution of human serum albumin in subjected to sonication to form minute gas-center microspheres, wherein the improvement comprises: (a) prior to sonication rapidly heating an aqueous solution of human serum albumin to a temperature of incipient denaturation of albumin; (b) dispersing a biocompatible gas in said heated solution; (c) flowing the gas-containing heated solution through a chamber enclosing an operating sonicator which provides a stationary horn immersed in the solution as it passes through said chamber; and (d) with a solution residence time in said chamber of from 1 to 20 seconds forming microspheres of less than 10 microns diameter at concentrations in excess of 40×10 6 microspheres per milliliter of solution, the stability of said microspheres being such that said solution maintains said excess concentration for over 8 weeks at 20° to 25° C.

Claim 2

The method of producing an imaging agent for diagnostic use in the human circulatory system in which an aqueous solution of human serum albumin in subjected to sonication to form minute gas-center microspheres, wherein the improvement comprises: (a) prior to sonication rapidly heating an aqueous solution of human serum albumin to a temperature of incipient denaturation of albumin; (b) dispersing a biocompatible gas in said heated solution; (c) flowing the gas-containing heated solution through a chamber enclosing an operating sonicator which provides a stationary horn immersed in the solution as it passes through said chamber; and (d) with a solution residence time in said chamber of from 1 to 20 seconds forming microspheres of less than 10 microns diameter at concentrations in excess of 40×10 6 microspheres per milliliter of solution, the stability of said microspheres being such that said solution maintains said excess concentration for over 8 weeks at 20° to 25° C.

Claim 5

The method of producing an imaging agent for diagnostic use in the human circulatory system in which an aqueous solution of human serum albumin is subjected to sonication to form minute air-center microspheres, wherein the improvement comprises: (a) prior to sonication rapidly heating an aqueous solution of human serum albumin to a temperature in the range from 70° to 75° C. without denaturing the albumin, said solution having an albumin concentration of from 0.5 to 7.5 percent by weight; (b) dispersing air in said heated solution; (c) flowing the air-containing heated solution through a chamber enclosing an operating sonicator which provides a stationary horn immersed in the solution as it passes through said chamber; and (d) with a solution residence time in said chamber of from 1 to 20 seconds forming microspheres predominately sized in the range from 3 to 8 microns diameter, said microspheres being formed at concentrations in excess of 40×10 6 microspheres per milliliter of solution, the stability of said microspheres being such that said solution maintains said excess concentration for over 8 weeks at 20° to 25° C.

Claim 6

The method of producing an imaging agent for diagnostic use in the human circulatory system in which an aqueous solution of human serum albumin is subjected to sonication to form minute air-center microspheres, wherein the improvement comprises: (a) prior to sonication rapidly heating an aqueous solution of human serum albumin to a temperature in the range from 70° to 75° C. without denaturing the albumin, said solution having an albumin concentration of from 0.5 to 7.5 percent by weight; (b) dispersing air in said heated solution; (c) flowing the air-containing heated solution through a chamber enclosing an operating sonicator which provides a stationary horn immersed in the solution as it passes through said chamber; and (d) with a solution residence time in said chamber of from 1 to 20 seconds forming microspheres predominately sized in the range from 3 to 8 microns diameter, said microspheres being formed at concentrations in excess of 40×10 6 microspheres per milliliter of solution, the stability of said microspheres being such that said solution maintains said excess concentration for over 8 weeks at 20° to 25° C.