Continuous sonication method for preparing protein encapsulated microbubbles

Claim 2

A sonication method for continously pro­ducing protein encapsulated microspheres, comprising the steps of: (a) preparing a dilute aqueous solution of a heat-denaturable, water-soluble, biocompatible protein; (b) rapidly heating increments of said solution to a temperature of incipient denaturation for the protein but without appreciable protein insolubiliz­ation; (c) flowing a biocompatible gas into incre­ments of said solution before, during, or after said heating for entrainment therein; (d) continuously passing said gas-containing heated increments of protein solution through a chamber enclosing an operating sonicator which provides a soni­cator horn in contact with the solution in the chamber, the resulting sonication foaming said solution and pro­ducing gas microbubbles therein while the protein there­in is heated to insolubilize a portion thereof; and (e) continuously forming stable protein-­encapsulated microspheres in the increments of solution passing through said chamber.

Claim 3

The method of claim 1 in which said pro­tein is human serum albumin.

Claim 4

The method of claim 1 in which said en­capsulated microspheres are predominately of diameters less than 10 microns.

Claim 5

The method of claim 1 in which said chamber has a cavity-providing wall portion arranged in close-spaced opposed relation to said sonicator horn, and said gas-containing heated increments of said solu­tion are introduced into said cavity.

Claim 6

The method of claim 1 in which said pro­tein is human serum albumin and the heating of step (b) is to a temperature between 70 and 75°C.

Claim 7

The method of claim 2 in which said solu­tion contains from 0.5 to 7.5 percent by weight of said albumin.

Claim 8

A sonication method for continuously producing protein encapsulated microspheres comprising the steps of: (a) preparing a dilute aqueous solution of human serum albumin; (b) rapidly heating increments of said solu­tion to a temperature of incipient denaturation for the albumin without appreciable albumin insolubilization; (c) flowing sterile air into the increments of said solution immediately after heating said solu­tion so that said air is entrained in said solution; (d) continuously passing said air-containing heated increments of albumin solution through a chamber enclosing an operating sonicator in contact with the solution in the chamber for sonication thereof, the re­sulting sonication foaming said solution and producing gas microbubbles while the albumin therein is heated to insolubilize a portion thereof; (e) continuously forming stable protein-­encapsulated microspheres in the increments of solu­tion passing through said chamber; (f) defoaming the microsphere-containing solution and separating air therefrom; and (g) recovering the encapsulated microspheres.

Claim 9

A sonication method for continuously producing protein encapsulated microspheres comprising the steps of: (a) preparing a dilute aqueous solution of human serum albumin; (b) rapidly heating increments of said solu­tion to a temperature of incipient denaturation for the albumin without appreciable albumin insolubilization; (c) flowing sterile air into the increments of said solution immediately after heating said solu­tion so that said air is entrained in said solution; (d) continuously passing said air-containing heated increments of albumin solution through a chamber enclosing an operating sonicator in contact with the solution in the chamber for sonication thereof, the re­sulting sonication foaming said solution and producing gas microbubbles while the albumin therein is heated to insolubilize a portion thereof; (e) continuously forming stable protein-­encapsulated microspheres in the increments of solu­tion passing through said chamber; (f) defoaming the microsphere-containing solution and separating air therefrom; and (g) recovering the encapsulated microspheres.

Claim 10

The method of claim 7 in which the heat­ing of step (b) is to a temperature between 70 and 75°C.

Claim 11

The method of claim 7 or claim 8 in which said solution contains from 0.5 to 7.5% by weight of said albumin.

Claim 12

The method of claim 7 or claim 8 in which said solution contains from 0.5 to 3% by weight of said albumin.