Friday, June 02, 2006

US Patent 7053034 - Nanospheres Within Microspheres For Controlled Delivery

Along the lines of the previously discussed patent, in which a core/shell structure was used to avoid reactivity between a nanoparticle and the environment, this patent provides microspheres each containing a plurality of nanospheres. The microspheres are formed of a pH sensitive material for controlled delivery of the nanospheres only under specific environmental conditions. This may be used in a variety of applications where timed or environment-specific delivery of nanoparticles is desired but interaction of the nanoparticles with the environment at earlier times or in an inappropriate enviroment needs to be avoided. Applications to hair care products and laundry detergent are cited. Claim 1 reads:

1. A controlled release composition comprising: a plurality of solid nano-spheres, each of said solid nano-spheres comprising an effective amount of a first active agent and a cationic surface active agent, said plurality of nano-spheres are formed of a hydrophobic material, said plurality of nano-spheres being encapsulated within a pH sensitive or salt sensitive micro-sphere, said pH sensitive or salt sensitive micro-sphere is formed of a pH sensitive or salt sensitive matrix material wherein each of said nano-spheres has an average size of about 0.05 to about 2 microns and said micro-sphere has a size of from about 2 microns to about 50 microns.

It is interesting to note that this is a case where, lacking the claimed ranges, the Patent Examiner rejected the claims but the addition of the claimed ranges resulted in allowability of the patent. This may not be unfounded since while it may be well known or obvious to encapsulate microparticles in larger particles, the fabrication process of nanoparticles within microspheres would require a different process.