Patent ID: 8147868

Claim:
A polymer micelle composition for encapsulating polypeptides or proteins, comprising: a polypeptide or protein having a molecular weight of at least 20,000 daltons having an isoelectric point (pI); and a block copolymer comprising hydrophilic segments composed of polyethylene glycol, and hydrophobic segments composed of a polyamino acid selected from the group consisting of acidic amino acids, hydrophobic derivatives thereof and mixtures of said acidic amino acids and said hydrophobic derivatives, the acidic amino acids and/or the hydrophobic derivatives having an isoelectric point (pI′), wherein the polypeptide or protein are combined with the block copolymer to form a micelle mixture, and the pH of the micelle mixture is: pI>pH>pI′ such that the hydrophobic segments of the block copolymer are negatively charged at the pH while the protein or polypeptide is positively charged, wherein the pH has a difference of at least 1 from the pI of the protein or polypeptide.