Stealth polymeric particles for delivery of bioactive or diagnostic agents

A blend of polymeric particles comprising a crosslinked copolymer which is a free radical dispersion polymerization copolymer of:

• a hydrophilic monomer selected from the group consisting of alkene glycol, polyalkylene glycol and mixtures thereof,
• a hydrophobic acrylate monomer, which copolymer is crosslinked with
• a hydrolysable crosslinking agent, the copolymer polymerized and crosslinked at 0° C. to about 25° C., the polymeric particles including a therapeutic agent contained in the particles.

A blend of polymeric particles comprising a polymer which is a free radical dispersion polymerization copolymer polymerized at 0° C. to about 25° C. and made from at least three monomers which provide the copolymer including structures represented by Formulas (I), (II), and (III):

• wherein R1-R5 each represent a group, which may be the same or different from each other, and the group is selected from the group consisting of a hydrogen, a halogen, and an alkyl group having one to five carbon atoms, wherein R6 represents another chain of the crosslinked polymer particle comprised of structures represented by Formulas (I), (II), and (III), wherein x, y, and z represent an integer from 1 to 100, wherein n represents an integer 1 to 10,000, wherein A1 is an oxygen atom or a secondary amine, where A2 is an oxygen atom or a secondary amine the polymeric particles including a drug in the particles and the structure of Formula III being hydrolysable to permit the release of the drug from the particles, the polymeric particles when made from a free radical dispersion polymerization at 25° C. having a higher drug-loading capacity than a drug-loading capacity of polymeric particles made from the same monomers which are polymerized at above about 60° C.