Efficient aqueous encapsulation and controlled release of bioactive agents

A porous self-healing polymer matrix suitable for encapsulation of an active macromolecules selected from net positively charged peptides and net positively charged proteins, wherein the matrix comprises a biodegradable polymer and has pores and wherein:

• a biopolymer is disposed within the pores;
• and
• a pH modifying species is disposed within the pores;
• wherein the biopolymer comprises a dextran sulfate and is present at a level of greater than 0.5% and below 10% by weight based on the weight of the biodegradable polymer, and
• wherein the pH modifying species comprises magnesium carbonate and is present at a level of 1% to 7% by weight based on the weight of the biodegradable polymer.