A protein nanocarrier from charge-conversion polymer in response to endosomal pH

A new type of polyion complex (PIC) micelle was prepared from lysozyme and the block copolymer, PEG-pAsp(EDA-Cit), that can switch the charge from anionic to cationic at the endosomal pH. The charge-conversion was due to the degradation of the citraconic amide side chain at pH 5.5. This abrupt charge-conversion can make the PIC micelles promptly release the internal protein in response to the endosomal pH. This pH-sensitive charge-conversion polymer is promising for the future design of nanocarriers for early endosomal release.