Complex carriers of affibody-displaying bio-nanocapsules and composition-varied liposomes for HER2-expressing breast cancer cell-specific protein delivery.

A bio-nanocapsule (BNC), a hollow particle composed of hepatitis B virus (HBV) surface antigen (HBsAg), and liposome (LP) conjugation method (BNC/LP) has been recently developed by Jung et al. (2008) . The BNC/LP complex carrier could successfully deliver fluorescence-labeled beads (100 nm) into liver cells. In this study, we report the promising delivery of proteins incorporated in the complex carriers, which were prepared by the BNC/LP conjugation method with specificity-altered BNC and composition-varied LPs. The specificity-altered BNC, Z(HER2)-BNC was developed by replacing the hepatocyte recognition site of BNC with Z(HER2) binding to HER2 receptor specifically. Using green fluorescent protein (GFP; 27 kDa) and cellular cytotoxic protein (exotoxin A; 66 kDa) for the delivery, we herein present the impact of different charges attributed to the composition of the LP on specific cell targeting and cellular uptake of the complex carriers. In addition, we demonstrate that the mixture prepared by mixing LPs with helper lipid possessing endosomal escaping ability boosts the functional expression of the cellular cytotoxic exotoxin A activity specifically. Finally, we further show the blending ratio of the LP mixture and Z(HER2)-BNC is a critical factor in determining the highly-efficient expression of the cytotoxic activity of exotoxin A.