UV-Vis absorption (A,C,E) and fluorescence (B,D,F, λex = 404 nm) spectra of free PpIX, PpIX-encapsulated micelles, and PpIX-conjugated micelles, respectively. Free PpIX (A,B) existed as monomers in ethyl acetate (EA), dimers in phosphate buffer (PB) at pH = 11, and aggregates in phosphate buffer (PB) at pH = 7 ([PpIX] = 8 μM in all samples). PpIX-encapsulated micelles (C,D) show PpIX existed as monomers at low loading density (<0.2%) and as aggregates at high loading density (>1%). In comparison, PpIX-conjugated micelles (E,F) showed that PpIX existed as monomers at low loading density (<0.2%) and as dimers at high loading density (>2%). All the micelles were measured at 2 mg/mL concentration except for those indicated by a dilution factor in C and E for higher loading PpIX-micelles.