Pyrene-Terminated, Amphiphilic Polypeptide and Its Hydrogen-Bonded Interpolymer Complex as Delivery Systems of Doxorubicin

[Image: see text] The intensity ratio between the first (373 nm) and the third (383 nm) vibronic peaks [I(1)/I(3), as the pyrene (Py) scale] of fluorescent Py was used to monitor the critical concentration, drug-loading, and -releasing behaviors of a Py-terminated, amphiphilic polypeptide PPM and its hydrogen-bonded interpolymer complex (HIPC) with poly(acrylic acid) (PAA). Primarily, an amphiphilic PPM with a hydrophobic Py terminal and hydrophilic methoxy-bis(ethylene oxide) pendant groups was synthesized through multiple preparative steps, and the resultant PPM was thoroughly mixed with PAA through a preferable hydrogen bond (H bond) interaction to form HIPC. The emission study suggested that the I(1)/I(3) ratio and the quantum yield (Φ(F)) are effective in determining the critical concentrations of the aqueous PPM and PPM/PAA solutions. Moreover, the I(1)/I(3) ratio and Φ(F) were found to be convenient measures for determining the amounts of doxorubicin drugs loaded by and released from the aqueous PPM and PPM/PAA solutions.