Multifunctional nanoplatforms for fluorescence imaging and photodynamic therapy developed by post-loading photosensitizer and fluorophore to polyacrylamide nanoparticles

We report a novel post-loading approach for constructing a multifunctional biodegradable polyacrylamide (PAA) nanoplatform for tumor-imaging (fluorescence) and photodynamic therapy (PDT). This approach provides an opportunity to post-load the imaging and therapeutic agents at desired concentrations. Among the PAA nanoparticles, a formulation containing the photosensitizer, HPPH [3-(1'-hexyloxyethyl) pyropheophorbide-a], and the cyanine dye in a ratio of 2: 1 minimized the undesirable quenching of the HPPH electronic excitation energy because of energy migration within the nanoparticles and/or Forster (fluorescence) resonance energy transfer (FRET) between HPPH and cyanine dye. An excellent tumor-imaging (NIR fluorescence) and phototherapeutic efficacy of the nanoconstruct formulation is demonstrated. Under similar treatment parameters the HPPH in 1% Tween 80/5% aqueous dextrose formulation was less effective than the nanoconstruct containing HPPH and cyanine dye in a ratio of 2 to 1. This is the first example showing the use of the post-loading approach in developing a nanoconstructs for tumor-imaging and therapy. From the Clinical Editor: Fluorescence imaging is a rapidly evolving and relatively high-throughput tool currently only utilized in preclinical imaging. The authors of this work demonstrate a tumor-specific florescence imaging nanoplatform that enables not only imaging, but photodynamic therapy as well. (C) 2012 Elsevier Inc. All rights reserved.