(600e) Encapsulating Indocyanine Green Using Novel Nanoparticle-Assembled Capsules

Indocyanine green (ICG) is an organic,
FDA-approved photosensitizer dye which is used for clinical optical imaging,
diagnostic and treatment. To address the rapid clearance and non-specific tissue
binding issues of ICG, we have developed a methodology to encapsulate ICG
within stable, non-liposomal nanoparticle/polymer hollow spheres called
nanoparticle-assembled capsules (NACs). To prepare ICG-containing NACs
(ICG-NACs), we combined aqueous solution of ICG, polyallylamine (PAH), and
phosphate anions in the proper ratios, with an aqueous suspension of 12-nm
silica nanoparticles (NPs). This simple procedure was carried at room
temperature and neutral pH. The ICG-NACs were recovered via centrifugation and redispersion
without damage. ICG loading could be readily controlled, with an attainable
maximum loading of ~52 wt%. There was negligible leakage of
ICG from the capsules after 8 hours at room temperature in isotonic solution. Only
20% of ICG was lost after 8 hrs at 37 °C. These ICG-containing microcapsules should
have demonstrated advantages over free ICG in phototherapy treatment.