Vaporization, photoacoustic and acoustic characterization of PLGA/PFH particles loaded with optically absorbing materials

Poly (lactide-co-glycolic acid) (PLGA) is an FDA approved biocompatible and biodegradable material that is commonly used in implantation and drug delivery applications. It can be used as a carrier for various chemotherapeutic drugs, imaging agents and targeting moieties. Perfluorocarbon (PFC) liquids have been used in various biomedical applications, and can be activated (i.e. the liquid core converted to gas) via laser irradiation through the incorporation of optically absorbing nanoparticles or dyes within the emulsions. PLGA particles were synthesized with nanoparticles (gold or iron oxide) or dyes (DiI or rhodamine) within the PLGA shell and perfluorohexane (PFH) in the core. The photoacoustic signals and vaporization threshold of individual micron-sized particles were examined to optimize the dye and nanoparticle combination. The PLGA/PFH particles containing gold nanoparticles and DiI had the lowest vaporization threshold, with each particle consistently requiring less than 100 mJ/cm² for vaporization. The effects of vaporization were then tested in cell culture. The particles were internalized by MDA breast cancer cells, and then irradiated with a laser. Once the particle was vaporized, a bubble formed within the cell which destroyed the cell. This work presents a first study of using a solid-shell PLGA particle encapsulating PFH liquid as a theragnostic agent.