Intraperitoneal <i>versus</i> intravenous administration of Flamma®-conjugated PEG-alendronate-coated upconversion nanoparticles in a mouse pancreatic cancer model

Pancreatic cancer is one of the most common forms of malignant disease with a poor survival prognosis. Currently, nanomedicine holds great promise for targeted diagnosis and treatment of this cancer, which also reduces toxic side effects. In this work, we prepared PEG-coated monodisperse upconversion nanoparticles (UCNPs) with a conjugated Flamma® fluorescent dye for imaging and detection of particle distribution <i>in vivo</i>. We performed a thorough physicochemical characterization of the particles and determined their colloidal and chemical stability in several aqueous media such as water, PBS, Dulbecco's modified Eagle's medium and artificial lysosomal fluid. Luminescence resonance energy transfer from the emission of UCNPs as a donor to the Flamma® as an acceptor was confirmed. Intraperitoneal <i>versus</i> intravenous administration was then compared in terms of biodistribution of particles in various organs in the orthotopic mice pancreatic cancer model. The intraperitoneal route was preferred over the intravenous one, because it significantly increased the accumulation of particles in the tumor tissue. These new UCNP@Ale-PEG-Flamma® nanoparticles are thus promising for new treatment avenues for pancreatic cancer.