In search of a safer alternative to the current solution, chemotherapy, Marrache et al. decided to use a method called photodynamic therapy (PDT). This method uses a light activated photosensitizer (PS) to kill cancer cells. However, photosensitizers, such as zinc phthalocyanine (ZnPc), have limitations of their own. PSs are hydrophobic which means that they have poor solubility in water, and they might become stuck in the also hydrophobic cell membranes. This makes it difficult to deliver such drug molecules to their intended targets. In order to solve this issue, Marrache and his co-workers hypothesize that they can use a hydrophilic polymer, poly(lactide-co-glycolide)-b-polyethyleneglycol (PLGA-b-PEG), to make a nanoparticle (NP) to contain the PSs and facilitate the delivery of the PS. In addition to being hydrophilic, the NPs are also positively charged which allows them to pass through the negatively charged mitochondria membrane.
Besides trying to deliver PS drugs into cancer cells more efficiently, these researchers also made an educated guess that they could take this method further by targeting mitochondria of cancer cells and inducing apoptosis, the process of programmed cell death. Dendritic cells (DCs), antigen presenting cells, would then pick up antigens