“…18 Therefore, to eliminate these concerns in conventional systems, our group has developed carrier-free prodrug nanoparticles, called nano-prodrugs (NPDs), which are fabricated from only prodrug molecules. [19][20][21][22] These NPDs maintain in the particle state until reaching cancer cells and do not release drugs. 20 Additionally, we have reported that the NPDs exhibit pharmacological effects after being taken up by cancer cells as intact particles.…”