Synthesis and evaluation of triphenylphosphonium conjugated 18 F-labeled silica nanoparticles for PET imaging

Accumulation of triphenylphosphonium (TPP) is normally observed in the mitochondria from the extracellular spaces due to the high difference in plasma membrane potential of the mitochondria. In the cancer cells, the mitochondrial membrane potential gap is higher as compared to that of normal cells resulting in elevated uptake of TPP. Silica nanoparticles (SNPs) being widely developed and used for biomedical applications, in this study, we tried to modify the surface of SNPs with varying amounts of TPP to verify their possible application as a positron emission tomography (PET) agent. The studies confirmed that the high level of TPP loading on the surface of SNPs possess higher positive charge (+ 31.5 mV). Owing to this behavior of plasma membrane potential of cancerous cells the uptake of positively charged SNPs was much higher in tumor cells than that of normal cells which was confirmed by PET imaging.