Effects of Heating Temperature and Duration by Gold Nanorod Mediated Plasmonic Photothermal Therapy on Copolymer Accumulation in Tumor Tissue

Previously, water-soluble N-(2-hydroxypropyl)-methacrylamide (HPMA) copolymers have been used with gold nanorod (GNR) mediated plasmonic photothermal therapy (PPTT) to induce hyperthermia (43 degrees C for 10 mm) and have been shown to improve delivery of hydrophobic drugs to treat cancer. However, it was unknown how altering the heating parameters (temperature and duration) of PPTT would affect HPMA copolymer accumulation and retention. This study aimed to investigate how changes in heating parameters, or thermal dose, would change polymer accumulation profiles with PPTT. It was observed that temperatures of either 40, 43, 46, or 49 degrees C at durations of 10 or 30 min had significant effects on HPMA copolymer accumulation. Mild temperatures led to transient enhancement in accumulation, but more severe temperatures led to tissue and vascular damage, creating slowed dynamics of inflow and outflow of the polymers from the tumor tissue.