Chapter 5 - Gold Nanoparticle-Based Technologies in Photothermal/Photodynamic Treatment: The Challenges and Prospects

Abstract

Recent studies on plasmonic photothermal (PTT) and photodynamic (PDT) therapies with usage of gold nanoparticles (AuNPs) have demonstrated the importance of dosage strategy for enhanced nanoparticle accumulation and efficient plasmonic-assisted therapy. Accumulation of AuNPs in tumor tissue dramatically shifts the therapy focus on the tumor without damage to healthy tissues. However, the optimal and safe doses of AuNPs administration for effective accumulation in tumors and optimal protocols of PTT and PDT have not been designed until now. This chapter presents novel approaches and summarizes results of our recent studies on improvement the efficacy of PTT and PDT when using gold nanorods (AuNRs). The effects of PTT and combined PTT and PDT in tumor-bearing rats with alveolar liver cancer PC-1 were demonstrated by using intratumoral injection of AuNRs and hematoporphyrin-loaded gold nanocomposites (NCs). We observed marked necrotic changes in tumor tissue after PTT and combined effects of PTT and PDT. However, there are serious unsolved problem of tumor recurrence, probably caused by the limited penetration of NIR laser light and inefficient spatial distribution of AuNPs and light intensity within large tumors. The last problem can be partially fixed through the multiple intravenous injection(IVI) of plasmonic nanonoparticles. Specifically, multiple IVI of AuNRs followed by PTT of rat cholangiocarcinoma resulted in significant improvement of damaging effect manifested in pronounced necrotic changes of tumor tissue and marked retardation in the tumor growth. More importantly, the multiple IVI PTT protocol ensured low toxicity as evidenced by histological examination of internal organs. In addition, the efficiency of PTT is shown to be depended on the presence of formed vasculature as revealed by three-dimensional Doppler ultrasound investigations.