Tailor-made PL-UC-C3 nanoparticles for fluorescence/computed tomography imaging-guided cascade amplified photothermal therapy

Xinhui Xie,1 Jialei Song,1 Yili Hu,1 Suyang Zhuang,1 Yuntao Wang,1 Yunlei Zhao,2 Qian Lu2 1Department of Orthopedics, Zhong Da Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu 210093, China; 2Department of Biomedical Engineering, College of Engineering and Applied Sciences, Nanjing University, Nanjing, Jiangsu 210093, China Background: Development of the burgeoning number of photothermal therapy (PTT) agents has drawn a huge amount of interest, since PTT treatment is a powerful and effective alternative to traditional treatments. Optimal PTT agents should integrate some essential preconditions including negligible systemic toxicity, deep penetration into tumor tissues, and maximum laser energy absorbance. Unfortunately, only few of the PTT agents reported could meet all of the above mentioned conditions.Methods: Here, we report a brand new PTT agent through the encapsulation of NaGdF4:Yb,Tm@NaGdF4:Yb (UCNPs) and an organic compound (C3) into poly-e-caprolactone-polyethylene-polyglycol (PCL-PEG) (PL-UC-C3 NPs).Results: UCNPs as an up-conversion material and C3 as a PTT agent both feature low cytotoxicity, and most importantly, UCNPs with superior conversion efficiency could efficiently absorb the energy of a 980 nm laser, transform the near-infrared laser light into visible light, and translate the palingenetic visible light to C3. The usage of a 980 nm laser ensures a deeper penetration and lower energy, while the highly efficient absorption and transformation process confers a cascade amplified hyperthermia for tumor treatment.Conclusion: In this regard, our research provides a powerful and robust breakthrough for florescence/computed tomography imaging-guided PTT treatment, lighting up the clinical application in cancer treatment. Keywords: photothermal therapy, PCL-PEG, up-conversion, excellent photothermal stability, high heat conversion efficiency