Nanotechnology and nanomaterials
Core-shell polymeric nanoparticles for photodynamic therapy guided by fluorescence imaging in second infrared window
Chepurna O.M. 1, Yakovliev A.1, Vretik L.O.2, Nikolaeva O.A.2, Losytskyy M.Y.2, Slominskii  Yu.L.3, Qu J.1, Ohulchanskyy T.Y.1 
1 Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, People's Republic of China 
E-mail: ok.chepurna@gmail.com
2Taras Shevchenko National University of Kyiv, Volodymyrs’ka Str., 64/13, Kyiv-01601, Ukraine
3Institute of Organic Chemistry NASU, Murmanska str. 5, 02094 Kyiv, Ukraine

Photodynamic therapy (PDT) is a minimally invasive treatment method that selectively eliminates malignant tumor tissue through light-induced generation of the cytotoxic reactive oxygen species (ROS) by the tumor targeting PDT agent (photosensitizer, PS). Fluorescence imaging can be employed to evaluate biodistribution of the fluorescent PS, visualizing its accumulation tumor before PDT. However, excitation of the PS, while assessing its biodistribution, results in premature photobleaching and can cause toxicity to healthy tissues. Combination of PS with near infrared fluorescence dyes (NIRFD), which can be excited without PS activation, eliminate disadvantages and allow for the safe tracking of PS delivery to cancer site, enhanced tumor imaging and PDT. Though, conjugation of the PS and conventional NIRFD were found to result in less efficient PDT as it affects the PS pharmacokinetics and also reduces PS efficacy due to undesirable electronic excitation energy transfer between PS and NIRFD [1]. Herein, we report polymeric nanoparticles loaded with PS and NIRFD for efficient image-guided PDT. The excitation and emission wavelengths for the selected NIRFD are shifted towards second infrared window of tissue transparency (NIR-II, ~1000-1350 nm), which has recently been identified as spectral range that is highly favorable for optical imaging in vivo. Use of NIR-II fluorescent dyes along with core-shell design of the nanoparticles allow us to obtain PS nanoformulation that is promising for enhanced PDT guided with advanced optical imaging.

1.	N.S. James, P. Joshi, T. Y. Ohulchanskyy, et al. Photosensitizer (PS)-cyanine dye (CD) conjugates: Impact of the linkers joining the PS and CD moieties and their orientation in tumor-uptake and photodynamic therapy (PDT) // Eur J Med Chem – 2016 – 122. – P. 770-785.