Seeded Growth of Cu<sub>2–<i>x</i></sub>Se Nanocrystals and Their Size-Dependent Phototherapeutic Effect Xianguang Ding Dongdong Fu Ye Kuang Yu Zou Xiuzhu Yang Liangzhu Feng Xia Sun Haiyan Wu Jiang Jiang 10.1021/acsanm.8b00516.s001 https://acs.figshare.com/articles/journal_contribution/Seeded_Growth_of_Cu_sub_2_i_x_i_sub_Se_Nanocrystals_and_Their_Size-Dependent_Phototherapeutic_Effect/6810041 Doped semiconductors supporting localized surface plasmon resonances, such as nonstoichiometric copper chalcogenides Cu<sub>2–<i>x</i></sub>Se, have been intensively researched for their potential applications in photoacoustic imaging and photothermal therapy. For these self-doped nanoparticles, their physicochemical attributes such as size and surface chemistry will not only affect their cellular uptake and biodistribution but also influence their own optical properties. Thus, optimization of the physicochemical properties is crucial for their nanobio-applications. Through a seeded growth approach, aqueous phase synthesis of monodisperse Cu<sub>2–<i>x</i></sub>Se with various sizes has been developed for the first time. Taking three different sized Cu<sub>2–<i>x</i></sub>Se NPs (35, 65, and 105 nm in diameter) as examples, their size-dependent optical cross-section, photothermal property, and cellular cytotoxicity have been investigated, and the 65 nm one displays the largest optical cross-section at 21.57 L g<sup>–1</sup> cm<sup>–1</sup> and best photothermal property per unit mass. In addition, Cu<sub>2–<i>x</i></sub>Se exhibits a size-dependent reactive oxygen species generation effect that is inversely proportional to their diameters. Finally, on the basis of optical property and cytotoxicity optimizations, the photothermal cancer cell ablation ability and potential use of Cu<sub>2–<i>x</i></sub>Se NPs as photoacoustic contrast enhancing agent has been demonstrated in vivo. 2018-06-25 00:00:00 photothermal cancer cell ablation ability Size-Dependent Phototherapeutic Effect Doped semiconductors NP Se Cu size-dependent reactive oxygen species generation effect photothermal property surface plasmon resonances