No abstract

With rapid technical advances, ionizing radiation has been put into wider application in ordinary living, with the worst cytological effect on the human body being cell death. Moreover, according to the Nomenclature Committee on Cell Death, the method of radiation-induced cell death, usually classified as interphase and proliferative death, undergoes more detailed classifications oriented by its molecular mechanism. Elaborating its mode and molecular mechanism is crucial for the protection and treatment of radiation injury, as well as the radiotherapy and recovery of tumors. Varying with the changes of the radiation dose and the environment, the diverse targets and pathways of ionizing radiation result in various cell deaths. This review focuses on classifications of radiation-induced cell death and its molecular mechanism. We also examine the main characteristics of ionizing radiation-induced cell death. The modes of radiation-induced cell death can be classified as apoptosis, necrosis, autophagydependent cell death, pyroptosis, ferroptosis, immunogenic cell death, and non-lethal processes. Once the dose is high enough, radiation effects mostly appear as destructiveness ("destructiveness" is used to describe a situation in which cells do not have the opportunity to undergo a routine death process, in which case high-dose radiation works like a physical attack). This breaks up or even shatters cells, making it difficult to find responses of the cell itself. Due to diversities concerning cell phenotypes, phases of cell cycle, radiation dose, and even cellular subregions, various methods of cell death occur, which are difficult to identify and classify. Additionally, the existence of common initial activation and signaling molecules among all kinds of cell deaths, as well as sophisticated crossways in cellular molecules, makes it more laborious to distinguish and classify various cell deaths.

DNA origami technique provides a programmable way to construct nanostructures with arbitrary shapes. The dimension of assembled DNA origami, however, is usually limited by the length of the scaffold strand. Herein, we report a general strategy to efficiently organize multiple DNA origami tiles to form super-DNA origami using a flexible and covalent-bound branched DNA structure. In our design, the branched DNA structures (B n : with a certain number of 2–6 branches) are synthesized by a copper-free click reaction. Equilateral triangular DNA origamis with different numbers of capture strands (T n : T1, T2, and T3) are constructed as the coassembly tiles. After hybridization with the branched DNA structures, the super-DNA origami (up to 13 tiles) can be efficiently ordered in the predesigned patterns. Compared with traditional DNA junctions (J n : J2–J6, as control groups) assembled by base pairing between several DNA strands, a higher yield and more compact structures are obtained using our strategy. The highly ordered and discrete DNA origamis can further precisely organize gold nanoparticles into different patterns. This rationally developed DNA origami ordering strategy based on the flexible and covalent-bound branched DNA structure presents a new avenue for the construction of sophisticated DNA architectures with larger molecular weights.