Nanoparticles Encapsulated in Red Blood Cell Membranes for Near-Infrared Second Window Imaging-Guided Photothermal-Enhanced Immunotherapy on Tumors.

Photothermal therapy (PTT), which uses the high thermal conversion ability of photothermal agents to ablate tumor cells at high temperatures, has gained significant attention because it has the advantages of high selectivity and specificity, precise targeting of tumor sites, and low invasiveness and trauma. However, PTT guided by the NIR-I has limitations in tissue penetration depth, resulting in limited imaging monitoring and therapeutic effects on deep-seated tumor tissues. Moreover, nanoparticles are easily cleared by the immune system and difficult to passively target tumor sites during the process of treatment. To address these issues, we prepared nanoparticles using NIR-II dyes IR1048 and DSPE-PEG-OH and further encapsulated them in red blood cell membranes derived from mice. These biomimetic nanoparticles, called RDIR1048, showed reduced clearance by the immune system and had long circulation characteristics. They effectively accumulated at tumor sites, and strong fluorescence could still be observed at the tumor site 96 h after administration. Furthermore, through mouse thermal imaging experiments, we found that RDIR1048 exhibited good PTT ability. When used in combination with an immune checkpoint inhibitor, anti-PD-L1 antibodies, it enhanced the immunogenic cell death of tumor cells caused by PTT and improved the therapeutic effect of immunotherapy, which demonstrated good therapeutic efficacy in the treatment of tumor-bearing mice. This study provides a feasible basis for the future development of NIR-II nanoparticles with long circulation properties.

The deviations of evaporation modes in two different morphologies of 2D WS2 film.

Exploring the inverse process of materials growth, evaporation of atoms from the material, is a crucial method to investigate the physical properties of two dimensional (2D) nanomaterials. Here, the evaporation modes of two different morphologies of 2D WS2 film, stacked film and normal film, were investigated by thermal annealing. It is found that the atomic evaporation rate increases and the crystallinity deteriorates when annealing temperature rises. During the evaporation process, atom evaporation firstly starts from the boundaries and defects. The evaporation rate is proportional to the free energy of S and W atoms, and inversely proportional to the local S-W atomic concentration. There is a striking difference in the evaporation modes between stacked film and normal film; layer-by-layer peeling off the surface only appears in normal film. These results imply that the interlayer coupling strength of stacked film is greater than that of the normal film with uniform thickness.