Promising two-dimensional rhenium diselenide nanosheets: Facile Preparation, characterization, in vivo tumor photoacoustic imaging and photothermal therapy

Nanoagent-mediated photothermal therapy (PTT) has been considered as an useful strategy for curing cancer. Nonetheless, identifying high-quality photothermal nanoagents with excellent biocompatibility testing, superior photothermal conversion efficiency (PTCE), and high treatment efficacy, is still a key dilemma for performing practical application in biomedicine field. In our work, a novel photothermal nanoagent named two-dimensional (2D) colloidal rhenium diselenide (ReSe2) nanosheets was exfoliated via a facile liqiud-assisted exfoliation approach. Owing to surface functionalization with poly-ethylene glycol (PEG), the obtained PEG-ReSe2 nanosheets demonstrated good solubility and excellent biocompatibility. Notably, the PEG-ReSe2 nanosheets showed excellent near infrared (NIR) photothermal activity. For the radiation of an NIR laser at 808 nm, an ultrahigh PTCE of 81.3 % was demonstrated. Owing to its high Re element and good photoacoustic effect, the PEG-ReSe2 nanosheets can serve as good contrast nanoagents for in vivo photoacoustic (PA) imaging. Furthermore, the PEG-ReSe2 nanosheets acted as excellent photothermal agents (PTAs) for performing PTT. Thanks to high photothermal effects of PEG-ReSe2 nanosheets, in vitro photothermal effects showed that, the mortality rate of 4T1 cells was almost 100 %. Meanwhile, in vivo experiments showed that mouse tumors were 100 % ablated. More importantly, the PEG-ReSe2 nanosheets exhibited negligible levels of toxicity, as demonstrated by in vivo cytotoxicity assays and histological analysis. Finally, changes in micro-RNA expression level was proposed to assess PTT treatment efficacy of PEG-ReSe2 nanoagent. Interestingly, the miRNAs such as miR-125b-5p, miR-20a-5p, miR-214–3p, miR-221–3p, miR-212–3p and miR-27b-3p, were down-regulated. In addiiton, the miRNAs including miR-451a, miR200c-3p, and miR-let-7d-3p, were up-regulated. More importantly, these obtained miRNAs can work as typical indicators for screening PTT outcomes of PEG-ReSe2 nanosheets-involved PTT. Our research suggested that, the PEG-ReSe2 nanoagent may represent potential therapeutic nanoagents for in vivo photoacoustic imaging and cancer therapy.