Rational Design Of Copper-Selenium Nanoclusters Cures Sepsis By Consuming Endogenous H₂S To Trigger Photothermal Therapy And ROS Burst

How to treat sepsis caused by bacterial infection is a huge challenge.At present,the clinical treatment methods mainly include symptomatic treatment and antibiotic treatment,among which symptomatic treatment cannot kill the pathogenic bacteria,and the emergence of drug-resistant strains makes the efficacy of antibiotics far less than before.The appearance of photothermal therapy has attracted the attention of researchers and provided a new strategy for the treatment of sepsis.We designed and synthesized Cu₂O encapsulated Se sphere core-shell nanoparticles（Se@Cu₂O）.First,the high content of endogenous H₂S caused by sepsis was used to sulfide Se@Cu₂O in vivo and then converted into Se@Cu₉S₈with photothermal effect,and then the sepsis in mice was treated synergistically by stimulating ROS and photothermal effect.The cuprous oxide-coated nano-selenium spheres were synthesized by the method of core-shell assembly.The properties of Se@Cu₂O were analyzed by transmission electron microscopy,scanning electron microscopy,elemental analysis,XPS,XRD,UV spectroscopy,Fourier transform infrared spectroscopy,particle size and Zeta potential.The structure,morphology,composition and particle size were characterized.The results showed that Se@Cu₂O was successfully synthesized with an average particle size of about 90 nm and good stability.In vitro,Na HS was used to simulate the sulfuration of endogenous H₂S with Se@Cu₂O to produce Se@Cu₉S₈.The generation of Se@Cu₉S₈was proved by UV spectroscopy,transmission electron microscopy,scanning electron microscopy,and elemental analysis.The minimum inhibitory concentration（MIC）,colony forming unit（CFU）,dead and live cell staining,nucleic acid and K⁺content of bacterial culture medium showed that Se@Cu₂O+Na HS+NIR at a concentration of 30μg/m L could significantly inhibit Escherichia coli（E.coli）and Staphylococcus aureus（S.aureus）,also Se@Cu₂O+Na HS+NIR can disrupt bacterial cell membranes and bacterial integrity.Using fluorescence microscopy,it was observed that Se@Cu₂O treated bacteria would produce higher levels of ROS,and glutathione（GSH）levels decreased and GR protein activity decreased.It was also shown that the ROS burst led to bacterial death after Se@Cu₂O treatment.The results of in vitro photothermal imaging and in vivo photothermal imaging showed that Se@Cu₂O was successfully sulfided to Se@Cu₉S₈to produce photothermal effect.In vivo antibacterial experiments such as wound healing experiments and sepsis models showed that 5 mg/kg of Se@Cu₂O under NIR illumination promoted the accelerated wound healing in mice by inhibiting bacterial infection-induced inflammation and apoptosis.Se@Cu₂O significantly reduced organ damage and decreased mortality in septic mice by inhibiting bacterial proliferation in vivo.Importantly,Se@Cu₂O exhibits low toxicity and side effects in vivo.（Excitation power of NIR light is 1 W/cm²）Our research shows that Se@Cu₂O is vulcanized by endogenous H₂S to produce Se@Cu₉S₈,triggering ROS eruption and photothermal effect have synergistic antibacterial effect,and Se@Cu₂O has the characteristics of low side effects and high biocompatibility.In conclusion,the results of the experiment confirm our design that Se@Cu₂O in situ vulcanization may be an effective strategy to treat sepsis by triggering ROS bursts and photothermal effects.