OBJECTIVE To synthesize and prepare nitric oxide donor(NODonor)-silicon phthalocyanine(SiPc) conjugated prodrug self-assembled nanoparticles(NO-SiPc-NO@NPs) and preliminarily evaluatetheir formulating properties and pharmacodynamics. METHODS Furoxan NO donor-phthalocyanine silicon photosensitizer couplings were synthesized by chemical reactions. The NO-SiPc-NO@NPs were prepared using a nanoprecipitation method,and the effects of different concentrations of NO-SiPc-NO, rotational speed, the volume ratio of the organic phase to the aqueous phase, and the content of the stabilizer DSPE-PEG_2K on particle sizes, polydispersity index(PDI), and Zeta potential of NO-SiPc-NO@NPs were investigated to obtain the better prescriptions. The release of NO and reactive oxygen species(ROS) yields as well as the photostability of NO-SiPc-NO were detected by the Griess method and the chemical probe method, respectively. On this basis, the storage stability and in vitro release of NO-SiPc-NO@NPs in phosphate buffer salt solutions of different pH were investigated. Finally, the photodynamic effect of nanoparticles was detected by CCK-8 method, and the effect of self-assembled nanoparticles on intracellular NO was observed by fluorescent probe. RESULTS The ¹H-NMR results showed that NO-SiPc-NO was successfully synthesized. The optimal preparation process conditions were:NO-SiPc-NO concentration of 2.5 mg·mL^-1, rotational speed of 1 000 r·min^-1, organic phase to aqueous phase volume ratio of 1∶3 and stabilizer content of 40%. The prepared self-assembled nanoparticles were(111.467±3.365) nm, (0.123±0.035) and (-11.433±0.850) mV in particle size, PDI and Zeta potential, respectively. The nanoparticles in transmission electron microscopy were spherical or spheroidal in shape, with a more intact morphology and homogeneous distribution. The results of NO and ROS release showed that the nanoparticles could release NO and ROS in solution with good photostability. NO-SiPc-NO@NPs were stable under both conditions, and there was no significant change in particle size, potential, PDI, encapsulation rate and drug loading. The results of in vitro drug release experiments showed that NO-SiPc-NO@NPs had a slow release and that their release followed a one-level kinetic model. CCK-8 experiments showed that all nanoparticle groups showed dose-dependent cytotoxicity, and the light-exposed NO-SiPc-NO@NPs had a stronger photodynamic effect on MCF-7 cells. In NO assay experiments, NO-SiPc-NO@NPs can produce large amounts of NO intracellularly. CONCLUSION NO-SiPc-NO@NPs are successfully prepared and the prepared self-assembled nanoparticles have good photodynamic activity and realize effective delivery of NO, which lays a theoretical foundation for the synergistic treatment of gas therapy and photodynamic therapy.