Objective:To construct bacterial cytoplasmic membrane nanovesicles(BMV)with overexpressing programmed death 1(PD-1),denoted as BMV-PD-1 and evaluate the targeting efficacy of BMV-PD-1 towards transplanted lung tumor tissues in mice.Methods:The fusion plasmid ClyA-PD-1-EGFP fused by PD-1 and Cytolysin A(ClyA)was transferred into Escherichia coli BL21-Codonplus through plasmid transformation.Laser confocal microscopy,SDS-PAGE,and WB were used to detect the expression of the fusion protein ClyA-PD-1-EGFP.Bacterial membranes were extracted and processed with an extruder to generate BMV-PD-1.TEM and NTA were utilized to assess the morphology,size distribution,and zeta potential of BMV-PD-1,while WB was used to verify the presence of PD-1 protein.Laser confocal imaging was conducted to monitor the uptake of BMV-PD-1 by Lewis lung cancer cells.A C57BL/6J mouse subcutaneous transplant tumor model of LLC lung cancer cells was constructed,and the tumor targeting of BMV-PD-1 was evaluated by small animal imaging system.Results:Laser confocal microscopy images demonstrated that the plasmid ClyA-PD-1-EGFP was transferred into BL21-Codonplus and successfully expressed into protein.SDS-PAGE results suggested that ClyA-PD-1-EGFP was overexpressed in BL21-Codonplus.WB analysis indicated that PD-1 was expressed in bacteria and highly expressed in BMV-PD-1(P<0.001).NTA and TEM analyses revealed that BMV-PD-1 were spherical vesicles with a diameter of(145±14)nm and a negative surface charge.Laser confocal imaging showed that the high expression of PD-1 significantly increased the uptake of BMV-PD-1 by lung cancer cells(P<0.01).In vivo imaging of small animals further confirmed that the high expression of PD-1 can effectively improve cancer targeting of BMV-PD-1(P<0.01).Conclusion:In this study,bacterial plasma membrane nanovesicles BMV-PD-1 with high PD-1 expression are successfully constructed,and it is found that PD-1 overexpression markedly improve the mouse lung cancer xenograft tissue targeting specificity of BMV-PD-1,laying the groundwork for further development of BMV-PD-1 as a carrier for targeted drug delivery systems in tumors.