Zinc oxide nanoparticles (ZnONPs) are inorganic nano-biomaterials with excellent antimicrobial properties. However, their effects on the anti-infection ability of the innate immune system remains poorly understood. The aim of the present study was to explore the potential immunomodulatory effects of ZnONPs on the innate immune system, represented by polymorphonuclear leukocytes (PMNs), and determine whether they can act synergistically to resist pathogen infections. In vitro experiment showed that ZnONPs not only exhibit obvious antibacterial activity at biocompatible concentrations but also enhance the antibacterial property of PMNs. In vivo experiments demonstrated the antibacterial effect of ZnONPs, accompanied by more infiltration of subcutaneous immune cells. Further ex vivo and in vitro experiments revealed that ZnONPs enhanced the migration of PMNs, promoted their bacterial phagocytosis efficiency, proinflammatory cytokine (TNF-α, IL-1β, and IL-6) expression, and reactive oxygen species (ROS) production. In summary, this study revealed potential synergistic effects of ZnONPs on PMNs to resist pathogen infection and the underlying mechanisms. The findings suggest that attempts should be made to fabricate and apply biomaterials in order to maximize their synergy with the innate immune system, thus promoting the host’s resistance to pathogen invasion.

BackgroundDisplaced femoral neck fractures are associated with a high revision rate. The new femoral neck system(FNS) offers advantages in fixation stability, potentially reducing the need for revision. The purpose of this study was to compare the revision rate of patients with different reduction quality treated with the FNS and cannulated screws (CS).MethodsThis retrospective study included patients with Garden III or IV femoral neck fractures who underwent osteosynthesis in a level 1 trauma center between July 2019 and June 2023. A total of 141 cases met the inclusion criteria and received treatment with either the FNS (N = 65) or CS (N = 76). The quality of fracture reduction, surgical complications (such as femoral neck shortening, avascular necrosis of femoral head, nonunion of fracture, implant failure and withdrawal), revision surgery and the reasons for revision were analyzed.ResultsThe mean age of the 141 cases was 52.0 years (range 18-65); with sixty-five cases being male (46.1%). Eighty-four fractures (59.6%) were classified as Garden type III. Reduction quality was good in 71 cases (50.4%) and fair in 70 cases. The mean follow-up period was 25.9 months (range 12-46). A total of 26 cases(18.4%) underwent revision surgery. The revision rate in cases with good reduction was 11.3% (8/71 cases), with seven cases (four hardware removal and three arthroplasty) in the CS group and one case (arthroplasty for fracture nonunion and implant failure) in the FNS group, a significant difference was found between the two groups(P = 0.041). Among the 18 cases (25.7%, 18/70) with fair reduction who underwent revision surgery, nine cases (six hardware removal and three arthroplasty) in the CS group, and nine cases (arthroplasty for implant failure and cut-out) in the FNS group, and there was no significant difference between the two groups (P = 0.672). The total revision rate between the FNS group (15.4%, 10/65) and the CS group (21.1%, 16/76) was not significantly different (P = 0.387).ConclusionsThe total revision rate between the FNS and CS group showed no difference. However, in cases with good reduction, the revision rate was lower in the FNS group compared to the CS group.