Coprecipitation method was used to prepare triiron tetroxide magnetic nanoparticles enclosed in L-DOPA, and then EDC was used to activate the carboxyl group of L-DOPA after the nanoparticles were synthesized. The carboxyl group of L-DOPA formed amide bond with specific amino on the aptamer by dehydration condensation reaction. The surfaces of magnetic nanoparticles were modified with aptamer and L-DOPA. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), nanoparticle size analysis (SEM), magnetic measurement (VSM) and other testing methods were used to detect the magnetic nanoparticles in different stages. The endothelial progeni-tor cells (EPCs) were cocultured with the surface modified magnetic nanoparticles to evaluate cell compatibility and the combination effect of nanoparticles on EPCs in a short period of time. Directional guide of the surface-modified magnetic nanoparticles to endothelial progenitor cells (EPCs) was evaluated under an applied magnetic field and simulated dynamic blood flow condition. The results showed that the prepared magnetic nanoparticles had good magnetic response, good cell compatibility within a certain range of the nanoparticle concentrations. The surface modified nanoparticles could combine with EPCs effectively in a short time, and those nanoparticles combined EPCs can be directionally guided on to a stent surface under the magnetic field in the dynamic flow environment.
Endothelial Progenitor Cells ; cytology ; drug effects ; Ferrosoferric Oxide ; chemistry ; Humans ; Levodopa ; chemistry ; Magnetite Nanoparticles ; chemistry ; Spectroscopy, Fourier Transform Infrared ; X-Ray Diffraction

Objective To discuss the Etiological Distribution of COPD patients and explore the potential influencing factors of COPD infection. Methods From January 2018 to January 2021, 134 patients with concurrent pulmonary infection and 131 patients without any infection were selected from all 295 patients with COPD treated in our hospital. A total of 265 patients (30 patients with accidental pulmonary infection and other organ system infection, which did not meet the inclusion and exclusion criteria of this study, were excluded). The study collected the basic information of subjects and the information of potential factors affecting pulmonary infection. SPSS statistical software package was used to analyze the research data. Firstly, the etiology of patients with COPD infection (134 cases) was further analyzed to explore the distribution characteristics of etiology. At the same time, the related conditions of COPD patients with infection (134 cases) and patients without any infection (131 cases) were compared and analyzed to explore the related factors affecting COPD patients with pulmonary infection. Results A total of 149 bacterial strains were detected in this study. Gram-negative bacteria accounted for a higher proportion of lung infection (97/149 , 65.10%), gram-positive bacteria 50 strains (50/149 , 33.56%), and other (fungi, etc.) 2 strains (2/149 , 1.34%). Gram-negative bacteria included acinetobacter baumannii (53/149 , 35.57%), Klebsiella pneumoniae (25/149 , 16.78%), Pseudomonas aeruginosa (16/149 , 10.74%) and Escherichia coli (3/149 , 2.01%). Gram-positive bacteria included staphylococcus aureus (24/149,16.11%), Staphylococcus superficial (13/149 , 8.72%), Staphylococcus haemolyticus (9/149 , 6.04%), and streptococcus pneumoniae (4/149,2.68%). Compared with chronic obstructive pulmonary disease (134 cases) and without any infection (131 cases), it was suggested that the proportion of patients aged >60 years, smoking history, type 2 diabetes mellitus, mechanical ventilation and antibiotics use time was >15 days (P<0.05). Further univariate and multivariate Logistics regression models were used to analyze the risk factors of increased pulmonary infection. Finally, multivariate analysis showed that age >60 years, smoking history, type 2 diabetes mellitus, and >15 OR duration of antimicrobial use were all risk factors, and all of them had P<0.05. Conclusion Gram negative bacteria are the main pathogens of lung infection in COPD patients. The risk of lung infection is higher in patients with high age, smoking history, type 2 diabetes and long time use of antibiotics, which is worthy of clinical attention.