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 progenitor 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.
The nucleic acid adapters of tumor serum markers are oligonucleotide molecules with high specificity and high affinity with tumor serum markers obtained by in vitro screening with systematic evolution of ligands by exponential enrichment (SELEX). Researchers take the advantage of the nucleic acid adapter to explore new tumor serum markers that have more diagnostic value for tumor diagnosis. Recently, some achievements have been achieved in the research of liver cancer and stomach cancer. This paper has reviewed nucleic acid adapter and its research in the serum tumor marker screening, and discussed the value of the nucleic acid adapter of serum tumor markers in the diagnosis, as well as current problems existing in the research. This paper is very useful to help people better understand the screening of nucleic acid adapters of tumor serum markers, and to provide help in discovering new tumor serum markers.
Nucleic acid aptamer is an oligonucleotide sequence screened by the exponential enrichment ligand system evolution technology (SELEX). Previous studies have shown that nucleic acid aptamer has a good application prospect in tumor diagnosis and treatment. Therefore, we reviewed the selection and identification of nucleic acid aptamer of lung cancer cells in recent years, and discussed the effect of aptamer as targeting drugs and targeting vectors on the diagnosis of tumors, which provide a new idea for early diagnosis and treatment of tumor.