[Tracing study of nanometer microspheres labeled with fluorescent dye on gastric cancer cells]

To explore the tracing role of nanometer microspheres tagged by fluorescent dye NIR-797 in gastric cancer cells in order to guide precise resection for gastric cancer.

Targeted polymer segment NH2-PEG-Pep-PCL and non-targeted polymer segment NH2-PEG- PCL(without Pep) were synthesized with NH2-PEG-NH2, gelatinase substrate peptides (Pep) and PCL-COOH by amidation method. Then nanometer microspheres were prepared by self-assemebly method. NIR-797 was linked into the end of PEG through chemical reaction. Molecular weight, particle size, polydispersity and surface potentials of the nanometer microspheres were detected. Uptake degree of human gastric SGC-7901 cells with targeted and non-targeted nanometer microspheres was observed under fluorescence microscope. Fluorescence intensity of above two nanometer microspheres in tumor sites of tumor-burdened nude mice after intravenous injection of nanometer microspheres at different time points was detected by multispectral imaging system.

The molecular weight of NH2-PEG-Pep-PCL and NH2-PEG-PCL were similar to original design. The diameter of targeted nanometer microspheres before and after NIR-797-tagging was (124.1±2.1) nm and (129.7±2.8) nm, and the diameter of non-targeted ones before and after NIR-797-tagging was (120.6±2.6) nm and (124.3±2.9) nm (all P>0.05). Fluorescence intensity of SGC-7901 cells and tumor sites was significantly higher in the targeted nanometer microspheres group as compared to the non-targeted group.

Targeted nanometer microspheres tagged by flourescent dye have higher targeted affinity to gastric cancer cells and better enrichment in tumor site, indicating a good tracing of tumor and a guidance for accurate resection of tumor.