| Objective:We modified the surface of gold nanoparticles with folic acid (FA) or anti-AFPmAb, targeting folate receptors or AFP of tumor cells. To investigate the targetingdifference between the two tracers, study gold nanoparticles (Au NPs) functions as theradiation sensitizer of60Co gamma rays. We’ll focus on the biological mechanism ofhow Au NPs improving radiation effect by changing the cell cycle.Methods1. Basing on the specific combination principle, we modified the surface of AuNPs with folic acid and anti-AFP mAb. Due to the light scattering of Au NPs, we canidentify the uptake amount of Au NP–FA and Au NP-anti-AFP mAb respectively byFR-positive Hela cells and AFP-positive7721cells by using laser scanning confocalmicroscopy (LSCM).2. We have screened out the concentration of Au NPs with good cell compatibilitywith MTT assay as the safe biologically concentration. We use cell cloning experimentto evaluate the gamma radiation toxicity enhanced by Au NPs. And we also measurecell relative growth rate after radiation with MTT assay to confirm the cloningexperiment. The Hela cells were cultured with Au NPs at different time, then flowcytometry (FCS) was applied to detect the changes of cell cycles.Results1. Folate targeted: The results of LSCM show that Hela cells began to uptake AuNPs after30minutes, and the amount gradually increased with time. One hour later, thespeed of Au NPs entering Hela cells increased significantly comparing to the bare AuNPs of control group, and they concentrated on the inner side of cell membranes. Two hours later, the uptake of Au NPs by Hela cells had reached saturation. The difference ofthe uptake rates between Au NPs-FA and bare Au NPs gradually decreased.AFP targeted:7721cells hadn’t uptook Au NPs after30minutes cultured, and noobvious change after7hours followed by LSCM, The same were found in controlgroup.2. The results of MTT assay show: when the concentration of Au NPs is0.330mmol/L, cell relative growth rate (RGR) is50.0%meaning cell toxicity is obvious,with concentration decreasing RGR of Hela cells increase gradually. When theconcentration of Au NPs is0.110mmol/L, RGR is up to97.1%, which shows that AuNPs almost have no impact on cell proliferation and cell compatibility is good as well.3. Colonognic cell survival tests was performed by culturing Hela cells with0.110mmol/L Au under60Co gamma rays dose of0.5、1、2、4、6and8Gy, but onlydifference between experimental group and control groups was found at1Gy dose.Itwas further confirmed by MTT assay, founding obviously enhanced irradiation effectswere only found under1Gy comparing to1.5and2Gy,. Meanwhile, the RGR of1、1.5、2Gy group all obviously decrease when Au NPs was0.041mmol/L.4. Hela cells appeared G1cell cycle arrest after24h cultured with Au NPs, and G1cell cycle arrest was obvious in36h analyzed and calculated by FCM.Concilsions1. Au NP–FA displayed higher affinity and more targeting activities, and theuptake rate of Au NPs by target cells can be improved via the receptor-mediatedendocytosis. The Au NP–FA can be a new targeting probe to label target tumor cells, inthe application of the accurate diagnosis and tumor treatment.2. We did not find obvious the enhanced toxicity-capability of Au NPs by60Cogamma rays, but we found that the enhancement of the toxicity of radiation depends onthe radiation dose and its concentration.3. Au NPs can change the distribution of cell cycles, and then change the radiationsensitivity of tumor cells on biology. |
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