^(131)I标记贝伐单抗偶联载紫杉醇超顺磁性氧化铁纳米粒的制作及生物分布实验

Preparation and biodistribution study of ^(131)I-BEV-PTX-SPIONs

为了研究^(131)I标记贝伐单抗偶联载紫杉醇超顺磁性氧化铁纳米粒(^(131)I-Bevacizumab-Paclitaxel-Superparamagnetic Iron Oxide Nanoparticles,^(131)I-BEV-PTX-SPIONs)的制备和生物学分布。将30只成瘤裸鼠分为单靶向组及双靶向组,再按时间点2 h、6 h、12 h、24 h及48 h分为5个亚组,每亚组各3只,尾静脉注射^(131)IBEV-PTX-SPIONs后,进行生物学分布及单光子发射计算机断层成像术(Single-Photon Emission Computed Tomography,SPECT)显像。^(131)I-BEV-PTX-SPIONs的粒径约220 nm,分散性尚可;^(131)I标记率为81.4%;放射性化学纯度(Radiochemical Purity,RCP)>99%;在PB缓冲液中稳定性良好;在体外PTX(Paclitaxel)缓释性能良好;与A549细胞有较好的亲和力。体内生物学分布结果:随着时间的延长,肿瘤组织的放射性计数相对增高,12 h达高峰;T/NT(Target to Nontarget)比值逐渐升高,48 h达7.80±0.50。6 h、12 h、24 h、48 h时,双靶向组的肿瘤组织放射性计数及T/NT比值均高于单靶向组,差异均具有统计学意义(P<0.05),且差异性随着时间延长越来越显著。SPECT显像结果:2 h肿瘤部位即有放射性聚集,且随着时间的延长,放射性聚集增加并持续稳定,T/NT比值持续上升。初步研究结果显示,^(131)I-BEV-PTX-SPIONs具有用于肺癌诊疗的潜质,值得进一步研究。

[Background]^(131)I-BEV-PTX-SPIONs is a type of nanoparticle used in cancer therapy.It is composed of four components:a radioactive isotope of iodine(^(131)I),a chemotherapy drug called paclitaxel(PTX),a type of nanoparticle called superparamagnetic iron oxide nanoparticles(SPIONs),and a molecule called bevacizumab(BEV)which is an antibody that targets and blocks the growth of blood vessels that supply tumors.[Purpose]This study aims to investigate the preparation and biological distribution of ^(131)I-BEV-PTX-SPIONs.[Methods]First of all,^(131)I-BEV-PTX-SPIONs were prepared,synthetized and identified.The transmission electron microscope(TEM)were employed to observe the particle characteristics.Then,30 tumor-burdened nude mice were divided into the single targeting group and the dual targeting group for evaluation of ^(131)I-BEV-PTX-SPIONs distribution in these nude mice,each group was divided into five sub-groups based on time points of 2 h,6 h,12 h,24 h and 48 h,3 in each sub group.Finally,^(131)I-BEV-PTX-SPIONs were injected into the caudal vein of these mice,and experiments of biological distribution in vivo and SPECT imaging were carried out,and results were analyzed using GraphPad Prism 8.3 software.[Results]The nanospheres in prepared ^(131)I-BEV-PTX-SPIONs are obtained in good mono dispersion with a diameter of approximately 220 nm by TEM observation.^(131)I-BEV-PTX-SPIONs obtained in a high radiolabeling yield is about 81.4%with the radiochemical purity of over 99%and good stability shown in the 0.2 mol·L−1 PB buffer.And it could attain sustained PTX release in vitro.Comparing with the cellular uptake of ^(131)I,a higher uptake and sustained PTX release in vitro are shown for ^(131)I-BEV-PTX-SPIONs.Biodistribution experimental results show:After the injection of ^(131)I-BEV-PTX-SPIONs,with the extension of time,the radiation count of the tumor is relatively higher,at 12 h reaching the peak.And the T/NT ratio increased gradually,and it reaches 7.8±0.50 at 48 h.The counts and the ratios at 6 h,12 h,24 h and 48 h are notably higher in the dual targeting group than the single targeting group(P<0.05),and over time the differences are more significant.SPECT examination results show:At 2 h after the injection of ^(131)I-BEV-PTX-SPIONs,the tumor site has a radioactive build-up.With the extension of time,the accumulation of radioactivity increased and remained stable,and the T/NT ratio rises steadily.[Conclusions]These results demonstrated the potential of ^(131)I-BEV-PTX-SPIONs in the diagnosis and treatment of lung cancer,and it was worthy of further study.