多功能磁振造影對比劑 CHC-[Gd(DOTA-NH2)]-FITC-Erb之合成與特性研究

Abstract

本研究中，使用不具毒性、生物相容性好的幾丁聚醣衍生物 (Carboxymethyl-hexanoyl chitosan, CHC) 作為載體，利用其表面官能基鍵結 [Gd(DOTA-NH2)]、螢光發光基團及單株抗體 (Erbitux)，發展為磁振造影、光學影像之對比劑 CHC-[Gd(DOTA-NH2)]-FITC-Erb，以應用於磁振造影及光學影像上。在 0.5T，37.0 ± 0.1 ℃ 下， [Gd(DOTA-NH2)] 弛緩率為 4.9 ± 0.7 mM-1s-1當鍵結上幾丁聚醣衍生物、螢光發光基團及單株抗體後，弛緩率上升至 15.4 ± 1.7 mM-1s-1。進一步體外 (In vitro) 磁振造影實驗之分析顯示，在 400 μΜ 下CHC-[Gd(DOTA-NH2)]-FITC-Erb 所得之訊號負增強百分比 (negative signal enhancement) 為 +126.4％ 明顯高於 [Gd(DOTA-NH2)] (+ 73.8％) 及市售對比劑Omniscan (+ 54.7％)；與腫瘤細胞 (A431、SKBR-3及 Colo-205) 共培養後，所得之磁振造影及光學影像分析顯示，CHC-[Gd(DOTA-NH2)]-FITC-Erb 能專一性標靶化至具有 EGFR 表現型腫瘤細胞，且其中又以 EGFR 表現量最高之 A431 細胞株效果最為顯著。由各分析結果顯示，本研究成功合成具專一性標靶化之對比劑，除了具備高生物相容性與低毒性外，同時也兼具磁振造影與光學影像雙重功能之特性。

In this study, the non-toxic and good biocompatibility of Carboxymethyl-hexanoyl chitosan (CHC) is used as a carrier, which can be utilized as the surface functional group to bond with [Gd(DOTA-NH2)], fluorophores and monoclonal antibody (Erbitux). The targeted biofunctional contrast agent CHC-[Gd(DOTA-NH2)]-FITC-Erb is synthesized and characterized for MR imaging and optical imaging . When conjucate CHC, fluorophores and monoclonal antibody, the relaxivity (r1) value of CHC-[Gd(DOTA-NH2)]-FITC-Erb is 15.4 ± 1.7 mM-1s-1 at 20MHz and 37.0 ± 0.1℃. This represents a 3-fold increase compared to [Gd(DOTA-NH2)]. Further in vitro MR-imaging analysis, CHC-[Gd(DOTA-NH2)]-FITC-Erb obtained negative signal enhancement is + 126.4％, better than those of [Gd(DOTA-NH2)] (+ 73.8％) and commercially available contrast agent Omniscan (+ 54.7％). Tumor cells (A431, SKBR-3 and Colo-205) were cultured with CHC-[Gd(DOTA-NH2)]-FITC-Erb. The results obtained from MR-imaging and optical imaging analysis indicate that the contrast agent CHC-[Gd(DOTA-NH2)]-FITC-Erb is the potential specific target for EGFR phenotype of tumor cells, espectially for A431. Our data shows that the successful synthesis of a specific targets of the image contrast agent CHC-[Gd(DOTA-NH2)]-FITC-Erb have not only the high biocompatibility and low toxicity, but also the image of both MRI and optical characteristics of the dual function.