囊泡型荧光纳米界面的构建及其对CD44蛋白的比例型传感

Fluorescent vesicular nanointerface: construction and ratiometric sensing behavior toward CD44 protein

本文设计合成了两亲性Eu(Ⅲ)配合物(Eu L^3+)、两亲性香豆素衍生物(CA)以及荧光素修饰的透明质酸(HA-FA).Eu L^3+和CA可在水中共组装形成带正电荷的囊泡型荧光纳米界面(Eu L^3+/CA).HA-FA可通过静电引力络合在Eu L^3+/CA表面,促使CA与FA之间发生有效的荧光共振能量转移,体系的荧光发射以荧光素的绿色荧光为主.当肿瘤细胞标识物CD44蛋白与络合在囊泡表面上的透明质酸发生特异相互作用后,降低了CA与FA之间的能量转移效率,体系的荧光发射从绿色转变为蓝色.据此,实现了对CD44的高灵敏检测(DL=1.79×10^-7g/m L),而所测试的氨基酸、蛋白质等生物分子几乎不对荧光纳米界面的荧光性质产生影响.基于此,我们成功地将Eu L^3+/CA/HA-FA用于人乳腺癌细胞MCF-7和MDA-MB-231悬浮液中CD44蛋白的高效检测,该工作为构建新型CD44蛋白荧光探针提供了思路,为癌症早期诊断和治疗奠定了基础.

A fluorescent vesicular nanointerface for CD44 protein sensing has been achieved by using amphiphilic Eu3+complexes and derivatives of a pair of fluorophores,fluorescein and coumarin.Both Eu3+complex and coumarin were designed to have hydrophobic tails,which facilitated their co-assembly to form vesicles(Eu L3+/CA).The negatively charged fluorescein-labeled hyaluronic acid(HA-FA)could bond onto Eu L3+/CA surface via coulombic interaction.The vesicles usually emit in the blue region,but they exhibited green fluorescence after HA-FA was bonded to the vesicle surface.This is due to the fluorescence resonance energy transfer(FRET)process between coumarin and fluorescein.As the CD44 protein was introduced to the system,intensity of the green emission of the assembly decreased,while the blue emission enhanced.This phenomenon is accounted for the specific binding between CD44 and hyaluronic acid thereby prohibiting the FRET process between HA-FA and Eu L3+/CA.The vesicular nanointerface was found to be sensitive and selective to CD44 sensing(DL=0.179μg/m L)while the amino acids and proteins tested did not affect the fluorescent properties of the assembly.What is more,the assembly could not only be used to detect CD44 in buffer solution,but also be applied to detect CD44 in cancer cells.