To optimize the lipophilicity and improve in vivo pharmacokinetics of near-infrared probes targeted Aβ plaques, we designed, synthesized, and evaluated a series of polyethylene glycol modified probes with hydroxyl and methoxyl terminals. The relationships between chemical structure and optical, biological properties were systemically elucidated. The results indicated that a desired Aβ probe should keep a balance among molecular rigidity, size, and lipophilicity. Probe 12d displayed improved properties including intense and selective response to Aβ1–42 aggregates (Kd = 7.3 nM, 22-fold fluorescence enhancement and emission maxima at 715 nm upon interaction with Aβ1–42 aggregates), sufficient blood–brain barrier penetration (3.04% ID/g), and fast wash out from the brain (brain2 min/brain60 min = 10.1). Clear fluorescence signals retention in transgenic mice than control mice in in vivo near-infrared imaging. Hence, polyethylene glycol modified probes retained favorable optical properties but displayed great improvement of biological properties for Aβ detection.
为了优化近红外探针的亲脂性并改善其针对Aβ斑块的在体药代动力学特性,我们设计、合成了具有羟基和甲氧基终端的一系列聚
乙二醇修饰探针,并系统评估了它们的光学和
生物学性质。结果表明,理想的Aβ探针应在分子刚性、尺寸和亲脂性之间保持平衡。探针12d展示了改进的特性,包括对Aβ1–42聚集物(亲和常数Kd = 7.3 nM,与Aβ1–42聚集体反应时荧光增强22倍,发射峰位于715 nm)的强烈且选择性响应,足够的血脑屏障渗透率(3.04% ID/g),以及快速从大脑中清除的特性(脑内2分钟/脑内60分钟比值为10.1)。在活体近红外成像中,转
基因小鼠相比对照小鼠展现出更持久的荧光信号。因此,聚
乙二醇修饰的探针在保留良好光学特性的同时,显著提升了针对Aβ检测的
生物学性能。