Ligand density effect on biorecognition by PEGylated gold nanoparticles:: Regulated interaction of RCA120 lectin with lactose installed to the distal end of tethered PEG strands on gold surface
Ligand density effect on biorecognition by PEGylated gold nanoparticles:: Regulated interaction of RCA120 lectin with lactose installed to the distal end of tethered PEG strands on gold surface
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DOI：
10.1021/bm049427e
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发表时间：
2005-03-01
影响因子：
6.2
通讯作者：
Kataoka, K
中科院分区：
文献类型：
--
作者：
Takae, S;Akiyama, Y;Kataoka, K
制备了直径为20 nm的聚乙二醇化金纳米颗粒，其远端具有0 ~ 65%的乳糖配体功能，探讨了配体密度对其凝集素结合性能的影响。纳米粒子水溶液的紫外可见光谱表明，PEG层具有较强的空间稳定特性，即使在生理盐浓度（离子强度，I = 0.15 M）下，纳米粒子也具有较高的分散稳定性。通过热重分析（TGA）确定单个颗粒上的PEG链数为520。在可控加速电压下的扫描电镜（SEM）观察显示，纳米颗粒上的聚乙二醇层厚度约为7层。然后根据TGA和SEM结果计算聚乙二醇化金纳米颗粒表面单个乳糖分子所占的面积，并根据乳糖功能（65-20%）在10-34 nm(2)范围内变化。具有40%和65%乳糖功能的聚乙二醇化金纳米颗粒在加入蓖麻凝集素（RCA(120)）凝集素（一种二价半乳糖特异性蛋白）的磷酸盐缓冲液中表现出选择性和时间依赖性聚集。通过加入过量的半乳糖，聚集体可以完全重新分散。600 ~ 750 nm紫外可见光谱延时监测表明，随着溶液中RCA（120）浓度的增加和纳米颗粒乳糖密度的增加，聚乙二醇化金纳米颗粒的聚集速度加快。此外，凝集素检测的灵敏度可以通过调节颗粒表面的乳糖密度来控制。有趣的是，观察到一个临界乳糖密度（> 20%）可以诱导可检测到的颗粒聚集，这表明颗粒之间的相互作用是由通过凝集素分子的多分子桥接触发的。
PEGylated gold nanoparticles (diameter: 20 nm) possessing various functionalities of lactose ligand on the distal end of tethered PEG ranging from 0 to 65% were prepared to explore the effect of ligand density of the nanoparticles on their lectin binding property. UV-visible spectra of the aqueous solution of the nanoparticles revealed that the strong steric stabilization property of the PEG layer lends the nanoparticles high dispersion stability even under the physiological salt concentration (ionic strength, I = 0.15 M). The number of PEG strands on a single particle was determined to be 520 from thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) observation under controlled acceleration voltage revealed the thickness of the PEG layer on the nanoparticle to be similar to 7 rim. The area occupied by a single lactose molecule on the surface of PEGylated gold nanoparticles was then calculated based on TGA and SEM results and was varied in the range of 10-34 nm(2) depending on the lactose functionality (65-20%). PEGylated gold nanoparticles with 40% and 65% lactose functionality showed a selective and time-dependent aggregation in phosphate buffer with the addition of Ricinus communis agglutinin (RCA(120)) lectin, a bivalent galactose specific protein. The aggregates can be completely redispersed by adding an excess amount of galactose. Time-lapse monitoring of UV-visible spectra at 600-750 nm revealed that the aggregation of PEGylated gold nanoparticles was accelerated with an increase in both RCA(120) concentration in the solution and the lactose density of the nanoparticles. Furthermore, the sensitivity of lectin detection could be controlled by the regulation of lactose density on the particle surface. Interestingly, there was a critical lactose density (> 20%) observed to induce detectable particle aggregation, indicating that the interaction between the particles is triggered by the multimolecular bridging via lectin molecules.