Unexpected Chirality of Nanoparticle Dimers and Ultrasensitive Chiroplasmonic Bioanalysis
Unexpected Chirality of Nanoparticle Dimers and Ultrasensitive Chiroplasmonic Bioanalysis
复制标题
纳米颗粒二聚体的意外手性和超灵敏手性等离子体生物分析
DOI：
10.1021/ja4095445
复制
发表时间：
2013-12-11
影响因子：
15
通讯作者：
Kotov, Nicholas A.
中科院分区：
文献类型：
--
作者：
Wu, Xiaoling;Xu, Liguang;Kotov, Nicholas A.
纳米颗粒（NP）的手性组装体通常构造为螺旋形或四面体几何形状。由于在假设其球形几何形状下进行的基本对称性考虑，预计简单的NP对不会显示手性。在这项研究中，我们证明了由两个金属纳米粒子组成的组件具有手性和强烈的旋转光的偏振。它们的手性等离子体特性归因于单个胶体颗粒的长形几何形状。当通过生物分子桥接时，NP对获得剪刀状几何形状，NP的长轴形成近似9度的角度。这个小的二面角导致NP对的手性，而由于桥接生物大分子的特定构象而导致的其符号的一致性破坏了NP对的对映体等效性。这些纳米组装体中的强极化旋转使得它们在生物分析中的利用成为可能。使用抗体-抗原桥制备金和银纳米颗粒的异源二聚体。利用它们的手性特性，我们研究了它们用于检测环境毒素微囊藻毒素-LR和癌症生物标志物前列腺特异性抗原的生物分析潜力。与所有其他分析技术相比，检测限的数量级改进归因于生物化合物的固有手性的等离子体增强，光子与具有扭曲几何形状的NP组件的强光学耦合，以及由于圆二色性带的双信号性质而引起的信号放大。
Chiral assemblies of nanoparticles (NPs) are typically constructed with helical or tetrahedral geometries. Simple pairs of NPs are not expected to display chirality due to basic symmetry considerations made under the assumption of their spherical geometry. In this study we demonstrate that assemblies consisting of two metallic NPs do possess chirality and strongly rotate polarization of light. Their chiroplasmonic properties are attributed to the prolate geometry of individual colloidal particles. When bridged by biomolecules, the NP pairs acquire scissor-like geometry, with the long axes of NPs forming an angle of similar to 9 degrees. This small dihedral angle results in chirality of the NP pair, while the consistency of its sign due to the specific conformation of the bridging biomacromolecules breaks the enantiomeric equivalence of the NP pairs. Strong polarization rotation in these nanoassemblies makes possible their utilization in biological analysis. Heterodimers of gold and silver NPs were made using antibody-antigen bridges. Taking advantage of their chiroplasmonic properties, we investigated their bioanalitical potential for detection of an environmental toxin, microcystin-LR, and a cancer biomarker, prostate-specific antigen. The order-of-magnitude improvements in limits of detection compared to all other analytical techniques are attributed to plasmonic enhancement of intrinsic chirality of biological compounds, strong optical coupling of photons with NP assemblies with twisted geometries, and signal amplification due to the bisignate nature of circular dichroism bands.