Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University , Chongqing 400715, People's Republic of China.
ACS Appl Mater Interfaces. 2015 Feb 25;7(7):4127-34. doi: 10.1021/am508137t. Epub 2015 Feb 16.
An enzyme-free electrochemical immunosensor based on the host-guest nanonets of N,N-bis(ferrocenoyl)-diaminoethane/β-cyclodextrins/poly(amidoamine) dendrimer-encapsulated Au nanoparticles (Fc-Fc/β-CD/PAMAM-Au) for procalcitonin (PCT) detection has been developed in this study. The signal probe was constructed as follows: amine-terminated β-CD was adsorbed to PAMAM-Au first, and then the prepared Fc-Fc was recognized by the β-CD to form stable host-guest nanonets. Next, secondary antibodies (Ab2) were attached into the formed netlike nanostructure of Fc-Fc/β-CD/PAMAM-Au by chemical absorption between PAMAM-Au and -NH2 of β-CD. Herein, the PAMAM-Au act not only as nanocarriers for anchoring large amounts of the β-CD and Ab2 but also as nanocatalysts to catalyze the oxidation of ascorbic acid (AA) for signal amplification. Moreover, the Fc-Fc could be stably immobilized by the hydrophobic inner cavity of β-CD as well as improving solubility by the hydrophilic exterior of β-CD. With the unique structure of two ferrocene units, Fc-Fc not only affords more electroactive groups to make the electrochemical response more sensitive but also plays a role of combining dispersive β-CD-functionalized PAMAM-Au to form the netlike nanostructure. Furthermore, Fc-Fc exhibits good catalytic activity for AA oxidation. When the detection solution contained AA, the synergetic catalysis of PAMAM-Au and Fc-Fc to AA oxidation could be obtained, realizing enzyme-free signal amplification. The proposed immunosensor provided a linear range from 1.80 pg/mL to 500 ng/mL for PCT detection and a detection limit of 0.36 pg/mL under optimal experimental conditions. Moreover, the immunosensor has shown potential application in clinical detection of PCT.
本研究开发了一种基于 N,N-双（二茂铁基）-二氨基乙烷/β-环糊精/聚（酰胺-胺）树枝状大分子包裹的金纳米粒子（Fc-Fc/β-CD/PAMAM-Au）的主客体纳米网的无酶电化学免疫传感器，用于降钙素原（PCT）检测。信号探针的构建如下：首先将胺基末端的β-CD 吸附到 PAMAM-Au 上，然后 Fc-Fc 被β-CD 识别，形成稳定的主客体纳米网。接下来，通过 PAMAM-Au 与β-CD 的-NH2 之间的化学吸附，将第二抗体（Ab2）附着到形成的 Fc-Fc/β-CD/PAMAM-Au 的网状纳米结构中。在此，PAMAM-Au 不仅作为锚定大量β-CD 和 Ab2 的纳米载体，而且作为纳米催化剂，催化抗坏血酸（AA）的氧化以进行信号放大。此外，Fc-Fc 可以通过β-CD 的疏水性内腔稳定固定，并通过β-CD 的亲水性外表面提高溶解度。由于具有两个二茂铁单元的独特结构，Fc-Fc 不仅提供了更多的电化学活性基团，使电化学响应更灵敏，而且还起到了结合分散的β-CD 功能化的 PAMAM-Au 形成网状纳米结构的作用。此外，Fc-Fc 对 AA 氧化表现出良好的催化活性。当检测溶液中含有 AA 时，PAMAM-Au 和 Fc-Fc 对 AA 氧化的协同催化作用得以实现，实现了无酶信号放大。在最佳实验条件下，该免疫传感器对 PCT 的检测范围为 1.80 pg/mL 至 500 ng/mL，检测限为 0.36 pg/mL。此外，该免疫传感器已显示出在 PCT 临床检测中的潜在应用。
