Institute of Nanomedicine and Nanobiosensing, MOE Key Laboratory for Analytical Science of Food Safety and Biology, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, College of Chemistry, Fuzhou University, Fuzhou, Fujian 350116, China.
College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing, Zhejiang 314001, China.
ACS Appl Mater Interfaces. 2020 Jul 8;12(27):30085-30094. doi: 10.1021/acsami.0c06240. Epub 2020 Jun 26.
In this work, -phenylenediamine is utilized as a precursor to synthesize the fluorescent emission wavelength switchable carbon dots (-CDs). Our investigation reveals that ferrous ions (Fe) can effectively induce fluorescence quenching of -CDs by chelation and aggregation. After the addition of hydrogen peroxide (HO), the fluorescence of -CDs recovers and the fluorescent color changes from yellow to green. As far as we know, -CDs are the first reported CDs with switchable fluorescence emission wavelength. In order to fabricate an enzyme-free immunosensor, an amino-functionalized dendritic mesoporous silica nanoparticle (DMSN)-gold nanoparticle (Au NP) nanostructure was fabricated as a glucose oxidase mimetic nanoenzyme by in situ coating of the Au NPs on the surface of the DMSNs. Then, the functionalized DMSN-Au NPs were modified on the detection antibody and hydrolyzed with glucose to produce HO. This immune induced recognition strategy combines with the -CDs+Fe signal generation system to achieve specific and sensitive detection of the target. The replacement of glucose oxidase by DMSN-Au NPs not only reduces the cost but also provides significantly amplified signals due to DMSNs haing a high specific surface area. We show the detection of carcinoembryonic antigen (CEA) as an example target to evaluate the analytical figure of merits of the proposed strategy. Under the optimal conditions, two-photon-based -CDs displayed excellent performances for CEA and the limit of detection as low as 74.5 pg/mL with a linear range from 0.1 to 80 ng/mL. The proposed fluorescent immunosensor provides an optional and potential scheme for low cost, high sensitivity, and versatile discovery of clinical biomarkers.
在这项工作中，-苯二胺被用作合成荧光发射波长可切换的碳点（-CDs）的前体。我们的研究表明，亚铁离子（Fe）可以通过螯合和聚集有效地使 -CDs 的荧光猝灭。加入过氧化氢（HO）后，-CDs 的荧光恢复，荧光颜色从黄色变为绿色。据我们所知，-CDs 是第一个报道的具有可切换荧光发射波长的 CDs。为了制备无酶免疫传感器，通过在介孔硅纳米颗粒（DMSN）表面原位包覆 Au NPs 制备了一种氨基功能化的树枝状介孔硅纳米颗粒（DMSN）-金纳米颗粒（Au NP）纳米结构作为葡萄糖氧化酶模拟纳米酶。然后，将功能化的 DMSN-Au NPs 修饰在检测抗体上，并与葡萄糖水解生成 HO。这种免疫诱导识别策略结合了 -CDs+Fe 信号产生系统，实现了对目标的特异性和灵敏检测。用 DMSN-Au NPs 替代葡萄糖氧化酶不仅降低了成本，而且由于 DMSNs 具有高比表面积，还提供了显著放大的信号。我们以癌胚抗原（CEA）为例，评估了所提出策略的分析优点。在最佳条件下，双光子基 -CDs 对 CEA 表现出优异的性能，检测限低至 74.5 pg/mL，线性范围为 0.1 至 80 ng/mL。所提出的荧光免疫传感器为低成本、高灵敏度和多功能发现临床生物标志物提供了一种可选的潜在方案。
