等离激元增强上转换发光及其分子检测应用

Plasmon⁃enhanced upconversion luminescence and application of molecular detection

针对荧光分子检测普遍灵敏度低和检测范围窄的问题,制备了具有等离子激元共振特性的重掺杂半导体纳米结构Cu_(2-x)S和典型的稀土掺杂上转换发光纳米颗粒NaYF_(4)∶Yb,Er,通过三相界面自组装方法获得了Cu_(2-x)S/NaYF_(4)∶Yb,Er薄膜基底。结合有限元模拟,计算了不同摆放情况下Cu_(2-x)S周围的局域电场分布,研究了在实际薄膜中Cu_(2-x)S纳米盘之间产生的等离激元耦合对上转换发光性能以及对拉曼信号增强的影响。结果表明,Cu_(2-x)S等离激元层与NaYF_(4)∶Yb,Er发光层的耦合,不仅得到了上转换3个数量级的提高,还实现了分子检测10^(-7)mol·L^(-1)的检测极限,并且获得了10^(-3)~10^(-7)mol·L^(-1)的宽线性响应,从而达到高灵敏度的定性和定量双功能的精确检测。

Fluorescence molecular detection exhibits limited development in detection applications due to generally low sensitivity and narrow detection range.The heavily doped semiconductor nanostructures Cu_(2-x)S with surface plasmon resonance effect and typical rare‐earth‐doped upconversion luminescent nanoparticles NaYF4∶Yb,Er were prepared,and further Cu_(2-x)S/NaYF_(4)∶Yb,Er film substrates were obtained by three‐phase interfacial self‐assembly method.Combined with finite element method simulations,the local electric field distributions around Cu_(2-x)S were calculated for different placement situations.The plasmon‐coupling effect generated between Cu_(2-x)S nanodisks was investigated on the upconversion luminescence performance and the Raman signals.Based on the intense upconversion luminescence caused by the excellent synergetic localized surface plasmon resonance effect,a dual detection method of qualitative before quantitative detection of Rhodamine B using surface‐enhanced Raman scattering signal monitoring and fluorescence sensing was established.The results show that the coupling of the Cu_(2-x)S plasmonic layer with the NaYF_(4)∶Yb,Er luminescent layer not only enables three orders of magnitude improvement of upconversion emission,but also achieves the detection limit of 10^(-7)mol·L^(-1)for molecular detection and obtains a broad linear response from 10^(-3)to 10^(-7)mol·L^(-1),and finally realizes the qualitative and quantitative bifunctionality of highsensitivity accurate detection.