Shehata Nader, Kandas Ishac, Samir Effat
Center of Smart Nanotechnology and Photonics (CSNP), SmartCI Research Center, Alexandria University, 21544 Alexandria, Egypt.
Department of Engineering Mathematics and Physics, Faculty of Engineering, Alexandria University, 21544 Alexandria, Egypt.
Nanomaterials (Basel). 2020 Feb 12;10(2):314. doi: 10.3390/nano10020314.
Cerium oxide (ceria) nanoparticles (NPs) have been proved to be an efficient optical fluorescent material through generating visible emission (~530 nm) under violet excitation. This feature allowed ceria NPs to be used as an optical sensor via the fluorescence quenching Technique. In this paper, the impact of in-situ embedded gold nanoparticles (Au NPs) inside ceria nanoparticles was studied. Then, gold-ceria NPs were used for sensing dissolved oxygen (DO) in aqueous media. It was observed that both fluorescence intensity and lifetime were changed due to increased concentration of DO. Added gold was found to enhance the sensitivity of ceria to DO quencher detection. This enhancement was due to optical coupling between the fluorescence emission spectrum of ceria with the surface plasmonic resonance of gold nanoparticles. In addition, gold caused the decrease of ceria nanoparticles' bandgap, which indicates the formation of more oxygen vacancies inside the non-stoichiometric crystalline structure of ceria. The Stern-Volmer constant, which indicates the sensitivity of optical sensing material, of ceria-gold NPs with added DO was found to be 893.7 M, compared to 184.6 M to in case of ceria nanoparticles only, which indicates a superior optical sensitivity to DO compared to other optical sensing materials used in the literature to detect DO. Moreover, the fluorescence lifetime was found to be changed according to the variation of added DO concentration. The optically-sensitivity-enhanced ceria nanoparticles due to embedded gold nanoparticles can be a promising sensing host for dissolved oxygen in a wide variety of applications including biomedicine and water quality monitoring.
氧化铈（二氧化铈）纳米颗粒（NPs）已被证明是一种高效的光学荧光材料，通过在紫光激发下产生可见光发射（~530nm）。这一特性使得二氧化铈纳米颗粒能够通过荧光猝灭技术用作光学传感器。本文研究了在二氧化铈纳米颗粒中原位嵌入金纳米颗粒（Au NPs）的影响。然后，金-二氧化铈纳米颗粒被用于检测水介质中的溶解氧（DO）。观察到由于溶解氧浓度的增加，荧光强度和寿命都发生了变化。发现添加的金增强了二氧化铈对溶解氧猝灭剂检测的灵敏度。这种增强是由于二氧化铈的荧光发射光谱与金纳米颗粒的表面等离子体共振之间的光学耦合。此外，金导致二氧化铈纳米颗粒的带隙减小，这表明在二氧化铈的非化学计量晶体结构中形成了更多的氧空位。发现添加溶解氧的二氧化铈-金纳米颗粒的斯特恩-沃尔默常数（表明光学传感材料的灵敏度）为893.7M，而仅二氧化铈纳米颗粒的情况为184.6M，这表明与文献中用于检测溶解氧的其他光学传感材料相比，对溶解氧具有更高的光学灵敏度。此外，发现荧光寿命根据添加的溶解氧浓度的变化而改变。由于嵌入金纳米颗粒而具有光学灵敏度增强的二氧化铈纳米颗粒在包括生物医学和水质监测在内的各种应用中可能是一种有前途的溶解氧传感主体。
