A Eu³⁺doped functional core-shell nanophosphor as fluorescent biosensor for highly selective and sensitive detection...

Lanthanide-doped core-shell nanomaterials have illustrated budding potential as luminescent materials, but their biological applications have still been very limited due to their aqueous solubility and biocompatibility. Here, we report a simple and cost-effective approach to construct a water-stable chitosan-functionalized lanthanoid-based core shell (Ca-Eu:Y₂O₃@SiO₂) nanophosphor. The as-synthesized Ca-Eu:Y₂O₃@SiO₂-chitosan (CEY@SiO₂-CH) nanophosphor has been characterized for its structural, morphological, and optical properties, by employing different analytical tools. This sensing platform is suitable for dsDNA probing by tracing the "turn on" fluorescence signal generated by CEY@SiO₂-CH nanophosphor with the addition of dsDNA. The ratio of fluorescence intensity enhancement is proportional to the concentration of dsDNA in the range 0.1-90 nM, with the limit of detection at ⁓16.1 pM under optimal experimental conditions. The enhancement in fluorescence response of functionalized core-shell phosphor with dsDNA is due to the antenna effect. Additionally, response of probe has been studied for the real samples displaying percent recovery in between 101 and 105, maximum RSD% upto 5.23 (n = 3). This outcome can be applied to the selective sensing of dsDNA through optical response. These findings establish the CEY@SiO₂-CH a simple, portable, and potential candidate as a sensor for rapid and analytical detection of dsDNA.