Abstract：
The identification and quantification of melatonin (MT) are crucial for early diagnosis of disorders associated with circadian rhythm disruption. Herein, novel blue-emissive carbon dots (BCDs) were synthesized through an improved hydrothermal treatment using serine and malic acid as reductant and carbon source. The excellent optical properties of the as-obtained BCDs were used for ratiometric sensing by strategically constructing a MT sensing system integrating BCDs with C3N4 nanosheets loaded with platinum/ruthenium nanoparticles (PtRu/CN). In this system, H2O2 activated the peroxidase-like activity of PtRu/CN to generate •OH and 1O2 for oxidizing the colorless o-phenylenediamine (OPD) into yellow 2,3-diaminophenazine (DAP) with fluorescence emission at 565 nm. Concurrently, the fluorescence emission of BCDs at 439 nm was quenched by the generated DAP via the static quenching and inner filter effect (IFE) process. However, MT rapidly scavenged the generated free radicals to reverse the ratio fluorescence signal. The developed BCDs/PtRu/CN/OPD/H2O2 sensing platform enabled quantitative analysis of MT at concentrations ranging from 0.06 to 600 μmol/L with a low detection limit of 23.56 nmol/L. Moreover, smartphone-based RGB sensing of MT was successfully developed for rapid visualization and portable processing. More broadly, novel insights into the preparation of carbon dots with sensitive fluorescence sensing properties were presented, promising for future considerations.
摘要：
褪黑激素（MT）的识别和定量对于与昼夜节律破坏相关的疾病的早期诊断至关重要。在这里，通过使用丝氨酸和苹果酸作为还原剂和碳源的改进的水热处理合成了新型的蓝色发射碳点（BCD）。通过策略性地构建MT传感系统，将BCD与载有铂/钌纳米颗粒（PtRu/CN）的C3N4纳米片集成在一起，从而将获得的BCD的出色光学特性用于比率传感。在这个系统中,H2O2激活PtRu/CN的过氧化物酶样活性以产生·OH和1O2，用于将无色邻苯二胺（OPD）氧化为黄色2,3-二氨基吩嗪（DAP），并在565nm处发射荧光。同时,通过静态猝灭和内部滤波效应（IFE）过程，生成的DAP猝灭了439nm处的BCD的荧光发射。然而,MT快速清除所产生的自由基以逆转比率荧光信号。开发的BCD/PtRu/CN/OPD/H2O2传感平台可对浓度为0.06至600μmol/L的MT进行定量分析，检测限低为23.56nmol/L。此外，成功开发了基于智能手机的MTRGB传感，用于快速可视化和便携式处理。更广泛地说,提出了制备具有灵敏荧光传感特性的碳点的新见解，希望将来考虑。
