A novel ratiometric emission N, S dual-doped carbon dots (N, S-CDs) were facilely developed for pH visual sensing via one-step hydrothermal method. The proposed N, S-CDs displayed intrinsic pH-sensitive behavior and exhibited ratiometric fluorescence emission (F_{563 nm}/F_{645 nm}) characteristic with the variation of pH values. Interestingly, a significant red shift of emission wavelength can be observed at 645 nm along with the emission at 563 nm decreased accordingly when the pH changed from 3.0 to 1.0. Simultaneously, the fluorescence of N, S-CDs aqueous solution was visually varied from yellow to red. The ratiometric pH linear response was in the region of 3.6 to 2.4 and the pK_a was 2.90. Moreover, the N, S-CDs hold unique optical properties, good reversibility, superior biocompatibility and low cytotoxicity, which was further employed to monitor the intracellular pH fluctuations through the visible fluorescence changes between yellow and red. All these findings demonstrated that N, S-CDs can be utilized as the visual biosensor platform for tracking pH variations in extremely acidic environments such as gastric juice, which provided novel insights for clinical medical disease diagnosis (e.g., stomach disease detection) and other biomedical fields.

通过一步水热法轻松开发了一种新型的比例发射N，S双掺杂碳点（N，S-CD），用于pH视觉检测。提出的N，S-CDs表现出固有的pH敏感行为，并且随着pH值的变化呈现出比例荧光发射（F _{563 nm} / F _{645 nm}）特性。有趣的是，当pH从3.0更改为1.0时，可以在645 nm处观察到发射波长的明显红移，而在563 nm处的发射相应地减少了。同时，N，S-CDs水溶液的荧光在视觉上从黄色变为红色。pH线性比例响应在3.6到2.4之间，pK _a是2.90。而且，N，S-CD具有独特的光学性质，良好的可逆性，优异的生物相容性和低细胞毒性，其进一步被用于通过黄色和红色之间可见的荧光变化来监测细胞内pH波动。所有这些发现表明，N，S-CD可用作可视化生物传感器平台，用于跟踪极端酸性环境（例如胃液）中的pH变化，这为临床医学疾病诊断（例如，胃病检测）和其他生物医学提供了新颖的见解。领域。