Folic acid (FA), is an essential mineral required to form healthy cells and red blood cells. Inadequate FA can lead to kidney, liver and heart diseases. Therefore, developing sensitive sensors for the trace detection of FA is vital. In this study, we prepared nitrogen-doped carbon quantum dots (N-CQDs) hydrothermally using citric acid and Urea as the respective carbon and nitrogen source. The as-synthesized nanosensor was characterized using Fourier-Transform Infra-red Spectroscopy (FTIR), a High-resolution transmission electron microscope (HRTEM), and ultraviolet-visible spectroscopy (UV–vis). The as-prepared nanosensors are spherical with an average particle diameter of 3.554 ± 0.755 nm and displayed blue emission at 440 nm when excited at 370 nm. FTIR affirmed the presence of hydroxyl, carboxyl, and amino functional groups. The developed material was sensitive to pH changes, with pH 6 being the optimum. Fluorometric studies showed that the presence of FA resulted in quenching the fluorescent intensity of the as-prepared nanoprobe with high selectivity amid interfering metal ions and biomolecules. A calculated detection limit of 0.39 µM was obtained. The photoluminescence quenching mechanism reveals static quenching. The as-synthesized nanoprobe can be utilized as a fast, reliable nanosensor in actual samples.

中文翻译：

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使用氮掺杂碳量子点 (N-CQD) 在干扰金属离子和生物分子中选择性、灵敏地测定叶酸

叶酸 (FA) 是形成健康细胞和红细胞所需的必需矿物质。FA 不足会导致肾脏、肝脏和心脏疾病。因此，开发用于痕量 FA 检测的灵敏传感器至关重要。在这项研究中，我们使用柠檬酸和尿素作为各自的碳源和氮源，通过水热法制备了氮掺杂碳量子点（N-CQD）。使用傅里叶变换红外光谱（FTIR）、高分辨率透射电子显微镜（HRTEM）和紫外-可见光谱（UV-vis）对合成的纳米传感器进行了表征。所制备的纳米传感器呈球形，平均粒径为3.554±0.755 nm，在370 nm激发时在440 nm处显示蓝色发射。FTIR 证实存在羟基、羧基和氨基官能团。所开发的材料对 pH 值变化敏感，pH 6 是最佳值。荧光研究表明，FA 的存在导致所制备的纳米探针的荧光强度在金属离子和生物分子的干扰下具有高选择性。计算得出的检测限为 0.39 µM。光致发光猝灭机制揭示了静态猝灭。合成的纳米探针可以在实际样品中用作快速、可靠的纳米传感器。