We developed a method to produce red fluorescent carbon dots from leaves (PCDs) through hydrothermal carbonization. These PCDs exhibit consistent photoluminescence, emitting light regardless of excitation, with a 6.01 ns fluorescence lifetime and a 10.2% quantum yield. They possess a fine size of 4.4 nm, excellent hydrophilicity, and stability in a pH range of 4–11. Leveraging their optical properties, these PCDs function as precise nano-probes for detecting Fe ions, demonstrating a linear correlation within 0 to 50 μM concentrations and a low detection limit of approximately 0.14 μM. Emitting light at about 620 nm, these PCDs remain visible even in daylight. When applied to fingerprints on various substrates and dried, they reveal distinct prints under 365 nm UV light, retaining stability for 24 h. This resilience is attributed to preventing fluorescence reduction, achieved through the coffee-ring effect and electrostatic interactions during drying. Employing deep learning with the algorithm, fluorescence images of these latent fingerprints (LFPs) exceptionally resemble standard controls. These PCDs serve a dual role as fluorescent ink and nanocomposite films within a PVA matrix, demonstrating potential in anti-counterfeiting applications. This study presents a straightforward method for synthesizing PCDs with intense red luminescence, establishing them as a versatile platform for Fe sensing, flexible fluorescent films, latent fingerprints, and anti-counterfeiting pursuits.

中文翻译：

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使用源自白鹳的碳点，通过无墨印刷和形状记忆行为增强可持续的潜指纹

我们开发了一种通过水热碳化从叶子（PCD）生产红色荧光碳点的方法。这些 PCD 表现出一致的光致发光，无论激发如何都会发光，荧光寿命为 6.01 ns，量子产率为 10.2%。它们具有 4.4 nm 的精细尺寸、优异的亲水性以及在 4-11 的 pH 范围内的稳定性。这些 PCD 利用其光学特性，充当检测 Fe 离子的精密纳米探针，在 0 至 50 μM 浓度范围内表现出线性相关性，检测限低至约 0.14 μM。这些 PCD 发出约 620 nm 的光，即使在日光下也保持可见。当应用于各种基材上的指纹并干燥时，它们在 365 nm 紫外线下显示出清晰的指纹，并保持 24 小时稳定性。这种弹性归因于防止荧光减少，这是通过干燥过程中的咖啡环效应和静电相互作用实现的。通过使用深度学习算法，这些潜在指纹 (LFP) 的荧光图像与标准对照异常相似。这些 PCD 在 PVA 基质中发挥着荧光油墨和纳米复合薄膜的双重作用，展示了防伪应用的潜力。这项研究提出了一种合成具有强烈红色发光的 PCD 的简单方法，将其建立为铁传感、柔性荧光膜、潜指纹和防伪追求的多功能平台。