A new method utilizing fluorescent ratiometry is proposed for detecting putrescine and spermidine. The method involves the use of a fluorescent probe comprising a 2D halide perovskite synthesized from octadecylamine-iodine and PbI₂ via a grinding-sonicating technique, along with a Eu³⁺-complex. Upon excitation at 290 nm, the probe fluoresces at two distinguishable wavelengths. The addition of putrescine and spermidine significantly decreases the emission of the 2D halide perovskite at 496 nm, while the emission of the Eu³⁺-complex at 618 nm remains stable. The color changes of the probe depend on the concentration of putrescine and spermidine, and the assay offers linearity over a wide concentration range (30–4000 ng mL⁻¹), a low detection limit (4 ng mL⁻¹ for putrescine, and 7 ng mL⁻¹ for spermidine), and a quick response time. Furthermore, a portable device based on a smartphone can be used to record the color change of the paper test strip using the prepared fluorescent materials. The fluorescence quenching mechanism of the probe is explained as dynamic quenching.

中文翻译：

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基于智能手机的纸条检测法，使用具有 Eu3+ 复合物的混合有机-无机钙钛矿检测腐胺和亚精胺

提出了一种利用荧光比率测定法检测腐胺和亚精胺的新方法。该方法涉及使用荧光探针，该荧光探针包含通过研磨超声处理技术由十八胺-碘和PbI ₂ 合成的2D卤化物钙钛矿以及Eu ³⁺络合物。在 290 nm 处激发后，探针会发出两个可区分波长的荧光。腐胺和亚精胺的添加显着降低了2D卤化物钙钛矿在496 nm处的发射，而Eu ³⁺配合物在618 nm处的发射保持稳定。探针的颜色变化取决于腐胺和亚精胺的浓度，并且该测定在较宽的浓度范围（30–4000 ng mL ^-1）内提供线性，检测限较低（腐胺为 4 ng mL ^-1，7 ng mL -1 ）。 ng mL ^-1（亚精胺）），并且响应时间快。此外，基于智能手机的便携式设备可用于记录使用所制备的荧光材料的纸质测试条的颜色变化。探针的荧光猝灭机制被解释为动态猝灭。