Abstract A solid fluorescence sensor composed of g-C3N4 nanosheets and chitosan solid film was fabricated by electrostatic interaction. The g-C3N4 nanosheet/chitosan solid film showed selectivity and sensitivity to Cu2+ which was higher than that of other metal ions in common use. Cu2+ ions were found to efficiently bind and quench the fluorescence of the g-C3N4 nanosheet/chitosan solid film. The absorption band of the g-C3N4 nanosheet/chitosan solid film was at 240 nm in the presence of Cu2+, and the maximum emission peak was at 380 nm. Copper ion concentrations were between 0 and 3.1 × 10−5 mol/L at pH 7, the detection limit is 5 nM, compared with previous reports, it was much lower than before. Good linear relationships existed between the metal ion concentration and fluorescence intensity of g-C3N4 nanosheets in the quenching and recovering processes. This is the first study to report on the detection of Cu2+ by utilizing g-C3N4 nanosheet/chitosan composite film. The as-prepared films were conveniently prepared, easy to operate, and recyclable, as well as sensitive and selective to detect Cu2+ in water. All these features indicate the sensor’s potential application in disease diagnosis.

中文翻译：

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使用带有 g-C3N4 纳米片的壳聚糖固体薄膜方便且高灵敏度地检测 Cu2+

摘要 通过静电相互作用制备了由g-C3N4纳米片和壳聚糖固体薄膜组成的固体荧光传感器。g-C3N4纳米片/壳聚糖固体薄膜对Cu2+的选择性和敏感性高于常用的其他金属离子。发现 Cu2+ 离子可以有效地结合和淬灭 g-C3N4 纳米片/壳聚糖固体膜的荧光。在Cu2+存在下g-C3N4纳米片/壳聚糖固体薄膜的吸收带在240 nm处，最大发射峰在380 nm处。铜离子浓度在 pH 7 时介于 0 到 3.1 × 10−5 mol/L 之间，检测限为 5 nM，与之前的报道相比，它比以前低得多。在淬灭和恢复过程中，金属离子浓度与g-C3N4纳米片的荧光强度之间存在良好的线性关系。这是首次报道利用 g-C3N4 纳米片/壳聚糖复合膜检测 Cu2+ 的研究。所制备的薄膜制备方便、易于操作、可回收利用，并且对检测水中的 Cu2+ 具有灵敏度和选择性。所有这些特征表明传感器在疾病诊断中的潜在应用。