Herein we propose a fluorescence turn-on strategy for the sensitive and selective detection of trypsin based on fluorescence resonance energy transfer (FRET) between gold nanoparticles (AuNPs) and amino-functionalized carbon dots (C-dots). In this assay, C-dots were treated as fluorometric reporter, while AuNPs were treated as fluorescence quencher. A specially designed negatively charged short peptide chain with one functioned cysteine group as the substrate for trypsin. The sensor works as follows: the negatively charged part of the peptide can be hydrolyzed by trypsin, resulting in the releasing of shorter and positively charged peptides. These shorter peptides then induces AuNPs aggregation due to the strong electrostatic interaction between positively charged peptides and the negatively charged AuNPs, thus leading to the restoration of the FRET-quenched fluorescence emission of C-dots. Measuring the changes in the fluorescence of C-dots, the concentrations of trypsin can be determined. Under the optimized conditions, we achieved quantitative evaluation of trypsin in a range of 2.5–80 ng mL⁻¹ with the detection limit of 0.84 ng mL⁻¹. Meanwhile, this sensing system also exhibited excellent selectivity and sensitivity for trypsin, and we successfully applied it for the detection of trypsin in human serum samples. Based on the above findings, we conclude that this new FRET based sensor might be significant in disease diagnosis in the future.

本文中，我们提出了一种基于金纳米颗粒（AuNPs）和氨基官能化碳点（C-dots）之间的荧光共振能量转移（FRET）来灵敏和选择性检测胰蛋白酶的荧光开启策略。在该测定中，将C点用作荧光报告剂，而将AuNPs作为荧光猝灭剂。一种特殊设计的带负电荷的短肽链，具有一个功能正常的半胱氨酸基团作为胰蛋白酶的底物。传感器的工作原理如下：肽的带负电荷的部分可以被胰蛋白酶水解，从而导致较短的带正电荷的肽释放出来。然后，由于带正电的肽与带负电的AuNPs之间的强静电相互作用，这些较短的肽会诱导AuNPs聚集，因此导致FRET猝灭的C点的荧光发射得以恢复。通过测量C点的荧光变化，可以确定胰蛋白酶的浓度。在最佳条件下，我们对2.5–80 ng mL范围内的胰蛋白酶进行了定量评估^-1的检出限为0.84 ng mL ^-1。同时，该传感系统对胰蛋白酶也表现出优异的选择性和灵敏度，我们成功地将其应用于人血清样品中胰蛋白酶的检测。基于以上发现，我们得出结论，这种基于FRET的新型传感器在未来的疾病诊断中可能具有重要意义。