A label-free, sensitive, simple and general colorimetric method was reported to monitor S1 nuclease activity based on protamine-assisted aggregation of gold nanoparticles (AuNPs). Here, protamine, a linear polycation, was used as a medium for causing the aggregation of negatively charged AuNPs by electrostatic interactions, resulting in changes in the surface plasmon resonance (SPR) absorption bands as well as the color of AuNPs. Here, the AuNPs were employed as an indicator to detect the level of S1 nuclease in the solution. Substrate DNA could be cleaved into small fragments by the specific S1 nuclease, which effectively prevents the electrostatic interaction between DNA and protamine and thus facilitates the interaction between protamine and AuNPs. The quantitative analysis of S1 nuclease activity can be performed via directly measuring the changes in the absorption spectra of the AuNPs. Using S1 nuclease as a model analyte, the limit of detection was estimated to be 1.0 × 10⁻⁴ U mL⁻¹. Furthermore, the proposed concept has been successfully applied in S1 nuclease analysis of serum samples, offering an ultrasensitive strategy for the speedy detection of the nuclease activity and providing a new avenue for high-throughput screening of nucleases and drugs with potential inhibition properties.

中文翻译：

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无标签的鱼精蛋白辅助比色传感器，用于S1核酸酶活性的高灵敏度检测

据报道，一种无标签，灵敏，简单且通用的比色方法可基于鱼精蛋白辅助的金纳米颗粒（AuNPs）聚集来监测S1核酸酶的活性。在这里，鱼精蛋白（一种线性聚阳离子）被用作通过静电相互作用引起带负电的AuNP聚集的介质，从而导致表面等离振子共振（SPR）吸收带以及AuNP的颜色发生变化。在这里，AuNP被用作指示剂来检测溶液中S1核酸酶的水平。底物DNA可被特异性的S1核酸酶切割成小片段，从而有效防止DNA和鱼精蛋白之间的静电相互作用，从而促进鱼精蛋白和AuNP之间的相互作用。S1核酸酶活性的定量分析可以通过直接测量AuNPs吸收光谱的变化。使用S1核酸酶作为模型分析物，检测极限估计为1.0×10 ^-4 U mL ^-1。此外，提出的概念已成功应用于血清样品的S1核酸酶分析中，为快速检测核酸酶活性提供了超灵敏的策略，并为核酸酶和具有潜在抑制特性的药物的高通量筛选提供了新途径。