Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, #08-03, Singapore 138634, Singapore.
Republic Polytechnic, School of Applied Science, 9 Woodlands Ave 9, Singapore 738964, Singapore.
Biomolecules. 2024 Jul 9;14(7):818. doi: 10.3390/biom14070818.
Cortisol is a key stress biomarker in humans and animals, including fishes. In aquafarming, stress monitoring using cortisol quantification can help to optimize aquaculture practices for welfare and productivity enhancement. However, most current methods for cortisol detection rely on invasive tissue sampling. In this work, we developed a gold nanoparticle (AuNP)-based cortisol sensor to address the demand of detecting picomolar ranges of cortisol from complex fish tank water matrices as a non-invasive alternative for more effective stress monitoring. We first identified a DNA aptamer with effective binding to cortisol and then conjugated the thiol-labelled aptamer to AuNPs together with a blocker molecule (CALNN) to form an Au-Apt-CALNN conjugate that is stable in fish tank water. The cortisol detection principle is based on magnesium chloride (MgCl)-induced particle aggregation, where the cortisol-bound aptamer on the AuNPs folds into a tertiary structure and provides greater protection for Au-Apt-CALNN against MgCl-induced aggregation due to steric stabilization. At an optimum MgCl concentration, the differential stability of particles with and without cortisol binding offers a limit of detection (LOD) of 100 pM for cortisol within a 35 min reaction. The aptasensor has been validated on recirculating aquaculture system (RAS) fish tank water samples by the HPLC method and was able to detect changes in water cortisol induced by two different stress paradigms. This on-site deployable and non-invasive sensor offers opportunities for more efficient and real-time fish stress monitoring for the optimization of aquaculture practices.
皮质醇是人类和动物（包括鱼类）的关键应激生物标志物。在水产养殖中，使用皮质醇定量监测应激可以帮助优化水产养殖实践，提高福利和生产力。然而，目前大多数皮质醇检测方法都依赖于有创的组织采样。在这项工作中，我们开发了一种基于金纳米粒子（AuNP）的皮质醇传感器，以满足从复杂的鱼缸水基质中检测皮摩尔范围皮质醇的需求，作为更有效应激监测的非侵入性替代方法。我们首先鉴定了一种与皮质醇有效结合的 DNA 适体，然后将巯基标记的适体与 AuNP 以及阻断分子（CALNN）缀合，形成 Au-Apt-CALNN 缀合物，在鱼缸水中稳定。皮质醇检测原理基于氯化镁（MgCl）诱导的颗粒聚集，其中 AuNP 上结合皮质醇的适体折叠成三级结构，并由于空间稳定化，为 Au-Apt-CALNN 提供了更大的保护，使其免受 MgCl 诱导的聚集。在最佳的 MgCl 浓度下，具有和不具有皮质醇结合的颗粒的差分稳定性提供了皮质醇的检测限（LOD）为 100 pM，反应时间为 35 分钟。该适体传感器已通过 HPLC 方法在循环水产养殖系统（RAS）鱼缸水样品上进行了验证，并能够检测两种不同应激范式引起的水中皮质醇的变化。这种现场可部署和非侵入性传感器为优化水产养殖实践提供了更高效和实时的鱼类应激监测机会。
