Li Na, Yu Lu, Zou Jiaqi
1Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL, USA.
J Lab Autom. 2014 Feb;19(1):82-90. doi: 10.1177/2211068213498240. Epub 2013 Aug 14.
In gold nanoparticle (GNP)-based colorimetric biosensors, the gradual color shift is often used to correlate with the concentration of target molecules, and therefore a UV-vis spectrometer is usually required for accurate quantification. Here, we present a critical coagulation concentration (CCC)-based salt titration as a generic and simple way to enable accurate quantification in GNP-based colorimetric biosensors without any analytical equipment. The titration is carried out by stepwise addition of a salt titrant to the premixture of sample and GNPs until the color changes rapidly from red to blue, determined solely by visual inspection. The number of titration steps or the final salt concentration required for a rapid color shift (i.e., CCC) is then used to quantitatively correlate with the concentration of target molecules in the sample. The salt titration-based quantification has been demonstrated with two previously reported GNP-based colorimetric biosensors. Compared with quantification based on the gradual color shift with a spectrometer, the visual quantification based on the rapid color shift in the salt titration eliminates the need for any analytical equipment without sacrificing the performance (i.e., sensitivity and accuracy) and therefore is highly suitable for applications in low-resource settings.
在基于金纳米颗粒（GNP）的比色生物传感器中，颜色的逐渐变化常被用来与目标分子的浓度相关联，因此通常需要紫外可见光谱仪进行准确的定量分析。在此，我们提出一种基于临界凝聚浓度（CCC）的盐滴定法，作为一种通用且简单的方法，无需任何分析设备即可在基于GNP的比色生物传感器中实现准确定量。滴定过程是通过向样品和GNP的预混物中逐步添加盐滴定剂来进行的，直到颜色从红色迅速变为蓝色，这仅通过目视检查来确定。然后，将快速颜色变化所需的滴定步骤数或最终盐浓度（即CCC）用于与样品中目标分子的浓度进行定量关联。基于盐滴定的定量方法已在两种先前报道的基于GNP的比色生物传感器中得到验证。与基于光谱仪颜色逐渐变化的定量方法相比，基于盐滴定中快速颜色变化的目视定量方法无需任何分析设备，同时不牺牲性能（即灵敏度和准确性），因此非常适合在资源匮乏的环境中应用。
