We have developed a colorimetric sensing strategy employing gold nanoparticles and a paper-based analytical platform for the diagnosis of tuberculosis (TB). By utilizing the surface plasmon resonance effect, we were able to monitor changes in the color of a gold nanoparticle colloid based on the effects of single-stranded DNA probe molecules hybridizing with targeted double-stranded TB DNA. The hybridization event changes the surface charge density of the nanoparticles, causing them to aggregate to various degrees, which modifies the color of the solution in a manner that can be readily measured to determine the concentration of the targeted DNA analyte. In order to adapt this TB diagnosis method to resource-limited settings, we extended this label-free oligonucleotide and unmodified gold nanoparticle solution-based technique to a paper-based system that can be measured using a smartphone to obtain rapid parallel colorimetric results with low reagent consumption and without the need for sophisticated analytical equipment. In this study, we investigated various assay conditions, including the denaturing temperature and time, different oligonucleotide probe sequences, as well as the ratio of single stranded probe and double stranded target DNA. After optimizing these variables, we were able to achieve a detection limit of 1.95 × 10^–2 ng/mL for TB DNA. Furthermore, multiple tests could be performed simultaneously with a 60 min turnaround time.

中文翻译：

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在纸质分析仪上使用比色金纳米颗粒诊断结核病

我们已经开发了一种使用金纳米颗粒的比色传感策略和一种用于诊断肺结核（TB）的基于纸张的分析平台。通过利用表面等离子体共振效应，我们能够基于与目标双链TB DNA杂交的单链DNA探针分子的作用，监测金纳米粒子胶体颜色的变化。杂交事件改变了纳米颗粒的表面电荷密度，使它们聚集到不同程度，从而以易于测量以确定目标DNA分析物浓度的方式改变了溶液的颜色。为了使这种TB诊断方法适应资源受限的设置，我们将这种无标签的寡核苷酸和未经修饰的金纳米粒子溶液基技术扩展到了纸基系统，可以使用智能手机对其进行测量，从而以较低的试剂消耗量获得快速的平行比色结果，而无需复杂的分析设备。在这项研究中，我们研究了各种测定条件，包括变性温度和时间，不同的寡核苷酸探针序列以及单链探针和双链靶DNA的比率。优化这些变量后，我们能够实现1.95×10的检测极限 包括变性温度和时间，不同的寡核苷酸探针序列以及单链探针和双链靶DNA的比例。优化这些变量后，我们能够实现1.95×10的检测极限 包括变性温度和时间，不同的寡核苷酸探针序列以及单链探针和双链靶DNA的比例。优化这些变量后，我们能够实现1.95×10的检测极限TB DNA为^–2 ng / mL。此外，可以在60分钟的转换时间内同时执行多个测试。