Department of Chemistry, Izmir Institute of Technology, Urla, 35430, Izmir, Turkey.
Center for Biomimetic Sensor Science, Nanyang Technological University, 637553, Singapore; School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore.
Talanta. 2020 Mar 1;209:120581. doi: 10.1016/j.talanta.2019.120581. Epub 2019 Nov 23.
Conjugated polyelectrolytes (CPEs) have been widely used as reporters in colorimetric assays targeting nucleic acids. CPEs provide naked eye detection possibility by their superior optical properties however, as concentration of target analytes decrease, trace amounts of nucleic acid typically yield colorimetric responses that are not readily perceivable by naked eye. Herein, we report a pixelated analysis approach for correlating colorimetric responses of CPE with nucleic acid concentrations down to 1 nM, in plasma samples, utilizing a smart phone with an algorithm that can perform analytical testing and data processing. The detection strategy employed relies on conformational transitions between single stranded nucleic acid-cationic CPE duplexes and double stranded nucleic acid-CPE triplexes that yield distinct colorimetric responses for enabling naked eye detection of nucleic acids. Cationic poly[N,N,N-triethyl-3-((4-methylthiophen-3-yl)oxy)propan-1-aminium bromide] is utilized as the CPE reporter deposited on a polyvinylidene fluoride (PVDF) membrane for nucleic acid assay. A smart phone application is developed to capture and digitize the colorimetric response of the individual pixels of the digital images of CPE on the PVDF membrane, followed by an analysis using the algorithm. The proposed pixelated approach enables precise quantification of nucleic acid assay concentrations, thereby eliminating the margin of error involved in conventional methodologies adopted for interpretation of colorimetric responses, for instance, RGB analysis. The obtained results illustrate that a ubiquitous smart phone could be utilized for point of care colorimetric nucleic acids assays in complex matrices without requiring sophisticated software or instrumentation.
聚电解质（CPEs）已被广泛用作针对核酸的比色测定中的报告分子。CPEs 通过其优异的光学性质提供了肉眼检测的可能性，但是，随着目标分析物浓度的降低，痕量的核酸通常会产生比色响应，而这些响应不易被肉眼察觉。在此，我们报告了一种用于将 CPE 的比色响应与浓度低至 1 nM 的核酸相关联的像素化分析方法，该方法在等离子体样品中利用智能手机和一种可以执行分析测试和数据处理的算法。所采用的检测策略依赖于单链核酸-阳离子 CPE 双链体和双链核酸-CPE 三聚体之间的构象转变，这些转变产生了明显的比色响应，从而能够进行核酸的肉眼检测。阳离子聚[N，N，N-三乙基-3-（（4-甲基噻吩-3-基）氧基）丙基-1-氨基溴化物]用作沉积在聚偏二氟乙烯（PVDF）膜上的 CPE 报告分子，用于核酸测定。开发了一种智能手机应用程序，用于捕获和数字化 PVDF 膜上 CPE 数字图像的各个像素的比色响应，然后使用算法进行分析。所提出的像素化方法能够精确定量核酸测定浓度，从而消除了传统比色响应解释方法（例如 RGB 分析）所涉及的误差幅度。所获得的结果表明，通用的智能手机可用于在复杂基质中进行即时护理比色核酸测定，而无需复杂的软件或仪器。
