Nucleic acid detection is of paramount importance in monitoring of microbial pathogens in food safety and infectious disease diagnostic applications. To address these challenges, a rapid, cost-effective label-free technique for nucleic acid detection with minimal instrumentations is highly desired. Here, we present paper microchip to detect and quantify nucleic acid using colorimetric sensing modality. The extracted DNA from food samples of meat as well as microbial pathogens was amplified utilizing loop-mediated isothermal amplification (LAMP). LAMP amplicon was then detected and quantified on a paper microchip fabricated in a cellulose paper and a small wax chamber utilizing crystal violet dye. The affinity of crystal violet dye toward dsDNA and positive signal were identified by changing the color from colorless to purple. Using this method, detection of Sus scrofa (porcine) and Bacillus subtilis (bacteria) DNA was possible at concentrations as low as 1 pg/μL (3.43 × 10 ^–1 copies/μL) and 10 pg/μL (2.2 × 10³ copies/μL), respectively. This strategy can be adapted for detection of other DNA samples, with potential for development of a new breed of simple and inexpensive paper microchip at the point-of-need.

中文翻译：

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循环介导的等温放大和结晶紫染料在纸微芯片上的比色核酸检测

在食品安全和传染病诊断应用中，核酸检测对于监测微生物病原体至关重要。为了解决这些挑战，非常需要一种快速，经济高效的无标记技术，只需最少的仪器即可进行核酸检测。在这里，我们提出了使用比色传感方式检测和定量核酸的纸微芯片。从肉类和微生物病原体的食物样本中提取的DNA使用环介导的等温扩增（LAMP）进行了扩增。然后在使用纤维素的纸微芯片和使用结晶紫染料的小蜡室中制造的纸微芯片上检测并定量LAMP扩增子。通过将颜色从无色变为紫色，可以鉴定出结晶紫染料对dsDNA的亲和力和阳性信号。使用这种方法枯草芽孢杆菌（细菌）DNA的浓度分别低至1 pg /μL（3.43×10 ^–1拷贝/μL）和10 pg /μL（2.2×10 ³拷贝/μL）。该策略可适用于检测其他DNA样品，并有可能在需要时开发一种新的简单廉价的纸微芯片。