Mechanical Engineering and Applied Mechanics, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA.
Analyst. 2021 Jun 28;146(13):4212-4218. doi: 10.1039/d1an00309g.
Molecular detection of pathogenic nucleic acids from patient samples requires incubating biochemical reactions at specific temperatures to amplify DNA. This incubation is typically carried out with an electrical heater and a temperature controller. To reduce test cost, to eliminate the need for manufacturing incubators, which may require significant time, and to enable electricity-free operation, we use energetic compounds such as an Mg(Fe) alloy mixed with a phase-change material (PCM) that undergoes phase transformation at the desired incubation temperature. We dubbed this composite Energetic Phase Change Material (EPCM). When the EPCM is brought into contact with water, the magnesium alloy interacts with the water to produce heat. The EPCM heats up to its phase transition temperature. Any excess heat is absorbed as latent heat and the system is maintained at its desired incubation temperature, independent of ambient temperatures, long enough to facilitate enzymatic amplification. The EPCM together with colorimetric amplicon detection facilitates an inexpensive, disposable, point-of-need diagnostic test that does not require any electric power. We demonstrate the feasibility of our approach by detecting SARS-Cov-2 in saliva samples either without any instrumentation or with a palm-size CCD camera that enables us to follow the amplification process in real time.
从患者样本中检测致病核酸需要在特定温度下孵育生化反应以扩增 DNA。这种孵育通常使用电加热器和温度控制器进行。为了降低测试成本、消除制造孵化器的需求（这可能需要大量时间）并实现无电操作，我们使用了能量化合物，例如与相变材料（PCM）混合的 Mg(Fe) 合金，该合金在所需的孵育温度下发生相变。我们将这种复合材料称为“能量相变材料（EPCM）”。当 EPCM 与水接触时，镁合金与水相互作用产生热量。EPCM 加热到相变温度。任何多余的热量都会被吸收为潜热，系统会保持在所需的孵育温度，而不受环境温度的影响，足以促进酶的扩增。EPCM 与比色扩增检测相结合，实现了一种廉价、一次性、即时诊断测试，不需要任何电力。我们通过在没有任何仪器或使用手掌大小的 CCD 相机的情况下从唾液样本中检测 SARS-CoV-2 来证明我们方法的可行性，这使我们能够实时跟踪扩增过程。
