In-Vitro Diagnostics Lab, Samsung Advanced Institute of Technology, Samsung Electronics Co., Ltd., Republic of Korea.
Anal Chem. 2012 Sep 18;84(18):7912-8. doi: 10.1021/ac3016533. Epub 2012 Aug 30.
We have developed a bead-packed microfluidic device with a built-in flexible wall to automate extraction of nucleic acids from methicillin-resistant Staphylococcus aureus (MRSA) in nasal swabs. The flexible polydimethylsiloxane (PDMS) membrane was designed to manipulate the surface-to-volume ratio (SVR) of bead-packed chambers in the range of 0.05 to 0.15 (μm(-1)) for a typical solid phase extraction protocol composed of binding, washing, and eluting. In particular, the pneumatically assisted close packing of beads led to an invariant SVR (0.15 μm(-1)) even with different bead amounts (10-16 mg), which allowed for consistent operation of the device and improved capture efficiency for bacteria cells. Furthermore, vigorous mixing by asynchronous membrane vibration enabled ca. 90% DNA recovery with ca. 10 μL of liquid solution from the captured cells on the bead surfaces. The full processes to detect MRSA in nasal swabs, i.e., nasal swab collection, prefiltration, on-chip DNA extraction, and real-time polymerase chain reaction (PCR) amplification, were successfully constructed and carried out to validate the capability to detect MRSA in nasal swab samples. This flexible microdevice provided an excellent analytical PCR detection sensitivity of ca. 61 CFU/swab with 95% confidence interval, which turned out to be higher than or similar to that of the commercial DNA-based MRSA detection techniques. This excellent performance would be attributed to the capability of the flexible bead-packed microdevice to enrich the analyte from a large initial sample (e.g., 1 mL) into a microscale volume of eluate (e.g., 10 μL). The proposed microdevice will find many applications as a solid phase extraction method toward various sample-to-answer systems.
我们开发了一种带有内置柔性壁的珠状微流控装置，可自动从鼻拭子中提取耐甲氧西林金黄色葡萄球菌（MRSA）的核酸。柔性聚二甲基硅氧烷（PDMS）膜的设计目的是将珠状室的表面积与体积比（SVR）在 0.05 至 0.15μm(-1)的范围内进行操作，这是一个典型的固相萃取方案，包括结合、洗涤和洗脱。特别是，气动辅助的珠状紧密填充导致不变的 SVR（0.15μm(-1)），即使珠的数量不同（10-16mg），这使得设备的操作一致，并提高了对细菌细胞的捕获效率。此外，通过异步膜振动进行的剧烈混合可使大约 10μL 的液体溶液从珠表面捕获的细胞中回收约 90%的 DNA。成功构建了用于从鼻拭子中检测 MRSA 的整个过程，即鼻拭子采集、预过滤、芯片上 DNA 提取和实时聚合酶链反应（PCR）扩增，并进行了检测以验证在鼻拭子样本中检测 MRSA 的能力。这种灵活的微设备提供了出色的分析 PCR 检测灵敏度，约为 61CFU/swab，置信区间为 95%，这与商业 DNA 检测技术相当或更高。这种出色的性能归因于灵活的珠状微设备将分析物从初始大样本（例如 1mL）浓缩到微体积洗脱液（例如 10μL）的能力。该微设备将在各种样品到答案系统中作为固相萃取方法找到许多应用。
