We present a disposable polymeric microfluidic device capable of reversibly binding and purifying Salmonella DNA through solid phase extraction (SPE). The microfluidic channels are first oxygen plasma treated and simultaneously micro-nanotextured, and then functionalized with amine groups via modification with L-histidine or poly-L-histidine. L-Histidine and poly-L-histidine bind on the plasma treated chip surface, and are not detached when rinsing with DNA purification protocol buffers. A pH-dependent protocol is applied on-chip to purify Salmonella DNA, which is first bound on the protonated amines at a pH (5.0) lower than their pKa of surface amine-groups which is 6.0 and then released at a pH higher than the pKa value (10.5). It was found that modification with poly-L-histidine resulted in higher surface density of amine groups onto microfluidic channel. Using the chip modified with poly-L-histidine, high recovery efficiency of at least 550 ng of isolated Salmonella DNA as well as DNA purification from Salmonella cell lysates corresponding to less than 5000 cells or 0.026 ng of Salmonella DNA was achieved. The protocol developed does not require ethanol or chaotropic solutions typically used in DNA purification, which are known inhibitors for downstream operations such as polymerase chain reactions (PCR) and which can also attack some polymeric microfluidic materials. Therefore, the microfluidic device and the related protocol hold promise for facile incorporation in microfluidics and Lab-on-a-chip (LOC) platforms for pathogen detection or in general for DNA purification.

中文翻译：

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聚-L-组氨酸包被的微流体装置，用于无需离液溶液的细菌DNA纯化。

我们提出了一种能够通过固相萃取（SPE）可逆地结合和纯化沙门氏菌DNA的一次性聚合物微流体装置。首先对微流体通道进行氧等离子体处理并同时进行微纳米结构化，然后通过L-组氨酸或聚-L-组氨酸的修饰用胺基官能化。L-组氨酸和聚-L-组氨酸结合在经过等离子体处理的芯片表面，并且在用DNA纯化方案缓冲液冲洗时不会脱离。pH依赖方案可在芯片上应用以纯化沙门氏菌首先在质子化胺上以低于表面胺基的pKa值6.0的pH（5.0）结合到质子化胺上的DNA，然后在高于pKa值（10.5）的pH值下释放。发现用聚-L-组氨酸进行修饰导致在微流体通道上的胺基的表面密度更高。使用经聚L-组氨酸修饰的芯片，至少550 ng分离的沙门氏菌DNA的高回收率以及从对应于少于5000个细胞或0.026 ng沙门氏菌的沙门氏菌细胞裂解物中提取DNA的效率获得了DNA。开发的协议不需要通常用于DNA纯化的乙醇或离液溶液，这些溶液是下游操作（例如聚合酶链反应（PCR））的已知抑制剂，并且也可能侵蚀某些聚合微流体材料。因此，微流控装置和相关协议有望在微流控和芯片实验室（LOC）平台上轻松整合，以进行病原体检测或用于DNA纯化。