Label-free detection of DNA using a light-addressable potentiometric sensor modified with a positively charged polyelectrolyte layer.
Label-free detection of DNA using a light-addressable potentiometric sensor modified with a positively charged polyelectrolyte layer.
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DOI：
10.1039/c4nr07225a
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发表时间：
2015-03
期刊：
影响因子：
6.7
通讯作者：
Chunsheng Wu;Thomas S. Bronder;A. Poghossian;C. Werner;M. Schöning
中科院分区：
文献类型：
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作者：
Chunsheng Wu;Thomas S. Bronder;A. Poghossian;C. Werner;M. Schöning
首次将聚烯丙胺盐酸盐（PAH）修饰的Al-p-Si-SiO2结构的多点（16点）光寻址电位传感器（MLAPS）应用于DNA（脱氧核糖核酸）的固定和杂交的无标记电检测。为了实现DNA链的优先平坦取向，从而减少DNA电荷和MLAPS表面之间的距离，使用简单的逐层（LbL）技术将带负电荷的探针单链DNA（ssDNA）静电吸附到带正电荷的PAH层上。这样，更多的DNA电荷可以位于德拜长度内，产生更高的传感器信号。由光电流-电压曲线沿着电压轴的位移确定由于表面改性步骤（PAH吸附、探针ssDNA固定、与互补靶DNA（cDNA）杂交、错配ssDNA的非特异性吸附）引起的每个斑点中的表面电位变化。在将探针ssDNA固定到PAH层上后，记录到83 mV的高传感器信号。随着cDNA浓度从0.1 nM增加到5 μM，杂交信号从5 mV增加到32 mV。相反，在完全错配的ssDNA（5 μM）的非特异性吸附情况下，记录到5 mV的小信号。所获得的结果表明，MLAPS与简单，快速的LbL固定化技术相结合的潜力，作为一个有前途的平台，为未来的发展多点光寻址无标记的DNA芯片与直接电读出。
A multi-spot (16 spots) light-addressable potentiometric sensor (MLAPS) consisting of an Al-p-Si-SiO2 structure modified with a weak polyelectrolyte layer of PAH (poly(allylamine hydrochloride)) was applied for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization by the intrinsic molecular charge for the first time. To achieve a preferentially flat orientation of DNA strands and thus, to reduce the distance between the DNA charge and MLAPS surface, the negatively charged probe single-stranded DNAs (ssDNA) were electrostatically adsorbed onto the positively charged PAH layer using a simple layer-by-layer (LbL) technique. In this way, more DNA charge can be positioned within the Debye length, yielding a higher sensor signal. The surface potential changes in each spot induced due to the surface modification steps (PAH adsorption, probe ssDNA immobilization, hybridization with complementary target DNA (cDNA), non-specific adsorption of mismatched ssDNA) were determined from the shifts of photocurrent-voltage curves along the voltage axis. A high sensor signal of 83 mV was registered after immobilization of probe ssDNA onto the PAH layer. The hybridization signal increases from 5 mV to 32 mV with increasing the concentration of cDNA from 0.1 nM to 5 μM. In contrast, a small signal of 5 mV was recorded in the case of non-specific adsorption of fully mismatched ssDNA (5 μM). The obtained results demonstrate the potential of the MLAPS in combination with the simple and rapid LbL immobilization technique as a promising platform for the future development of multi-spot light-addressable label-free DNA chips with direct electrical readout.