Mertens Johann, Rogero Celia, Calleja Montserrat, Ramos Daniel, Martín-Gago Jose Angel, Briones Carlos, Tamayo Javier
Bionanomechanics Lab, IMM-CNM, CSIC, 28760 Tres Cantos, Madrid, Spain.
Nat Nanotechnol. 2008 May;3(5):301-7. doi: 10.1038/nnano.2008.91. Epub 2008 Apr 20.
The properties of water at the nanoscale are crucial in many areas of biology, but the confinement of water molecules in sub-nanometre channels in biological systems has received relatively little attention. Advances in nanotechnology make it possible to explore the role played by water molecules in living systems, potentially leading to the development of ultrasensitive biosensors. Here we show that the adsorption of water by a self-assembled monolayer of single-stranded DNA on a silicon microcantilever can be detected by measuring how the tension in the monolayer changes as a result of hydration. Our approach relies on the microcantilever bending by an amount that depends on the tension in the monolayer. In particular, we find that the tension changes dramatically when the monolayer interacts with either complementary or single mismatched single-stranded DNA targets. Our results suggest that the tension is mainly governed by hydration forces in the channels between the DNA molecules and could lead to the development of a label-free DNA biosensor that can detect single mutations. The technique provides sensitivity in the femtomolar range that is at least two orders of magnitude better than that obtained previously with label-free nanomechanical biosensors and with label-dependent microarrays.
纳米尺度下水的特性在许多生物学领域都至关重要，但生物系统中亚纳米级通道内水分子的受限情况却相对较少受到关注。纳米技术的进步使得探索水分子在生命系统中所起的作用成为可能，这有可能推动超灵敏生物传感器的发展。在此我们表明，通过测量单链DNA自组装单层在硅微悬臂梁上因水合作用导致的单层张力变化，能够检测到水的吸附情况。我们的方法依赖于微悬臂梁弯曲的程度，该程度取决于单层中的张力。特别地，我们发现当单层与互补或单碱基错配的单链DNA靶标相互作用时，张力会发生显著变化。我们的结果表明，张力主要由DNA分子间通道中的水合力控制，这可能会促成一种能够检测单基因突变的无标记DNA生物传感器的开发。该技术提供了飞摩尔级别的灵敏度，比之前无标记纳米机械生物传感器和基于标记的微阵列所获得的灵敏度至少高出两个数量级。
