Ordered Self-Assembled Locked Nucleic Acid (LNA) Structures on Gold(111) Surface with Enhanced Single Base Mismatch Recognition Capability

摘要

Locked nucleic acid (LNA) is a conformationallynrestricted nucleic acid analogue, which is potentially a betternalternative than DNA for application in the nucleic acid basednbiosensor technologies, due to its efficient and sequence-specificnDNA/RNA detection capability and lack of molecule−surfaceninteraction on solid surfaces, compared to DNA. We report, fornthe first time, a straightforward way (based on simple immersionnmethod) of generating an ordered self-assembled LNAnmonolayer, which is bioactive, onto a gold(111) surface. Thisnlayer is capable of giving rise to a stronger DNA recognitionnsignal (4−4.5 times) than its DNA counterpart, and importantly,nit can differentiate between a fully complementary DNA target and that having a single base mismatch, where the mismatchndiscrimination ratio is almost two times compared to the ratio relevant in case of DNA-based detection. We have presented highresolutionnatomic force microscopy (AFM) topographs of the well-defined one-dimensional LNA molecular ordering (fewnhundred nanometers long) and of the two-dimensional ordered assembly formed over a large area (7 μm × 7 μm) due to parallelnpositioning of the one-dimensional ordered arrangements. The effects of different parameters such as LNA concentration andnincubation time on LNA self-assembly have been investigated. Further, reflection absorption infrared (RAIR) spectroscopy hasnbeen applied to obtain information about the orientation of the surface-immobilized LNA molecules for the first time. It has beennfound that the LNA molecules undergo an orientational transition from the “lying down” to the “upright” configuration in a timenscale of few hours.