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The characteristics of the interface between DNA and metallic carbon nanotube (CNT) in supramolecular assemblies are important to understand for electronic and sensing applications. We study the mechanical stability and electronic properties of these interfaces with amino and ester linkers using computational experiments. Our study demonstrates that both linkers significantly enhance the mechanical stability of DNA–CNT systems, with the DNA adopting a stable and lower energy perpendicular orientation relative to the CNT as opposed to a conventional parallel arrangement. This lower energy configuration is driven by nonbonded interactions between the DNA base and the CNT surface. Our calculations also reveal that interface resistance is primarily governed by DNA–CNT interactions with negligible contribution from the linkers. In the case of the amino linker, we predict a 100-fold transmission ratio between parallel and perpendicular configurations of DNA relative to CNT. This observation can be used to build an electromechanical switch with fast switching times (30 ns). The ester linker, on the contrary, enables a better electronic coupling between the DNA and CNT even when strained. 

Force fields were developed for metal-mediated DNA (mmDNA) structures, using ab-initio methods to parameterize metal coordination. Two mmDNA were considered, comprising of a cytosine/thymine mismatch with coordinated Ag/Hg metal atoms. These basepairs were parameterized with the proposed computational framework and subjected to multiple validation steps. The generated force fields result in enhanced structural stability, with metallated basepairs rotating into the major groove. Our findings show a higher propeller angle associated with metalated base pair, which agrees with previously reported experimental data. Molecular dynamics (MD) simulations showed that the metallated basepairs stabilized the DNA structure, with the mismatch bases locking together via metal coordination. We anticipate the developed force fields can help in unveiling the structural dynamics of long metallo-DNA nanowires. 

Aptamer binding to DNA increases conductance over tenfold, enabling high-resistance contrast DNA strands for molecular electronics development.