Additive transport in DNA molecular circuits

Abstract

Self-assembly of two complementary single-stranded DNA chains via hybridization increases (approximately doubles) the single molecule DNA conductance leading to additive transport in double-stranded DNA molecular circuits.

Hybrid Nanoparticle/DNAzyme Electrochemical Biosensor for the Detection of Divalent Heavy Metal Ions and Cr3+

“…It is thus obvious that such devices are extremely sensitive to any variation in their environment, such as any decrease or increase in inter-nanoparticle distance, changes in the dielectric constant of the surrounding medium, and the introduction of functionalization materials between distinct NPs or between NP aggregates. On the other hand, dsDNA exhibits interesting electrical properties and is known to facilitate charge transport via tunneling over shorter oligonucleotides or via multi-step hopping over longer DNA paths [ 54 ]; this is also the case for ssDNA, albeit with conductivity that is order of magnitudes lower than that of dsDNA [ 55 ]. The electrical properties of dsDNA and its respective charge transport, using the HOMO/LUMO and the π-electronic system of stacked base pairs, have been studied extensively, yet many phenomena still need to be understood; more specifically, distinctive DNA base pairs have been found to promote charge transport, while others act as electric barriers [ 54 ].…”

“…On the other hand, dsDNA exhibits interesting electrical properties and is known to facilitate charge transport via tunneling over shorter oligonucleotides or via multi-step hopping over longer DNA paths [ 54 ]; this is also the case for ssDNA, albeit with conductivity that is order of magnitudes lower than that of dsDNA [ 55 ]. The electrical properties of dsDNA and its respective charge transport, using the HOMO/LUMO and the π-electronic system of stacked base pairs, have been studied extensively, yet many phenomena still need to be understood; more specifically, distinctive DNA base pairs have been found to promote charge transport, while others act as electric barriers [ 54 ]. Overall, dsDNA conductivity in aqueous environments relies both on base pair π-stacking as well as charge transport via the outer sphere of the sugar phosphodiester backbone of the DNA, including bound water molecules.…”

“…In the case of amino DNAzymes without any functionalization on the sensor’s surface, our experiments did not result in the detection of any HMIs in sufficiently low concentrations (i.e., under 200 nM); hence, they were not included in this paper. At this point, it is worth noting that the quality of the anchoring group (i.e., amino or thiol) can play a crucial role in device conductivity with thiol modification groups, offering improved charge transport due to stronger bonds with the metallic NPs [ 54 ]. In our case, the low sensitivity observed in the case of amino DNAzymes led to the incorporation of a surface functionalization process (as described in the experimental section of the paper) in order to enhance the attachment of the amino groups on the Pt NP film and, hence, improve the device performance.…”

“…In addition, the results discussed herein highlight the importance and impact of DNA functional groups (i.e., amino and thiol) on the biosensor’s performance, allowing for the optimization of the biosensor; optimization is achieved both in terms of improved biosensor performance as well as in terms of simpler and faster fabrication. Overall, the biosensor presented herein poses as a unique sensing solution within the field of electrochemical biosensors as it utilizes the NP layer in a radically different manner than most electrochemical-based sensing systems and by taking advantage of double stranded (ds) DNA’s electrical properties [ 54 ]. In addition, the biosensors stand out as an attractive and cost-effective solution by avoiding many of the common drawbacks encountered in most nanomaterial/DNAzyme electrochemical-sensing systems, namely arduous and expensive development that often involves the use and combination of numerous and wildly varying materials and/or complicated fabrication techniques.…”

Theoretical Study on the Open-Shell Electronic Structure and Electron Conductivity of [18]Annulene as a Molecular Parallel Circuit Model

“…Vazquez et al indicated that the conductance of a model molecule consisting of two parallel benzenes is larger than twice that of a single benzene, both experimentally and theoretically [ 50 ]. Recently, some exceptions to Equation (1) have been reported [ 51 , 52 ]; therefore, Equation (1) is still under discussion in terms of aromaticity, frontier orbital theory, and orbital interaction [ 51 ]. Concerning open-shell systems, the relationship between the conductivity of a molecular circuit, quantum interference, and open-shell nature has not yet been discussed.…”