DNA-programmable multiplexing for scalable, renewable redox protein bio-nanoelectronics.

A universal, site-addressable DNA linking strategy is deployed for the programmable assembly of multifunctional, long-lasting redox protein nanoelectronic devices. This addressable linker, the first incorporated into a redox enzyme-nanoelectronic system, promotes versatility and renewability by allowing the reconfiguration and replacement of enzymes at will. The linker is transferable to all redox proteins due to the simple conjugation chemistry involved. The efficacy of this linking strategy is assessed using two model enzymes, glucose oxidase (GOx) and alcohol dehydrogenase (ADH), self-assembled onto separate nanoelectrode regions comprised of a highly ordered carbon nanotube (CNT) array. The sequence-specificity of DNA hybridization provides the means of encoding spatial address to the self-assembling process that conjugates enzymes tagged with single-stranded DNA (ssDNA) to the tips of designated CNTs functionalized with the complementary strands. In this study, we demonstrate the feasibility of multiplexed, scalable, reconfigurable and renewable transduction of redox protein signals by virtue of DNA addressing.

Wiring efficiency of a metallizable DNA linker for site-addressable nanobioelectronic assembly.

We report the first demonstration of DNA oligonucleotide tags used to address the site-specific assembly of multiple redox enzymes onto spatially distinct regions of a nanoelectronic platform, establishing a direct electrical contact. The resulting system constitutes a multiplexed carbon nanotube-redox protein biosensor capable of detecting varying concentrations of several different substances in real time. The efficiency and robustness of the enzyme linking scheme is explored in detail, showing a high degree of preservation of enzymatic activity and an efficient electrical contact at the enzyme-nanoelectrode interface. While five proteins have been used as a demonstration in this study, there is virtually no limit to the number of enzymes that could be bound in parallel using this linking strategy, which is universally applicable to all proteins due to the simple conjugation chemistry involved. We further demonstrate metallization of the linker in the presence of a divalent metal cation, inducing elevated electron transfer efficiency relative to the native DNA link.

Site-specific assembly of DNA and appended cargo on arrayed carbon nanotubes.

We describe a strategy that permits discrete regions of arrayed carbon nanotubes (CNTs) to be functionalized simultaneously and specifically with DNA oligonucleotides. The different chemical properties of two regions on single CNTs and orthogonal chemical coupling strategies have been exploited to derivatize CNTs within highly ordered arrays with multiple DNA sequences. Through duplex hybridization, we then targeted different DNA sequences with appended metal nanoparticles to distinct sites on the CNT architecture with precise spatial control. The materials generated from these studies represent the first CNTs with bipartite functionalization. The approach described provides a high level of precision in parallel and directed assembly of DNA sequences and appended cargo and is useful for the preparation of novel hybrid bionanomaterials.