Multivalued Logic Gates Based on DNA

Abstract

Binary logic is the basis of modern computers, in which every bit is coded by 0 or 1, corresponding to a low or high signal, respectively. Simple Boolean logic gates receive one or more binary (0, 1) input signals and produce a single binary output signal. The principles of binary logic can be applied to the signal transduction operated by molecular switches.[1] In the past decade, molecular systems capable of performing Boolean logic operations have been attractive for the construction of molecular-level devices and machines. [1,2] Various materials, such as organic molecules, [2] protein, [3] nucleic acids, [4][5][6][7][8][9][10][11][12] enzymatic biochemical network, [13,14] supramolecular hydrogel, [15] and polymer-ligand interactions [16,17] have been used to process chemical signals, mimicking Boolean logic operations. These logic gates show great promise, but at the same time face substantial challenges.With the development of biological computing and quantum computing, the dominance of binary logic is challenged and multi-valued logic gates attract intense interest for research. Boolean binary logic has only two states that are true and false, or on and off. However, quite often, the logic gates suffer a certain degree of uncertainty and imprecision. In these cases, it is difficult to process information based on binary logic. Multi-valued logic is likely to play an increasingly important role in the conception and design of a molecular computer, since it would be able to deal with uncertain information. Multi-valued logic is defined as a nonbinary logic and involves the switching between more than two states. The number of distinguishable states increases, which allows for higher information densities.[18] The common application of a multi-valued variable is coding. The Morse code, which uses three different symbols, is probably the best known. The more different symbols there are, the shorter the code words.[19] A ternary or three-valued logic function is one that has two inputs that can assume three states (say 0, 1 and 2) and generates one output signal that can have one of these three states. Thus ternary logic is the extension of predominating binary logic. Recently, a multi-valued logic function was realized by using a nanofluidic diode based on conical nanopores functionalized with polyprotic acid chains.[20] The low, medium, and high pH values constitute the inputs, and the conductance values constitute the outputs. Pischels group has reported a tristable molecular fluorescent switch of the fluorophore 1 -spacer-receptor-spacer-fluorophore 2 dyad.[21] A careful assignment of the logic operation yielded a ternary NOR logic gate. In addition, Cervera et al. reported a multi-valued XOR logic gate implemented with metallic nanoparticles and organic ligands.[22] However, until now, the description of a ternary logic gate operation based on nucleic acids remains rare. Nucleic acids exhibit many advantages in comparison with organic molecules, such as easy synthesis with high reproducibility and purity,...

ChemInform Abstract: Anion Sensors as Logic Gates: A Close Encounter

“…[6][7][8][9][10][11] Since then many materials, such as supramolecules, organic molecules, nucleic acids, proteins,D NA and polymers, have been used as input signals to mimic logic operations. [12][13][14][15][16][17] These molecular logic gates work as down-scaleds witchest hat can be utilised in variouss tates from solutiont os olid. [11,[18][19][20][21][22] In recent years, increasing attention has been paid to the development of molecular logic gates based on anion/cation-detecting receptors.…”

Logic Functions with Stimuli‐Responsive Single Nanopores

“…Table 1 shows some electrochemical effects used to externally tune the nanopore conductance, which are well understood on the basis of simple theoretical approaches. [7,16,18,30,[48][49][50][51][52] Previous theoretical and experimental logical schemes at the nanoscale were based on molecular devices and self-assembled monolayers, [53] nanopore arrays, [54] enzyme-based [55] and DNA [56] biomolecular systems.…”

“…fluorescence) signals as outputs. [56] The inside surface of glass nanopore electrodes can be modified with optically active moieties to impart photochemical control of transport. [68] Optical gating has also been demonstrated in polymeric nanopores [48,69,[70][71][72] decorated with a monolayer of photo-labile hydrophobic molecules that can be removed by irradiation, leading to hydrophilic groups.…”

Anion Sensors as Logic Gates: A Close Encounter?

“…in 1993 and to this day the research group has published reports on a variety of molecular logic gates with various applications, including review articles . Since then many materials, such as supramolecules, organic molecules, nucleic acids, proteins, DNA and polymers, have been used as input signals to mimic logic operations . These molecular logic gates work as down‐scaled switches that can be utilised in various states from solution to solid .…”