Multiple Logic Gates Research Articles

Implementation of dynamic dual input multiple output logic gate via resonance in globally coupled Duffing oscillators.

We have used a system of globally coupled double-well Duffing oscillators under an enhanced resonance condition to design and implement Dual Input Multiple Output (DIMO) logic gates. In order to enhance the resonance, the first oscillator in the globally coupled system alone is excited by two forces out of which one acts as a driving force and the other will be either sub-harmonic or super-harmonic in nature. We report that for an appropriate coupling strength, the second force coherently drives and enhances not only the amplitude of the weak first force to all the coupled systems but also drives and propagates the digital signals if any given to the first system. We then numerically confirm the propagation of any digital signal or square wave without any attenuation under an enhanced resonance condition for an amplitude greater than a threshold value. Further, we extend this idea for computing various logical operations and succeed in designing theoretically DIMO logic gates such as AND/NAND, OR/NOR gates with globally coupled systems.

Polyethylenimine-Derived Fluorescent Nonconjugated Polymer Dots with Reversible Dual-Signal pH Response and Logic Gate Operation

A kind of nonconjugated polymer dot possessing autofluorescence was synthesized by hyperbranched polyethylenimine and salicylaldehyde via environmentally friendly imine cross-linking and self-assembly in the aqueous phase. Both fluorescence and ultraviolet–visible (UV–vis) absorption of the polymer dots showed a sensitive and reversible response to pH. The mechanism of pH-dependent optical properties was investigated. The existence of two proton-responsive functional groups (phenolic hydroxyl groups and amine groups) on the polymer dot surface is crucial. The pH-dependent fluorescence is ascribed to electron transfer, which is controlled by the protonation degree of amine groups, while the pH-dependent UV–vis absorption is induced by ionization of phenolic hydroxyl groups. Based on the pH-mediated optical properties, a colorimetric and fluorescent dual-signal pH sensor and multiple logic gates were developed. The fluorescent nonconjugated polymer dots with easy preparation and sensitive response to pH are...

Spectroscopic and TD-DFT studies on the dual mode fluorescent chemosensors based on pyrene thiosemicarbazones, and its application as molecular-scale logic devices

Two newly synthesised pyrene based molecules are hereby reported as molecular switches. The absorption and emission response for receptors with and without F−, CN− and Cu2+ ions can mimic multiple logic gate such as AND, NOR, XNOR, OR, XOR, INHIBITION and TRANSFER gates. The fluorescence reversibility was checked with the alternative addition of fluoride and calcium ions, which can be explained by the “Read-Erase-Read-Write” logic loop. The calculated binding constant value show PyBTSC is better chemosensor than PyCTSC, and the binding affinity is in the order of Cu2+˃F-˃CN−. The detailed mechanism was investigated using DFT and TD-DFT calculations. The fluorescence quenching behaviour of receptor-F complex can be explained by PET mechanism along with ESPT process. The proton attached to the nitrogen which is adjacent to pyrene moiety is first make the hydrogen bond with fluoride ion at the excited state, which has confirmed by natural bond orbital (NBO) and potential energy surface (PES) analysis.

Fluorescence switching of BSA–[Fe(III)–salen]Cl and implementation of its multiple logic gates

In this study, [Fe(III)–salen]Cl (complex 1) was synthesized and its interaction with bovine serum albumin (BSA) was investigated by fluorescence spectroscopy. The estimated distance between BSA and 1 indicated that energy transfer from the excited state of BSA to 1 was achieved with high efficiency. BSA sensors based on fluorescent off–on (1- Na2H2EDTA) and on–off (OH−–H+) were examined and the results confirmed that BSA could operate as molecular logic gate upon interaction with 1, Na2H2EDTA, and OH− as chemical inputs. Multiple logic gates including NOR, NOT, and IMP were constructed through consecutive association of 1 with BSA.

Design of Multiple Logic Gates Based on Chemically Triggered Fluorescence Switching of Functionalized Polyethylenimine.

In this study, two new functionalized polyethylenimine (PEI), PEIR and PEIQ, have been synthesized by covalently conjugating rhodamine 6G (R6G) or 8-chloroacetyl-aminoquinoline (CAAQ) and have been investigated for their sensing capabilities toward metal ions and anions basing on fluorescence on-off and off-on mechanisms. When triggered by protons, metal ions, or anions, functionalized PEIs can behave as a fluorescence switch, leading to a multiaddressable system. Inspired by these results, functionalized PEI-based logic systems capable of performing elementary logic operations (YES, NOT, NOR, and INHIBIT) and integrative logic operations (OR + INHIBIT) have been constructed by observing the change in the fluorescence with varying the chemical inputs such as protons, metal ions, and anions. Due to its characteristics, such as high sensitivity and fast response, developing functionalized PEI as a new material to perform logic operations may pave a new avenue to construct the next generation of molecular devices with better applicability for biomedical research.

A Finite-Point Method for Efficient Gate Characterization Under Multiple Input Switching

Timing characterization of standard cells is one of the essential steps in VLSI design. The traditional static timing analysis (STA) tool assumes single input switching models for the characterization of multiple input gates. However, due to technology scaling, increasing operating frequency, and process variation, the probability of the occurrence of multiple input switching (MIS) is increasing. On the other hand, considering all possible MIS scenarios for the characterization of multiple input logic gates, is computationally intensive. To improve the efficiency, this work proposes a finite-point-based characterization methodology for multiple input gates with the effects of MIS. Furthermore, delay variation due to MIS is integrated into the STA flow through propagation of switching windows. The proposed modeling methodology is validated using benchmark circuits at the 45nm technology node for various operating conditions. Experimental results demonstrate significant reduction in computation cost and data volume with less than ∼10% error compared to that of traditional SPICE simulation.

Chemically induced fluorescence switching of carbon-dots and its multiple logic gate implementation.

Investigations were carried out on the carbon-dots (C-dots) based fluorescent off - on (Fe3 + - S2O32−) and on - off (Zn2 + - PO43−) sensors for the detection of metal ions and anions. The sensor system exhibits excellent selectivity and sensitivity towards the detection of biologically important Fe3 + , Zn2 + metal ions and S2O32−, PO43− anions. It was found that the functional group on the C-dots surface plays crucial role in metal ions and anions detection. Inspired by the sensing results, we demonstrate C-dots based molecular logic gates operation using metal ions and anions as the chemical input. Herein, YES, NOT, OR, XOR and IMPLICATION (IMP) logic gates were constructed based on the selection of metal ions and anions as inputs. This carbon-dots sensor can be utilized as various logic gates at the molecular level and it will show better applicability for the next generation of molecular logic gates. Their promising properties of C-dots may open up a new paradigm for establishing the chemical logic gates via fluorescent chemosensors.

The universal magnetic tunnel junction logic gates representing 16 binary Boolean logic operations

The novel devices are expected to shift the paradigm of a logic operation by their own nature, replacing the conventional devices. In this study, the nature of our fabricated magnetic tunnel junction (MTJ) that responds to the two external inputs, magnetic field and voltage bias, demonstrated seven basic logic operations. The seven operations were obtained by the electric-field-assisted switching characteristics, where the surface magnetoelectric effect occurs due to a sufficiently thin free layer. The MTJ was transformed as a universal logic gate combined with three supplementary circuits: A multiplexer (MUX), a Wheatstone bridge, and a comparator. With these circuits, the universal logic gates demonstrated 16 binary Boolean logic operations in one logic stage. A possible further approach is parallel computations through a complimentary of MUX and comparator, capable of driving multiple logic gates. A reconfigurable property can also be realized when different logic operations are produced from different level of voltages applying to the same configuration of the logic gate.

Multiple and configurable optical logic systems based on layered double hydroxides and chromophore assemblies.

Multiple and configurable fluorescence logic gates were fabricated via self-assembly of layered double hydroxides and various chromophores. These logic gates were operated by observation of different emissions with the same excitation wavelength, which achieve YES, NOT, AND, INH and INHIBIT logic operations, respectively.

A single fluorophore to address multiple logic gates.

Logic gates with different radixes have been constructed using a biologically active molecule, 2-(4'-N,N-dimethylaminophenyl)imidazo[4,5-b]pyridine (DMAPIP-b). Taking advantage of the multiple binding sites of the fluorophore, a series of different molecular logic gates are developed using fluorescence intensities at different wavelengths. The high emission of the molecule is drastically quenched in the presence of Fe(3+). It is regained by the addition of an equivalent amount of F(-). The fluorescence On-Off nature has been used to construct molecular full subtractor and molecular keypad lock system with Boolean logic. A ternary system is generated by considering three defined fluorescence intensities at particular wavelengths. The smooth dependency of emission intensities with analyte concentration is utilized to construct an infinite-valued fuzzy logic system. The fuzzy logic system is further coupled with a neuro-adaptation method to predict more accurately the dependency of molecular intensity on external inputs.

A triangular three-dye DNA switch capable of reconfigurable molecular logic

Structural DNA nanotechnology has developed profoundly in the last several years allowing for the creation of increasingly sophisticated devices capable of discrete sensing, locomotion, and molecular logic. The latter research field is particularly attractive as it provides information processing capabilities that may eventually be applied in situ, for example in cells, with potential for even further coupling to an active response such as drug delivery. Rather than design a new DNA assembly for each intended logic application, it would be useful to have one generalized design that could provide multiple different logic gates or states for a targeted use. In pursuit of this goal, we demonstrate a switchable, triangular dye-labeled three-arm DNA scaffold where the individual arms can be assembled in different combinations and the linkage between each arm can be physically removed using toehold-mediated strand displacement and then replaced by a rapid anneal. Rearranging this core structure alters the rates of Forster resonance energy transfer (FRET) between each of the two or three pendant dyes giving rise to a rich library of unique spectral signatures that ultimately form the basis for molecular photonic logic gates. The DNA scaffold is designed such that different linker lengths joining each arm, and which are used as the inputs here, can also be used independently of one another thus enhancing the range of molecular gates. The functionality of this platform structure is highlighted by easily configuring it into a series of one-, two- and three-input photonic Boolean logic gates such as OR, AND, INHIBIT, etc., along with a photonic keypad lock. Different gates can be realized in the same structure by altering which dyes are interrogated and implementation of toehold-mediated strand displacement and/or annealing allows reconfigurable switching between input states within a single logic gate as well as between two different gating devices.

Phase-change material used to create single bits that act as multiple logic gates

Phase-change material used to create single bits that act as multiple logic gates

"Light-on" sensing of antioxidants using gold nanoclusters.

Depletion of intracellular antioxidants is linked to major cytotoxic events and cellular disorders, such as oxidative stress and multiple sclerosis. In addition to medical diagnosis, determining the concentration of antioxidants in foodstuffs, food preservatives, and cosmetics has proved to be very vital. Gold nanoclusters (Au-NCs) have a core size below 2 nm and contain several metal atoms. They have interesting photophysical properties, are readily functionalized, and are safe to use in various biomedical applications. Herein, a simple and quantitative spectroscopic method based on Au-NCs is developed to detect and image antioxidants such as ascorbic acid. The sensing mechanism is based on the fact that antioxidants can protect the fluorescence of Au-NCs against quenching by highly reactive oxygen species. Our method shows great accuracy when employed to detect the total antioxidant capacity in commercial fruit juice. Moreover, confocal fluorescence microscopy images of HeLa cells show that this approach can be successfully used to image antioxidant levels in living cells. Finally, the potential application of this "light-on" detection method in multiple logic gate fabrication was discussed using the fluorescence intensity of Au-NCs as output.

Catalytic Molecular Logic Devices by DNAzyme Displacement

Chemical reactions catalyzed by DNAzymes offer a route to programmable modification of biomolecules for therapeutic purposes. To this end, we have developed a new type of catalytic DNA-based logic gates in which DNAzyme catalysis is controlled via toehold-mediated strand displacement reactions. We refer to these as DNAzyme displacement gates. The use of toeholds to guide input binding provides a favorable pathway for input recognition, and the innate catalytic activity of DNAzymes allows amplification of nanomolar input concentrations. We demonstrate detection of arbitrary input sequences by rational introduction of mismatched bases into inhibitor strands. Furthermore, we illustrate the applicability of DNAzyme displacement to compute logic functions involving multiple logic gates. This work will enable sophisticated logical control of a range of biochemical modifications, with applications in pathogen detection and autonomous theranostics.

Integration of graphene oxide and DNA as a universal platform for multiple arithmetic logic units

By a combination of graphene oxide and DNA, a universal platform was developed for integration of multiple logic gates to implement both half adder and half subtractor functions. A constant undefined threshold range between high and low fluorescence output signals was set for all the developed logic gates.

Intelligent layered nanoflare: "lab-on-a-nanoparticle" for multiple DNA logic gate operations and efficient intracellular delivery.

DNA strand displacement cascades have been engineered to construct various fascinating DNA circuits. However, biological applications are limited by the insufficient cellular internalization of naked DNA structures, as well as the separated multicomponent feature. In this work, these problems are addressed by the development of a novel DNA nanodevice, termed intelligent layered nanoflare, which integrates DNA computing at the nanoscale, via the self-assembly of DNA flares on a single gold nanoparticle. As a "lab-on-a-nanoparticle", the intelligent layered nanoflare could be engineered to perform a variety of Boolean logic gate operations, including three basic logic gates, one three-input AND gate, and two complex logic operations, in a digital non-leaky way. In addition, the layered nanoflare can serve as a programmable strategy to sequentially tune the size of nanoparticles, as well as a new fingerprint spectrum technique for intelligent multiplex biosensing. More importantly, the nanoflare developed here can also act as a single entity for intracellular DNA logic gate delivery, without the need of commercial transfection agents or other auxiliary carriers. By incorporating DNA circuits on nanoparticles, the presented layered nanoflare will broaden the applications of DNA circuits in biological systems, and facilitate the development of DNA nanotechnology.

Anthraquinone-based demultiplexer and other multiple operations at the molecular level

Anthraquinone-based chemosensor L with pyridine units as additional functional groups has been found to show pH-dependent multiple coordination modes towards different metal ions (Co2+, Ni2+ and Cu2+). Based on these different absorption changes, this differential colorimetric chemosensor L has found promising applications as a multiple-mode molecular logic system, i.e., OR, three – input NOR, three – input INHIBIT, TRANSFER and 1:2 DEMUX. Anthraquinone based chemosensor L with pyridine units has been used for elaboration of multiple logic gates, viz. OR, three – input NOR, three – input INHIBIT, TRANSFER and 1:2 DEMUX.

Cover Picture: Molecular Switches and Multiple Logic Gates Based on 4‐(2‐Pyridylazo)resorcinol (Chin. J. Chem. 6/2013)

Cover Picture: Molecular Switches and Multiple Logic Gates Based on 4‐(2‐Pyridylazo)resorcinol (Chin. J. Chem. 6/2013)

Molecular Switches and Multiple Logic Gates Based on 4‐(2‐Pyridylazo)resorcinol

AbstractA simple‐structured 4‐(2‐pyridylazo)resorcinol (PAR) system presents interesting properties with dual fluorescent outputs. Modulated by solution pH two kinds of reversible switch behaviors, "ON‐OFF" and "OFF‐ON", were realized with the PAR system. Stimulated by different combination of external stimulus, such as metal ions, UV irradiation and solution pH, the PAR system could perform multiple logic functions including three inputs AND, two inputs INHIBIT and combinatorial "NOR/AND" in parallel. The operation of the designed system is very simple and detected with a high sensitive fluorescent signal.

Synthetic circuits integrating logic and memory in living cells

Logic and memory are essential functions of circuits that generate complex, state-dependent responses. Here we describe a strategy for efficiently assembling synthetic genetic circuits that use recombinases to implement Boolean logic functions with stable DNA-encoded memory of events. Application of this strategy allowed us to create all 16 two-input Boolean logic functions in living Escherichia coli cells without requiring cascades comprising multiple logic gates. We demonstrate long-term maintenance of memory for at least 90 cell generations and the ability to interrogate the states of these synthetic devices with fluorescent reporters and PCR. Using this approach we created two-bit digital-to-analog converters, which should be useful in biotechnology applications for encoding multiple stable gene expression outputs using transient inputs of inducers. We envision that this integrated logic and memory system will enable the implementation of complex cellular state machines, behaviors and pathways for therapeutic, diagnostic and basic science applications.