General Modeling Method of Threshold-Type Multivalued Memristor and Its Application in Digital Logic Circuits

This paper presents a general modeling method for threshold-type multivalued memristors. Through this memristor modeling method, it is very simple to establish threshold-type memristor behavior models with different numbers of memristance elements, and these models are verified by numerical MATLAB simulations. A corresponding circuit-level SPICE model of the ternary memristor behavior model is developed and simulated in LTspice, shown to be consistent with the MATLAB results. Finally, the SPICE model is used to design the AND gate, OR gate, and three NOT gates of ternary state-based logic, and the effectiveness of the circuit is proved by LTSpice simulation.

Two-input protein logic gate for computation in living cells

Advances in protein design have brought us within reach of developing a nanoscale programming language, in which molecules serve as operands and their conformational states function as logic gates with precise input and output behaviors. Combining these nanoscale computing agents into larger molecules and molecular complexes will allow us to write and execute “code”. Here, in an important step toward this goal, we report an engineered, single protein design that is allosterically regulated to function as a ‘two-input logic OR gate’. Our system is based on chemo- and optogenetic regulation of focal adhesion kinase. In the engineered FAK, all of FAK domain architecture is retained and key intramolecular interactions between the kinase and the FERM domains are externally controlled through a rapamycin-inducible uniRapR module in the kinase domain and a light-inducible LOV2 module in the FERM domain. Orthogonal regulation of protein function was possible using the chemo- and optogenetic switches. We demonstrate that dynamic FAK activation profoundly increased cell multiaxial complexity in the fibrous extracellular matrix microenvironment and decreased cell motility. This work provides proof-of-principle for fine multimodal control of protein function and paves the way for construction of complex nanoscale computing agents.

FLT3 OR CD33 NOT EMCN Logic Gated CAR-NK Cell Therapy (SENTI-202) for Precise Targeting of AML

Background: While chimeric antigen receptor (CAR) cell therapies have provided extraordinary clinical responses in some hematological malignancies, developing effective CAR cell therapies for acute myeloid leukemia (AML) has been challenging due to: (a) the lack of a single target antigen robustly expressed across both AML leukemic stem cell (LSC) and immature leukemic blast cell subpopulations, and (b) the lack of truly AML-specific target antigens, since current targets are also expressed on healthy tissues and may result in off-tumor toxicity. Using logic gated gene circuits, we are engineering our SENTI-202 CAR-NK cell therapy to overcome these long-standing challenges to treating AML patients. Methods: To maximize clearance of AML tumor subpopulations and minimize off-tissue toxicities, we used a proprietary bioinformatics paired antigen discovery platform to identify the optimal combinations of AML tumor-associated and healthy tissue antigens to target using an OR and NOT logic gated CAR gene circuit approach. The SENTI-202 therapeutic candidate is a FLT3 OR CD33 NOT Endomucin (EMCN) gene circuit-enabled allogeneic CAR-NK cell, designed to broadly target FLT3 and/or CD33-expressing AML tumor cells (including both LSCs and blasts) but not healthy hematopoietic stem cells (HSCs). Results: First, for the OR GATE portion of the logic circuit we demonstrated that engineered primary human NK cells expressing activating CARs (aCARs) that recognize both FLT3 and CD33 outperformed more traditional single target CAR approaches with FLT3 (p<0.05) or CD33 (p<0.01), and exhibited >80% cytotoxicity and significant cytokine secretion (GrB, IFN-g, and TNF-a) against multiple leukemia cell lines in vitro, including MOLM13, THP1, and SEM. We successfully engineered FLT3 OR CD33 CAR-NK cells using both bicistronic and bivalent CAR configurations, where bicistronic CARs possess separate FLT3 and CD33 CARs linked via a 2A peptide, and bivalent CARs use a loop structure to connect FLT3 and CD33 scFvs within the same CAR. While both approaches demonstrated robust efficacy against AML cells, the bivalent approach enabled greater CAR expression and cytotoxicity (p<0.05). Importantly, our FLT3 OR CD33 CAR-NK cells demonstrated significant cytotoxicity against primary AML patient samples (p<0.01-0.001) and significantly reduced tumor burden and improved mouse survival in MOLM13 (p<0.05) and MV4-11 (p<0.01) xenograft AML models. We believe that our strategy of concurrently targeting FLT3 and CD33 will result in a more robust synergistic anti-tumor effect, leading to a more durable remission with decreased risk of relapse due to single antigen escape. Second, for the NOT GATE portion of the logic circuit to protect healthy HSCs, we developed NK and T cell inhibitory CARs (iCARs) consisting of an scFv against a healthy cell antigen, hinge and transmembrane domains, and functional intracellular domains derived from inhibitory co-receptors containing immunoreceptor tyrosine-based inhibitory motifs. In the case of SENTI-202, the iCAR scFv recognizes EMCN, a surface antigen expressed on up to 76% of healthy HSCs but not on AML cells. Using two different iCAR configurations, we demonstrated that FLT3 (CD28z) aCAR-NK cells engineered with an EMCN-specific iCAR protected up to 67% (iCAR#1, p<0.01) or 50% (iCAR#2, p<0.01) of FLT3+ EMCN+ cells from FLT3 aCAR-mediated cytotoxicity. Next, to replicate a clinical context more closely, we mixed FLT3+ EMCN- (AML-like) and FLT3+ EMCN+ (HSC-like) target cells and demonstrated that FLT3 NOT EMCN CAR-NK cells exhibit preferential killing of FLT3+ EMCN- target cells (p<0.0001), demonstrating that our NOT GATED gene circuit controls NK-mediated responses on a cell-by-cell basis. Conclusion: SENTI-202 is a novel NK cell product candidate to be engineered with both OR and NOT logic gated CAR gene circuits, wherein the OR gate is designed to increase AML LSC/blast tumor clearance (to prevent relapse), and the NOT gate is designed to protect healthy HSCs from off-tumor toxicity, enabling regeneration of a healthy hematopoietic system and mitigating the need for a bone marrow transplant. Beyond AML, OR and NOT logic gated CAR-NK cell therapy has applicability to other cancer-associated antigen targets that are potentially limited by antigen escape and/or off-tumor toxicity, increasing the potential for enhanced efficacy and reduced risk of undesirable side effects. Disclosures No relevant conflicts of interest to declare.

Threshold Logic Technology based E-cube Routing on a 4-dimensional hypercube

Hypercube network connection is formed by connecting different N number of nodes that are expressed as a power of 2. If each node has an address of m bits then the total number of nodes in the Hypercube network is N=2^m. In calculating the predefined routing path for the case of this E-cube network, we apply deterministic algorithm which gives a deadlock free concept. For determining predefined routing path, node addresses involved in the path are calculated by using the exclusive operation, firstly, on the node addresses of source and destination, next, on the derived nodes according to the algorithm. In the present work, the Exclusive-OR operation is performed with the help of electron-tunneling based XOR gate which is made up of Multiple input threshold logic gate. This multiple input threshold logic gate technology is really different from the existing one. By using an emerging technology we are capable of making an electronic circuit with high speed, low cost, high concentration density, light in weight, reduced gate numbers and low power consumption. This technology is relies on the condition of linear threshold logic and electron-tunneling event. When we are interested in implementing a circuit, a multi-inputs but one-output based logic-gate will be taken account of consideration. In this work, we have designed an E-cube Routing on a 4-dimensional hypercube to find out the node addresses for predefining the deadlock free routing path from source to destination. To develop this “E-cube Routing on a 4-dimensional hypercube”, we must require a specific logic called Exclusive-OR gate and for this, some small components like 2-input OR gate, 2-input AND gates of different input conditions are essential. After arranging this XOR gate in a pattern discussed in section 2, a desired circuit is implemented. All the circuit we are intended to construct are given in due places with their threshold logic and simulation set, the simulation results are provided as well. Different truth tables, derivation of threshold logic expressions are given for clear understanding. We have taken our consideration of whether the present work circuits are faster or slower than the circuits of CMOS based- and Single electron transistor (SET) based-circuits. The power consumed at the time of tunneling event for a circuit is measured and sensed that it exists in the range between 10meV to 250meV which is very small amount. All the combinational circuits we have presented in this work are of ‘generic multiple input threshold logic gate’-based.

FPGA Implementation of Threshold-Type Binary Memristor and Its Application in Logic Circuit Design

In this paper, a memristor model based on FPGA (field programmable gate array) is proposed, and the circuit of AND gate and OR gate composed of memristors is built by using this model. Combined with the original NOT gate in FPGA, the NAND gate, NOR gate, XOR gate and the XNOR gate are further realized, and then the adder design is completed. Compared with the traditional gate circuit, this model has obvious advantages in size and non-volatility. At the same time, the establishment of this model will add new research methods and tools for memristor simulation research.