Chemiluminescent Logic Gates Based on Functionalized Gold Nanoparticles/Graphene Oxide Nanocomposites

Label‐free logic gates (AND, OR, and INHIBIT) based on chemiluminescence (CL) as new optical readout signal have been developed by taking advantage of the unique CL activity of luminol‐ and lucigenin‐functionalized gold nanoparticles/graphene oxide (luminol‐lucigenin/AuNPs/GO) nanocomposites. It was found that Fe²⁺ ions could induce the CL emission of luminol‐lucigenin/AuNPs/GO nanocomposites in alkaline solution. On this basis, by using Fe²⁺ ions and NaOH as the inputs and the CL signal as the output, an AND logic gate was fabricated. When the initial reaction system contained luminol‐lucigenin/AuNPs/GO nanocomposites and NaOH, either Fe²⁺ ions or Ag⁺ ions could react with the luminol‐lucigenin/AuNPs/GO nanocomposites to produce a strong CL emission. This result was used to design an OR logic gate using Fe²⁺ ions and Ag⁺ ions as the inputs and CL signal as the output. Moreover, two INHIBIT logic gates for Fe²⁺ and Ag⁺ were also developed using by NaClO and L ‐cysteine as their CL inhibitors, respectively. Furthermore, the proposed logic gates were successfully used to detect Fe²⁺, Ag⁺, and L ‐cysteine, respectively. The developed logic gates may find future applications in sensing, clinical diagnostics, and environmental monitoring.     

Enhancement of Bioelectrocatalytic Processes by the Rotation of Mediator‐Functionalized Magnetic Particles on Electrode Surfaces: Comparison with a Rotating Disk Electrode

The rotation of redox‐functionalized magnetic particles (MPs) by means of an external magnet is a common practice for enhancing bioelectrocatalytic processes and for the amplification of biosensing events. The current densities generated by rotating redox‐functionalized MPs in two bioelectrocatalytic systems are compared to the current densities generated by rotating disc electrodes (RDE) functionalized with similar redox functionalities. The bioelectrocatalytic systems consist of pyrroloquinoline quinone (PQQ)‐functionalized MPs that oxidize NADH, and ferrocene‐functionalized MPs that mediate the bioelectrocatalyzed oxidation of glucose in the presence of glucose oxidase. The results reveal that only ca. 1% of the area of the redox‐functionalized MPs are electrically contacted with the electrode. Also, the current densities generated by the rotating MPs at high rotation speeds are lower than theoretically expected, presumably due to lose of electrical contact between the MPs and the electrode, and incoherent rotation of the particles on the electrode, due to insufficient magnetization. The comparison of the current densities in the bioelectrocatalytic systems in the presence of the rotating redox‐functionalized MPs to the analogous RDE systems allows us to elucidate the kinetics of electron transfer at the redox‐active MPs.     

Bioelectronic Interface Connecting Reversible Logic Gates Based on Enzyme and DNA Reactions

It is believed that connecting biomolecular computation elements in complex networks of communicating molecules may eventually lead to a biocomputer that can be used for diagnostics and/or the cure of physiological and genetic disorders. Here, a bioelectronic interface based on biomolecule‐modified electrodes has been designed to bridge reversible enzymatic logic gates with reversible DNA‐based logic gates. The enzyme‐based Fredkin gate with three input and three output signals was connected to the DNA‐based Feynman gate with two input and two output signals—both representing logically reversible computing elements. In the reversible Fredkin gate, the routing of two data signals between two output channels was controlled by the control signal (third channel). The two data output signals generated by the Fredkin gate were directed toward two electrochemical flow cells, responding to the output signals by releasing DNA molecules that serve as the input signals for the next Feynman logic gate based on the DNA reacting cascade, producing, in turn, two final output signals. The Feynman gate operated as the controlled NOT gate (CNOT), where one of the input channels controlled a NOT operation on another channel. Both logic gates represented a highly sophisticated combination of input‐controlled signal‐routing logic operations, resulting in redirecting chemical signals in different channels and performing orchestrated computing processes. The biomolecular reaction cascade responsible for the signal processing was realized by moving the solution from one reacting cell to another, including the reacting flow cells and electrochemical flow cells, which were organized in a specific network mimicking electronic computing circuitries. The designed system represents the first example of high complexity biocomputing processes integrating enzyme and DNA reactions and performing logically reversible signal processing.     

Highly Sensitive INHIBIT and XOR Logic Gates Based on ICT and ACQ Emission Switching of a Porphyrin Derivative

Fluorescence‐switch‐based logic devices are very sensitive compared with most of the reported devices based on UV/Vis absorption systems. Herein, we demonstrate that a simple molecule, 5,10,15,20‐tetra‐(4‐aminophenyl)porphyrin (TAPP), shows protonation‐induced multiple emission switches through intramolecular charge transfer and/or aggregation‐caused quenching. Highly sensitive INHIBIT and XOR logic gates can be achieved by combining the intermolecular assembly with the intramolecular photoswitching of diprotonated TAPP (TAPPH₂²⁺). In addition, molecular simulations have been performed by DFT for a better understanding of the emission‐switching processes.     

Implication and Inhibition Boolean Logic Gates Mimicked with Enzyme Reactions

The enzyme system mimicking Implication (IMPLY) and Inhibition (INHIB) Boolean logic gates has been designed. The same enzyme system was used to operate as the IMPLY or INHIB gate simply by reformulating the input signals. The optical analysis of the logic operation confirmed the output generation as expected for the studied logic gates. The conceptual approach to the IMPLY and INHIB logic gates allows their construction with many other enzymes operating in a similar way.     

Reversible Logic Gates Based on Enzyme‐Biocatalyzed Reactions and Realized in Flow Cells: A Modular Approach

Reversible logic gates, such as the double Feynman gate, Toffoli gate and Peres gate, with 3‐input/3‐output channels are realized using reactions biocatalyzed with enzymes and performed in flow systems. The flow devices are constructed using a modular approach, where each flow cell is modified with one enzyme that biocatalyzes one chemical reaction. The multi‐step processes mimicking the reversible logic gates are organized by combining the biocatalytic cells in different networks. This work emphasizes logical but not physical reversibility of the constructed systems. Their advantages and disadvantages are discussed and potential use in biosensing systems, rather than in computing devices, is suggested.     

聚乙烯亚胺功能化磁性纳米颗粒制备及其吸附分离蒽醌类阴离子染料性能研究

在室温下,采用戊二醛化学交联法制备聚乙烯亚胺功能化的磁性纳米吸附剂(Fe3O4-PEI).利用TEM、XRD、FT-IR、VSM和TGA等手段对其进行结构表征,并以茜素红、核固红及茜素绿3种蒽醌类染料为目标吸附质,通过静态吸附实验考察了pH值、吸附时间、染料初始浓度、操作温度等因素对吸附的影响,同时进行了吸附动力学和吸附等温线模拟研究.结果表明,在pH=3和温度303 K的条件下,茜素红、核固红和茜素绿的最大吸附量分别为256.1,138.8和134.6 mg/g;初始浓度和吸附时间对染料吸附效率有明显的影响,吸附可在60 min内达到平衡,且吸附过程符合准二级动力学模型;Langmuir等温线模型能更好地描述染料的吸附;蒽醌类染料在Fe3O4-PEI上的吸附是一个自发的吸热过程.另外,Fe3 O4-PEI良好的稳定性和重复使用性,使其可作为一种潜在的水处理吸附剂.     

The Construction of DNA Logic Gates Restricted to Certain Live Cells Based on the Structure Programmability and Aptamer-Cell Affinity of G-Quadruplexes

DNA computation is considered a fascinating alternative to silicon-based computers; it has evoked substantial attention and made rapid advances. Besides realizing versatile functions, implementing spatiotemporal control of logic operations, especially at the cellular level, is also of great significance to the development of DNA computation. However, developing simple and efficient methods to restrict DNA logic gates performing in live cells is still a challenge. In this work, a series of DNA logic gates was designed by taking full advantage of the diversity and programmability of the G-quadruplex (G4) structure. More importantly, by further using the high affinity and specific endocytosis of cells to aptamer G4, an INHIBIT logic gate has been realized whose operational site is precisely restricted to specific live cells. The design strategy might have great potential in the field of molecular computation and smart bio-applications.     

INHIBIT‐Inspired Two‐Output DNA Logic Gates Based on Surface‐Enhanced Raman Scattering

Herein, we presented a novel logic gate based on an INHIBITION gate that performs parallel readouts. Logic gates performing INHIBITION and YES/OR were constructed using surface‐enhanced Raman scattering as optical outputs for the first time. The strategy allowed for simultaneous reading of outputs in one tube. The applicability of this strategy has been successfully exemplified in the construction of half‐adder using the two‐output logic gates as reporting gates. This reporting strategy provides additional design flexibility for dynamic DNA devices.     

Molecular Logic Operations Based on Surfactant Nanoaggregates

Two molecular logic gates, FS1 and FS2, which display a UV and fluorescence behavior that is dependent on the pH value and the sodium dodecyl sulfate (SDS) surfactant concentration, are demonstrated based on the intramolecular charge‐transfer mechanism. They are constructed according to the inorganic salts that induce transformation from premicelle to micelle. The absorption band of FS1 at 480 nm is significantly enhanced only when both SDS and Na₂SO₄ are the input at high concentrations, in accordance with an AND logic gate. The OR logic function can be realized in a 3.5 mM SDS/FS2 aqueous solution with SDS and Na₂SO₄ as inputs along with the emission intensity as output. Furthermore, half addition and half subtraction can be incorporated in FS1. This is facilitated by the surfactant, due to its versatility.     

一种基于磁性纳米粒子PCR的高通量SNP分型方法

利用磁性纳米粒子PCR扩增(MNPs-PCR)和等位基因特异性双色荧光探针(Cy3, Cy5)杂交, 建立了一种单核苷酸多态性(SNP)分型的新方法. 应用该方法对9个样本MTHFR基因的C677T多态进行检测, 野生和突变型样本正错配信号比大于9.0, 杂合型正错配信号比接近1.0, 分型结果经测序验证. 此方法无须产物纯化、浓缩, 扫描分型结果快速、直观, 是一种操作简单、快速、高通量、高灵敏度的分型方法.     

基于四氧化三铁磁性纳米粒子的微囊藻毒素免疫传感器研究

采用化学共沉淀法制备四氧化三铁(Fe3O4)磁性纳米粒子(MNPs),依次用3-氨基丙基三乙氧基硅烷(APTS)、丁二酸酐(SAH)对Fe3O4 MNPs表面进行修饰,得到羧基功能化的核壳型磁性纳米粒子(Fe3O4@APTS·SAH MNPs),分别采用透射电镜(TEM)、磁滞回线、X射线光电子能谱(XPS)和傅里叶红外光谱(FTIR)对其进行了表征.将此纳米粒子修饰在自制的磁性玻碳电极(MGCE)表面,用1-(3-二氨基丙基)-3-乙基碳二亚胺盐酸盐(EDC)和N-羟基琥珀酰亚胺(NHS)活化纳米粒子表面的羧基,通过与氨基的共价交联,将抗微囊藻毒素-(亮氨酸-精氨酸)(MCLR)抗体(anti-MCLR)固定于该修饰电极上,用牛血清白蛋白(BSA)封闭非特异性吸附位点,构建了一种检测MCLR的电流型免疫传感器.采用直接竞争免疫反应模式,在标记物辣根过氧化物酶(HRP)的MCLR (MCLR-HRP)存在下,利用差分脉冲伏安法(DPV)测定溶液中的微囊藻毒素.在优化的实验条件下,免疫传感器对MCLR的线性测定范围为0.05 ～ 100 μg/L,检出限为0.01 μg/L(S/N=3).构建的免疫传感器呈现出良好的重现性、稳定性和特异性.将本传感器用于实际水样的测定,加标回收率为94.3％ ～ 99.5％.     

Development of a Perchlorate Chemical Sensor Based on Magnetic Nanoparticles and Silicon Nitride Capacitive Transducer

We report in this work the development of a novel capacitance electrochemical sensors based on silicon nitride substrate (Si₃N₄) chemically modified with a structure of Cobalt phthalocyanine, C,C,C,C‐tetracarboxylic acid‐Polyacrylamide (Co(II)Pc‐PAA). This sensitive layer was tested with and without magnetic nanoparticles (MNP) for perchlorate ( ) detection. The developed chemical sensor with Si₃N₄/APTES‐MNP/Co(II)Pc‐PAA structure has shown a better performance when compared to the other structure based on Si₃N₄/Co(II)Pc‐PAA. Contact angle measurements (CAM) and atomic force microscopy (AFM) characterizations have been performed to characterize the functionalization of the chemical sensors surface. Under the optimized structure of the chemical sensor, electrochemical measurements were carried out using Mott‐Schottky analysis for detection within the large range of 10⁻¹⁰ to 10⁻⁴ M with a very low detection limit of 2×10⁻¹⁰ M. The chemical sensor has demonstrated a high selectivity toward when compared to other interfering anions such as Cl⁻, SO₄²⁻, and CO₃²⁻. The present capacitive chemical sensor is very promising for sensitive and rapid detection of for environmental applications.     

DNA Hybridization at Magnetic Nanoparticles with Electrochemical Stripping Detection

A simple and practical method for electrochemical DNA hybridization assay has been developed to take advantage of magnetic nanoparticles for ssDNA immobilization and zinc sulfide nanoparticle as oligonucleotide label. Magnetic nanoparticles were prepared by coprecipitation of Fe²⁺ and Fe³⁺ with NH₄OH, and then amino silane was coated onto the surface of magnetite nanoparticles. The magnetic nanoparticles have the advantages of easy preparation, easy surface modification and low cost. The target ssDNA with the phosphate group at the 5′ end was then covalently immobilized to the amino group of magnetite nanoparticles by forming a phosphoramidate bond in the presence of 1‐ethyl‐3‐(3‐dimeth‐ylaminopropyl)carbodiimide (EDAC). The zinc sulfide (ZnS) nanoparticle‐labeled oligonucleotides probe was used to identify the target ssDNA immobilized on the magnetic nanoparticles based on a specific hybridization reaction. The hybridization events were assessed by the dissolution of the zinc sulfide nanoparticles anchored on the hybrids and the indirect determination of the dissolved zinc ions by anodic stripping voltammetry (ASV) at a mercury film glassy carbon electrode (GCE). The proposed method couples the high sensitivity of anodic stripping analysis for zinc ions with effective magnetic separation for eliminating nonspecific adsorption effects and offers great promise for DNA hybridization analysis.     

Multi‐Level Logic Gate Operation Based on Amplified Aptasensor Performance

Conventional electronic circuits can perform multi‐level logic operations; however, this capability is rarely realized by biological logic gates. In addition, the question of how to close the gap between biomolecular computation and silicon‐based electrical circuitry is still a key issue in the bioelectronics field. Here we explore a novel split aptamer‐based multi‐level logic gate built from INHIBIT and AND gates that performs a net XOR analysis, with electrochemical signal as output. Based on the aptamer–target interaction and a novel concept of electrochemical rectification, a relayed charge transfer occurs upon target binding between aptamer‐linked redox probes and solution‐phase probes, which amplifies the sensor signal and facilitates a straightforward and reliable diagnosis. This work reveals a new route for the design of bioelectronic logic circuits that can realize multi‐level logic operation, which has the potential to simplify an otherwise complex diagnosis to a “yes” or “no” decision.     

Versatile Logic Devices Based on Programmable DNA‐Regulated Silver‐Nanocluster Signal Transducers

A DNA‐encoding strategy is reported for the programmable regulation of the fluorescence properties of silver nanoclusters (AgNCs). By taking advantage of the DNA‐encoding strategy, aqueous AgNCs were used as signal transducers to convert DNA inputs into fluorescence outputs for the construction of various DNA‐based logic gates (AND, OR, INHIBIT, XOR, NOR, XNOR, NAND, and a sequential logic gate). Moreover, a biomolecular keypad that was capable of constructing crossword puzzles was also fabricated. These AgNC‐based logic systems showed several advantages, including a simple transducer‐introduction strategy, universal design, and biocompatible operation. In addition, this proof of concept opens the door to a new generation of signal transducer materials and provides a general route to versatile biomolecular logic devices for practical applications.