Electronic transport properties of electrically doped cytosine‐based optical molecular switch with single‐wall carbon nanotube electrodes

This study represents an empirical model of cytosine‐based optical molecular switch. This possible biomolecular switch has been designed using the first principle approach which is based on density functional theory and non‐equilibrium Green''s function. The quantum‐ballistic transport property and current–voltage (I–V) characteristics of cytosine‐based optomolecular switch have been investigated at 25 THz operating frequency. The influence of highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) gaps on the electronic transmission and I–V characteristics has been discussed in detail. The aim of this study is to highlight the minimum conformational change during a single ON–OFF switching cycle. The biomolecule comprises switching behaviour when converts from straightened to twisted form during photo‐excitement. The straightened and twisted forms of the molecule are represented as logic ‘0’ and logic ‘1’, respectively. This p and n regions of this switch has been made using electrical doping process. The current through the twisted form of the cytosine biomolecule is ∼1000 times higher than the straightened form. The maximum switching ratio 62.1 is obtained at 1 V bias. The origin of the switching behaviour of the biomolecule can be interpreted by quantum–ballistic transport model along with HOMO–LUMO gaps.Inspec keywords: ballistic transport, organic compounds, Green''s function methods, ab initio calculations, density functional theory, molecular biophysics, optical switches, single‐wall carbon nanotubes, electrochemical electrodesOther keywords: electrical doping process, cytosine biomolecule, electronic transport properties, single‐wall carbon nanotube electrodes, cytosine‐based optical molecular switch, density functional theory, electronic transmission, HOMO‐LUMO gaps, current–voltage characteristics, biomolecular switching behaviour, quantum–ballistic transport property model, electrically doped cytosine‐based optical molecular switch, first principle approach, nonequilibrium Green''s function, I‐V characteristics, highest occupied molecular orbital–lowest unoccupied molecular orbital gaps, single ON–OFF switching cycle, photoexcitement, frequency 25.0 THz, voltage 1.0 V, C     

First principle approach towards logic design using hydrogen‐doped single‐strand DNA

Molecular logic gate has been proposed using single‐strand DNA (ssDNA) consisting of basic four nucleobases. In this study, density functional theory and non‐equilibrium Green''s function based first principle approach is applied to investigate the electronic transmission characteristics of ssDNA chain. The heavily hydrogen‐doped‐ssDNA (H‐ssDNA) chain is connected with gold electrode to achieve enhanced quantum‐ballistic transmission along 〈1 1 1〉 direction. Logic gates OR, Ex‐OR, NXOR have been implemented using this analytical model of H‐ssDNA device. Enhanced logic properties have been observed for ssDNA after H adsorption due to improved electronic transmission. Dense electron cloud is considered as logic ‘high’ (1) output in presence of hydrogen molecule and on the contrary sparse cloud indicate logic ‘low’ (0) in the absence of hydrogen molecule. Device current is significantly increased from 0.2 nA to 2.4 µA (approx.) when ssDNA chain is heavily doped with hydrogen molecule. The current–voltage characteristics confirm the formation of various Boolean logic gate operations.Inspec keywords: molecular electronics, Green''s function methods, hydrogen, logic gates, density functional theory, adsorption, DNA, logic design, logic circuitsOther keywords: hydrogen molecule, contrary sparse cloud, current–voltage characteristics, Boolean logic gate operations, first principle approach, logic design, hydrogen‐doped single‐strand DNA, molecular logic gate, density functional theory, electronic transmission characteristics, H, analytical model, NXOR logic gates, Ex‐OR logic gates, OR logic gates, hydrogen‐doped‐ssDNA chain, nonequilibrium Green''s function, nucleobases, dense electron cloud, improved electronic transmission, enhanced logic properties, H‐ssDNA device, enhanced quantum‐ballistic transmission, gold electrode     

Extracellular biosynthesis of biocompatible CdSe quantum dots

An extracellular biosynthesis method has been developed to prepare cadmium selenide (CdSe) quantum dots (QDs) with strong fluorescence emission by incubating cheap Cd and Se inorganic salts with Escherichia coli (E.coli) bacteria. Ultraviolet–visible absorption spectra, photoluminescence (PL) spectra, and high‐resolution transmission electron microscopy analysis showed that the biosynthesised CdSe QDs have an average size of 3.1 nm, the excellent optical properties with fluorescence emission around 494 nm, and the good crystallinity. It was found that addition of 80 mg of mercaptosuccinic acid resulted in the formation of CdSe QDs with highest PL intensity. Furthermore, Fourier‐transform infrared spectra of as‐synthesised CdSe QDs confirmed the presence of a surface protein capping layer. The biosynthesised CdSe QDs were incorporated into the yeast cells as illustrated by laser confocal scanning microscopy images, showing a great potential in bio‐imaging and bio‐labelling application.Inspec keywords: microorganisms, molecular biophysics, fluorescence, visible spectra, nanofabrication, nanobiotechnology, proteins, cellular biophysics, nanostructured materials, wide band gap semiconductors, cadmium compounds, semiconductor quantum dots, II‐VI semiconductors, transmission electron microscopy, photoluminescence, optical microscopy, ultraviolet spectra, Fourier transform infrared spectra, biological techniques, semiconductor growthOther keywords: biocompatible CdSe quantum dots, extracellular biosynthesis method, cadmium selenide quantum dots, high‐resolution transmission electron microscopy analysis, biosynthesised CdSe QDs, Fourier‐transform infrared spectra, Escherichia coli, ultraviolet‐visible absorption spectra, PL intensity, fluorescence emission, photoluminescence spectra, optical properties, surface protein capping layer, laser confocal scanning microscopy images, bioimaging, biolabelling application, yeast cells, f mercaptosuccinic acid, CdSe     

Investigation of the morphological cell structures and their optical significances of Aeshna cyanea

The transparent wing of the dragonfly Aeshna cyanea has been investigated using scanning electron microscopy (SEM), optical microscopy (OPM), energy‐dispersive X‐ray spectroscopy (EDS) and reflectance spectroscopy. Four cells (D1–D4) were studied and classified according to their general morphology. The OPM depicted the vein‐joint characterised by the distribution of resilin. EDS technique showed common elements such as carbon, oxygen, and chlorine. SEM analysis revealed thin membranes reinforced with a network of hallow veins. Spikes and round shape of microstructures were identified. The roughness of the pruinosity was estimated, which indicates the shape and curvature of the microstructures that essentially play a significant role in the optical response observed. The study can be essential to design and improve micro‐air vehicles.Inspec keywords: bio‐optics, optical microscopy, biomembranes, light reflection, X‐ray chemical analysis, scanning electron microscopy, crystal microstructureOther keywords: transparent wing, EDS technique, SEM analysis, morphological cell structures, optical microscopy, dragonfly Aeshna cyanea, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, reflectance spectroscopy, vein‐joint characterization, resilin distribution, carbon, oxygen, chlorine, thin membrane reinforced hallow vein network, microstructure spikes, microstructure round shape, micro‐air vehicles     

Cytotoxicity properties of functionalised carbon nanotubes on pathogenic bacteria

Nanobiotechnology is a promising field concerned with the using of engineered nanomaterials, which leads to the improvement of new human remedial against pathogenic bacteria modalities. In this work, silver nanoparticles (AgNPs) were prepared by an easy, cheap and low‐cost electro‐chemical method. The AgNPs were then loaded successfully on to multi‐walled carbon nanotubes (MWCNTs) using a modified chemical reaction process. The AgNPs on the MWCNTs were well spread and evenly distributed on the surfaces of the long nanotubes with well‐graphitised walls as examined by high‐resolution transmission electron microscopy. X‐ray diffraction and transmission electron microscopy were used for sample characterisation. Good dispersion of AgNPs was obtained on the surface of MWCNTs, resulting in an efficient reactivity of the carbon nanotubes surfaces. Finally, the antibacterial activity of AgNPs/MWCNTs hybrid was evaluated against two pathogenic bacteria Pseudomonas aeruginosa and Staphylococcus aureus exhibited excellent activity.Inspec keywords: nanocomposites, X‐ray diffraction, nanofabrication, nanoparticles, transmission electron microscopy, toxicology, silver, antibacterial activity, microorganisms, nanomedicine, multi‐wall carbon nanotubes, electrochemistryOther keywords: engineered nanomaterials, human remedial, pathogenic bacteria modalities, silver nanoparticles, multiwalled carbon nanotubes, modified chemical reaction process, well‐graphitised walls, high‐resolution transmission electron microscopy, cytotoxicity properties, functionalised carbon nanotubes, carbon nanotube surfaces, nanobiotechnology, low‐cost electrochemical method, AgNP‐MWCNT hybrid, X‐ray diffraction, antibacterial activity, Pseudomonas aeruginosa, Staphylococcus aureus, Ag‐C     

Bio‐green synthesis ZnO‐NPs in Brassica napus pollen extract: biosynthesis,antioxidant, cytotoxicity and pro‐apoptotic properties

The bio‐green methods of synthesis nanoparticles (NPs) have advantages over chemo‐physical procedures due to cost‐effective and ecofriendly products. The goal of current investigation is biosynthesis of zinc oxide NPs (ZnO‐NPs) and evaluation of their biological assessment. Water extract of Brassica napus pollen [rapeseed (RP)] prepared and used for the synthesis of ZnO‐NPs and synthesised ZnO‐NP characterised using ultraviolet–visible, X‐ray diffraction, Fourier‐transform infrared spectroscopy, field emission scanning electron microscope and transmission electron microscope. Antioxidant properties of ZnO‐NPs, cytotoxic and pro‐apoptotic potentials of NPs were also evaluated. The results showed that ZnO‐NPs have a hexagonal shape with 26 nm size. ZnO‐NPs synthesised in RP (RP/ZnO‐NPs) exhibited the good antioxidant potential compared with the butylated hydroxyanisole as a positive control. These NPs showed the cytotoxic effects against breast cancer cells (M.D. Anderson‐Metastasis Breast cancer (MDA‐MB)) with IC₅₀ about 1, 6 and 6 μg/ml after 24, 48 and 72 h of exposure, respectively. RP/ZnO‐NPs were found effective in increasing the expression of catalase enzyme, the enzyme involved in antioxidants properties of the cells. Bio‐green synthesised RP/ZnO‐NPs showed antioxidant and cytotoxic properties. The results of the present study support the advantages of using the bio‐green procedure for the synthesis of NPs as an antioxidant and as anti‐cancer agents.Inspec keywords: II‐VI semiconductors, wide band gap semiconductors, ultraviolet spectra, toxicology, X‐ray diffraction, biochemistry, zinc compounds, nanomedicine, enzymes, biomedical materials, particle size, antibacterial activity, transmission electron microscopy, molecular biophysics, visible spectra, nanofabrication, cellular biophysics, nanoparticles, cancer, field emission scanning electron microscopy, Fourier transform infrared spectra, semiconductor growthOther keywords: bio‐green synthesis ZnO‐NPs, zinc oxide NPs, synthesised ZnO‐NP, field emission scanning electron microscope, transmission electron microscope, antioxidant properties, bio‐green synthesised RP‐ZnO‐NPs, Fourier‐transform infrared spectroscopy, X‐ray diffraction, breast cancer cells MDA‐MB, pro‐apoptotic potentials, cytotoxic effects, catalase enzyme, bio‐green procedure, time 48.0 hour, time 72.0 hour, size 26.0 nm, time 24.0 hour, ZnO     

Comprehensive analysis of retroreflection in Papilio crino Fabricius, 1792 wings

Multilayer thin‐film structures in the wings of a butterfly; Papilio crino produce a colourful iridescence from reflected light. In this investigation, scanning electron microscope images show both the concave cover scales and pigmented air‐chamber ground scales. The microstructures with the concavities retroreflect incident light, thus causing the double reflection. This gives rise to both the colour mixing and polarisation conversion clearly depicted in the optical images. The result of the numerical and theoretical analysis via the CIELAB, and optical reflection and transmission of light through the multilayer stacks with the use of transfer method show that the emerging colouration on the Papilio crino is structural and is due to the combination of colours caused by multiple bounces within the concavities. The butterfly wing structure can be used as the template for designing the photonic device.Inspec keywords: bio‐optics, scanning electron microscopy, photodiodes, optical sensors, optical images, light reflection, reflectivity, colour, optical links, multilayers, optical multilayers, light polarisationOther keywords: pigmented air‐chamber ground scales, concavities, incident light, double reflection, colour mixing, polarisation conversion, optical images, numerical analysis, theoretical analysis, optical reflection, multilayer stacks, emerging colouration, butterfly wing structure, papilio crino fabricius, thin‐film structures, colourful iridescence, reflected light, electron microscope images, concave cover scales     

Investigating conformational changes of Prefoldin β1 as result of applying external mechanical force without any position constraint

Manipulating molecular scale bio‐nanorobots and influencing their behaviour is one of the major challenges of new researches. Many coiled coil type proteins are involved in important biological functions due to physical properties that make them ideal for both nanoscale manipulation and sensing. The Prefoldin beta subunit from Thermococcus strain KS‐1(Prefoldin β1) is one of the possible proteins that can serve as a new bio‐nano‐actuator. Besides having a balanced architecture, Prefoldin β1 can exhibit a wide range of exclusive authorities. In this study, steered molecular dynamics simulation is applied along with the centre of mass pulling and analyses of Prefoldin β1 conformational changes to characterise some of those abilities. Thus, applying external mechanical force without any position constraint shows that it has no movement throughout simulations. This proposes a novel method to capture different sizes and shapes of cargoes. During simulations, each arm was found to be very flexible, allowing it to enlarge its central cavity and capture different cargoes. For a more accurate analysis, the variations in the cavity of nano‐actuator are investigated qualitatively and quantitatively with different parameters. Also, the force analysis of the arms can provide us with decent information about the performance of this nano‐actuator.Inspec keywords: nanobiotechnology, proteins, molecular biophysics, microrobots, molecular dynamics method, biological techniquesOther keywords: external mechanical force, coiled coil type proteins, nanoscale manipulation, Thermococcus strain KS‐1, steered molecular dynamics simulation, prefoldin beta subunit, bionanoactuator, prefoldin β1 conformational changes, molecular scale bionanorobots, centre‐of‐mass pulling     

Small‐sized probe for local measuring electrical properties of the tissues inside of human body: design,modelling and simulation

In this study, a new idea is suggested for designing an appropriate bio‐impedance probe in the form of a biopsy forceps to measure the electrical properties of the tissues inside the body. First, by analytically solving the Laplace equation for wedge‐shaped tissue in the mouth of the probe, the relationship between electric potential (results from excitation current) in a different point on the tissue and the electrical properties of the tissue is obtained. Then, to evaluate the designed bio‐impedance probe using the finite element method and the experimental data obtained for different tissues by Gabriel et al., modelling and simulation at different frequencies from 50 Hz to 5 MHz were done. Finally, to evaluate the performance of the designed probe in comparison to other methods, measurements were carried out using three methods for the same tissue. Nyquist curves were drawn and electrical properties extracted for all the three methods. It was found that the designed probe results are close to the actual values with an error of <2%. The main features of the designed probe are small size and non‐invasive measurement.Inspec keywords: Laplace equations, biological tissues, finite element analysis, electric impedance measurement, bioelectric potentials, biomedical measurementOther keywords: noninvasive measurement, local measuring electrical properties, human body, wedge‐shaped tissue, electric potential, finite element method, bio‐impedance probe, small‐sized probe, biopsy forceps, excitation current, Nyquist curves, frequency 50.0 Hz to 5.0 MHz     

Design of dynamic genetic memory

In electronic systems, dynamic random access memory (DRAM) is one of the core modules in the modern silicon computer. As for a bio‐computer, one would need a mechanism for storage of bio‐information named ‘data’, which, in binary logic, has two levels, logical high and logical low, or in the normalised form, ‘1’ and ‘0’. This study proposes a possible genetic DRAM based on the modified electronic configuration, which uses the biological reaction to fulfil an equivalent RC circuit constituting a memory cell. The authors implement fundamental functions of the genetic DRAM by incorporating a genetic toggle switch for data hold. The results of simulation verify that the basic function can be used on a bio‐storage module for the future bio‐computer.Inspec keywords: DRAM chips, genetic engineering, biocomputers, bioinformatics, equivalent circuits, RC circuitsOther keywords: dynamic genetic memory design, electronic systems, dynamic random access memory, modern silicon computer, biocomputer, bioinformation, binary logic, logical high level, logical low level, normalised form, genetic DRAM, modified electronic configuration, biological reaction, equivalent RC circuit, memory cell, fundamental functions, genetic toggle switch, data hold, biostorage module     

Construction of active bio‐nanocomposite by inseminated metal nanoparticles onto activated carbon: probing to antimicrobial activity

The bio‐nanocomposite role in wastewater treatment is a primary concern of this research. The physical, chemical, mechanical stability and antimicrobial activity of these bio‐nanocomposites were investigated. The method is based on the biological reduction of aqueous copper sulphate pentahydrate, lead nitrate, silver nitrate, zinc sulphate heptahydrate salt using seed extract of Eucalyptus globulus as reducing agent at ambient temperature. The synthesised metal nanoparticles (MNPs) were analysed by UV‐visible spectroscopy and Fourier transform infrared spectroscopy analyses. An ex‐situ method involves constructing bio‐nanocomposite by blending MNPs with tea waste activated carbon. Cross‐linking in activated carbon takes place which was confirmed by changes in the mixture of components. The present yield of activated carbon was characterised by scanning electron microscopy and energy dispersive X‐ray measurements. A few micro or nano range, spherical shape of activated carbon was studied by SEM. The main elements found in the activated carbon by EDX are C, O, S, Ag, Cl and Cu. The efficacy of such active bio‐nanocomposite (ABN) tested against human pathogen includes both type of bacteria and fungus. The inhibitory effects of ABN are discernible from the results that reveal biologically inseminated MNPs can be used to clean up the contaminated environment.Inspec keywords: nanocomposites, activated carbon, wastewater treatment, copper compounds, nitrogen compounds, Fourier transform infrared spectra, scanning electron microscopyOther keywords: active bio‐nanocomposite, inseminated metal nanoparticles, activated carbon, antimicrobial activity, wastewater treatment, mechanical stability, biological reduction, aqueous copper sulphate pentahydrate, lead nitrate, silver nitrate, zinc sulphate heptahydrate salt, Eucalyptus globulus, synthesised metal nanoparticle, MNP, UV‐visible spectroscopy, Fourier transform infrared spectroscopy analysis, scanning electron microscopy, energy dispersive X‐ray measurement, SEM     

Electrochemical assessment of the interaction of microbial living cells and carbon nanomaterials

This work considers the effects of various carbon nanomaterials and fibres on bioelectrocatalytic and respiratory activity of bacterial cells during the oxidation of ethanol in the presence of an electron transport mediator. Gluconobacter oxydans sbsp. industrius VKM B‐1280 cells were immobilised on the surfaces of graphite electrodes and had an adsorption contact with a nanomaterial (multi‐walled carbon nanotubes, thermally expanded graphite, highly oriented pyrolytic graphite, graphene oxide, reduced graphene oxide). The electrochemical parameters of the electrodes (the polarisation curves, the value of generated current at the introduction of substrate, the impedance characteristics) were measured in two‐electrode configuration. Modification by multi‐walled carbon nanotubes led to the increase of microbial fuel cell (MFC) electric power by 26%. The charge transfer resistance of modified electrodes was 47% lower than unmodified ones. Thermally expanded and pyrolytic graphites had a slight negative effect on the electrochemical properties of modified electrodes. The respiratory activity of bacterial cells did not change in the presence of nanomaterials. The data can be used in the development of microbial biosensors and MFC electrodes based on Gluconobacter cells.Inspec keywords: nanofabrication, catalysis, microorganisms, adsorption, charge exchange, microbial fuel cells, electrochemical electrodes, graphite, graphene, oxidation, multi‐wall carbon nanotubes, cellular biophysicsOther keywords: reduced graphene oxide, electrochemical parameters, two‐electrode configuration, multiwalled carbon nanotubes, microbial fuel cell, respiratory activity, bacterial cells, microbial biosensors, MFC electrodes, microbial living cells, electron transport mediator, graphite electrodes, adsorption contact, highly oriented pyrolytic graphite, Gluconobacter oxydans sbsp. industrius VKM B‐1280 cells, polarisation curves, bioelectrocatalytic activity, ethanol, thermally expanded graphite, charge transfer resistance, C     

Nucleic acid detection strategy using gold nanoprobe of two diverse origin

In recent years, nanoparticles especially with gold and silver nanoparticles based point of care diagnostic methods is being developed for the lethal diseases like dengue. This study focused to work on the dengue virus detection in a simplest method using gold nanoparticles probe (AuNPs) with thiol tagged single strand DNA (ss‐DNA). A sensitive, fluorescence‐based detection strategy was designed to examine and quantified the hybridisation process and also elucidated the behaviour of AuNPs before and after interaction of biomolecule. The detection process was focused on aggregation of gold nanoprobe in the presence of complementary strand (target region). Hence the percentage of aggregation was measured and as a result, the limit of detection was found to be 10⁻⁶ dilutions. Current detection method was highly sensitive, easy to perform and the reaction timing is rapid between 5 and 10 min, and it can be observed through naked eye.Inspec keywords: patient diagnosis, microorganisms, nanomedicine, gold, fluorescence, nanosensors, DNA, nanoparticles, molecular biophysics, diseases, optical sensorsOther keywords: nucleic acid detection strategy, gold nanoprobe, silver nanoparticles, lethal diseases, dengue virus detection, gold nanoparticles probe, thiol tagged single strand DNA, hybridisation process, detection process, aggregation, complementary strand, current detection method, point‐of‐care diagnostic methods, fluorescence‐based detection strategy, Au     

Facile synthesis of multi‐walled carbon nanotube via folic acid grafted nanoparticle for precise delivery of doxorubicin

The motive of work was to develop a multi‐walled carbon nanoplatform through facile method for transportation of potential anticancer drug doxorubicin (DOX). Folic acid (FA)‐ethylene diamine (EDA) anchored and acid functionalised MWCNTs were covalently grafted with DOX via π–π stacking interaction. The resultant composite was corroborated by ¹ H NMR, FTIR, XRD, EDX, SEM, and DSC study. The drug entrapment efficiency of FA‐conjugated MWCNT was found high and stability study revealed its suitability in biological system. FA‐EDA‐MWCNTs‐DOX conjugate demonstrated a significant in vitro anticancer activity on human breast cancer MCF‐7 cells. MTT study revealed the lesser cytotoxicity of folate‐conjugated MWCNTs. The obtained results demonstrated the targeting specificity of FA‐conjugate via overexpressed folate receptor deemed greater scientific value to overcome multidrug protection during cancer therapy. The proposed strategy is a gentle contribution towards development of biocompatible targeted drug delivery and offers potential to address the current challenges in cancer therapy.Inspec keywords: toxicology, nanoparticles, biomedical materials, scanning electron microscopy, drug delivery systems, nanofabrication, nanomedicine, nanocomposites, cellular biophysics, cancer, drugs, multi‐wall carbon nanotubes, Fourier transform infrared spectra, X‐ray chemical analysis, differential scanning calorimetry, proton magnetic resonance, organic compoundsOther keywords: facile synthesis, multiwalled carbon nanotube, precise delivery, multiwalled carbon nanoplatform, drug entrapment efficiency, FA‐conjugated MWCNT, stability study, biological system, human breast cancer MCF‐7 cells, MTT study, folate‐conjugated MWCNTs, overexpressed folate receptor, cancer therapy, biocompatible targeted drug delivery, anticancer drug doxorubicin, π‐π stacking interaction, composite material, ¹ H NMR, in vitro anticancer activity, folic acid grafted nanoparticle, folic acid‐ethylene diamine, acid functionalised MWCNT, FTIR spectra, XRD, EDX, SEM, FA‐EDA‐MWCNT‐DOX conjugate, cytotoxicity, DSC, C     

Synthesis,characterisation and bactericidal effect of ZnO nanoparticles via chemical and bio‐assisted (Silybum marianum in vitro plantlets and callus extract) methods: a comparative study

Currently, the evolution of green chemistry in the synthesis of nanoparticles (NPs) with the usage of plants has captivated a great response. In this study, in vitro plantlets and callus of Silybum marianum were exploited as a stabilising agent for the synthesis of zinc oxide (ZnO) NPs using zinc acetate and sodium hydroxide as a substitute for chemical method. The contemporary investigation defines the synthesis of ZnO NPs prepared by chemical and bio‐extract‐assisted methods. Characterisation techniques such as X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and energy dispersive X‐ray were used to confirm the synthesis. Although chemical and bio‐assisted methods are suitable choices for NPs synthesis, the bio‐assisted green assembly is advantageous due to superior stability. Moreover, this report describes the antibacterial activity of the synthesised NPs against standard strains of Klebsiella pneumonia and Bacillus subtilis.Inspec keywords: zinc compounds, II‐VI semiconductors, wide band gap semiconductors, nanoparticles, nanofabrication, semiconductor growth, antibacterial activity, X‐ray diffraction, X‐ray chemical analysis, scanning electron microscopy, Fourier transform infrared spectra, nanobiotechnologyOther keywords: chemical methods, bio‐assisted methods, Silybum marianum in vitro plantlets methods, Silybum marianum in vitro callus extract methods, green chemistry, zinc oxide nanoparticles, sodium hydroxide, zinc acetate, X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X‐ray analysis, bio‐assisted green assembly, antibacterial activity, Klebsiella pneumonia, Bacillus subtilis, ZnO     

Multi‐bit Boolean model for chemotactic drift of Escherichia coli

Dynamic biological systems can be modelled to an equivalent modular structure using Boolean networks (BNs) due to their simple construction and relative ease of integration. The chemotaxis network of the bacterium Escherichia coli (E. coli ) is one of the most investigated biological systems. In this study, the authors developed a multi‐bit Boolean approach to model the drifting behaviour of the E. coli chemotaxis system. Their approach, which is slightly different than the conventional BNs, is designed to provide finer resolution to mimic high‐level functional behaviour. Using this approach, they simulated the transient and steady‐state responses of the chemoreceptor sensory module. Furthermore, they estimated the drift velocity under conditions of the exponential nutrient gradient. Their predictions on chemotactic drifting are in good agreement with the experimental measurements under similar input conditions. Taken together, by simulating chemotactic drifting, they propose that multi‐bit Boolean methodology can be used for modelling complex biological networks. Application of the method towards designing bio‐inspired systems such as nano‐bots is discussed.Inspec keywords: cell motility, microorganisms, Boolean functionsOther keywords: multibit Boolean approach, conventional BNs, high‐level functional behaviour, steady‐state responses, chemoreceptor sensory module, drift velocity, chemotactic drifting, multibit Boolean methodology, complex biological networks, bio‐inspired systems, multibit Boolean model, chemotactic drift, dynamic biological systems, equivalent modular structure, Boolean networks, simple construction, chemotaxis network, bacterium Escherichia coli, biological systems     

Characterisation of optically driven microstructures for manipulating single DNA molecules under a fluorescence microscope

Optical tweezers are powerful tools for manipulating single DNA molecules using fluorescence microscopy, particularly in nanotechnology‐based DNA analysis. We previously proposed a manipulation technique using microstructures driven by optical tweezers that allows the handling of single giant DNA molecules of millimetre length that cannot be manipulated by conventional techniques. To further develop this technique, the authors characterised the microstructures quantitatively from the view point of fabrication and efficiency of DNA manipulation under a fluorescence microscope. The success rate and precision of the fabrications were evaluated. The results indicate that the microstructures are obtained in an aqueous solution with a precision ∼50 nm at concentrations in the order of 10⁶ particles/ml. The visibility of these microstructures under a fluorescence microscope was also characterised, along with the elucidation of the fabrication parameters needed to fine tune visibility. Manipulating yeast chromosomal DNA molecules with the microstructures illustrated the relationship between the efficiency of manipulation and the geometrical shape of the microstructure. This report provides the guidelines for designing microstructures used in single DNA molecule analysis based on on‐site DNA manipulation, and is expected to broaden the applications of this technique in the future.Inspec keywords: DNA, molecular biophysics, fluorescence, optical microscopy, radiation pressure, biological techniquesOther keywords: optically driven microstructures, single DNA molecule analysis, fluorescence microscopy, optical tweezers, nanotechnology‐based DNA analysis, manipulation technique, aqueous solution, fine tune visibility, yeast chromosomal DNA molecules, geometrical shape, on‐site DNA manipulation     

CdO nanoparticles,c‐MWCNT nanoparticles and CdO nanoparticles/c‐MWCNT nanocomposite fibres: in vitro assessment of anti‐proliferative and apoptotic studies in HeLa cancer cell line

A simple ultrasonic assisted chemical technique was used to synthesise cadmium oxide (CdO) nanoparticles (NPs) and CdO NPs/c‐Multiwalled carbon nanotube (c‐MWCNT) nanocomposite fibres.To confirm the physio‐chemico properties and to analyse surface morphology of the obtained nanomaterials X‐Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) were performed. To evaluate the anti‐cancer property of CdO NPs, c‐MWCNT NPs and CdO NPs/c‐MWCNT nanocomposite fibres, an anti‐proliferative assay test (Methylthiazolyl diphenyl‐ tetrazolium bromide ‐ MTT assay) were performed on HeLa cells which further estimated IC50 value (Least concentration of sample in which nearly 50% of cells remain alive) under in‐vitro conditions. On comparison, CdONPs/c‐MWCNT based system was found to be superior by achieving 52.3% cell viability with its minimal IC50 value of 31.2 μg/ml. Lastly, the CdO NPs based system was taken up for an apoptotic study using DNA fragmentation assay for estimating its ability to cleave the DNA of the HeLa cells into internucleosomal fragments using the agarose gel electrophoresis method. In conclusion, based on our observations, CdO NPs/c‐MWCNT hybrid based system can be further used for the development of efficient drug delivery and therapeutic systems.Inspec keywords: drug delivery systems, electrophoresis, oxidation, toxicology, DNA, nanoparticles, drugs, field emission electron microscopy, scanning electron microscopy, nanofabrication, surface morphology, cancer, X‐ray diffraction, nanomedicine, cellular biophysics, filled polymers, biomedical materials, molecular biophysics, biochemistry, Fourier transform infrared spectra, multi‐wall carbon nanotubesOther keywords: c‐MWCNT nanoparticles, apoptotic study, HeLa cancer cell line, cadmium oxide nanoparticles, c‐MWCNT NPs, anti‐proliferative assay test [methyl thiazolyl diphenyl‐tetrazolium bromide assay], human epithelioid cervix carcinoma cells, live cells, CdO NP‐based system, IC50 concentration, HeLa cell line, cell deaths, CdO‐C     

Colorimetric‐based detection of Ureaplasma urealyticum using gold nanoparticles

Ureaplasma urealyticum (uu) is one of the most common agents of urogenital infections and is associated with complications such as infertility, spontaneous abortion and other sexually transmitted diseases. Here, a DNA sensor based on oligonucleotide target‐specific gold nanoparticles (AuNPs) was developed, in which the dispersed and aggregated states of oligonucleotide‐functionalised AuNPs were optimised for the colorimetric detection of a polymerase chain reaction (PCR) amplicon of U. urealyticum DNA. A non‐cross‐linking approach utilising a single Au‐nanoprobe specific of the urease gene was utilised and the effect of a PCR product concentration gradient evaluated. Results from both visual and spectral analyses showed that target–Au‐nanoprobe hybrids were stable against aggregation after adding the inducer. Furthermore, when a non‐target PCR product was used, the peak position shifted and salt‐induced aggregation occurred. The assay''s limit of detection of the assay was 10 ng with a dynamic range of 10–60 ng. This procedure provides a rapid, facile and low‐cost detection format, compared to methods currently used for the identification of U. urealyticum.Inspec keywords: patient diagnosis, diseases, enzymes, nanosensors, microorganisms, molecular biophysics, DNA, nanoparticles, aggregation, cellular biophysics, colorimetry, genetics, gold, nanomedicineOther keywords: urogenital infections, infertility, spontaneous abortion, sexually transmitted diseases, DNA sensor, oligonucleotide target‐specific gold nanoparticles, oligonucleotide‐functionalised AuNPs, colorimetric detection, polymerase chain reaction amplicon, noncross‐linking approach, single Au‐nanoprobe specific, urease gene, visual analyses, spectral analyses, target–Au‐nanoprobe hybrids, nontarget PCR product, salt‐induced aggregation, rapid cost detection format, facile cost detection format, low‐cost detection format, PCR product concentration, Ureaplasma urealyticum DNA, Au     

Effect of solution pH and adsorbent concentration on the sensing parameters of TGN‐based electrochemical sensor

The response of trilayer graphene nanoribbon (TGN)‐based ion‐sensitive field‐effect transistor (ISFET) to different pH solutions and adsorption effect on the sensing parameters are analytically studied in this research. The authors propose a TGN‐based sensor to electrochemically detect pH. To this end, absorption effect on the sensing area in the form of carrier concentration, carrier velocity, and conductance variations are investigated. Also, the caused electrical response on TGN as a detection element is analytically proposed, in which significant current decrease of the sensor is observed after exposure to high pH values. In order to verify the accuracy of the model, it is compared with recent reports on pH sensors. The TGN‐based pH sensor exposes higher current compared to that of carbon nanotube (CNT) counterpart for analogous ambient conditions. While, the comparative results demonstrate that the conductance of proposed model is lower than that of monolayer graphene‐counterpart for equivalent pH values. The results confirm that the conductance of the sensor is decreased and V_g‐min is obviously right‐shifted by increasing value of pH. The authors demonstrate that although there is not the experimental evidence reported in the part of literature for TGN sensor, but the model can assist in comprehending experiments involving nanoscale pH sensors.Inspec keywords: adsorption, graphene, ion sensitive field effect transistors, nanoribbons, electrochemical sensors, pH measurement, nanosensors, absorptionOther keywords: adsorbent concentration, TGN‐based electrochemical sensor, trilayer graphene nanoribbon‐based ion‐sensitive field‐effect transistor, adsorption effect, carbon nanotube counterpart, monolayer graphene‐counterpart, nanoscale pH sensors, pH solution effect, TGN‐based pH sensor, ISFET, CNT, C