Nanoscience & Nanotechnology-Asia - Volume 9, Issue 4, 2019

Background: Tissue engineering is a highly evolving field in periodontology which incorporates the use of cells, signalling molecules and scaffolds thereby creating a three dimensional microenvironment facilitating cellular growth and function for restoration of lost tissues due to periodontal disease. This review discusses the various types, ideal characteristics, properties and applications of potential scaffolds that can be used in periodontal regeneration with the help of principles of tissue engineering. Methods: Research work pertaining to bioscaffolds for periodontal regeneration were selected using key words in major databases and internet sources. Results: Studies related to various features of scaffold and its inherent properties were searched and analysed. Data were organized considering the sources of its origin and salient features of these inert matrices. Specific probe into the techniques and medium used for developing scaffolds were cited. Further, bioactive ceramic materials which are involved in stimulating cell proliferation, and bone tissue regeneration, which may also facilitate periodontal regeneration were mentioned. Likewise, few data linked to different types of biodegradable synthetic scaffolds and its advantages were considered. The progress of science in various fabrication techniques and newer advances using modern technology such as tissue engineering approaches, 3D printing and physical chemical methods to enhance the physical properties are being used to make them more versatile for the application in the field of biomedical science. Conclusion: In lieu of the available literature search and vast progress in material science, scaffolds construction for cellular regeneration requires wide exploration. Furthermore, when these scaffolds are placed at a particular site, it should be able to restore lost periodontal tissue. Also, the newer innovative technologies like the 3D version of biomimicking, nano/micro-based scaffolds displays potential for further extensive research and complete regeneration of periodontal tissues.

Introduction: Nanotechnology is a branch of nanosciences which includes the manipulation of particles at their atomic level in order to obtain certain desirable properties that enhance their use in the treatment of various metabolic disorders as well as other life-threatening diseases including cancer. Photosynthesized nanoparticles are eco-friendly, reliable and cost-effective. This biogenic route of nanoparticles synthesis is emerging as a beneficial method as plants contain diverse bioactive phytochemicals which act as reducing and capping agent thus, increase the stability and reduction rate of nanoparticles. The most commonly used nanoparticles are of silver, gold, iron oxides and copper. In few studies, bimetallic nanoparticles have been reported to have anti-cancer potential. The use of medicinal plants for the purpose of designing nanoparticles has paved a way for targeting a drug to the particular affected site of the tumor. Conclusion: This review focuses on the anti-cancerous potential of nanoparticles of different metals using a variety of medicinal plants. These biogenic nanoparticles could limit the use of chemotherapy and radiation therapy, as these therapies have huge side effects which cannot be tolerated by the cancer patients, and in many cases, the patients die because of these treatments. Hence nanoparticles mediated therapy is now gaining attention for the treatment of cancer as targeted drug therapy, without having undesirable side effects.

Ion transport in the solid state has been regarded as imperative with regards to high energy density electrochemical storage devices (for instance, batteries) for efficient electric mobility. Of late, there is another niche application involving ion transport in solid state which manifested itself as nonvolatile memory namely memristor. Such memories are classified under the emerging category of novel solid state Resistive Random Access Memories (RRAM). In 2008, HP labs unveiled the first practical memristor device employing TiO2 and non-stoichiometric titania as bilayer stack structure and on both sides of two titania layers platinum (pt) are used as blocking electrode for ions. It is understood that switching fundamentals are correlated to the filamentary conduction in metal oxide memristors owing to the formation and rupture of the filament-like nano-dendrites, one of the key mechanisms widely accepted in the arena of memristor analysis. This paper critically reviews the fundamental materials being employed in novel memristor memories. It is believed that solid electrolytes (fast ion conductors) are the fundamental building blocks of these memories. We have chosen a few archetypes, solid electrolytes are considered and their impact on the state-of-art research in this domain is discussed in detail. An indepth analysis of the fundamentals of resistive switching mechanism involved in various classes of memristive devices viz., Electrochemical Metallization Memories (ECM) and Valence Change Memories (VCM) is elucidated. A few important applications of memristors such as neuristor and artificial synapse in neuromorphic computing are reviewed as well.

Introduction: Cell separation is one of the important steps of purification in downstream processes. Some separation techniques such as centrifugation and filtration are expensive and would affect cell viability. Magnetic separation can be a good alternative for laboratory and industrial cell separation processes. Methods: For this purpose, L-lysine coated Iron Oxide Nanoparticles (IONs) were synthesized and used for magnetic separation of Escherichia coli as the most applied microbial cell in biotechnological processes. Results: IONs have successfully decorated the bacterial cells and cells were completely separated by applying an external magnetic field. Conclusion: This study showed that coating of E. coli cells with IONs could help to isolate cells from culture media without using expensive instruments.

Introduction: By using Cu(NO3)2 as precursor and polyvinylpyrrolidone (PVP) as surfactant, nanosheets of Cu2(OH)3NO3, nanowires of Cu(OH)2 or the mixture of the two were prepared under different molar ratios of OH− to Cu2+. Materials and Methods: The crystal structures and morphologies of the products were characterized by X-Ray Diffraction (XRD) and Transmission Electron Microscope (TEM). Results: When the molar ratio of OH− to Cu2+ in reaction solution is lower than 1.28, pure Cu2(OH)3NO3 nanosheets were obtained. The thickness of one piece of nanosheet is about 167 nm. The Cu2(OH)3NO3 nanosheets consists of two types of crystal structures, monoclinic phase and orthorhombic phase. With increase of the molar ratio of OH− to Cu2+, the monoclinic phase of Cu2(OH)3NO3 was transferred to the orthorhombic phase of Cu2(OH)3NO3. When the molar ratio of OH− to Cu2+ is within 1.28-2.24, the product is the mixture of Cu2(OH)3NO3 nanosheets and Cu(OH)2 nanowires. And when this molar ratio is higher than 2.24, only Cu(OH)2 nanowires were produced. The lengths and the diameters of the Cu(OH)2 nanowires are in the region of 50-250 nm and 10 nm, respectively. Conclusion: The reason of the Cu2(OH)3NO3 nanosheets changing into the Cu(OH)2 nanowires is that the OH− anions replace the NO3 − anions in the layered Cu2(OH)3NO3 nanosheets, which causes the rupture of hydrogen bonds connecting the adjacent layers. The Cu(OH)2 nanowires were not stable and found to become spindled CuO nanosheets in air at room temperature.

Background: Owing to their remarkable chemical, physical and biological properties, silver nanoparticles have been widely used in water purification, electronics, bio-sensing, clothing, food industry, paint and medical devices. Various approaches, such as using harsh reducing and stabilising agents for reverse micelle and thermal decomposition, were proposed for silver nanoparticle production. However, these methods are not eco-friendly. Thus, the aim of this paper is to synthesise silver nanoparticles through a cost-effective and environmentally friendly approach. Materials and Methods: A green approach was presented for the synthesis of silver nanoparticles. This approach involved the treatment of silver nitrate and hibiscus leaf extract, which acts as reducing and capping agent. The synthesis was performed at room temperature. The resulting silver nanoparticles were characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and Fourier transform infrared (FTIR) spectroscopy. Results: Spherical, rod-like, hexagonal and triangular silver nanoparticles were obtained through the proposed synthesis method. The crystalline nature of each nanoparticle was revealed by XRD and selected area electron diffraction (SAED). The average spherical size of the silver nanoparticles produced in this route was 44.3 nm. The obtained FTIR band at 1622 cm-1 corresponded to the C=O stretch in the amine I group, which is commonly found in protein. Thus, the protein was believed to serve as capping agent that was responsible for the stabilisation of silver nanoparticles. Conclusion: In conclusion, silver nanoparticles had been successfully synthesised using hibiscus leaf extract and a plausible formation mechanism of silver nanoparticles was proposed.

Introduction: Today, nano-composite gels based on multi-walled carbon nanotubes in room temperature ionic liquid (MWCNTs-IL-Gel) are an interesting subject. Materials and Methods: The nano-composite gels showed convenient electrochemical properties against redox activities of electroactive biomolecules. Also, the evaluation of hemoglobin concentration is a critical point in the clinical sample. So, the kind of nano-composite gel which is composed of NH2 functionalized MWCNTs and [amim] Br IL and anthraquinone 2-carboxilic acid (AQ) was fabricated and applied in electrochemical detection of hemoglobin. Cyclic voltammograms of NH2.MWCNTs-IL-AQ modified electrode exhibited redox peak sat -0.5 V (vs. Ag/AgCl) in 0.1 M phosphate buffer solution ((pH 7.0). Results: As the hemoglobin added into the measured solution, the redox current decreased. Conclusion: It can be concluded that the increment in the concentration of hemoglobin caused the decrease in the redox currents in cyclic voltammetry. The NH2.MWCNTs-IL-AQ would detect the concentration of hemoglobin from 1.64 x10−8 to 4.89x10−7 M.

Introduction: Intrinsic resistive switching properties of Pt/TiO2-x/TiO2/Pt crossbar memory array has been examined using the crossbar (4×4) arrays fabricated by using DC/RF sputtering under specific conditions at room temperature. Materials and Methods: The growth of filament is envisaged from bottom electrode (BE) towards the top electrode (TE) by forming conducting nano-filaments across TiO2/TiO2-x bilayer stack. Non-linear pinched hysteresis curve (a signature of memristor) is evident from I-V plot measured using Pt/TiO2-x /TiO2/Pt bilayer device (a single cell amongst the 4×4 array is used). It is found that the observed I-V profile shows two distinguishable regions of switching symmetrically in both SET and RESET cycle. Distinguishable potential profiles are evident from I-V curve; in which region-1 relates to the electroformation prior to switching and region-2 shows the switching to ON state (LRS). It is observed that upon reversing the polarity, bipolar switching (set and reset) is evident from the facile symmetric pinched hysteresis profile. Obtaining such a facile switching is attributed to the desired composition of Titania layers i.e. the rutile TiO2 (stoichiometric) as the first layer obtained via controlled post annealing (650oC/1h) process onto which TiO2-x (anatase) is formed (350oC/1h). Results: These controlled processes adapted during the fabrication step help manipulate the desired potential barrier between metal (Pt) and TiO2 interface. Interestingly, this controlled process variation is found to be crucial for measuring the switching characteristics expected in Titania based memristor. In order to ensure the formation of rutile and anatase phases, XPS, XRD and HRSEM analyses have been carried out. Conclusion: Finally, the reliability of bilayer memristive structure is investigated by monitoring the retention (104 s) and endurance tests which ensured the reproducibility over 10,000 cycles.

Background: In this article the Boundary layer flow and Cattaneo-Christov Heat flux of nonlinear stretching sheet in a suspended carbon nanotube is analyzed. Methods: The governing classical PDE’s are changing into ODE’s using the similarity transformation method. This boundary value problem is solved by using numerical method known as Runge-Kutta fourth order method with effective shooting technique. Presently in this analysis , the flow, velocity and heat transfer characteristics for different heat transferphysical parameters such as nanofluid (#149;), suction parameter (N>0), heat flux parameter (β) and Prandtl number (Pr) are studied for two cases i.e., single Wall Carbon Nanotube (SWCNT) and Multiwall Carbon Nanotube (MWCNT) respectively. Results: Our results are in good agreement within a limiting condition comparing with previously published results. This study signifies that practical applications in science and engineering fields for example in functional ceramics, nano metals for energy and environmental applications. Conclusion: A theoretical study of boundary layer flow and Catteneo-Christove heat flux is carried out. In this study some of the important findings are collected as follows: 1. The result of nanoparticle volume fraction f and suction parameter N shows that, as increasing f it increases the flow, velocity and temperature while as increasing N which increases the flow and temperature but decreases the velocity at boundary layer. 2. A comparison result is plotted which is an excellent agreement with previously published results. 3. As increasing the Prandtl number and relaxation time of heat flux parameter in the thermal boundary layer which decreases the temperature of thermal boundary layer. 4. Effect of relaxation time of heat flux is same for both local skin friction and local nusselt number i.e. increasing.

Introduction: A new analytical model is designed for Workfunction Modulated Rectangular Recessed Channel-Silicon On Insulator (WMRRC-SOI) MOSFET that considers the concept of groove gate and implements an idea of workfunction engineering. Methods: The impact of Negative Junction Depth (NJD) and oxide thickness (tox) are analyzed on device performances such as Sub-threshold Slope (SS), Drain Induced Barrier Lowering (DIBL) and threshold voltage. Results: The results of the proposed work are evaluated with the Rectangular Recessed Channel-Silicon On Insulator (RRC-SOI) MOSFET keeping the metal workfunction constant throughout the gate region. Furthermore, an analytical model is developed using 2D Poisson’s equation and threshold voltage is estimated in terms of minimum surface potential. Conclusion: In this work, the impact of Negative Junction Depth (NJD) on minimum surface potential and the drain current are also evaluated. It is observed from the analysis that the analog switching performance of WMRRC-SOI MOSFET surpasses RRC-SOI MOSFET in terms of better driving capability, high Ion/Ioff ratio, minimized Short Channel Effects (SCEs) and hot carrier immunity. Results are simulated using 2D Sentaurus TCAD simulator for validation of the proposed structure.

Introduction: Cancer is one of the current leading cause of death all over the world. Among the various emerging technologies, nanotechnology plays a prominent role in delivering the drug to the target region. Materials and Methods: In this study, the In vitro effect of doxorubicin adsorbed gold nanoparticles synthesized by Azadirachta Indica leaves extract as reducing agent and the doxorubicin entrapped modified liposomes called transfersomes was compared over the cervical cancer cell line (HeLa cell lines). The synthesized gold nanoparticles were characterized using a UV-visible spectrophotometer, SEM analysis. Results: The UV-Visible spectrum showed the peak at 537nm and the incorporation of drug over the nanoparticles was conformed using FTIR and SEM analysis. The drug entrapment onto transfersomes was also characterized using FTIR and SEM analysis. When compared, the drug entrapped transfersomes shows significant effect with the lowest concentration of drug (0.25 μg/mL) than the drug adsorbed nanoparticles. Conclusion: Hence, the transfersomes may also become the promising drug carrier in the future.