Current Nanomaterials - Volume 2, Issue 2, 2017

Background/Objective: The significance of protein and peptide use as therapeutic agents in parallel with conventional drugs has long been established with the use of insulin, growth hormones and antibiotics for treatment of diseases. Method: Proteins and peptides offer high specificity, precise function and low immune response from the body. These therapeutic molecules are administered via intravenous and subcutaneous injection, oral administration and nasal inhalation. However, their macromolecular size and high susceptibility to degradation in the body when administered hamper their effective delivery and action. Nanoencapsulation of proteins and peptides is an attractive strategy to improve the stability of proteins and peptides and maintain activity at the target site. Results: Encapsulation into nanoparticles ensures that the proteins and peptides are more stable, bioavailable and more effective due to sustained release and targeted delivery; the smaller size equals larger surface area to volume ratio allows for better absorption in the intestinal lumen. However, challenges are still present in formulating nanoparticles with desired physicochemical properties for their effective action and sustained release. Conclusion: The need for case- by case formulation of protein/ peptide, limitations in the available methods for fabrication, characterization and analysis of the nanoparticles, as well as difficulty in translating lab- scale research into commercial stage are the current problems that need to be addressed. Furthermore, it is important to assess that nanoparticle formulations are commercially sustainable next to free form drugs. Many gaps need to be filled in understanding the nature of proteins and peptides, their fabrication into nanoparticles, and successful translation into clinical products. Continued focus into research in these areas is the way forward for the future of protein and peptide delivery.

Background: Due to excellent properties such as degradability, high strength, and biocompatibility, polylactic acid (PLA) has received enormous attention recently as a promising potential candidate material to replace petroleum-based polymers. However, PLA shows high brittleness as well as low toughness which may limit its application. Objective: In this work, PLA was melt blended with thermoplastic polyurethane (TPU) and then filled with carbon nanotubes (CNTs) to produce environmentally friendly polymeric materials with improved mechanical properties. Method: The specimens were prepared by using an internal mixer, followed by compression molding. Morphology of the matrix and particles dispersion state in the composite was investigated by using Scanning Electron Microscopy (SEM), while mechanical properties were evaluated via impact and tensile tests. Results: Observation from SEM's micrograph showed that two distinct phases were present in the blend, with selective localization of CNTs at one of the phases in the system. Thermodynamic calculation using Owen and Wendt's equation predicted that the CNTs were preferably dispersed at TPU phase. As CNTs content increased, the toughness of TPU/CNT and TPU/PLA/CNT composites increased whereas the toughness of PLA/CNT composite decreased, that might be ascribed to the phenomenon of selective localization of the CNTs. Other than that, the elongation at break of PLA/CNT, PLA/TPU/CNT and TPU/CNT also increased with the addition of CNT. The incorporation of TPU in the TPU/PLA blends also imparted ductility to the blends. Conclusion: In conclusion, the selective localization prediction is in line with the trends observed in mechanical properties of PLA/TPU/MWCNT composites.

Background: Powder mixed dielectric fluid is being used recently to cut difficult to cut ceramic materials such as aluminium oxide (Al2O3) and zirconium oxide (ZrO2) where process development and optimization are found to be critical issues. Objective: This paper investigates and compares the average surface roughness (Ra) in micro Electrical Discharge Machining (EDM) of electrically nonconductive zirconium oxide (ZrO2) ceramic using clean and tantalum carbide (TaC) nano powder mixed kerosene dielectric fluid. Method: The design of experiment was applied by response surface methodology with face centred composite design. The gap voltage, capacitance and concentration of TaC powder are considered as the variable parameters for the investigation while other conditions are kept constant. Results: The study shows that the powder concentration has a significant negative effect on the average surface roughness of ZrO2. Conclusion: The optimized values of gap voltage and powder concentration are found to be 100 pF, 94.4 V and 6.3 g/l, respectively for a minimum surface roughness in micro-EDM of ZrO2. Without powder introduction, a minimum Ra surface roughness of 170 nm achieves 100 pF and 81 V.

Background: It is known that wastewater from textile industries are responsible for producing large amounts of highly contaminated effluents by various types of synthetic dyes. These compounds can be toxic, and in some cases, are carcinogenic and mutagenic and its removal is recommended. Application: In the area of water purification, nanomaterials have been applied for removal of several compounds. Of the four classes of nanomaterials, zeolites have demonstrated good results for the removal of dyes. Nanozeolite synthesized from bottom ash and modified with hexadecyltrimethylamonium (ZMB) was used as adsorbent to removal of Solophenyl Navy (SN), Solophenyl Turquoise (ST) and their hydrolyzed forms (SNH and STH, respectively) from simulated textile wastewater. Method: The physical-chemical characterization of materials was presented by using relevant analytical methods (XRD, SEM, BET surface area, etc.). Effects of parameters such as initial dye concentration, contact time and equilibrium adsorption were evaluated. The adsorption kinetics followed the pseudo-second-order model. Results: Langmuir isotherm model shows the best fit for most dyes-ZMB systems. In order to identify if ZMB presented toxicity for the environment, bioassay and toxicity identification evaluation (TIE) with C. dubia were performed. The leached of ZMB was toxic to daphinids (11.3 TU). Conclusion: TIE results appointed that the main cause of the toxicity could be due the surfactant and metal ions presents in aqueous solution.

Objective: Explore ways to create open and closed cages with graphene nanoparticles (GNPs) by appropriately placing hydrogen atoms on their surfaces. Method: Density Functional Theory (DFT) have been used for geometry optimization of the GNPs. Results: The controllable release of hydrogen and methane entrapped inside the open nanocages have been studied by adjusting the temperature with ab initio molecular dynamic. Conclusion: New type of open cages has been found with seashell-like geometries and partially open cages with a tongue-like structure.

Background: This manuscript deals with identifying the fracture pattern in defective Double Walled Carbon Nanotubes (DWCNT). It has been projected in a number of published papers that CNTs always possess defects like vacancies in their structure, hence this type of analysis is helpful in studying the pattern of fracture when subjected to tensile and other types of forces. Method: Molecular structural mechanics approach is used to model the defective DWCNT and finite element method is used to simulate the responses of the non-linear force field of the C–C bonds for analysing the systematic fracture in double walled carbon nanotube structure with beam elements. The model has been studied with reference to arm chair and zigzag DWCNTs with an atomic vacancy and exposed to critical tension. The defect presented here (model) is one lacking atom at the outer tube of the double walled carbon nanotube. Results: The failure pattern is found to be different in all the two types of DWCNTs mainly because of the orientation of the covalent bond between carbon - carbon atoms. This orientation further leads to the change in the stiffness of the bonds which further leads to increase in the stress at the junction and later on failure of the tube. The type of pattern evaluated in this manuscript has not been studied previously in DWCNTs. Conclusion: Catastrophic failure took place after fifteen consecutive iterations, for zigzag and armchair of DWCNT. It shows that Zigzag DWCNT ((14,0)@(8,0)) has better strength compared to Arm chair DWCNT ((8,8)@(6,6)).

Objective: An eco-friendly, cost-effective mosquito larvicidal and antimicrobial silver nanoparticle was produced from Wrightia tinctoria leaves. Method: The green route synthesis of silver nanoparticles using aqueous and methanol extract of W. tinctoria leaves and synthesized AgNPs were characterized by UV-Vis, FT-IR, EDAX, XRD and SEM. The antimicrobial potentials of AgNPs using well diffusion method against human bacterial pathogens and mosquito larvicidal activity were also observed on treatment with AgNPs using mortality test and FT-IR spectral studies. Results: The maximum absorbance was observed between 400 nm to 480 nm for the synthesized AgNPs, the synthesized AgNPs were spherical shaped with size ranging between 50-90 nm. The EDAX spectrum clearly showed a strong peak for silver at 3 keV. The AgNPs showed antibacterial potential against clinical pathogens such as Escherichia coli, Pseudomonas aeruginosa, Pseudomonas fluorescens, Proteus vulgaris and Staphylococcus aureus and inhibited the mosquito larval growth as parricidal agent. Thus an eco-friendly and cost-effective production of antimicrobial and parricidal AgNPs from W. tinctoria leaves will enable biocontrol of mosquitoes.