Nanoscience & Nanotechnology-Asia - Volume 11, Issue 4, 2021

Background: Obesity has been a serious health issue over the last decades, both in the affluent western world and developing countries. Obesity is linked to major health complications, such as diabetes, cardiac disorder, cancer, hypertension, sleep apnoea, etc. Available treatments, such as bariatric surgery and pharmacotherapy are often accompanied by adverse side effects and poor patient compliance. Nanotechnology is a discipline that is concerned with material characteristics at the nanoscale, and offers novel techniques for disease detection, management, and prevention. Objectives: Recent progress in the field of obesity research at its interface with nanotechnology is the main focus of this study. Nanomedicine has greatly enhanced the health status of the people suffering from obesity as it provides non-obtrusive techniques for the management and treatment of obesity. Methods: Literature survey was performed using PubMed, Science Direct, and Web of Science search engines with- terms nanotechnology, nanomedicine and obesity. The research focused primarily on articles published between the years 2000 and 2019. Results: Original and innovative approaches in the developments of nano-technology based drug delivery strategies have been described. Nanotechnology has been widely proposed to combine herbal medicine for the treatment of obesity, because nano-structured systems might be able to potentiate the action of plant extracts, reducing the required dose and side effects, and improving activity. This will offer a wide era of treatment options, which will directly improve the patient’s compliance. Conclusion: This review surveys recent developments of nanotechnology-­128;based drug delivery strategies, which are highlighted and discussed for obesity treatment with an emphasis on the enhanced therapeutic efficiency and minimized side effects. The insights for future development related to the management of obesity have also been discussed.

The biological applications of nanoparticles have been rapidly advancing in the field of cancer detection and its treatment. Many drug delivery systems have been developed and some are still developing based on the concept of nanotechnology for cancer diagnosis. These unique systems have the potential to diagnose, treat and reduce the chances of cancer. Some captivating fields with many applications have been developed when nanotechnology is combined with biotechnology. In this review, many systems have been described, which are based on nanotechnology used to treat cancer. Carbon nanotubes, aptamer, polymersomes, dendrimers, nanoshells and many more have been described in this review. Cancers like brain cancer, lung cancer and breast cancer have been explained with their method of treatment. The review also focuses on the advantage of the different types of systems based on nanoparticles with their application in the treatment of cancer.

Metal nanoparticular synthesis techniques essentially involve a reduction of metal ions to convert them into nanoparticles. Reducing agents originate from natural and synthetic sources. Chemical methods involve the application of synthetic agents that are not healthy and eco-friendly and thus, there is a need for green methods. Green synthesis methods involve the reduction of metal ions using plant-based extracts or phytoconstituents and microorganisms like bacteria, yeast, and fungi. These methods have been found to be cost-effective, more efficient and eliminate the application of hazardous chemicals. The phytoconstituents involved in the synthesis of metal nanoparticles are rich in polyols and antioxidants, which in addition to reducing properties, also offer stabilization of formed nanoparticles. Moreover, the size of nanoparticles can also be controlled based on the mechanism of reducing agent involved therein. The present review is an attempt to highlight the methods of synthesis of metallic nanoparticles with a special mention of applications of various natural antioxidants in their synthesis.

Background: In this paper, transient two-dimensional laminar boundary layer viscous incompressible free convective flow of water based nanofluid with carbon nanotubes (CNTs) past a moving vertical cylinder with variable surface temperature is studied numerically in the presence of thermal radiation and heat generation. Methods: The prevailing partial differential equations which model the flow with initial and boundary conditions are solved by implicit finite difference method of Crank Nicolson type, which is unconditionally stable and convergent. Results: Influence of Grashof number (Gr), nanoparticle volume fraction (), heat generation parameter (Q), temperature exponent (m), radiation parameter (N) and time (t) on velocity and temperature profiles are sketched graphically and elaborated comprehensively. Conclusion: Analysis of Nusselt number and Skin friction coefficient is also discussed numerically for both single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs).

Background: Conventional chemical fertilizers enhance agricultural output but deteriorate soil quality and fertility while causation of health and environmental issues. Therefore, the continual use of chemical fertilizers is not sustainable. Control release nanofertilizer is one of the solutions to said issues. Nanofertilizers use metallic nanoparticles and toxic cross-linkers (e.g. Glutaraldehyde, Glyoxal and Methacrylic Acid), which also pose risks to health and the environment. Synthetic, nonbiodegradable costly raw material based nanofertilizers will also create new-generation-waste in the future, which is not sustainable. Objective: Development of an environment-friendly nanofertilizer for prolonged control release of plant macronutrients-Nitrogen, Phosphorous and Potassium (NPK). Methods: Chitosan was obtained from the deacetylation of chitin, which was extracted from the shrimp exoskeleton. Micro/nanoparticles of chitosan were synthesized with the ionotropic gelation method, excluding toxic cross-linkers. Macronutrient loaded nanoparticles were impregnated to micro and nanopores in activated coir fiber followed by coating with a natural exudate water diffusional barrier. Macronutrient release behaviour and efficacy of control release fertilizer were studied against conventional bulk fertilizer. Results: Mean size of nanoparticles was 100 nm. FTIR analysis showed the macronutrient interaction with micro/nanoparticles of chitosan. Macronutrients were incorporated into nanoparticles at 12% loading efficiency and 20% entrapment efficiency. The developed fertilizer showed control release of macronutrients even beyond 90 days, whereas commercial fertilizer showed an initial burst lasting a negligible release after 30 days. Results from pot trials indicated that nanofertilizer enhances the yield performance of rice plants against commercial fertilizer. Conclusion: A green nanofertilizer can be developed with a simple method using biocompatible, biodegradable, non-toxic and renewable natural based raw materials to prolong the control release of plant macronutrients excluding toxic chemicals. Since the starting materials are coir fiber and shrimp exoskeleton, which is a waste, it could significantly reduce the production cost hence present study discloses an economically sound, environment-friendly and socially responsible nanofertilizer.

Background: Cyanide is an immensely poisonous chemical that is exceedingly noxious to the human body. Methods: Considering this issue, we present a Rectangular core photonic crystal fiber (RPCF) to detect the cyanide. Zeonex is chosen as base material and the investigation is accomplished in the terahertz (THz) frequency region. Results: The RPCF model proffers high sensitivity, enlarged effective area, and insignificant confinement loss. Conclusion: It is very worthy to note that the proposed model structure can be fabricated by applying the existing fabrication techniques.

Objective: A facile, effectively and environmentally friendly method for preparation of well dispersed silver nanoparticles was reported. Methods: In the method, Capsicum annuum L. extract was used as both reducing and stabilizing agent without addition of any other reducing and capping agent. The generation of silver nanoparticles was found by alteration of color from light yellow to red and the UV-vis absorption spectroscopy. The effect of extract and silver nitrate amounts on the formation of silver nanoparticles was investigated. Results: The shape of the as obtained silver nanoparticles was determined by using TEM and SEM, which illustrated that the silver nanoparticles are global in shape with a narrowly distribution from 5 nm to 25 nm. Conclusion: The crystalline structure of the silver nanoparticles was examined by XRD and FT-IR analysis, which showed that the silver nanoparticles were highly crystalline of nature and coated with biomolecule.

Background: In recent years, the green synthesis of nanoparticles has taken a lead role over the conventional chemical and physical approach due to its non-toxic, cost-effective parameters and has found its place in various applications. Objectives: The major objectives of this study were to synthesise and characterise the copper nanoparticles using the rose extract at different set of conditions and analyse these nanoparticles as a source of dye degradation agent under sunlight. Methods: Present study was conducted with the aim to synthesize the copper nanoparticle using the rose petal extract. The components present in the extract act as the reduction and stabilization agents for the synthesis of CuNPs. The synthesized nanoparticles were characterized by using UVVIS, FTIR, XRD and SEM analysis. Photocatalytic degradation of two dyes (Malachite Green and Carbol fuchsin) was analysed using double beam spectroscopic analysis. Results: UV-Vis analysis indicated the presence of a peak at around 630 nm. The FT-IR analysis indicated the involvement of various biomolecules during the synthesis of nanoparticles. The structure and the conformation were elucidated using XRD and SEM showed the agglomerated form of the synthesized nanoparticles with the size range of about 60-90 nm. The synthesised copper nanoparticles were used for the degradation of malachite green and carbol fuchsin dye using photocatalytic under sunlight irradiation. UV-Vis spectral analysis indicated that synthesised copper nanoparticle act more effective in degradation of malachite green (around 95%) whereas carbol fuchsin showed a maximum degradation by 52% therefore suggesting that CuNPs act as an efficient photocatalyst in dye degradation. Conclusion: The results obtained from this study indicate that rose extract has the potential of synthesis of copper nanoparticles which is non-toxic and convenient approach as compared to physical and chemical synthesis. These nanoparticles can be effectively employed as dye decolourisation agents to treat industrial effluent and prevent environmental pollution.

Background: The synthesis of Metal Nanoparticles is a growing area of research interest due to its potential in the applications and development of advanced technologies. Here, we have stressed the Facile green synthesis approach that connects nanotechnology with biotechnology. Methods: The method involves the use of a biological reducing agent cum stabilizing agent (capping agent). A comparative account of particle dimension and surface properties of the synthesized Nanoparticles using Broccoli (Brassicaoleracea var. italica) extract is also presented. Results: The reduction process used in the synthesis was simple and convenient to handle and monitored by UV-vis spectroscopy showing the absorbance maxima of various samples at 322 nm, 496 nm, and 536 nm using different solvents. The presence of active proteins and phenolic groups present in biomass before and after reduction was identified by FT-IR. Conclusion: The crystalline morphology and size of the nanoparticles were examined by TEM, SEM, and X-ray diffraction studies, which showed the average particle size of Silver Nanoparticles in the range of 40-50 nm, as well as revealed their FCC structure.

Background: Lysozyme level in body fluids is a significant indicator of various diseases. Cheap and simple colorimetric detection of lysozyme, in biological sample, by gold and silver nanoparticles is a field of interest of nanoparticle research for more than a decade. Objective: We report here an attempt to improve the sensitivity part of the colorimetric lysozyme detection process by using citrate capped gold-silver core-shell nanoparticles without any functionalization. Methods: Performance of gold-silver core-shell nanoparticles in determining of lysozyme concentration in water is done using colorimetric/spectroscopic technique. Gold nanoparticles, silver nanoparticles and mixed colloidal suspension of gold and silver nanoparticles, for comparison have also been studied. Selectivity study has been performed through spectroscopic analysis, red-greenblue colour component analysis and fractal dimension analysis of the nanoparticles interacted with several low and high isoelectric point proteins. Results: Gold-silver core-shell nanoparticles showed higher sensitivity for a wider range of lysozyme concentration compared to gold and silver nanoparticles prepared by us or reported in literature. Gold nanoparticles showed higher sensitivity compared to the core-shell nanoparticles, but for a narrow concentration range of lysozyme. For silver nanoparticles and the mixed nanoparticle system, both sensitivity and range of determination of lysozyme concentration were much smaller compared to the core-shell nanoparticles. Core-shell nanoparticles showed better selectivity compared to gold nanoparticles in identifying aquatic solution of lysozyme from that of other proteins. Conclusion: Gold-silver core-shell nanoparticles have higher sensitivity in determining wide range of lysozyme concentration in water compared to gold and silver nanoparticles reported in literature.

Introduction: This paper demonstrates the design of a sensor model for the detection of Sodium Chloride (NaCl) in an effective and efficient manner. Photonic Crystal Fiber (PCF) has been used to design this sensor model. Objective: Using Comsol Multiphysics software, the sensor model has been implemented and simulated to carry out an in-depth analysis of the sensing performance of the proposed model. Methods: The confinement loss, effective material loss, effective area, birefringence, and relative sensitivity were analyzed to estimate the sensing efficiency of this model. The sensor performance has been analyzed for five different concentrations of NaCl. Results: From the analysis, it is found that for all the analytes, confinement loss maintains a moderate value for the frequency band ranging from 0.9 to 1.2 THz. However, it approaches absolute zero immediately after 1.2 THz. The sensor model results in a high effective area, which is highly desirable for every PCF. It shows 3.78 × 105, 3.77 × 105, 3.76 × 105, 3.75 × 105, and 3.743 × 105 μm2 effective areas for 0%, 20%, 40%, 60% and 80% NaCl, respectively, at 1.4 THz. The effective material loss for this model is about 3.7×10-3, 3.63×10-3, 3.68×10-3, 3.672×10-3 and 3.652×10-3 cm-1 for 80%, 60%, 40%, 20% and 0% NaCl, respectively, at 1.4 THz. Birefringence is also high for the proposed model. The values of birefringence are approximately 0.002, 0.0018, 0.0017, 0.0016 and 0.0015 at 1.4 THz for 0%, 20%, 40%, 60% and 80% NaCl, respectively. In addition to the above positive outcomes, the sensor model exhibits high sensitivity for both x and y polarization. The peak sensitivity of this sensor is 91.5%, 91.42%, 91.34%, 91.25% and 91.10% in x polarization direction whereas the peak sensitivity is 91.70%, 91.60%, 91.49%, 91.40% and 91.25% in y polarization direction for 80%, 60%, 40%, 20% and 0% NaCl, respectively, at 1.8 THz. The value of sensitivity is above 90% at 1.4 THz for all the five concentrations of NaCl. Conclusion: The analyzed optical properties signify the higher efficiency and effectiveness of the sensor model in the detection of NaCl.

Background: Research has been focused on improving the thermal properties of single nanofluid components for recent years. Therefore, hybrid nanofluids or composites have been developed to improve heat transfer performance. Stability and thermal conductivity of Al2O3-TiO2- SiO2 nanoparticles are suspended in the fluid base of water (W) and ethylene glycol (EG) mixture with volume ratio of 60:40. Methods: Experiments were tri-hybrid nanofluid stability was investigated for volume concentration of 0.5 ~ 3.0%, and temperature conditions from 30 to 70°C for thermal conductivity measurements using a KD2 Pro Thermal Properties Analyzer. The experimental results show that the tri-hybrid nanofluid stability analysis was performed using a stable UV-Vis method for up to 30 days after preparation with 10 hour sonication time. Results: Comparison of data concentration ratios with sedimentation for single, hybrid, and trihybrid nanofluids yielding a stable tri-hybrid nanofluid with 80-90% value. Evaluation of zeta potential for tri-hybrid nanofluids yielded 63.72 mV in excellent stability classification. Sedimentation of this visual observation is influenced by the gravity of the movement of particles in the tube after 30 days. Conclusion: The highest thermal conductivity for tri-hybrid nanofluids was obtained at 3.0% and a maximum increase of up to 27% higher than that of the basic fluid (EG/W). Tri-hybrid nanofluids with a concentration of 0.5% gave the lowest effective thermal conductivity of 13.4% at 70°C.