Biosynthesis of silver nanoparticles using indigenous Xanthorrhoea glauca leaf extract and their antibacterial activity against Escherichia coli and Staphylococcus epidermis

Background:This study for the first time presents an environmentally friendly, room temperature procedure for synthesizing silver (Ag) nanoparticles via the leaf extract taken from Xanthorrhoea glauca.Methods: The simple and straightforward green chemistry based technique uses the leaf extract that acts as both reducing agent and capping agent to produce Ag nanoparticles which are subsequently quantified using advanced characterisation techniques. In addition, antibacterial studies were conducted using the Kirby-Bauer sensitivity method.Results: Advanced characterisation revealed the synthesised particles had a variety of shapes including cubes, truncated triangular and hexagonal plates, and ranged in size from 50 nm up to 200 nm. The Gram-positive bacteria Staphylococcus epidermis showed the maximum zone of inhibition at 11 mm.Conclusions: The study has shown that the leaf extract was able to synthesis Ag nanoparticles with antibacterial activity against Escherichia coli and Staphylococcus epidermis

Biogenic synthesis of silver nanoparticles via indigenous Anigozanthos manglesii, (red and green kangaroo paw) leaf extract and its potential antibacterial activity

Background: Metallic silver nanoparticles with antibacterial properties were biosynthesised for the first time using an indigenous Australian plant Anigozanthos manglesii.Methods: A practical, straight-forward and eco-friendly technique used the Anigozanthos manglesii leaf extract, which acted as both reducing and capping agents to create stable silver nanoparticles. The antibacterial activities of the nanoparticles were investigated using the Kirby-Bauer sensitivity method.Results: Characterisation revealed the nanoparticles ranged in size from 50 nm up to 150 nm, and their morphologies included cubes, triangular plates and hexagonal plates. Antibacterial studies revealed Deinococcus was sensitive and susceptible to the biosynthesised nanoparticles. Escherichia coli and Staphylococcus Epidermis strains were also found to be less susceptible to the silver nanoparticles.Conclusions: The present study has shown that silver nanoparticles biosynthesised using Anigozanthos manglesii leaf extracts have antibacterial activity against Deinococcus, Escherichia coli and Staphylococcus Epidermis bacterial strains

Green synthesis of gold nanoparticles from waste macadamia nut shells and their antimicrobial activity against Escherichia coli and Staphylococcus epidermis

Background: The study for the first time demonstrates an eco-friendly and room temperature procedure for biosynthesizing gold (Au) nanoparticles from waste Macadamia nut shells. Currently Australia contributes around 40% to the global market and generates around AUS $150 million of export revenue. However, a consequence of large nut production is the generation of large quantities of waste nut shells. The green chemistry-based method is clean, nontoxic and eco-friendly. The method presented in this study produced a variety of Au nanoparticle sizes and shapes.Methods: The straightforward green chemistry-based technique used waste Macadamia nut shells to generate Au nanoparticles, which were subsequently studied using several advanced characterization techniques. Furthermore, the Kirby-Bauer sensitivity method was used to evaluate the antibacterial properties of the extracts and synthesized gold nanoparticles.Results: Advanced characterisation revealed the Au nanoparticles were crystalline, ranged in size from 50nm up to 2µm, and had spherical, triangular and hexagonal morphology. The gram-negative bacteria Escherichia coli produced a maximum inhibition zone of 11mm, while Staphylococcus epidermidis produced a maximum inhibition zone of 9mm.Conclusions: The study has shown that waste Macadamia nut shell extracts have no antibacterial activity, but the synthesised Au nanoparticles did display antibacterial activity to both Escherichia coli and Staphylococcus epidermidis. Thus, the present work has demonstrated a waste valorisation strategy that can be used to produce high-value Au nanoparticles with antimicrobial properties for use in future pharmaceuticals

Biocompatibility of nanometre scale porous anodic aluminium oxide membranes towards the RK 13 epithelial cell line: A preliminary study

Background: This study for the first time examines the biomedical potential of using anodic aluminium oxide (AAO) for culturing Oryctolagus cuniculus (European Rabbit) Kidney (RK-13) epithelial cells.Methods: The cellular response of RK-13 cells towards in-house synthesised AAO membranes, a commercially available membrane and glass controls were investigated by examining cell adhesion, morphology and proliferation. The in-house membranes were anodized using a two-step procedure to produce a highly ordered hexagonal pore and channel structure.Results: Cell proliferation over a 48 h period indicated that the AAO membranes were more than comparable with the glass control substrates. Subsequent microscopy observations revealed evidence of focal adhesion sites and cellular extensions interacting with the underlining porous membrane surface structure.Conclusions: The study has shown that AAO membranes have the potential to culture RK-13 cells and indicate a possible tissue engineering technique for producing tissues

Biogenic synthesis of gold nanoparticles from waste watermelon and their antibacterial activity against Escherichia coli and Staphylococcus epidermidis

Background: Globally, large quantities (tonnes) of diverse sources of food wastes derived from horticulture are produced and offer a valuable renewable source of biochemical compounds. Developing new recycling and food waste utilisation strategies creates unique opportunities for producing gold (Au) nanoparticles with desirable antibacterial properties. The present study used an eco-friendly procedure for biologically synthesizing gold (Au) nanoparticle shapes from waste Citrullis lanatus var (watermelon).Methods: The green chemistry-based procedure used in this study was straightforward and used both red and green parts of waste watermelon. The generated Au nanoparticles were subsequently evaluated using several advanced characterization techniques. The antibacterial properties of the various extracts and synthesised nanoparticles were evaluated using the Kirby-Bauer sensitivity method.Results: The advanced characterization techniques revealed the Au particles ranged in size from nano (100 nm) up micron (2.5 µm) and had a variety of shapes. The red watermelon extract tended to produce spheres and hexagonal plates, while the green watermelon extract tended to generate triangular shaped nanoparticles. Both red and green watermelon extracts produced nanoparticles with similar antibacterial properties. The most favourable response was achieved using a 5:1 green watermelon-based mixture for Staphylococcus epidermidis, which produced a maximum inhibition zone of 12 mm. While gram-negative bacteria Escherichia coli produced a maximum inhibition zone of 10 mm for the same mixture.Conclusions: The study has shown both red and green parts of waste watermelon can be used to produce Au nanoparticles with antibacterial activity towards both Escherichia coli and Staphylococcus epidermidis. The study has also demonstrated an alternative method for producing high-value Au nanoparticles with potential pharmaceutical applications

Ultrasonic synthetic technique to manufacture a pHEMA nanopolymeric-based vaccine against the H6N2 avian influenza virus: a preliminary investigation

This preliminary study investigated the use of poly (2-hydroxyethyl methacrylate) (pHEMA) nanoparticles for the delivery of the deoxyribonucleic acid (DNA) vaccine pCAG-HAk, which expresses the full length hemagglutinin (HA) gene of the avian influenza A/Eurasian coot/Western Australian/2727/1979 (H6N2) virus with a Kozak sequence which is in the form of a pCAGGS vector. The loaded and unloaded nanoparticles were characterized using field-emission scanning electron microscopy. Further characterizations of the nanoparticles were made using atomic force microscopy and dynamic light scattering, which was used to investigate particle size distributions. This preliminary study suggests that using 100 μg of pHEMA nanoparticles as a nanocarrier/adjuvant produced a reduction in virus shedding and improved the immune response to the DNA vaccine pCAG-HAk

Electrochemical Synthesis, Characterisation, and Preliminary Biological Evaluation of an Anodic Aluminium Oxide Membrane with a pore size of 100 nanometres for a Potential Cell Culture Substrate

Abstract In this study we investigate the electrochemical synthesis and characterisation of a nanometre scale porous anodic alumin iu m o xide (AAO) membranes with a mean pore diameter of 100 n m. The membranes exhib it interesting properties such as controllable pore diameters, periodicity and density distribution. These properties can be preselected by adjusting the controlling parameters of a temperature controlled two-step anodization process. The surface features of the nanometre scale memb rane such as pore density, pore diameter and inter-pore d istance were quantified using field emission scanning electron microscopy (FESEM) and ato mic fo rce microscopy (AFM). A preliminary bio logical evaluation of the memb ranes was carried out to determine cell adhesion and morphology using the Cercopithecus aethiops[African green monkey -(Vero)] kidney epithelial cell line. Optical microscopy, FESEM and AFM investigations revealed the presence of focal adhesion sites over the surface of the porous membranes. The positive outcomes of the study, indicates that AAO memb ranes can be used as a viable tissue scaffold for potential tissue engineering applications in the future

Monatomic reactions with single vacancy monolayer h-BN: DFT studies

Hexagonal boron nitride (h-BN) has been widely utilized in various strategic applications. Fine-tuning properties of BN towards the desired application often involves ad-atom adsorption of modifying its geometries through creating surface defects. This work utilizes accurate DFT computations to investigate adsorption of selected 1st and 2nd row elements (H, Li, C, O, Al, Si, P, S) of the periodic table on various structural geometries of BN. The underlying aim is to assess the change in key electronic properties upon the adsorption process. In addition to the pristine BN, B and N vacancies were comprehensively considered and a large array of properties (i.e., atomic charges, adsorption energies, density of states) were computed and contrasted among the eight elements. For instance, we found that the band gap to vary between 0.33 eV (in case of Li) and 4.14 eV (in case of P). Likewise, we have illustrated that magnetic contribution to differ substantially depending on the adatom adsorbents. Results from this work has also lays a theoretical foundation for the use of decorated and defected BN as a chemical sensor for CO gase

Progress towards Sustainable Utilisation and Management of Food Wastes in the Global Economy

In recent years, the problem of food waste has attracted considerable interest from food producers, processors, retailers, and consumers alike. Food waste is considered not only a sustainability problem related to food security, but also an economic problem since it directly impacts the profitability of the whole food supply chain. In developed countries, consumers are one of the main contributors to food waste and ultimately pay for all wastes produced throughout the food supply chain. To secure food and reduce food waste, it is essential to have a comprehensive understanding of the various sources of food wastes throughout the food supply chain. The present review examines various reports currently in the literature and quantifies waste levels and examines the trends in wastage for various food sectors such as fruit and vegetable, fisheries, meat and poultry, grain, milk, and dairy. Factors contributing to food waste, effective cost/benefit food waste utilisation methods, sustainability and environment considerations, and public acceptance are identified as hurdles in preventing large-scale food waste processing. Thus, we highlight the need for further research to identify and report food waste so that government regulators and food supply chain stakeholders can actively develop effective waste utilisation practices