ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.