UV-Vis detection of E. coli 0157:H7 using Vitis vinifera and Musa paradaisica modified Au-NPs.

Herein, we demonstrate the simple one-pot novel green synthesis of gold nanoparticles (Au-NPs) functionalised with a combination of banana peel (Musa paradaisica) and grape (Vitis vinifera) fruit extracts. The reaction mixture of aqueous gold chloride, banana peel and grape extracts revealed a purple colour after a reaction time of one hour, an indication of the presence and the successful synthesis of gold nanoparticles. The optical and structural properties of the green synthesized nanoparticles were analysed using Ultraviolet-Visible spectroscopy (UV-Vis) and Fourier Transform Infrared Spectroscopy (FTIR) while their surface morphology was determined using X-Ray Diffraction (XRD), High-Resolution Transmission Microscopy (HRTEM) and Small Angle X-Ray (SAX). Furthermore, a quick and simple surface plasmon resonance (SPR) study in the form of an optical sensor for the detection of Escherichia coli 0157:H7 strain was also achieved using UV-Vis. The obtained limit of detection (LOD) value for SPR for the GBPE|Au-NPs|GCE-based system was found to be 1 × 102 CFU/mL, a value well in the range for detection in seawater.•Green synthesis of gold nanoparticles (Au-NPs) was functionalised using banana peel (Musa paradaisica) and grape (Vitis vinifera) fruit extracts as capping and stabilizing agents.•Structural characterization of the Au-NPs was achieved using Ultraviolet-Visible spectroscopy (UV-Vis) and Fourier Transform Infrared Spectroscopy (FTIR) while their surface morphology was determined using X-Ray Diffraction (XRD), High-Resolution Transmission Microscopy (HRTEM) and Small Angle X-Ray (SAX).•The green synthesized Au-NPs were used to detect Escherichia coli 0157:H7 (E. coli 0157:H7) strain using Ultraviolet-Visible spectroscopy (UV-Vis) where the surface plasmon resonance (SPR) was studied.

A green synthesis of zinc oxide nanoparticles using Musa Paradisiaca and Rooibos extracts.

This study describes the single pot synthesis of zinc oxide nanoparticles (ZnO NPs) using a mixture of Aspalathus linearis and Musa paradisiaca for use against the fungi Candida albicans. These nanoparticles are known to be one of the most multifunctional inorganic nanoparticles with effective antifungal and antibacterial activity. The synthesized ZnONPs were characterized by a peak at 290 nm in the UV-vis spectrum while HRSEM confirmed rod-shaped nanoparticles. The FTIR data clearly revealed that the extracts contained -OH  functional groups whose role was capping agents during the nanoparticle synthesis. This study also found that the purity of the green synthesised ZnO NPs (GZnO NPs) was 94.4 %, 91.5 %, and 82.1 %, respectively, using XRD, HRTEM, and HRSEM-EDS. The antifungal activity of ZnONPs was tested against Candida albicans using the Kirby Bauer method. The maximum inhibition zone observed in the ZnO NPs against Candida albicans was confirmed to be 24 mm, a clear indication that the synthesized ZnO NPs have great potential to act as effective antifungal agents.•Zinc nitrate hexahydrate [Zn(NO3)2·6H2O] was used as the inorganic metal oxide precursor.•Extracts of banana (Musa paradisiaca) peel and tea leaves of Rooibos (Aspalathus linearis) infused with Buchu (Agathosma betulina) were the organic constituents used as reducing and capping agents during GZnO NPs synthesis.•Validation of the formed GZnO NPs was done using; Ultraviolet-visible spectroscopy (UV-Vis), X-ray spectroscopy (XRD), Fourier-transform Infrared Spectroscopy (FTIR), High-resolution Transmission Electron Microscopy (HRTEM) and Selected Area Electron Diffraction (SAED), and High-Resolution Scanning Electron Microscopy with Energy-Dispersive Spectroscopy (HRSEM-EDS).