Comparative Evaluation of Antibacterial Efficacy of Biological Synthesis of ZnO Nanoparticles Using Fresh Leaf Extract and Fresh Stem-Bark of Carica papaya

Abstract

The study compared the antibacterial activity of synthesized ZnO nanoparticles (NPs) from fresh leaf and fresh stem bark aqueous extracts of Carica papaya against five selected microbes: Staphylococcus aureus, (Gram positive (+ve)), Escherichia coli (Gram negative (-ve)), Acinetobacter baumanni (Gram-ve), Exiguobacterium aquaticum (Gram+ve), and Klebsielia pneumonia (Gram +ve). The morphological features of the biosynthesized ZnO NPs were analyzed using transmission electron microscope (TEM) and scanning electron microscope (SEM); the Fourier-transform infrared spectrometer (FTIR) technique was used to observe the surface functional groups. The experimental results indicated that ZnO NPs were successfully synthesized using modified hydrothermal technique, which showed agglomerated flake-like or petal-like shapes with the organic extract surrounding the formed particles. The average particle size of the synthesized ZnO nanoparticles determined by SEM ranged between 54-97 nm with the width and length of the petal-like structures been 30 nm and 62 nm respectively. The average ZnO NPs from fresh stem bark extract of Carica papaya with higher concentrations (100-1000 ppm) demonstrated a higher antibacterial activity than the fresh leaf extracts. On the other hand, ZnO NPs from fresh leaf extracts of lower concentrations (25-50 ppm) rather showed a suitable result than the fresh stem bark. In general, ZnO NPs showed a positive antibacterial result towards the selected microbes. This shows that, the synthesized ZnO NP can be a substitute to chemical methods.

Variation of Alkali Concentration and Temperature: Its Effect on the Morphology of ZnO Nanoparticles Synthesized via Solvothermal Technique

“…Meanwhile, structural morphology of the samples was observed by scanning electron microscope (Carl Zeiss GeminiSEM 500) operating at 10.0 kV and transmission electron microscope (JEOL 1230, Japan). Sample preparation prior to analysis for the different characterization techniques was carried out using the method outlined by Droepenu and Asare [26] and Droepenu et al [27].…”

Coinage Metals Doped ZnO Obtained by Sol-Gel Method—A Brief Review

“…The hydrothermal, solvothermal, sol-gel, chemical bath deposition, wet chemical process, spray pyrolysis, microemulsion, and precipitation methods are included in the chemical synthesis approach [11][12][13][14][15][16][17][18][19][20]. Plant or microbial extracts are biocompatible and can act as capping agents to stabilize the NPs in the green or biogenic synthesis of metal oxide nanomaterials [21,22].…”