Synthesis and Antibacterial Efficacy of Nipa Palm Vinegar-Graphene Quantum Dots against Staphylococcus aureus and Escherichia coli

Nongyao Teppaya1,, Paweena Porrawatkul2,, Parintip Rattanaburi3,, Amnuay Noypha4,, Arnannit Kuyyogsuy2,, Saksit Chanthai5, and Prawit Nuengmatcha1,2,*,

1Creative Innovation in Science and Technology, Faculty of Science and Technology, Nakhon Si Thammarat Rajabhat University, Nakhon Si Thammarat 80280, Thailand

2Nanomaterials Chemistry Research Unit, Department of Chemistry, Faculty of Science and Technology, Nakhon Si Thammarat Rajabhat University, Nakhon Si Thammarat 80280, Thailand

3Department of General Science, Faculty of Education, Nakhon Si Thammarat Rajabhat University, Nakhon Si Thammarat 80280, Thailand

4Department of Physics, Faculty of Education, Nakhon Si Thammarat Rajabhat University, Nakhon Si Thammarat 80280, Thailand

5Materials Chemistry Research Center, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand

*Corresponding author: Tel/Fax: +66 7 5377443; E-mail: pnuengmatcha@gmail.com

Abstract

Nipa palm vinegar (NPV) is an essential product from the Pak Phanang district in the Nakhon Si Thammarat Province, Thailand. NPV is used for cooking and its antibacterial activity reduces dependency on toxic chemicals such as antibiotics and preservative foods. Using NPV as the precursor, nipa palm vinegar–graphene quantum dots (NPV-GQDs) were successfully synthesized through pyrolysis. Preliminary screening of the antibacterial activities of NPV and NPV-GQDs against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacterial strains were determined by using the agar well diffusion method. The broth macro-dilution method determined the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The diameter of the inhibition zones of S. aureus and E. coli reached 29.30 mm and 23.50 mm, respectively. The MIC of NPV-GQDs against S. aureus and E. coli was 6.25 mg/mL and 12.50 mg/mL, respectively, whereas the MBC of NPV-GQDs against S. aureus and E. coli was 50.00 mg/mL. These results signify the potential healthcare application of NPV-GQDs as high-quality and valuable antimicrobial agents, thereby reducing chemical usage toxic to the body in the future.

Keywords

Nipa palm vinegar, Graphene quantum dots, Antibacterial activity.

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