Green Synthesis of Silver Nanoparticles Using Spent Coffee Ground and its Antibacterial Activity

Ng, Kai Song-Aaron (2019) Green Synthesis of Silver Nanoparticles Using Spent Coffee Ground and its Antibacterial Activity. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Silver nanoparticles are well known and used in a variety of medical applications due to their antibacterial properties. Green synthesis of silver nanoparticles is relatively new, and the investigation of this phenomenon has acquired attention due to the increase of bacterial resistance towards antibiotics. Hence, the aim of this study was to determine antimicrobial properties of silver nanoparticles synthesized through green synthesis method using spent coffee ground. First, silver nanoparticles were synthesized by mixing with silver nitrate solution and coffee extract. Then, the mixture was then purified by repeated centrifugation which the supernatant produced was discarded and pellet was resuspended in distilled water. Next, the silver nanoparticles were characterised using Malvern Zetasizer analyser for size determination. Antibacterial properties of silver nanoparticles produced were determined by agar disc diffusion and broth dilution assays. From the agar disc diffusion results, Escherichia coli (zone of inhibition = 10.17 ± 0.58 mm) and Klebsiella pneumoniae (zone of inhibition = 7.25 ± 0.75 mm) were more susceptible to silver nanoparticles as compared to Proteus mirabilis (zone of inhibtion = 7.33 ± 0.62 mm) and Pseudomonas aeruginosa (zone of inhibition = 10 ± 0.29mm). In broth dilution assay, K.pneumonia (MIC = 200μg/ml) is most susceptible to silver nanoparticles, while P.mirabillis (MIC = 500μg/ml) is the least susceptible. In conclusion, silver nanoparticles produced by green synthesis method of spent coffee ground possessed antibacterial properties against K. pneumoniae, P. mirabilis, E. coli and P. aeruginosa.