Synthesis of Gold (Au) Nanoparticles by using Bioreductor of Cocoa (Theobroma cacao L.) Rind Extract and It's Antibacterial Activity Test

Abstract

Research on the Synthesis of Gold (Au) Nanoparticles by using Bioreductor 

of Cocoa (Theobroma cacao L.) Rind Extract and Its Antibacterial Activity Test has been 

done. This Green Synthesis method uses methanol as a solvent to extract organic 

compounds in the cocoa rind that function as bioreductants. The results of the synthesis 

were continued by testing its activity as an antibacterial. The form of gold nanoparticles 

can be confirmed after 30 minutes of stirring. The characterization of gold nanoparticles 

was carried out using a UV-Vis spectrophotometer, Fourier Transform Infrared (FTIR), 

X-Ray Diffraction (XRD), and Scanning Electron Microscopy-Energy Dispersive X-Ray 

(SEM-EDX). Based on the analysis of UV-Vis spectrophotometer, the maximum 

wavelength was at 553 nm with an absorbance value of 0.164. The FTIR results indicate 

the presence of a hydroxyl group that acts as a metal ion reducing agent so that it is not 

charged, while the results of the XRD analysis confirm that the gold nanoparticle crystals 

are Face Centered Cubic (FCC) and based on the Scherrer approach the particle size 

distribution has an average diameter of 6.303 nm. The SEM-EDX results showed that 

the gold nanoparticles had a spherical shape and were located in the M electron shell. 

The gold nanoparticles had an inhibitory zone of 8.9 mm in Pseudomonas aeruginosa

and 7.6 mm in Bacillus subtilis bacteria.