Gold Nanoparticles Induction Using Kombucha SCOBY Disc

Abstract

SCOBY disc is a unique structure of bacteria and fungi. It was known in the mid-Seventies in Egypt as "Tea fish." To the author's knowledge, no reports since then were published to use them in producing nanoparticles worldwide. The addition of 1mM of (HAuCl4.3H2O) solution into the cell-free extract (CFE) of SCOBY disc grew on black tea medium, resulted in gold nanoparticles AuNPs at 25ºC (Au 3+ →Au 0 ) momentarily. The surface plasmon resonance peaks of the gold colloidal solution produced showed an absorption peak at 530 nm. (TEM) exhibited AuNPs in spherical and triangle shapes (12 to 35 nm). X-ray diffraction reflected four distinct peaks at 2θ = 38.1°, 44.3°, 64.5°, and 77.7°. All four peaks corresponded to standard Bragg reflections ( 111), ( 200), ( 220), and (311) of face center cubic. (FTIR) analysis showed the presence of two amide groups in 1721 & 1033 respectively, which appeared to be responsible for the stability of gold nanoparticles. The mean particle size and polydispersity index (PDI) of AuNPs induced by SCOBY were 61.23 ± 0.416 with a negative charge -10.2 ± 1.73 mV that cause electrostatic repulsion among the nanoparticles and good colloidal stability. Moreover, the effect of AuNPs on inducing apoptosis in liver cancer cells HepG2. 3-(4,5dimethylthiazol-2-yl)-2-5-diphenyltetrazolium bromide (MTT) assay showed that AuNPs produced had selective toxic effects to HepG2 cells with IC-50 value 176 µM/mL compared to control cells. These results suggested the use of those green synthesized AuNPs in cancer treatment and further studies are recommended.