Jem 2100

Epigallocatechin gallate (EGCG; 989-51-5, Sigma-Aldrich) was dissolved in phosphate-buffered saline (PBS). Sodium-tetrachloroaurate (NaAuCl4; 13874-02-7, Sigma-Aldrich) was used to prepare the EGCG-conjugated AuNPs. Celastrol (34157-83-0, Sigma-Aldrich) was used as a positive control, after being dissolved in < 0.1% dimethyl sulfoxide (DMSO), at a safe concentration. All buffers and reagents were analytical-grade (Sigma-Aldrich, USA) unless otherwise mentioned. EGCG-conjugated AuNPs (EGCG-AuNPs) were prepared, as described by Zhu et al. (2019) . Transmission electron microscopy (TEM) (Joel Jem-2100), performed with a Malvern Zetasizer Nano ZS instrument, with a He/Ne laser, and absorption spectroscopy (Evolution 300 UV-Vis spectrophotometer, Thermo Scientific, USA) were used to characterize the size and absorption spectrum of EGCG-AuNPs. The in vitro stability of the EGCG-AuNPs was tested in phenol redfree Dulbecco's modified Eagle medium (DMEM), both with and without 10% fetal bovine serum (FBS), after 1 h and 24 h. The absorption at 530 nm confirmed the retention of nanoparticles in the medium. The Folin-Ciocalteu colorimetric assay revealed the loading capacity for EGCG on AuNPs (Zhu et. al 2019) .