The preparation and characterization of gold-conjugated polyphenol nanoparticles as a novel delivery system

Dar-Shih Hsieh^1,2, Hsiu-Chin Lu⁵, Cheng-Cheung Chen^1,3, Chang-Jer Wu^1,*, Ming-Kung Yeh<sup>4,*

1</sup>Department of Food Science, National Taiwan Ocean University, Keelung, Taiwan; ²Division of Urology, ³Department of Pathology, Tri-Service General Hospital, ⁴Institute of Preventive Medicine, National Defence Medical Center, Taipei, Taiwan; ⁵Department of Laboratory Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan

*These authors contributed equally to this work

Abstract: Nanogold particles are commonly used in nanomedicine. We generated physical nanogold (pNG) conjugated with different ratios of epigallocatechin-3-gallate (EGCG) and evaluated its physicochemical properties, antioxidant activity, and cytotoxicity in vitro as well as anticancer activity in vivo. Results showed that the EGCG-pNG conjugates were successfully prepared at ratios between 23:1 and 23:5, with the percentage of EGCG content increasing with the EGCG:pNG ratio from 23:1 (2.0% ± 0.02%) to 23:5 (28% ± 0.3%). EGCG-pNG particles at ratios of 23:1 and 23:5 demonstrated significantly decreased size from 500 to 20 nm and decreasing zeta potentials of 21 mV to –22 mV, respectively. At a ratio of 23:2.5, the EGCG-pNG particles (27% EGCG, 50 nm in size, zeta potential of –8 mV) showed longer EGCG activity half-life (110 days vs 5 hours), controlled release (2 hours vs 30 minutes), and higher antioxidant activity (four times), as well as inhibition of tumor cell growth, than controls. The present study indicated that EGCG-pNG possesses promising therapeutic potential, based on its strong free-radical scavenging and anticancer activities.

Keywords: EGCG, nanoparticles, antioxidant, antitumor activity, nanogold