Preparation and mechanistic aspect of natural xanthone functionalized gold nanoparticle

Herein, a facile scale up and shape variable synthesis of gold nanoparticle (AuNP) and reaction mechanism by natural xanthone derivative (mangiferin) has been reported. Mangiferin (C19H18O11; 1,3,6,7-tetra-hydroxyxanthone-C2-beta-D-glucoside), a xanthone derivative is isolated from Mangifera indica L. leaves which efficiently reduces Au3+ ions to Au-0 and stabilizes the formed AuNP. The structural, optical and plasmonic properties of synthesized AuNP have been investigated through different instrumental techniques like UV-Vis and FTIR spectroscopy, powder XRD, FESEM and TEM analysis. It is observed that variation of the concentration of Au3+ ions and mangiferin has a great effect on controlling size and shape of nanoparticles. The role of reaction temperature is also notable. An interesting observation is that with same concentration ratio of HAuCl4/mangiferin (0.025 mM/0.002%) at the room temperature kidney shaped AuNP is produced, whereas it is spherical at boiling temperature. Moreover, mangiferin allows high scale synthesis of AuNPs (0.025 mM to 10 mM) without changing the particles size and shape. The mechanistic investigation through UV-Vis, FTIR and GCMS analyses reveal the cleavage of glucose unit and oxidation of phenolic OH groups during AuNP formation. Non-toxicity of mangiferin conjugated AuNP on normal human breast cell line (MCF-10A) suggesting its future application as a drug delivery system and other related medicinal purposes.