Fig. 1

Successive color changes during the synthesis of Au@AgNPs using ethanoic extract of propolis. AI and BI. The water is at zero point. AII and BII The water containing 3% propolis extract at zero point. AIII and BIII An intermediate step in forming the AuNPs after 80 min. AIV and BIV A late step in synthesizing the AuNPs after 120 min. AV and BV A final step in producing the Au@AgNPs, after 90 min of adding AgNO₃ to green synthesized AuNPs