Optimizing the Synthesis of Silver Nanoparticles Using Five Curcuma Species under UV Irradiation as a Potent Suncreen Substrate

Curcuma rhizome is reported to have a high total phenolics that could act as reducing agents for metals to nanoparticles. Rhizomes of five curcuma species were selected as bioreductors, namely white turmeric (Curcuma zedoaria), black turmeric (C. aeruginosa), fingerroot (C. rotunda), temu giring (C. heyneana), and mango ginger (C. amada). The research was designed to select the reductor from five Curcuma rhizomes mentioned above for silver nanoparticles synthesis, optimizing the synthesis condition, and evaluating its potential as a sunscreen agent. Silver nanoparticles (AgNPs) were synthesized by mixing the extracts with AgNO3 and irradiating the solution under a 366 nm UV lamp at certain times and pHs. Based on the spectra, the highest absorbance of silver nanoparticles was detected on the temu kunci extract. The optimum conditions for silver nanoparticle-temu kunci (AgNPs-TK) were determined using a Box-Behnken Design and Minitab. Statistical results showed that 0.13 g of silver nitrate irradiated for 162.7 min at pH 11.34 was the optimum condition for AgNPs synthesis. The synthesized AgNPs were characterized by PSA/DLS, XRD, and TEM. The TEM analysis confirmed that silver particles are spherical. The size of the AgNPs produced based on TEM analysis is 5-50 nm. Sunlight inhibition activity, determined spectrophotometrically, indicated that the sun protection factor of AgNPs-TK is categorized as a minimum protection in concentration of 25 ppm.