Synthesis of AgNPs Using Flowers Exhibiting Different Photoresponse

Abstract

Biological synthesis or green synthesis of nanoparticles has proven to be cost effective, rapid and safe. Flowers exhibit different colours due to wavelength selective absorption and light scattering. In this study, four differently coloured flowers, i.e. Bauhinia purpurea – Fabaceae, Couroupita guianensis – Lecithydaceae, Gerbera jamesonii – Asteraceae and Gomphrena globosa – Amaranthaceae were studied for their potency to synthesize silver nanoparticles. The UV-Vis spectrophotometric analysis of the aqueous extracts of B. purpurea, C. guianensis, G. jamesonii and G. globosa flowers recorded their respective peaks at 562, 498, 524 and 548 nm in response to their pigments. The synthesized silver particles were characterized through UV-Vis spectrophotometry, scanning electron microscopy, energy dispersive electron spectroscopy, particle size analyzer and fourier transform infrared spectroscopy. The resonance peak in the UV-Vis spectrum was recorded at 430, 420, 445 and 435 nm respectively, for the AgNPs synthesized using B. purpurea, C. guianensis, G. jamesonii and G. globosa. SEM analysis revealed the size range of 107-498 nm for B. purpurea, 15-75 nm for C. guianensis, 17-51 nm for G. jamesonii and 20-91 nm for G. globosa. The presence of silver was confirmed by EDS. The silver particles synthesized using the extracts of B. purpurea, C. guianensis, G. jamesonii and G. globosa showed the average size as 431.3, 71.51, 30.11 and 33.93 nm as assessed through PSA. FTIR studies confirmed the involvement of O-H, N-H, C-C=C, N=O, -NO2 and C-O stretches. In the present study, the silver particles synthesized by C. guianensis, G. jamesonii and G. globosa were in the nanoscale, whereas those synthesized by B. purpurea were in microscale. The synthesis of AgNPs is attributed to the pigments or the metabolites present in the floral extracts. Further studies on the potential of flowers exhibiting different photoresponse in the synthesis of nanoparticles are recommended.