Green preparation and spectroscopic characterization of plasmonic silver nanoparticles using fruits as reducing agents

Abstract

Chemicals typically available in plants have the capability to reduce silver and gold salts and to create silver and gold nanoparticles. We report the preparation of silver nanoparticles with sizes between 10 and 300 nm from silver nitrate using fruit extract collected from pineapples and oranges as reducing agents. The evolvement of a characteristic surface plasmon extinction spectrum in the range of 420 nm to 480 nm indicates the formation of silver nanoparticles after mixing silver nitrate solution and fruit extract. Shifts in plasmon peaks over time indicate the growth of nanoparticles. Electron microscopy shows that the shapes of the nanoparticles are different depending on the fruit used for preparation. The green preparation process can result in individual nanoparticles with a very poor tendency to form aggregates with narrow gaps even when aggregation is forced by the addition of NaCl. This explains only modest enhancement factors for near-infrared-excited surface enhanced Raman scattering. In addition to the surface plasmon band, UV-visible absorption spectra show features in the UV range which indicates also the presence of small silver clusters, such as Ag 4 2+. The increase of the plasmon absorption correlates with the decrease of absorption band in the UV. This confirms the evolution of silver nanoparticles from silver clusters. The presence of various silver clusters on the surface of the "green" plasmonic silver nanoparticles is also supported by a strong multicolor luminesce signal emitted by the plasmonic particles during 473 nm excitation.

Green preparation and spectroscopic characterization of plasmonic silver nanoparticles using fruits as reducing agents

“…The most popular process among the bottom up methods might be the preparation of silver and gold nanoparticles in aqueous solution by the reduction of silver and gold salts using sodium citrate or sodium borohydride as reducing agent [ 9 ]. Recently it has been identified that also plant extracts have the capability to reduce silver and gold salts and to create silver and gold nanoparticles [ 10 – 19 ]. Many different chemical compounds are present in various parts of different plants.…”

“…Here we study the formation of silver nanoparticles using fruit extracts from oranges and pineapples and check their capability as enhancing plasmonic structures for surface enhanced Raman scattering (SERS). Extracts from these two fruits have been used for preparing silver and gold nanoparticles [ 12 , 15 – 19 ]. Here we explore the formation of nanoparticles by varying conditions in the preparation process such as ratios of the mixtures of silver nitrate and fruit extracts and the presence or absence of light.…”

Unveiling the cytotoxicity of phytosynthesised silver nanoparticles using Tinospora cordifolia leaves against human lung adenocarcinoma A549 cell line

“…The AgNPs were synthesised by the reduction of silver ions (Ag 2+ ) in to silver metal (Ag 0 ). Colour changes of reaction mixture indicate the biosynthesis of AgNPs and it was favoured by various reports [6, 9, 29]. Out of different tested concentrations of AgNO 3 , 5 mM showed maximum absorbance at 440 nm which confirmed the optimum concentration of AgNO 3 solution.…”

“…Phyto‐fabrication of metallic NPs by using plant extract as reducing agents is an alternate and advantageous over physical and chemical methods [5]. Several plants viz., Bougainvillea spectabilis, Azhadirachta indica, Crataegus douglasii, Prosopis farcta and Ananas comosus have been reported for efficient and rapid extra cellular synthesis of silver nanoparticles (AgNPs) [6–10].…”

Antibacterial potential of silver nanoparticles biosynthesised using Canarium ovatum leaves extract

“…Further, plant extracts mediated reduction of silver salts to AgNPs also provides capping for stability. Moreover, AgNPs synthesised from plant extract, have been reported to lack the ability towards aggregate formation and tend to remain dispersed even when aggregation is forced by any agent [5, 6]. Numerous studies have investigated plants extracts for the biosynthesis of AgNPs including, Cinnamon zeylancium bark, Coleus amboinicus Lour, Medicago sativa , Panax ginseng, Weissella oryza, Citrus sinensis peel, Terminalia arjuna .…”