Optimization of Parameters of Sonochemical Synthesis of Silver Nanoparticles Using Spectrophotometry

Abstract

Background and aim of the study: Silver Nanoparticles AgNPs have unique physical, chemical, and biological properties, as well as high antiviral and antibacterial activities which depend on the size of these particles. AgNPs show a conspicuous absorbance peak in visible spectrum between 390 – 450 nm due to its Localized Surface Plasmon Resonance LSPR. Spectrophotometry is one of the simplest, easiest, fastest, and most economic methods for characterizing synthesized AgNPs and optimizing synthesis parameters due to the correlation between LSPR wavelength and the size of AgNPs. This research aims to optimize by Spectrophotometry the pH and the concentration and the type of starch used to reduce Ag⁺ ions and stabilize AgNPs synthesized by Sonochemical method.

Materials and methods: AgNPs were synthesized from AgNO₃ (0.5 mmol) using 1.0 % w/v of soluble starch (dissolved in distilled water by heat) in different pH values ranging from 5.0 to 11.7. It also has been used three concentrations (0.5%, 1.0%, and 1.5% w/v) of each of soluble starch (dissolved either with heat or without heat) and ordinary corn starch. Each sample has been sonicated for 30 minutes, then it has been scanned with spectrophotometer. The scans have been repeated after one month to evaluate the stability.

Results: The UV-Vis spectrum of synthesized AgNPs in different pH values showed that the pH value that gives the least LSPR wavelength, the highest corresponding intensity, and the highest stability was pH= 11.0. It was also found that the least LSPR wavelength, the highest corresponding intensity, and the highest stability was obtained when soluble starch (dissolved with heat) was used, and the optimum concentration was 1.5% w/v.

Conclusions: spherical AgNPs were successfully synthesized using Sonochemical method. The results of this study revealed that the optimum pH value was 11.0, and the optimum type and concentration of the starch used was soluble starch when dissolved with heat in concentration of 1.5% w/v. AgNPs synthesized using these parameters were sufficiently stable for one month.