Glucose-Reduced Silver Nanoparticles Prepared with Amylose-Sodium Palmitate Inclusion Complexes and Their Dry Storage and Reconstitution

Abstract

Methods for producing silver nanoparticles for antimicrobial and other applications using green chemistry approaches have many variables that affect their properties. The authors have previously shown that using amylose‐sodium palmitate inclusion complexes enabled exchange of silver ions with the sodium ions of the complexed sodium palmitate, leading to production of smaller nanoparticles than those obtained with soluble starch. In this study, silver nitrate, glucose, and sodium hydroxide are added to aqueous solutions of complexes to generate silver nanoparticles with average diameters of 3.45–3.94 nm. When waxy starch is used, which contains no amylose, the reduction reactions did not progress beyond 1 h and silver nanoparticles are larger (14.5 nm). Acidification to pH 3.5 of nanoparticles prepared with amylose complexes results in microgel formation, and when these gel fragments are freeze‐dried and reconstituted, TEM reveal nanoparticles averaging 3.69 nm within the hydrated gel fragments. This procedure enables the silver nanoparticles to be stored in a dry state and later reconstituted in water to obtain silver nanoparticles with known characteristics, making de novo synthesis of silver nanoparticles from the starting materials unnecessary. This novel approach will facilitate the incorporation of silver nanoparticles into a variety of products.

Spectroscopic analyses of particle and energy aggregations at the interface of silver nanoparticles and fluorescent carbon nanodots

“…First, CDs, like many other nanomaterials, are usually not rigorously purified or otherwise checked for impurities before use. Incidentally, some of the CDs said to reduce silver ions are prepared from materials that are themselves capable of reducing silver ions, such as glucose 19–21 , citric acid 22 , p -phenylenediamine 23–25 , ethylenediamine, 26,27 and antioxidant-rich natural products. 28 It is not impossible that the residual starting material in such a CD preparation is the actual reducing agent.…”