Comparison of Blueberry and Dandelion Aqueous Extracts in the Synthesis of Gold and Silver Nanostructures, and Their Applications as Anti‐Pseudomonas aeruginosa Agent

Abstract

We performed a comparative study using aqueous extracts of dandelion flowers and blueberry fruits to synthesize gold‐ (Au) and silver‐ (Ag) nanostructures (NSs). The blueberry extracts gave nanowire and spherical AuNSs upon changing the ratio of the extracts to Au3+precursor while altering the ratio for the dandelion extracts resulted in formation of only anisotropic AuNSs. Similar results were obtained during the AgNSs, where the dandelion extracts resulted in formation of quasi‐spherical AgNSs at the tested ratio (extract/AgNO3 ratio) while altering the ratio for the blueberry extracts resulted in nanorod and nanoplates formation. We argued that this could be from dominancy of a lone compound or a group of compounds and tested this claim by introducing chrysin and amino acid mixtures to the blueberry extracts. Altering the added chrysin amount triggered nanoplate and spherical AuNSs formation while alteration in amino acid mixture content did not change the morphology, and spherical AuNSs were obtained. The antibacterial studies revealed the AgNSs are toxic to Pseudomonas aeruginosa with 8 μg/mL MBC (minimum bactericidal concentration) and 3 μg/mL values for the blueberry and dandelion extracts synthesized AgNSs while penicillin/streptomycin sulfate mixture carrying Dandelion‐AuNSs gave 12‐times lower MBC value in comparison to free penicillin/streptomycin sulfate mixture.

Identification of Marker Molecules in Aqueous Plant Extracts Affecting the Gold Nanostructures’ Morphology and Size

“…We also performed a linear regression analysis for the tested 37 phytochemicals, total phenolic, total flavonoid, reducing carbohydrate and protein amounts. Based on a previous study, it was observed that most concentrated phenolics and most concentrated flavonoids play the key roles in determining the shape and morphology of the AuNSs [54] . Therefore, the sum of the most concentrated phenolic acids was divided into the sum of the most concentrated flavonoids and multiplied with the ratio of total phenolic to total flavonoid.…”