The Enhancement of the Antibacterial Activity for Silver Nanoparticles Synthesized from the Extract of Citrus grandis Peel Under LED Irradiation

In this work, a novel synthesis for silver nanoparticles (AgNPs) was investigated by using a pectic polysaccharide as a reducing and stabilizing agent in the extract of Citrus grandis (C. grandis) peel under the exposure of light-emitting diode (LED) irradiation. Extraction conditions of C. grandis peel such as the concentration of powdered peel, extraction temperature, and extraction time on AgNP formation have been determined. Pectin in the extract of C. grandis peels not only reduced silver ions but also stabilized nanoparticles, resulting in the formation of AgNPs with a high-pure phase at an absorption maximum of 420 nm. The synthesis process of AgNPs in the absence and presence of different LED lights was also compared under the same synthesis conditions. The presence of LED irradiations was a potential factor to enhance the efficient formation of AgNPs in terms of small particles and high antibacterial efficiency. Blue LED irradiation was found to be the best condition for the synthesis of AgNPs with an average diameter of 14.1 nm. Among tested gram-positive/negative bacteria, the synthesized AgNPs-L exhibited the most effective activity toward Pseudomonas aeruginosa (IC50 = 2.2 pM).