Composite Liquid Media Influence on the Optical and Bactericidal Properties of Silver Nanoparticles Synthesized by Pulsed Laser Ablation in Liquids

Abstract

Pulsed laser ablation in liquid (PLAL) is a convenient, single step and green method for nanomaterial synthesis. Controlling nanoparticle size is crucial for various scientific and technological applications. In this paper, the effect of mixing ratio of composite liquid media and laser pulse energy on size distribution of silver nanocollides was exhibited. Mixing ratio of blend of high and low viscosity fluids—ethylene glycol and deionized water—was varied in the range from 0% to 100%. Additionally, the impact of laser pulse energy on AgNP size was explored while keeping the mixing ratio constant. Properties of the particles, including morphology, size, and plasmonic behavior, were examined using SEM, EDX, and optical absorption spectroscopy, and the underlying mechanisms are discussed. The colloids were of spherical shape and showed surface plasmon resonance around 400 nm. The size of the nanoparticle appeared to vary from 15 nm to 86 nm by increasing the concentration of ethylene glycol in the mixture. A similar effect was observed with the laser energy: the particle size increased from 24 nm to 75 nm as the laser energy was varied from 70 mJ to 150 mJ. The nanocolloids were also effective as antibacterial agents against Gram-positive and Gram-negative bacteria: the small-sized particles showed higher toxicity compared to the large particles. In addition to the laser energy, variation in nanoparticle size distribution by the interplay of mixing ratio of the liquid media is an interesting aspect of the findings.