No abstract

The pulsed laser ablation in liquid (PLAL) technique was used to successfully synthesise silver nanoparticles (Ag NPs). With the goal of controlling their size, a laser wavelength of 1064 nm was focused on the Ag bulk target immersed in distilled water in a glass vessel with different laser fluences. The effect of laser fluence, and thus Ag NPs concentration on the bacterial pathogenic was investigated. While the Fourier-transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) patterns confirm the presence of Ag NPs, UV–vis spectrophotometry revealed a significant absorption peak at around 405 nm, which is attributed to the obtained Ag NPs’ characteristic surface plasmon resonance (SPR) peak. The SPR peak shifted towards a shorter wavelength as the laser fluence was increased, indicating that the Ag NPs have reduced in size. The transmission electron microscopy and size distribution images of Ag NPs clearly showed the effects of laser fluence on size reduction of Ag NPs. Bacteria activity was effectively inhibited by the Ag NPs which are found to be more effective against Gram-negative (Escherichia coli) than Gram-positive strains (Streptococcus aureus). PLAL has proven to be an effective method for controlling the size of NPs, which can be used in a variety of applications.