1 Comparative study of physicochemical and 2 antibacterial properties of ZnO nanoparticles prepared 3 by laser ablation of Zn target in water and air 4

Here, we report on ZnO nanoparticles (NPs) generated by nanosecond pulsed laser 16 (Nd:YAG, 1064 nm) through ablation of metallic Zn target in water and air and their comparative 17 analysis as potential nanomaterials for biomedical applications. The prepared nanomaterials were 18 carefully characterized in terms of their structure, composition, morphology and defects. It was 19 found that in addition to the main wurtzite ZnO phase, which is conventionally prepared and 20 reported by others, the sample laser-generated in air also contained some amount of monoclinic 21 zinc hydroxynitrate. Both nanomaterials were then used to modify model wound dressings based 22 on biodegradable poly-L-lactic acid. The as-prepared model dressings were tested as biomedical 23 materials with bactericidal properties towards S. aureus and E.coli strains. The advantages of the 24 NPs prepared in air over their counterparts generated in water found in this work are discussed. 25