Abstract
Objectives of the present study were to evaluate the antibacterial activity of the two types of inorganic magnesium hydroxide [Mg(OH)(2)] and calcium carbonate [CaCO3] nanoparticles (NPs) on the growth of three Gram-negative bacteria, e.g., Escherichia coli, Pseudomonas aeruginosa and Serratia marcescens and three Gram-positive bacteria, e.g., Streptococcus pyogenes, Staphylococcus aureus and Streptococcus bovis. The synthesis of these NPs was done by a microwave hydrothermal method. The structures and sizes of synthesized nanoparticles were investigated using X-ray diffractometer. Antimicrobial susceptibility of different NPs was determined at 20, 50 and 100 mg/mL by the agar-well diffusion method, growth reduction at the aqueous solution and time-kill assay. The antimicrobial effects across NPs and bacterial species were shown to be dose-dependent. The results of the different experiments indicated that smaller NP sizes have higher antibacterial effects. M29 [Mg(OH)(2)-29] nanoparticles followed by silver (Ag) and C1 (CaCO3-1) showed the highest influence on bacterial growth rates, while similar ability to kill bacteria across treatment time. In addition, Gram-negative bacteria were more affected in terms of the inhibition zone and reduction of growth rates after 24 h as well as in terms of the prolonged treatment of NPs up to 36 h due to the influence of different nanoparticles. We recommend to search the chance of further using M29 and C1 in medicine and industry.