Phytosynthesis and radiation-assisted methods for obtaining metal nanoparticles

Metallic nanoparticles represent an important area of research, as their unique properties can be tuned for the desired application. Several "green" methods were proposed for obtaining metallic nanoparticles, including phytosynthesis (using natural extracts) and radiation-assisted synthesis. The present work studies the differences in terms of biological properties (antimicrobial properties, cytotoxicity and phytotoxicity) of silver nanoparticles obtained using those two very different approaches. The obtained nanoparticles were analytically characterized using transmission electron microscopy, X-ray diffraction and UV-Vis spectrometry, for the evaluation of their morphological properties, which can be linked to their biological properties. The results showed that the radiation-assisted path led to smaller dimension nanoparticles (7-10 nm), while the phytosynthesis led to nanoparticles with 10-12 nm in diameter (as determined by XRD), depending on the used materials. The phytosynthesized nanoparticles seemed to be more effective antimicrobial agents (effect studied against Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853 and Candida albicans ATCC 10231), while those obtained by the radiological path had a stronger mitoinhibitory effect. The growth of the root and of the stem was less affected by the samples containing radiological synthesized nanoparticles. The differences in terms of biological activity observed when modifying the agents used for the reduction of the metallic salt are also discussed.