Nanopartículas coloidais de ouro e platina produzidas por ablação a laser de pulsos nano e picossegundo - efeitos de size quenching induzidos por íons e pH

Abstract

Nanoparticles produced by laser ablation of solids in liquid environment (PLAL) have been proposed as an alternative to the nanoparticles produced by chemical synthesis routes. By this method, nanoparticles are synthesized by laser radiation on a solid target in a liquid medium. The advantage of this method is the possibility of producing particles without needing to add any stabilizers and also without residual chemical precursors. Hence, the use of toxic substances which may occasionally adsorb onto the nanoparticle surface is avoided. Produced ligand-free nanoparticles allows applications in the field of biomedicine and catalysis. In the present work, gold and platinum nanoparticles were synthesized by PLAL using nanosecond and picosecond lasers. Different synthesis parameters were applied. Samples were characterized by UV-vis spectroscopy and disc centrifuge (CPS®). The influence of electrolytes on gold nanoparticles stability by electrostatic repulsion was confirmed by observation of solutions with ionic strength values from 0,001 to 10 mM. Size quenching effects were also observed for different synthesis parameters. For ionic strength values in the range of 0,1 to 3 mM nanoparticles synthesized with NaOH were in the size range of 6,68 to 9,15 nm with nanosecond laser and of 6,8 to 10,6 nm with picosecond laser. For synthesized samples with NaCl, particles sizes were between 5,17 and 7,1 nm and 5 to 6,22 using a nanosecond and a picosecond laser, respectively.