Design of “Green” Plasmonic Nanocomposites with Multi-Band Blue Emission for Ultrafast Laser Hyperthermia

Non-toxic nanoscale materials are widely employed for different healthcare applications but their performance is still considerably limited. In this paper, various approaches of the environment-friendly ultrafast laser processing were employed for remodelling IV group semiconductor nanostructures and synthesizing highly-stable (ξ-potential is up to –47 mV) colloidal solutions of plasmonic (525 nm) nanocomposites with a strong size-dependent chemical content. All nanocomposites exhibited a remarkable lamp-excited multi-band blue emission centred at around 420 nm that is considerably (~10-fold for Au-SiC) stronger for nanocomposites prepared by the laser co-fragmentation technique. The latter formed a larger amount of smaller narrowly-dispersed (~ 4 nm for Au-Si) plasmonic nanostructures as compared to the direct laser ablation. Moreover, it also led to a higher content of semiconductor elements (~1.7-fold for Au-Ge) in nanocomposites correlating with a lower (~ 30 %) electrical conductivity. Aqueous colloidal solutions revealed a higher degree (~ 80 %) of the femtosecond laser-induced heating for all nanocomposites formed by the direct laser ablation. These findings highlight the peculiarities of the used laser processing approaches and considerably facilitate designing of specific multi-modal plasmono-fluorescence (biosensing, bioimaging, hyperthermia) nanocomposites with a required performance significantly enlarging the application area of semiconductor nanostructures.