Innovative plasmonic nanostructures generated by laser ablation in liquid solution: magnetic-plasmonic nanoparticles for biomedical applications and Au-Fe nanoalloys with superior plasmon absorption

By a synthetic approach based on laser ablation of a solid target in a liquid solution (LASiS), it is possible to access a library of nanomaterials with plasmonic or magnetic-plasmonic properties, whose surface is easily available to bioconjugation.[1] The surface enhanced Raman scattering (SERS) and/or the magnetic properties allows the development of multifunctional tools for nanomedicine applications, such as the SERS labelling of cancer cells.[2] In this contribution we focus on the special case of magnetic-plasmonic Au-Fe alloy nanoparticles.[3] These nanoalloys show promising performances as multimodal contrast agents for medical imaging with magnetic resonance imaging, x-ray computed tomography and Raman imaging.[4] Besides, we discovered by numerical calculations that the absorption cross section of gold nanoparticles is sensibly increased when iron is included in the lattice as a substitutional dopant, i.e. in a gold-iron nanoalloy.[5] Such increase is size and shape dependent, with the best performances observed in nanoshells where a 90-190% improvement is found in a size range that is crucial for practical applications. This finding is unexpected according to the common believe and previous experimental observations that alloys of Au with transition metals show depressed plasmonic response. Overall, these results show that Au-Fe nanoalloys are attractive  nanostructures with plasmonic and magnetic properties, of special interest for nanomedicine applications, and are promising for the design of efficient plasmonic converters of light into heat. [1] a) V. Amendola, M. Meneghetti; Phys.Chem.Chem.Phys. 2009, 11, 3805-3821; b) V. Amendola, M. Meneghetti, Phys.Chem.Chem.Phys. 2013, 15, 3027-3046; c) V. Amendola, M. Meneghetti, Adv.Funct.Mater. 2012, 22: 353–360; [2] a) M. Meneghetti, A. Scarsi, L. Litti, G. Marcolongo, V. Amendola, M. Gobbo, M. Di Chio, A. Boscaini, G. Fracasso, M. Colombatti, Small, 2012, 8, 3733–3738; b) F. Bertorelle, M. Ceccarello, M. Pinto, G. Fracasso, D. Badocco, V. Amendola, P. Pastore, M. Colombatti, M. Meneghetti; J. Phys. Chem. C 2014, 118, 14534-14541; c) V. Amendola, M. Meneghetti, S. Fiameni, S. Polizzi, G. Fracasso, A. Boscaini, M. Colombatti; Anal. Chem. 2011, 3, 849-856. [3] a) V. Amendola, M. Meneghetti, O. M. Bakr, P. Riello, S. Polizzi, D. H. Anjum, S. Fiameni, P. Arosio, T. Orlando, C. de Julian Fernandez, F. Pineider, C. Sangregorio and A. Lascialfari, Nanoscale, 2013, 5, 5611-5619. b) V. Amendola, S. Scaramuzza, S. Agnoli, S. Polizzi and M. Meneghetti, Nanoscale, 2014, 6, 1423-1433. [4] Amendola, V., Scaramuzza, S., Litti, L., Meneghetti, M., Zuccolotto, G., Rosato, A., Nicolato, E., Marzola, P., Fracasso, G., Anselmi, C., Pinto, M. and Colombatti, M., Small, 2014, 10, 2476–2486. [5] V. Amendola, R. Saija, O. M. Marago, M.A. Iati, Nanoscale, 2015, 7, 8782-8792.