Scuola di dottorato
Università degli Studi di Milano-Bicocca
Mercoledì 3 dicembre 2014 – ore 15.00
Aula seminari U5, via Cozzi 55 – 20125 Milano
Noble metal nanoparticles and
coordination complexes for materials and
devices in nanomedicine
Piersandro Pallavicini
inLAB - Dipartimento di Chimica Generale, Università di Pavia
Coordination compounds are used for nanomedical applications by forming covalently-grafted monolayers of
ligands and complexes on bulk surfaces, that imparts them antimicrobial properties against Gram+ and Grambacterial strains. Layer-by-layer growth techinques are exploited to further graft on the same complexes or on
suitably terminated molecular monolayers spherical silver and star-shaped gold nanoparticles (GNS), that can in
turn be over-coated by grafting molecular species. Monolayers of silver nanoparticles exert an antibacterial action
both by Ag+ release and by a direct interaction on the bacteria membranes. Monolayers of GNS exploit a further
valuable feature: gold nanostars have localized surface plasmon resonances in the bio-transparent Near IR range
(750-950 nm) that once irradiated thermally relax with huge local temperature jumps. Materials capable of induce
through-tissues photothermal death in floating bacteria and on biofilms have been prepared with such an
approach and new-generation mixed gold-silver antibacterial surfaces are presented.
Gold nanostars are used for biomedical applications also as their colloidal solutions, provided that they are coated
with stable and biocompatible polymers that allows in-vivo delivery. Negligible intrinsic cytoxicity is found when
GNS interact either with tumoral or non-tumoral cell strains, while their two-photon luminencence (NIR
irradiation) allows in-vitro and potential in-vivo tracking. GNS photothermal properties are used for localized
hyperthermal treatments of tumour cells. Positively charged coatings allows GNS loading with negatively charged
polymeric drugs such as siRNA, whose delivery may act sinergetically with photothermal treatments. Finally, GNS
can be co-coated with empty ligands suitable for strongly binding 64Cu2+ cations, this opening the path for
theranostic devices capable of simultaneous tracking, imaging (by PET) and photothermal treatment.
Examples of all these topics are illustrated in the talk, with particular attention to aspects typically neglected in
nanomedical applications such as coating stability with temperature and medium, quantitative determination of
surface concentrations of coatings in bulk or nanosurfaces, reproducibility in preparations.
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