Development of laser-excited nano-gold and graphene for drug delivery and sensing

We review our experimental and preclinical activities on the exploitation of a light excitation produced by a laser source to "activate" suitable nanotransducers like plasmonic nanoparticles and graphene sheets for applications to drug release and SERS sensing. For drug release, nano-gold and other light-responsive nanomaterials have been employed for the development of an implantable device for on demand chemical release in the form of a light-activated sponge-like scaffold. The photothermal response of the gold nanoparticles contained inside the sponge triggers a contraction in proximal drug-loaded thermosensitive micelles, thus promoting the expulsion of the drug from the sponge in a very controllable and reproducible way. An advanced version of these devices consists in a dispersion of graphene nanosheets in a biopolymer matrix, which is activated by millisecond-long light pulses for confined and precisely dosed drug release. Examples of the potential of organized assemblies of gold and silver nanocubes decorated with a graphene film will be described for the direct Surface Enhanced Raman Scattering (SERS) analysis of proteins and biomarkers. In this regard, we introduce a SERS sensor we engineered for the rapid and reproducible quali-quantitative detection of toxic amyloid oligomers associated with neurodegenerative diseases. The platform consists of an extended bidimensional array of gold concave nanocubes (CNCs) supported on a PDMS film. CNCs are closely-packed through face-face and face-corner interactions generating a monolayered arrangement featuring well distributed nanoholes. Here the protein under analysis experiences a homogeneous E.M.-field enhancement, which causes a large number of vibrations to be contemporarily amplified and thus clearly detectable in the SERS spectrum. Moreover, in order to improve the sensitivity of the sensor, we realized silver nancube assemblies covered with graphene oxide films, which indicated promising applications for versatile SERS detection of complex proteins.