Plasmons are electromagnetic modes associated with the coherent excitation by photons of the free electrons at the interface between a metal and a dielectric material. Their extremely sensitivity to the geometry of the metallic nanostructures allows an extensive tuning of both the spectral properties and associated electromagnetic field distribution by appropriate structural design. In fact, plasmons can be usefully coupled to hybrid organic/inorganic as well as gain materials in order to enhance several optical properties of the nanostructures, e.g. coupling strength, losses mitigation, light to heat conversion on the nanoscale).
Main topic here is to study the interplay between gain media and plasmon elements in metamaterials for visible light. The exciton-plasmon dynamics arising by specific coupling configurations has been the core of scientific discussions and experimental studies to explain extraordinary physical processes. In fact, the plasmon-gain coupling has been proposed as a challenging solution to tackle and solve the unavoidable issue of optical losses in metal-based nanostructures with plasmonic resonances at optical frequencies. The fascinating ability of metal nanostructures to localize light at scales much shorter than visible wavelengths is accompanied by enormous ohmic losses, with direct consequences as the remarkable increasing of the extinction cross section of the material. This implies that extraordinary physical properties related to light localization effects at the nanoscale cannot be harnessed to design optical materials because of the strong radiation damping. The idea to bring gain molecules in close proximity to metallo-dielectric nanostructures is based on coherent effects of excitation energy transfer between resonant bands of the two materials. It is well known that relevant modifications of the fluorescence of dye molecules placed in close proximity to metal NPs are due to mutual interactions with NPs surface plasmons, including resonant energy transfer (RET).
The research strategies reported here deal with cross-disciplinary approaches that involve design and tailoring of electromagnetic properties, materials preparation, advanced experimental studies and theoretical modeling. Materials functionalization and experimental investigations, like time-resolved and transient absorption spectroscopy, spectrophotometry and spectroscopic ellipsometry, are only a few of the experimental techniques utilized to study how gain-plasmon dynamics can be directed to mitigate optical losses across scales.
Plasmonic photothermal therapy (PPTT) is a minimally-invasive oncological treatment strategy in which photonenergy is selectively administered and converted into heat sufficient to induce cellular hyperthermia. To this end, Plasmonic metallic nanoparticles (NPs) are a particular class of nanomaterials which possess the capability to localize light down to the nanoscale by exploiting a phenomenon called Localized Plasmon Resonance (LPR). NPs have been used in therapeutics by triggering drug release or enhancing ablation of diseased tissues, while minimizing damage to healthy tissues. We have performed a Scanning Electron-Microscopy (SEM) characterization of an immortal cell line used in scientific research called “HeLa cell”. The breakthrough idea is based on the possibility to deliver NPs in the tumor site and by exploiting the efficient conversion of Near Infrared (NIR) light to heat opens up a new “drug-free” cancer therapy.
Gene delivery is the process of introducing foreign DNA, RNA into host cells as potential therapeutic strategies for various diseases by means of a nano-vehicle. In particular, the properties of an ideal non-viral vector are: low degradation, target specific cells avoiding immune response in the patient. One of the most promising alternative technologies for gene theraphy is the use of NPs as delivery vehicles. The optical properties of NPs and their biocompatibility provide an efficient tool like non-viral vector for gene therapy. We have combined NPs and a human whole genomic DNA exploiting the possibility to realize applications on the Plasmonic Gene Theraphy (PGT). We have characterized the interaction between NPs and nucleic acids of different length by using analytical techniques, such as electrophoretic mobility assay and scanning electron-microscopy.
Scanning Electron-Microscopy (SEM); Electrophoretic mobility assay; Zeta-potential mesaures.
Collaborators: Luciano De Sio, Nelson Tabirian – Beam Engineering for Advanced Measurements Company, Florida , USA; Giulio Caracciolo, Daniela Pozzi – Dipartimento di Medicina Molecolare, Università La Sapienza, Roma; Tiziana Placido, Roberto Comparelli, Maria Lucia Curri – CNR-IPCF Istituto per i Processi Chimici e Fisici, Sez. Bari, c/o Dip. Chimica, Bari; Angela Agostiano – Università degli Studi di Bari, CNR-IPCF Istituto per i Processi Chimici e Fisici, Bari
POLAFLOW: Polariton condensates: from fundamental physics to quantum based devicesStarting Grant ,FP7 – IDEAS – ERC-2012-StG, panel PE2 (2012-2017)
Gain-Plasmon Coupling in Metal-Dielectric Nanostructures: Loss Compensation towards Laser Action, PRIN 2012