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2021-05-20
Colloquia 2021: Mariacristina Gagliardi
11:00 - 12:00
Date and Time: Thursday 20 May 2021 - 11:00
Streaming at: https://meet.google.com/tcu-rsiq-dfb
Once connected, please switch off your microphone and camera.
If you have questions, please use the chat to ask for attention.
Speaker: Mariacristina Gagliardi (NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore)
Title: Polymer nanoparticles for brain targeting
Abstract: Krabbe disease (KD) is a lysosomal storage disorder (LSD) caused by a deficient activity of the enzyme galactosylceramidase (GALC). An impaired GALC activity causes increased psycosine (PSY) levels in neural tissues, leading to a widespread degeneration of glial cells and demyelination. While KD causes early mortality (within 2 years after birth), an effective cure is still lacking. The ideal therapeutic approach would be the systemic administration of the enzyme. This approach fails because of the blood brain barrier (BBB) hampering GALC translocation toward the central nervous system (CNS). A winning strategy is to exploit targeted nanovectors capable of inducing GALC transcytosis across the BBB.
In the present work, we developed a new delivery platform based on polymeric degradable reversed micelles (RMs) loaded with GALC and targeted to cross the BBB. RMs are produced with the amphiphilic di-block copolymer methoxy polyethylene glycol-block-poly(lactide-co-glycolide) (mPEG-b-PLGA). The copolymer is functionalized with chemical units suitable for the application. RMs are externally crosslinked to improve their physical stability and GALC retention without affecting degradation and biocompatibility. The conjugation of the ligand Angiopep-2 endows RMs with targeting capabilities toward the CNS. RMs opportunely formulated are administered in vivo in the murine model of KD, the Twitcher (TWI) mouse, via retro-orbital administration. Mice are sacrificed at fixed times after the treatment to evaluate the enzymatic activity recovery. Results show high RMs stability, and a good biocompatibility of the administered formulation. Enzymatic activity recovery is around 10% in respect to that measured in healthy mice. This is a suitable value for KD treatment. In conclusion, the developed system shows some potential and could be considered a good candidate for the KD treatment.
Host:
Fabio Taddei (9038) - fabio.taddei@nano.cnr.it
Stefan Heun (9472) - stefan.heun@nano.cnr.it
FIM-S3 SEMINAR - Dr Thibault Sohier
16:00 - 17:00
Date and Time: Thursday May 20th, 16:00 (SHARP)
Link (Google Meet): https://meet.google.com/yud-upbp-mno
Speaker: Dr Thibault Sohier -
University of Liège (Belgium)
Title: Electron-phonon interactions in transition metal dichalcogenides. Effects of doping and valley structure
Abstract:
Owing to the multi-valley and spin-textured nature of their electronic structure, semiconducting transition-metal dichalcogenides (TMDs) offer the possibility for a combined manipulation of charge, spin, and valley degrees of freedom, leading to fascinating fundamental physics and technological prospects. Charge, spin and valley transport all depend on the scattering of carriers by phonons. In parallel, further control of those degrees of freedom is often achieved via electrostatic doping.
Thus, it is essential to understand the interplay between electronic structure, doping and electron-phonon interactions in TMDs. Density functional theory and analytical models are used to build an extensive and predictive model of electron-phonon scattering as a function of valley structure and doping.
Intervalley scattering depends on doping mostly via the position of the Fermi level with respect to the different valleys and the associated energy selection rules. Intravalley scattering, however, displays a rather complex doping dependency via two kinds of electronic screening depending on the phonon perturbation. The first is the standard free carrier screening which reduces the coupling as carrier density increases. In contrast, the second surprisingly leads to an enhanced electron-phonon interaction at high doping, when multiple valleys are occupied. The impact of those mechanisms on the physical properties of TMDs is illustrated by computing the mobility of semiconducting TMDs and showing large variations as a function of doping and valley structure.
Host:Marco Gibertini (FIM, UNIMORE) and Claudia Cardoso (S3, CNR-NANO)
Flyer