3D halide perovskites used in light emitters and PV systems exhibit an unusual anharmonicity, which is not accounted for in nowadays descriptions of phonons and electron-phonon coupling. Therefore, the low frequency lattice vibrations and relaxations were investigated in single crystals of the four 3D hybrid organolead perovskites, MAPbBr3, FAPbBr3, MAPbI3, and FAPbI3, at the Brillouin zone center using Raman and Brillouin scattering and at the zone boundary using inelastic neutron scattering. The temperature dependence of the PbX6 lattice modes in the four compounds can berenormalized into universal curves and no soft vibration is observed excluding a displacive-like transitional dynamics related to structural phase transitions. The reorientational (pseudospin) motions of the molecular cations exhibit a seemingly order-disorder character recalling that of plastic crystals, but attributed to a secondary order-parameter. At ultra-low frequency, a quasi-elastic component evidenced by Brillouin scattering and associated to the unresolved central peak observed in neutron scattering, is attributed to center of mass anharmonic motions and rattling of the molecular cations in the perovskite cavities. 3D halide perovskites are therefore in a very unusualsituation where anharmonicity prevails. It is leading to partial, extensive and ultraslow critical and stochatic dynamics connected to structural instabilities. The extensive disorder of the lattice at normal operation temperatures for devices is similar to premelting where only long-range acoustic normal modes survive.

Lattice dynamics in 3D lead halide hybrid perovskites is analyzed together with the possible consequences for device applications

Pancreatic cancer is one of the deadliest cancers with an increasing incidence due to a lack ofearly-stage diagnostics and effective treatment [1]. The RAS/RAF/ MAPK/CDK4 pathway is frequentlydysregulated in pancreatic cancer and CDK4 constitutes an attractive target since several drugs havebeen approved by the FDA to inhibit its activity: Abemaciclib, Ribociclib and Palbociclib [2,3] (Figure1) However these inhibitors are not efficient in monotherapy and have only been approved for breastcancer. In order to propose an efficient therapeutic strategy to target CDK4 in pancreatic cancer, wepropose to deliver Abemaciclib using carbon nanotubes.
Carbon nanotubes are promising materials for nanomedicine applications and especially fordrug delivery. [4] In this project, we adsorb Abemaciclib onto single-walled carbon nanotubes (SWNT)for delivery of the drug into pancreatic cancer cells. In order to study adsorption, we investigate thechanges in the optical signatures of SWNTs in the near-infrared (NIR) by coupling NIR absorption,photoluminescence and Raman spectroscopies. [5] Typical kinetic spectroscopic results, assigned tothe adsorption of Abemaciclib on SWNT, dispersed in water using carbomethylcellulose (CMC), arepresented in Figure 2. We discuss the results in terms of changes of the dielectric environment of thenanotubes, leading to modulation of their excitonic and optical properties. We have furtherinvestigated the inhibitory potential of SWNT-Abemaciclib on proliferation of PANC1 cells comparedto Abemaciclib alone and have determined the toxicthreshold of SWNT dispersed in CMC.

Poly(N-isopropyl acrylamide) (PNIPAM) is a thermo-responsive polymer which undergoes a reversible coil-to-globule transition in water at temperatures close to the human body temperature [1]. Consequently, PNIPAM-based microgels show a volume phase transition (VPT) under heating. Photo-responsive hybrid microgels have been prepared by incorporating gold nanoparticles in PNIPAM microgels [2]. The outstanding photo-thermal and optical properties of single-walled carbon nanotubes (SWNTs) make them promising candidates to prepare multi-responsive hybrid microgels. However, no thorough studies have been reported so far.
In this work, we report the preparation and properties of aqueous dispersions of PNIPAM/SWNTs hybrid microgels (Figure 1a). We study their structure by transmission electron microscopy and dynamic light scattering. We investigate their optical properties and changes when heated at the VPT by near infrared (NIR) absorption, Raman and photoluminescence (PL) spectroscopies [3]. Furthermore, we use optical microscopy (Figure 1b), light scattering and NIR Raman/PL spectroscopy to show that the VPT transition can be triggered by NIR photo-thermal excitation.

We present a phase-shifting digital holographic microscopy technique, where a digital micromirror device enables to perform a precise phase-only shift of the reference wave. By coupling the beam into a monomode fiber, we obtain a laser mode with a constant phase shift, equally acting on all pixels of the hologram. This method has the advantage of being relatively simple and compatible with high frame rate cameras, which makes it of great interest for the observation of fast phenomena. We demonstrate the validity of the technique in an off-axis configuration by imaging living paramecia caudata.