Raman spectroscopy uses visible light to acquire vibrational fingerprints of molecules, thus making it a powerful tool for chemical analysis in a wide range of media. Its potential for optical imaging at high resolution is, however, severely limited by the fact that the Raman effect is weak. Here, we report the discovery of a giant Raman scattering effect from encapsulated and aggregated dye molecules inside single-walled carbon nanotubes (SWNTs). Measurements performed on rod-like dyes, such as α-sexithiophene and βcarotene, assembled inside SWNTs as highly polarizable J-aggregates indicate a resonant Raman cross-section (CS) of ~10-21 cm 2 /sr, which is well above the CS required for detecting individual aggregates at the highest optical resolution. Free from fluorescence background and photobleaching, this giant Raman effect allows the realization of a library of functionalized and biocompatible nanoprobe labels for Raman imaging with robust detection using multispectral analysis.

It has been shown that mixtures of monoalkylated amphiphiles and sterols can form liquid-ordered (lo) lamellar phases. These bilayers can be extruded using conventional methods to obtain large unilamellar vesicles (LUVs) that have very low permeability and a specific response to a given stimulus. For example, pH variations can trigger the release from LUVs formed with palmitic acid and sterols. In the present work, the possibility to form non phospholipid liposomes with mixtures of stearylamine (SA) and cholesterol (Chol) was investigated. The phase behavior of these mixtures was characterized by differential scanning calorimetry, infrared, and (2)H NMR spectroscopy. It is found that this particular mixture can form a lo lamellar phase that is pH-sensitive as the system undergoes a transition from a lo phase to a solid state when pH is increased from 5.5 to 12. LUVs have been successfully extruded from equimolar SA/Chol mixtures. Release experiments as a function of time revealed the relatively low permeability of these systems. The fact that the stability of these liposomes is pH dependent implies that these LUVs display an interesting potential as new cationic carriers for pH-triggered release. This is the first report of non phospholipid liposomes with high sterol content combining an overall positive charge and pH-sensitivity.

imaging is presented as a powerful method to acquire quantitative as well as qualitative information on lowdimensional materials. The method is, however, not widely used due to limitations of the Raman scanning instruments. Here we present a hyperspectral Raman system based on Bragg tunable filtering that is capable of global imaging with significantly reduced acquisition time and improved sensitivity compared to scanning confocal Raman microscopes. The operation principles of the instrument are presented, and the performance is benchmarked using a calibrated carbon nanotube sample. Examples of various applications are shown to illustrate the abilities of the technique to characterize samples deposited on oxidized silicon substrates, including graphene stacks prepared by chemical-vapor deposition, exfoliated MoS 2 , and carbon nanotubes filled with dye molecules. The wealth of information available through this hyperspectral Raman imaging technique opens many new ways to probe the properties of complex low-dimensional materials.