Ternary compounds of transition metal dichalcogenides are emerging as an interesting class of crystals with tunable electronic properties, which make them attractive for nanoelectronic and optoelectronic applications. Among them, Mo x W1–x S2 is one of the most studied alloys due to the well-known and remarkable features of its binary constituents, MoS2 and WS2. The band gap of this compound can be modeled varying Mo and W percentages in the sample, and its vibrational modes result from a combination of MoS2 and WS2 phonons. In this work, we report transmission measurements on a Mo0.5W0.5S2 single crystal in the far-infrared range. Absorbance spectra collected at ambient conditions enabled for the first time a classification of the infrared-active phonons, complementary to Raman studies. High-pressure measurements allowed the study of the evolution of both the lattice dynamics and the free carrier density up to 31 GPa, suggesting the occurrence of an isostructural semiconductor-to-metal transition above 18 GPa, in very good agreement with the theoretical calculation reported in the literature.

The demand for next-generation multifunctional nanovectors, combining therapeutic effects with specific cellular targeting, has significantly grown during the last few years, pursuing less invasive therapy strategies. Polyphenol-conjugated silver nanoparticles (AgNPs) appear as potential multifunctional nanovectors, integrating the biorecognition capability and the antioxidant power of polyphenols, the antimicrobial activity of silver, and the drug delivery capability of NPs. We present a spectroscopic and microscopic investigation on polyphenol-synthesized AgNPs, selecting caffeic acid (CA) and catechol (CT) as model polyphenols and using them as reducing agents for the AgNP green synthesis, both in the presence and in the absence of a capping agent. We exploit the plasmonic properties of AgNPs to collect Surface-Enhanced Raman Scattering (SERS) spectra from the nanosized region next to the Ag surface and to characterize the molecular environment in the proximity of the NP, assessing the orientation and tunable deprotonation level of CA, depending on the synthesis conditions. Our results suggest that the SERS investigation of such nanovectors can provide crucial information for their perspective biomedical application.

Amyloid-β peptide (Aβ) aggregates are known to be correlated with pathological neurodegenerative diseases. The fibril formation process of such peptides in solution is influenced by several factors, such as the ionic strength of the buffer, concentration, pH, and presence of other molecules, just to mention a few. In this paper, we report a detailed analysis of in vitro Aβ42 fibril formation in the presence of cortisol at different relative concentrations. The thioflavin T fluorescence assay allowed us to monitor the fibril formation kinetics, while a morphological characterization of the aggregates was obtained by atomic force microscopy. Moreover, infrared absorption spectroscopy was exploited to investigate the secondary structure changes along the fibril formation path. Molecular dynamics calculations allowed us to understand the intermolecular interactions with cortisol. The combined results demonstrated the influence of cortisol on the fibril formation process: indeed, at cortisol-Aβ42 concentration ratio (ρ) close to 0.1 a faster organization of Aβ42 fragments into fibrils is promoted, while for ρ = 1 the formation of fibrils is completely inhibited.