UV Resonance Raman (UVRR) scattering offers several advantages with respect to spontaneous Raman one, such as the significant increment of the detection limit and the selectivity needed to incisively monitor specific chromospheres within the sample. Here we present a synchrotron-based Resonance Raman instrument that exploits the wide and continuously tunable UV emission provided by the synchrotron source. As an example, we discuss the solvation dynamics of two model peptides, N-acetyl-leucine-methylamide (NALMA) and N-acetyl-glycine-methylamide (NAGMA), by putting in evidence on the advantages of the use of SR-based UVRR. The experimental results evidence that the fine tuning of the excitation wavelength allows to choose the best working conditions that ensure to reliably detect the spectral changes of the amide signals, as function of concentration and temperature of peptide. The analysis of the spectra provides new insights on the hydrogen-bond interactions at the peptides backbone.
Although Deoxyribonucleic acid (DNA) is considered substantially stable in aqueous solution, slow hydrolysis can damage its double-helix structure and cause denaturation when it is stored for several months. Therefore, the design of aqueous solvents that are able to stabilize and maintain DNA conformation is a challenging issue. Ionic liquids (ILs) appear as ideal water co-solvents for DNA biotechnology due to their unique properties. We have investigated the thermal stability of DNA in 1-butyl-3-methylimidazolium aqueous solutions by synchrotron-based UV Resonance Raman (UVRR) spectroscopy with the aim to clarify the role played by concentration of IL in stabilizing the DNA natural conformation. The synchrotron-based UV source for UVRR measurements allows us to enhance specific vibrational signals associated to nitrogenous bases of DNA, through an appropriate tuning of the excitation wavelength. Such approach permits to probe the rearrangements in the local environment around specific nucleotides as a function of thermal conditions.