The vibrational dynamics of cyclodextrin nanosponges (CDNS), a new class of nanostructured soft materials synthesized via cross-linking reaction of natural cyclic oligosaccharide β-cyclodextrin (β-CD) with suitable organic reagents, is investigated by means of the combined use of Raman and infrared spectroscopy, supported by numerical simulations. The vibrational spectra of the polymers show significant changes in the frequency ranges 3000–3700 and 1500–1800 cm–1 correlated to the relative amount of cross-linker with respect to monomeric CD. By using band deconvolution and best-fit procedure of the experimental data and quantum chemical computations, a correlation between such changes and the degree of cross-linking of the polymeric network is proposed. This experimental–numerical approach, here applied to a model class of nanoporous polymeric systems, appears to be of general application for the study of polymeric matrixes of interest for biolife applications.

An integrated experimental approach, based on inelastic light-scattering techniques, has been here employed for a multilength scale characterization of networking properties of cyclodextrin nanosponges, a new class of cross-linked polymeric materials built up from natural oligosaccharides cyclodextrins. By using Raman and Brillouin scattering experiments, we performed a detailed inspection of the vibrational dynamics of these polymers over a wide frequency window ranging from gigahertz to terahertz, with the aim of providing physical descriptors correlated to the cross-linking degree and elastic properties of the material. The results seem to suggest that the stiffness of cross-linked polymers can be successfully tuned by acting on the type and the relative amount of the cross-linker during the synthesis of a polymer matrix, predicting and controlling their swelling and entrapment properties. The proposed experimental approach is a useful tool for investigating the structural and physicochemical properties of polymeric network systems.

Hydrogen peroxide to propylene oxide (HPPO) reaction is an attractive process exploiting titanium silicalite-1 (TS-1) as a catalyst in combination with aqueous hydrogen peroxide as an oxidizing agent. Beyond the industrial interest, TS-1 represents one of the most widely characterized catalysts due to its unique properties. However, a unified description on the speciation of the different Ti species and their correlation to catalytic performances is missing in the literature. This work aims to exploit spectroscopic techniques (namely, diffuse reflectance UV–vis, Raman, FT-IR, and Ti K-edge XANES) in a qualitative and quantitative way to thoroughly characterize Ti sites in a selected set of industrially relevant TS-1 samples, each one owning a peculiar Ti speciation. The outcomes of this study have been then related to the activity of each catalyst in HPPO reaction, showing its linear correlation with the content of perfect Ti sites (i.e., isomorphously substituting Si in the zeolitic framework). Other Ti species, such as amorphous TiO x and bulk titania, are instead not involved in the peroxide conversion (neither in a detrimental way).

The vibrational dynamics of a new class of cross‐linked polymers obtained from both native and modified cyclodextrin, referred to as cyclodextrin nanosponges, is here investigated. The main purpose is to spot the structure of these materials at molecular level unlikely to be characterized by diffraction methods due to the low or null degree of crystallinity. The analysis of the spectral features of the vibrational bands observed between 1650 and 1800 cm−1 in both Raman and infrared spectra, and assigned to the carbonyl stretching modes of the polymeric network, is performed by using band deconvolution procedures. At the same time, a detailed inspection of the low‐wavenumber vibrational dynamics of these polymers is carried out, focusing on the modifications occurring on the so‐called boson peak. The simultaneous analysis of different wavenumber ranges in Raman and infrared spectra of cyclodextrin nanosponges allows us to develop a reliable strategy for exploring both the cross‐linking degree and the elastic properties of these innovative materials. The overall results give a complete characterization of the structural and dynamical properties of the system, in turn strictly connected to the entrapment/transport ability of these polymeric matrices. Copyright © 2013 John Wiley & Sons, Ltd.

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The phase transition from gel to liquid suspension in cyclodextrin (CD)-based hydrogels is in depth monitored by using Fourier transform infrared spectroscopy in attenuated total reflectance geometry. Cyclodextrin nanosponges (CDNS) synthesized by polymerization of CD with the cross-linking agent ethylenediaminetetraacetic dianhydride at different cross-linking agent/CD molar ratios have been left to evolve from gel phase into liquid suspension upon gradual increase of the hydration level. Measurements of the changes occurring in the vibrational dynamics of the system during this transition provide direct evidence of the gel-sol progress of the CNDS hydrogel, by accounting for the connectivity pattern of water molecules concurring to the gelation process. The experimental results clearly indicate that the increase of the hydration level is accompanied by the corresponding increase of the population of H2O molecules engaged in high-connectivity hydrogen-bond networks. The water tetrahedral arrangement is thus dominant above a characteristic cross-over hydration level, experimentally determined for all the investigated samples. The observation of this characteristic cross-over point for the CDNS hydrogel and its correlation with other parameters of the system (e.g. the absorption ability of CDNS and elasticity of the polymer matrix) is, once again, modulated by the cross-linking agent/CD molar ratio. The latter seems indeed to play a key role in defining the nano- and microscopic properties of nanosponge hydrogels.

We report on the use of the UV Raman technique to monitor the oxidative damage of deoxynucleotide triphosphates (dATP, dGTP, dCTP and dTTP) and DNA (plasmid vector) solutions. Nucleotide and DNA aqueous solutions were exposed to hydrogen peroxide (H2O2) and iron containing carbon nanotubes (CNTs) to produce Fenton's reaction and induce oxidative damage. UV Raman spectroscopy is shown to be maximally efficient to reveal changes in the nitrogenous bases during the oxidative mechanisms occurring on these molecules. The analysis of Raman spectra, supported by numerical computations, revealed that the Fenton's reaction causes an oxidation of the nitrogenous bases in dATP, dGTP and dCTP solutions leading to the production of 2-hydroxyadenine, 8-hydroxyguanine and 5-hydroxycytosine. No thymine change was revealed in the dTTP solution under the same conditions. Compared to single nucleotide solutions, plasmid DNA oxidation has resulted in more radical damage that causes the breaking of the adenine and guanine aromatic rings. Our study demonstrates the advantage of using UV Raman spectroscopy for rapidly monitoring the oxidation changes in DNA aqueous solutions that can be assigned to specific nitrogenous bases.