title: Guest-matrix interactions affect the solvation of cyclodextrin-based polymeric hydrogels: a UV Raman scattering study.
abstract: The focus of the present work is to shed light on possible modifications of the molecular properties of polysaccharide hydrogels induced by the establishment of specific non-covalent interactions during the loading of a guest compound inside the gel phase. With this aim, a case study of the encapsulation of caffeine (Caf) inside cyclodextrin-based hydrogels, namely, cyclodextrin nanosponges (NS), is systematically investigated here by using UV Raman scattering experiments. The UV Raman spectra of the hydrogels, analysed as a function of temperature, concentration of the guest molecule loaded in the gel phase and pH, prove particularly informative both on the structural rearrangements of the hydrophobic/hydrophilic groups of the polymeric network and on the breaking/formation of specific guest-matrix interactions. Analysis of the temperature dependence of dynamical parameters, i.e., the dephasing time associated with specific vibrational modes of the polymer backbone, enables the proposal of a molecular picture in which the loading of Caf in NS hydrogels tends to favour access of the water solvent to the more hydrophobic portions of the polymer matrix, which is in turn reflected in a marked increase in the solvation of the whole system. The achievements of this work appear of interest with respect to the design of new possible strategies for controlling the diffusion/release of bioactive molecules inside hydrogel networks, besides corroborating the potential of UV Raman scattering experiments to give new molecular insights into complex phenomena affecting hydrogel phases.
authors.affiliation: Elettra - Sincrotrone Trieste, Strada Statale 14 km 163.5, Area Science Park, 34149 Trieste, Italy. barbara.rossi@elettra.eu and Department of Physics, University of Trento and INSTM Local Unit, via Sommarive 14, 38123 Povo, Trento, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Rossi
authors.affiliation: Department of Physics and Earth Sciences, University of Messina and INSTM Local Unit, Viale Ferdinando Stagno D'Alcontres 31, 98166 Messina, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Venuti
authors.affiliation: Elettra - Sincrotrone Trieste, Strada Statale 14 km 163.5, Area Science Park, 34149 Trieste, Italy. barbara.rossi@elettra.eu.
authors.forename: F
authors.initials: F
authors.lastname: D'Amico
authors.affiliation: Elettra - Sincrotrone Trieste, Strada Statale 14 km 163.5, Area Science Park, 34149 Trieste, Italy. barbara.rossi@elettra.eu.
authors.forename: A
authors.initials: A
authors.lastname: Gessini
authors.affiliation: Department of Chemistry, Materials and Chemical Engineering "G. Natta", Politecnico di Milano and INSTM local unit, Piazza L. da Vinci 32, 20133 Milano, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Mele
authors.affiliation: Department of Chemistry, Materials and Chemical Engineering "G. Natta", Politecnico di Milano and INSTM local unit, Piazza L. da Vinci 32, 20133 Milano, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Punta
authors.affiliation: Department of Chemistry, Materials and Chemical Engineering "G. Natta", Politecnico di Milano and INSTM local unit, Piazza L. da Vinci 32, 20133 Milano, Italy and Università degli Studi e-Campus, Via Isimbardi 10, 22060 Novedrate, Como, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Melone
authors.affiliation: Department of Physics and Earth Sciences, University of Messina and INSTM Local Unit, Viale Ferdinando Stagno D'Alcontres 31, 98166 Messina, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Crupi
authors.affiliation: Department of Physics and Earth Sciences, University of Messina and INSTM Local Unit, Viale Ferdinando Stagno D'Alcontres 31, 98166 Messina, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Majolino
authors.affiliation: Elettra - Sincrotrone Trieste, Strada Statale 14 km 163.5, Area Science Park, 34149 Trieste, Italy. barbara.rossi@elettra.eu.
authors.forename: C
authors.initials: C
authors.lastname: Masciovecchio