cyclodextrin nanosponges (CDNS) are cross-linked polymers synthetized by condensation reaction of the OH groups of the glucose units of cyclodextrins (CD) with a poly-functional cross-linker agent (CL). The reaction of polymerization leads to the formation of a three-dimensional network of CD units showing both hydrophilic and hydrophobic nano-sized cavities. These polymers are safe and biodegradable material with negligible toxicity on cell cultures and they are considered to exhibit superior inclusion ability with respect to native CD by incorporating a large class of molecules within their structure. Recently, we applied variable contact time (VCT) 1H-13C CP/MAS NMR techniques as powerful investigating tool for CDNS in the solid state. Such approach provided us with two relaxation parameters, TCH, the cross-relaxation time, and T1 , the spin lattice relaxation of the protons in the rotating frame. Both parameters are affected by the local dynamics and thus are suitable descriptors for the local motion. This approach can be conveniently extended to the study of the dynamics of encapsulated molecules within the polymeric network of nanosponges. In this contribution, we present the results of solid-state NMR experiments aimed at providing an atomic length scale description of the chemical-physical interactions that regulate the molecular encapsulation of a model drug inside the CDNS polymer network. In particular, important structural and dynamical information will be extracted by the study of the dynamics of the cross-polarization (CP) process applied to the case study of Ibuprofen sodium salt encapsulated in CDNS, in dry state. As a matter of fact, CP experiments are particularly sensitive to the inter-nuclear distances and to the mobility of molecules of functional groups involved. The results reported in this contribution are of particular interest because the knowledge and control of the guest- polymer interactions in solid phase is a fundamental preliminary step in view of the possibile use of CDNS as scaffold in specific pharmaceutical formulations.
Relaxation properties of a drug model in cyclodextrin-based cross-linked polymers by solid-state NMR spectroscopy
W Panzeri;
2015
Abstract
cyclodextrin nanosponges (CDNS) are cross-linked polymers synthetized by condensation reaction of the OH groups of the glucose units of cyclodextrins (CD) with a poly-functional cross-linker agent (CL). The reaction of polymerization leads to the formation of a three-dimensional network of CD units showing both hydrophilic and hydrophobic nano-sized cavities. These polymers are safe and biodegradable material with negligible toxicity on cell cultures and they are considered to exhibit superior inclusion ability with respect to native CD by incorporating a large class of molecules within their structure. Recently, we applied variable contact time (VCT) 1H-13C CP/MAS NMR techniques as powerful investigating tool for CDNS in the solid state. Such approach provided us with two relaxation parameters, TCH, the cross-relaxation time, and T1 , the spin lattice relaxation of the protons in the rotating frame. Both parameters are affected by the local dynamics and thus are suitable descriptors for the local motion. This approach can be conveniently extended to the study of the dynamics of encapsulated molecules within the polymeric network of nanosponges. In this contribution, we present the results of solid-state NMR experiments aimed at providing an atomic length scale description of the chemical-physical interactions that regulate the molecular encapsulation of a model drug inside the CDNS polymer network. In particular, important structural and dynamical information will be extracted by the study of the dynamics of the cross-polarization (CP) process applied to the case study of Ibuprofen sodium salt encapsulated in CDNS, in dry state. As a matter of fact, CP experiments are particularly sensitive to the inter-nuclear distances and to the mobility of molecules of functional groups involved. The results reported in this contribution are of particular interest because the knowledge and control of the guest- polymer interactions in solid phase is a fundamental preliminary step in view of the possibile use of CDNS as scaffold in specific pharmaceutical formulations.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
