Model of Drug-Loaded Fluorocarbon-Based Micelles Studied by Electron-Spin Induced 19F Relaxation NMR and Molecular Dynamics Simulation

• Published in: Langmuir Vol. 24; no. 3; pp. 692 - 700
• Main Authors: Mathias, Errol V, Liu, Xiangli, Franco, Osmundo, Khan, Imran, Ba, Yong, Kornfield, Julia A
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 05.02.2008
• Subjects: Chemistry; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Micelles. Thin films; Surface physical chemistry; Water; Drug; Molecular structure; Spin; Molecular dynamics; Micelle; Polymer; NMR spectrometry; Fluorocarbon; Hydrophobicity; Colloidal gel; Ethylene oxide polymer; Relaxation; Halogenated hydrocarbon; Simulation; Spin label; Sol gel process; Affinity; Models; Hydrogel; Electrons
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la701833w

R f-IPDU-PEGs belong to a class of fluoroalkyl-ended poly(ethylene glycol) polymers (R f-PEGs), where the IPDU (isophorone diurethane) functions as a linker to connect each end of the PEG chain to a fluoroalkyl group. The R f-IPDU-PEGs form hydrogels in water with favorable sol−gel coexistence properties. Thus, they are promising for use as drug delivery agents. In this study, we introduce an electron-spin induced 19F relaxation NMR technique to probe the location and drug-loading capacity for an electron-spin labeled hydrophobic drug, CT (chlorambucil-tempol adduct), enclosed in the R f-IPDU-PEG micelle. With the assistance of molecular dynamics simulations, a clear idea regarding the structures of the R f-IPDU-PEG micelle and its CT-loaded micelle was revealed. The significance of this research lies in the finding that the hydrophobic drug molecules were loaded within the intermediate IPDU shells of the R f-IPDU-PEG micelles. The molecular structures of IPDU and that of CT are favorably comparable. Consequently, it appears that this study opens a window to modify the linker between the R f group and the PEG chain for achieving customized structure-based drug-loading capabilities for these hydrogels, while the advantage of the strong affinity among the R f groups to hold individual micelles together and to interconnect the micellar network is still retained in hopes of maintaining the sol−gel coexistence of the R f-PEGs.