Sharlene R. Williams

Synthesis and characterization of poly(ethylene glycol)-glutathione conjugate self-assembled nanoparticles for antioxidant delivery.

Functional oligomers based on glutathione (GSH) and poly(ethylene glycol) diacrylate (PEGDA) were synthesized via Michael addition. Well-defined, spherical nanoparticle self-assembly was confirmed via dynamic light scattering and transmission electron microscopy. In addition, a series of Michael addition oligomers containing GSH were prepared with various molecular weights of poly(ethylene glycol) (PEG). Thermal analysis indicated that the oligomers were thermally stable to approximately 160 degrees C, and the Tg increased as the PEG molecular weight increased. In addition, thiol-terminated PEG was synthesized and reacted with GSH to form disulfide-linked oligomers to probe potential antioxidant therapies. SH-SY5Y cells were utilized in cell culture experiments, and hydrogen peroxide induced oxidative stress on the cells. Disulfide-linked GSH oligomers were 100% effective at protecting SH-SY5Y cells from oxidative stress, whereas the Michael addition GSH oligomers did not offer protection.

Synthesis and Characterization of Novel Segmented Polyionenes Based on Polydimethylsiloxane Soft Segments

Novel polydimethylsiloxane (PDMS) based polyionenes were synthesized by a modified Menschutkin reaction involving reaction between bromo-terminated PDMS oligomers and various ditertiary amino compounds. In this study, the nature of the hard segment was varied by using various ditertiary amino compounds and in some cases by incorporating chain extenders, while the soft segment content was varied by changing the molecular weight of the PDMS oligomers. The mechanical properties of these materials were found to be dependent on both the nature and amount of the hard segments. These materials also showed distinct evidence of a microphase-separated morphology where under normal conditions, the hard segments formed in what are believed to be cylindrical ion-rich microdomains dispersed randomly in the soft PDMS matrix. When subjected to uniaxial deformation, the ionic cylinders were found to orient along their long axes in the stretch direction.