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Poly (2, 3, 4, 5, 6-pentafluorostyrene) (5FPS) was prepared by bulk radical polymerization. The spin-cast films of this polymer were analyzed using time-of-flight secondary ion mass spectrometry (ToF-SIMS) at various temperatures ranging from room temperature to 120 °C. Principal component analysis (PCA) of the ToF-SIMS data revealed a transition temperature (TT) at which the surface structure of 5FPS was rearranged. A comparison between the results of the PCA of ToF-SIMS spectra obtained on 5FPS and polystyrene (PS) indicate that the pendant groups of 5FPS and PS moved in exactly opposite directions as the temperature increased. More pendant groups of 5FPS and PS migrated from the bulk to the surface and verse versa, respectively, as the temperature increased. These results clearly support the view that the abrupt changes in the normalized principal component 1 value was caused by the surface reorientation of the polymers and not by a change in the ion fragmentation mechanism at temperatures above the TT. Contact angle measurement, which is another extremely surface sensitive technique, was used to monitor the change in the surface tension as a function of temperature. A clear TT was determined by the contact angle measurements. The TT values determined by contact angle measurements and ToF-SIMS were very similar. [ABSTRACT FROM AUTHOR]

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to quantitatively correlate to the surface chemical composition determined from XPS in poly(styrene-co-p-hexafluorohydroxyisopropyl-α-methyl styrene)/poly(4-vinyl pyridine) (PS(OH)/PVPy) blends or complexes when the p-(hexafluoro-2-hydroxyisopropyl)-α-methylstyrene (HFMS) contents in PS(OH) copolymers were gradually increased. It was found that different mixing thermodynamics, such as immiscibility, miscibility, and complexation, have little effect on the quantitative analysis of PS(OH) copolymers in the blends or complexes using TOF-SIMS. In the positive spectra, either the normalized intensities or relative peak intensities can be used to quantitatively analyze the surface HFMS, PS(OH), or PVPy concentration when peaks at m/z = 257, 271, 285, and 373 are used for HFMS, peaks at m/z = 91, 103, 105, 115 for styrene, and peaks at m/z = 132, 195, 209 for PVPy. In the negative spectra, the normalized intensities of peaks characteristic of PVPy seem to be not affected by hydrogen bonding formation and can be used in quantitative analysis, whereas peaks characteristic of HFMS, such as a peak at m/z = 283, cannot be used in quantitative analysis due to enhancement of its secondary ion yield resulting from hydrogen bond formation. [ABSTRACT FROM AUTHOR]

Purpose: The objective of the present study was to evaluate the therapeutic efficacy of ciliary neurotrophic factor (CNTF) delivered through encapsulated cells directly into the vitreous of the eye in an rcd1 canine model of retinitis pigmentosa. The dose-range effect of the treatment was also investigated., Methods: Polymer membrane capsules (1.0 cm in length and 1.0 mm in diameter) were loaded with mammalian cells that were genetically engineered to secrete CNTF. The cell-containing capsules were then surgically implanted into the vitreous of one eye of rcd1 dogs at 7 weeks of age, when retinal degeneration is in progress but not complete. The contralateral eyes were not treated. The capsules remained in the eyes for 7 weeks. At the end of the studies, the capsules were explanted, and CNTF output and cell viability were evaluated. The eyes were processed for histologic evaluation., Results: In each animal, the number of rows of photoreceptor nuclei in the outer nuclear layer (ONL) was significantly higher in the eye that received a CNTF-secreting implant than in the untreated contralateral eye. No adverse effects were observed on the retina in the treated eyes. The explanted capsules produced a low level of CNTF. The cells in the capsules remained viable and densely distributed throughout., Conclusions: CNTF delivered through encapsulated cells directly into the vitreous of the eye protects photoreceptors in the PDE6B-deficient rcd1 canine model. Furthermore, sparing of photoreceptors appeared dose-dependent with minimum protection observed at CNTF doses of 0.2 to 1.0 ng/d. Incrementally greater protection was achieved at higher doses. The surgically implanted, cell-containing capsules were well tolerated, and the cells within the capsule remained viable for the 7-week implantation interval. These results suggest that encapsulated cell therapy may provide a safe and effective strategy for treating retinal disorders in humans.