Structure and dynamics of water in native and tanned collagen fibers: Effect of crosslinking

Gelatin-carrageenan hydrogels: role of pore size distribution on drug delivery process

Naturally occurring biomaterials, such as gelatin and carrageenan are known to act as good drug delivering agents. The physical properties of these hydrogels are derived from their pore network. The effect of pore size distribution of hydrogel on the drug delivery process has been studied in this work. Gelatin-carrageenan hydrogel has been characterized using DSC, TGA and SEM. Thermoporometry technique has been used since it offers the measurement to be carried out in native state without drying the sample. Release of quercetin (Q,3,5,7,3',4'-pentahydroxyflavone), a member of the flavonoids family, which exerts many beneficial health effects has been studied using gelatin-carrageenan hydrogel. The addition of gelatin to carrageenan is found to improve the thermal stability of the gelatin-carrageenan fibers in the composite hydrogels. The in vitro drug release studies have shown that an increase in porosity results in the improved drug release. The tuning of pore size distribution for drug delivery applications using thermoporometry is feasible.

Anisotropic analysis of multi-component T2 and T1ρ relaxations in achilles tendon by NMR spectroscopy and microscopic MRI

PURPOSE

To study the anisotropic characteristics of both multi-component T2 and T1ρ relaxation times in tendon.

MATERIALS AND METHODS

T2 and T1ρ were measured in tendon by NMR spectroscopy at different orientations and by microscopic MRI at the magic angle. Several experimental issues in the multi-component relaxation measurements were investigated, including the effects of echo spacing, the resolution of MRI experiments, the influence of the specimen orientations, and the strengths of different spin-lock frequencies in T1ρ experiments.

RESULTS

Both the values and fractions of T2 in tendon showed significant orientational dependence. The values and fractions of T1ρ strongly depended on both the specimen orientation and the spin-lock strength. The imaging resolution (35-280 μm) had little influence in the T2 experiments. Both the echo spacings (0.6-3.0 ms) in the T2 experiment and the spin-lock strengths (0.5-5 kHz) in the T1ρ experiment affected the quantification of the multi-component relaxation. Up to three T2 and T1ρ components were resolved in tendon.

CONCLUSION

Multi-component relaxations could be attributed to different populations of water in the tissue. The transitions between a mono-component and multi-component result call for the caution in interpreting the relaxation results.

Effect of UV irradiation on the physico-chemical properties of iron crosslinked collagen

Collagen is the main component of connective tissue and finds immense applications as a biomaterial. In this study, effect of UV irradiation on collagen crosslinked with iron has been carried out. The physical and optical properties of crosslinked collagen affected by UV irradiation were analyzed using electrospectral and fluorescence studies. The electronic spectral studies showed that the photoproducts formed on UV radiation decrease in the presence of iron. Circular dichroic studies revealed that the conformational changes brought about in the protein due to UV irradiation have been reduced owing to the crosslinking with iron. However, prolonged irradiation does bring about conformational changes to the protein.