<i>In Situ</i> Crosslinkable Thiolated Chitosan as Scaffold Material for Tissue Engineering

The scope of the study was to investigate the potential of thiolated chitosan as scaffold material for tissue engineering. Porous scaffolds were fabricated by freeze-drying method and stailized via disulfide bond formation. Characterizations were focused on morphological structure and degree of disulfide cross-linking. Renal proximal tubule epithelial cells (RPTECs) were used as model cell line. Chitosan-thioglycolic acid conjugate (chitosan-TGA) displayed 624.8 ± 21.2 and 1195.9 ± 61.0 µmol thiol groups/g polymer (chitosan-TGA 625 and chitosan-TGA 1196, respectively). After 4 days of incubation, the attachment of cells on the chitosan-TGA 625 and chitosan-TGA 1196 scaffolds were 101 ± 6.36 and 157.5 ± 2.82 cells/mm2, respectively. However, RPTECs did not grow on the unmodified chitosan scaffolds. These results confirm the potential utility of chitosan-TGA as a novel candidate being used as scaffold material in tissue engineering.</jats:p

The Impact of Vehicles on the Mucoadhesive Properties of Orally Administrated Nanoparticles: a Case Study with Chitosan-4-Thiobutylamidine Conjugate

The aim of this study was to evaluate the impact of various vehicles on mucoadhesive properties of thiolated chitosan nanoparticles both in vitro and in vivo. Nanoparticles (NPs) were prepared by in situ gelation technique followed by labeling with fluorescein diacetate. Comparative studies on mucoadhesion were done with these thiolated chitosan NPs and unmodified chitosan NPs (control). The obtained nanoparticles displayed a mean diameter of 164.2 ± 6.9 nm and a zeta potential of 21.5 ± 5 mV. In an in vitro adhesion study, unhydrated thiolated NPs adhered strongly to freshly excised porcine small intestine, which was more than threefold increase compared to the control. In contrast, in the presence of various vehicles (PEG 300, miglyol 840, PEG 6000, cremophor EL, and caprylic triglyceride), the mucoadhesive properties of thiolated NPs were comparatively weak. Thiolated NPs suspended in caprylic triglyceride, for example, had a percent mucoadhesion of 22.50 ± 5.35% on the mucosa. Furthermore, results from in vivo mucoadhesion studies revealed that the dry form of nanoparticles exhibits the strongest mucoadhesion, followed by nanoparticles suspended in PEG 300, miglyol, and 100 mM phosphate buffer, in that order. Three hours after administration, the gastrointestinal residence time of the dry form of thiolated NPs was up to 3.6-fold prolonged. These findings should contribute to the design of highly effective oral mucoadhesive nanoparticulate drug delivery systems