The aim of this study was to investigate the effects of a type of hydrophobic moiety, extent of N-substitution (ES), and degree of quaternization (DQ) of chitosan (CS) on the transepithelial electrical resistance and permeability of Caco-2 cells monolayer, using fluorescein isothiocyanate dextran 4,400 (FD-4) as the model compound for paracellular tight junction transport. CS was substituted with hydrophobic moiety, an aliphatic aldehyde (n-octyl) or aromatic aldehyde (benzyl), for the improved hydrophobic interaction with cell membrane, and they were quaternized with Quat-188 to render CS soluble. The factors affecting the epithelial permeability have been evaluated in the intestinal cell monolayers, Caco-2 cells. Cytotoxicity was evaluated by using the trypan blue and MTT viability assay. The results revealed that at pH 7.4 CSQ appeared to increase cell permeability in dose-dependent manner, and this effect was relatively reversible at the lower doses of 0.05-1.25 mM. The higher DQ and ES caused the higher permeability of FD-4. Cytotoxicity of CSQ was concentration, %DQ, and %ES dependent. Substitution with hydrophobic moiety caused decreasing in permeability of FD-4 and cytotoxicity by benzyl group had more effect than octyl group. These studies demonstrated that these novel modified chitosan derivatives had potential for using as absorption enhancers.

No abstract

Abstract. The aim of this study was to investigate the effect of methylated N-(4-N,N-dimethylaminobenzyl) chitosan, TM-Bz-CS, on the paracellular permeability of Caco-2 cell monolayers and its toxicity towards the cell lines. The factors affecting epithelial permeability, e.g., degree of quaternization (DQ) and extent of dimethylaminobenzyl substitution (ES), were evaluated in intestinal cell monolayers of Caco-2 cells using the transepithelial electrical resistance and permeability of Caco-2 cell monolayers, with fluorescein isothiocyanate dextran 4,400 (FD-4) as a model compound for paracellular tight-junction transport. Cytotoxicity was evaluated with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide viability assay. The results revealed that, at pH 7.4, TM-Bz-CS appeared to increase cell permeability in a concentration-dependent manner, and this effect was relatively reversible at lower doses of 0.05-0.5 mM. Higher DQ and the ES caused the permeability of FD-4 to be higher. The cytotoxicity of TM-Bz-CS depended on concentration, %DQ, and %ES. These studies demonstrated that this novel modified chitosan has potential as an absorption enhancer.

Background: Peptide-based subunit vaccines require strong adjuvants (immunostimulant) for therapeutic potency. There is strong demand for the discovery of new safe adjuvants and vaccine delivery systems that can be produced in a highly controlled manner. The pH dependent self-assembly of isopeptide derivatives into fibrils has been reported. Appropriately designed fibrils may have adjuvanting potency. Methods: Isopeptides conjugated to B-cell peptide epitopes (antigens) were synthesized. Properties of the resultant conjugates and their ability to undergo O-N intramolecular acyl migration reaction were analysed by HPLC, circular dichroism, and transmission electron microscopy. Results: The conjugates were converted to "parent" peptides via the pH-triggered O-N acyl migration reaction. The parent peptides aggregated into fibrils. The differences in conjugates composition resulted in different fibril morphology. Aggregation of produced peptides induced desired secondary conformation of antigens (peptide epitopes). Conclusions:The isopeptide approach presented herein may serve as a new self-adjuvanting delivery system for peptide-based vaccines. Such vaccines could be stable when stored in a non-aggregative form, and then converted on demand to the active form in pH-controlled manner. The use of a vaccine that is solely composed of endogenous components may reduce vaccine-associated side effects.

The effect of methylated N-(4-N,N-dimethylaminocinnamyl) chitosan (TM-CM-CS) was investigated on paracellular permeability and its toxicity towards Caco-2 cells. Fluorescein isothiocyanate dextran 4,400 (FD-4) was used as the model compound for paracellular transport. The factors, i.e. the degree of quaternization (DQ) and the extent of N-substitution (ES) of the derivatives, were studied for the effect on transepithelial electrical resistance (TEER) and permeability. The results revealed that at pH 7.4, TM-CM-CS appeared to increase cell permeability in a dose-dependent manner, and the effect was relatively reversible at lower doses of 0.05-0.5 mM. The difference of the DQ and the ES of TM-CM-CS slightly affected the decrease of TEER values and the FD-4 permeability. The cytotoxicity of TM-CM-CS was concentration-dependent and did not cause an acute cytotoxic effect as analyzed by the MTT assay. These studies demonstrated that this novel modified chitosan has the potential to be used as an intestinal absorption enhancer of therapeutic macromolecules.

No abstract

Purpose: To investigate different structures of modified chitosan containing different chain lengths and aromatic moieties for vaccine delivery capacity. Methods:The characteristics of the modified chitosan, namely,Ndimethylaminobenzyl) chitosan chitosan

In the present study, methylated N-(4-N,N-dimethylaminocinnamyl) chitosan (TM65CM50CS) was synthesized and investigated for oral protein drug delivery by combining with liposomes entrapped bovine serum albumin (FITC-BSA), a model protein. FITC-BSA liposomes composed of egg yolk phosphatidylcholine and sodium oleate in molar ratio of 10:2 were prepared by thin film hydration method. The TM65CM50CS coated liposomal FITC-BSA was evaluated for transport of protein and its cytotoxicity in Caco-2 cells. Moreover, the in vitro stability of BSA in TM65CM50CS coated liposomes was also examined by the degradation of protein from pancreatin. The mean particle size and zeta-potential of liposomes were 101+0.02 nm and -27.44+2.02 mV, respectively. Initial FITC-BSA (2.5% w/w) to lipid showed the highest percentage entrapment efficiency (50.13%) and FITC-BSA content (8.08 mg/g of lipid). The results of FITC-BSA transport showed that TM65CM50CS coated FITC-BSA liposomes enhanced protein permeability across Caco-2 cell monolayers with low cytotoxicity. In addition, these liposomes could protect the degradation of protein from pancreatin. Our studies demonstrated that TM65CM50CS coated liposomes have the potential to be used as an oral protein drug delivery.