Delivery of B. subtilis into Animal Intestine Using Chitosan-Derived Bioresorbable Gel Carrier: Preliminary Results

The oral delivery of bacteria in the human intestine is of great interest because of its potential to correct the gut microbiota and treat inflammatory bowel diseases. The aim of this study was to evaluate sodium N-(2-sulfonatoethyl)chitosan gel cross-linked with glutaraldehyde as a delivery carrier for probiotic bacteria to the gut using in vitro and in vivo experiments. The bacterial test strain was B. subtilis 20. The cytotoxicity of the gel was evaluated via cell culture using flow cytometry and light microscopy. The gel as a delivery system was assessed by the dye release in medium with different pH levels in vitro, and by bacterial titer monitoring in mouse feces using the microbiology method in vivo. Results of an in vitro experiment showed that tested gel has no cytotoxicity. The use of gel as a carrier for bacterial delivery into the intestine was more effective than oral gavage of bacterial suspension. Therefore, gel delivery of bacteria decreased the titer level by up to two times. However, a gavage of bacterial suspension decreased the titer level by over 200 times. Tested gel has the potential to be a carrier for the safe delivery of bacteria to the intestine through the stomach, reducing the rate of the elimination of probiotic bacteria from the intestine.

Synthesis, Chemical and Biomedical Aspects of the Use of Sulfated Chitosan

This work is devoted to the chemical synthesis of sulfated chitosan and its experimental verification in an animal model of early atherosclerosis. The method of chitosan quaternization with sulfate-containing ingredients resulted in a product with a high content of sulfate groups. Implantation of this product into the fascial-muscular sheath of the main limb artery along the leg and thigh in rabbits led to the extraction of cholesterol from the subintimal region. Simplified methods for the chemical synthesis of quaternized sulfated chitosan and the use of these products in a model of experimental atherosclerosis made it possible to perform a comparative morphological analysis of the vascular walls of the experimental and control limbs under conditions of a long-term high-cholesterol diet. The sulfated chitosan samples after implantation were shown to change the morphological pattern of the intimal and middle membranes of the experimental limb artery. The implantation led to the degradation of soft plaques within 30 days after surgical intervention, which significantly increased collateral blood flow. The implantation of sulfated chitosan into the local area of the atherosclerotic lesions in the artery can regulate the cholesterol content in the vascular wall and destroy soft plaques in the subintimal region.

Selective adsorption of silver(I) ions over copper(II) ions on a sulfoethyl derivative of chitosan

This study presents a simple and effective method of preparation of N-(2-sulfoethyl) chitosan (NSE-chitosan) that allows obtaining a product with a degree of modification up to 1.0. The chemical structure of the obtained polymers was confirmed by FT-IR and 1H NMR spectroscopies. Cross-linking of N-(2-sulfoethyl) chitosans by glutaraldehyde allows preparation of sorbents for removal and concentration of metal ions. Capacity of sorbents towards hydroxide ions was determined depending on the degree of sulfoethylation under static and dynamic conditions. Dissociation constants of functional amino groups of the analyzed sorbents were determined by potentiometric titration. It was shown that basicity of the amino groups decreased (wherein pKa decreased from 6.53 to 5.67) with increase in degree of sulfoethylation. It explains the significant influence of sulfo groups on selectivity of sorption of metal ions on N-(2-sulfoethyl) chitosan-based sorbents. The investigated substances selectively remove copper(II) and silver(I) ions from solutions of complex composition. Wherein the selectivity coefficient KAg/Cu increased to 20 (pH 6.5, ammonium acetate buffer solution) with increase in degree of sulfoethylation of the sorbent up to 1.0.

Simple synthesis and chelation capacity of N-(2-sulfoethyl)chitosan, a taurine derivative

This study presents a simple and effective synthesis method of N-(2-sulfoethyl)chitosan (NSE-chitosan) via a reaction between sodium 2-bromoethanesulfonate and chitosan that allows polymer transformation without using additional reagents and organic solvents. The chemical structure of the obtained NSE-chitosan was characterized by FT-IR and (1)H NMR spectroscopies. Thermogravimetric study of NSE-chitosan coupled with FT-IR analysis has shown stability of the polymer up to 200 °C, which almost does not change with the increase of degree of substitution (DS). The sorption of transition and alkaline earth metal ions from multicomponent solutions on NSE-chitosan was investigated. The synthesized sorbents showed the selective recovery of silver(I) and copper(II) ions from ammonium acetate buffer solution. The increase of DS enhanced the selectivity to silver(I) ions sorption in comparison with copper(II) ions. Selectivity coefficients K(Ag/Cu) increase from 1.3 to 10.9 with DS increasing up to 0.7 (ammonium acetate buffer solution, pH 6.5). Sorption isotherms of transition metal ions on NSE-chitosan with DS = 0.5 have been fitted using Langmuir, Freundlich, and Redlich-Peterson models. The maximum sorption capacities of sorbent in ammonium acetate buffer solution at pH 6.0 were 1.72 mmol/g for Cu(II), 1.23 mmol/g for Ag(I) and below 0.5 mmol/g for Co(II), Zn(II), Cd(II), Pb(II), Mn(II) and Ni(II) ions.