Michał Tylman

Chitosan-based hydrogel implants enriched with calcium ions intended for peripheral nervous tissue regeneration.

A new method for fabrication of chitosan-based hydrogel implants intended for peripheral nervous tissue regeneration was developed. The method is based on an electrodeposition phenomenon from a solution of chitosan and organic acid. In order to increase the mechanical strength of the implant, the solution was enriched with hydroxyapatite. Hydroxyapatite served as a source of calcium ions too. The influence of the concentration of the polymer and the additive on chemical, mechanical as well as biological properties of the obtained implant was evaluated. The study showed great dependence of the initial solution composition mainly on the physicochemical properties of the resulting structure. Basic in vitro cytotoxic and pro-inflammatory assays showed biocompatibility of manufactured implants, therefore, animal experimentations may be considered.

Biopolymeric matrices based on chitosan for medical applications

AbstractChitosan (CS) based materials in a form of composite with poly(lactic acid) (PLA) granules, films and freeze-dried scaffolds also with blend form with hydroxypropylocellulose (HPC), as well as dibutyrylchitin films were obtained. These structures are intended especially for controlled drug delivery systems, including transdermal and oral dosage forms. Excellent adhesion of biopolymer matrices to PLA microspheres or hydroxyapatite (HAp) particles was proven. The Iorder drug (ibuprofen (IBU)) release kinetics from obtained films is stated.

Assessment of degradation and biocompatibility of electrodeposited chitosan and chitosan-carbon nanotube tubular implants.

Designing three-dimensional tubular materials made of chitosan is still a challenging task. Availability of such forms is highly desired by tissue engineering, especially peripheral nerve tissue engineering. Aiming at this problem, we use an electrodeposition phenomenon in order to obtain chitosan and chitosan-carbon nanotube hydrogel tubular implants. The in vitro biocompatibility of the fabricated structures is assessed using a mouse hippocampal cell line (mHippoE-18). As both implants do not induce significant cytotoxicity, they are next subjected to in vitro degradation studies in the environment simulating in vivo conditions for specified periods of time: 7, 14, and 28 days. The mass loss of implants indicates their stability at the tested time period; therefore, the materials are subcutaneously implanted in Sprague Dawley rats. The explants are collected after 7, 14, and 28 days. The assessment of composition and changes in tissues surrounding the implanted materials is made in respect to surrounding tissue thickness as well as the number of blood vessels, macrophages, lymphocytes, and neutrophils. No symptoms of acute inflammation are noticed at any point in time. The observed regular healing process allows concluding that both chitosan and chitosan-carbon hydrogel tubular implants are biocompatible with high application potential in tissue engineering.

Epineurium-mimicking chitosan conduits for peripheral nervous tissue engineering.

In this investigation, we report on a fabrication method of epineurium-mimicking tubular conduits based on electrodeposition from chitosan solution. The pre-enrichment of electrodeposition solution with hyaluronic acid and/or collagen components results in structures which structural, morphological, and physicochemical properties can be controlled. In order to determine the optimal composition of the initial chitosan solution resulting in conduits meeting the requirements imposed on peripheral nerve implants, we perform chemical, physical, and biological studies. Both the molecular weight of hyaluronic acid and the concentration of additives are found to be crucial for the final mechanical as well as biological performance of conduits. Because, the obtained structures show biocompatibility when contacting with a mouse hippocampal cell line (mHippoE-18), we further plan to test their application potential on an animal model.

Novel Technique of Polymer Composite Preparation for Bone Implants

Extensive interest in bone tissue engineering focuses on bio-degradable materials based on natural polymers. One of these polymers is chitosan which is deacetylated derivative of chitin. The paper presents preparation of chitosan scaffolds containing collagen and hydroxyapatite by electrolytic method. Chitosan dissolved in acetic acid forms chitosan acetate which is polyelectrolyte (protonated group NH3+). The flow of current through a solution of chitosan acetate causes its reduction and accumulation of chitosan on cathode. Formed structure is highly hydrated porous hydrogel. Hydrogel structure can be coated (in the process of electrodeposition) by nano-silver having a bactericidal effect. Subsequently hydrogel was frozen at -37°C for 24h and freeze-drying. Obtained scaffold has a high porosity (more than 88%) with average pore size of about 0.1-3 μm (micropores) and 0,1- few millimeters (macropores).

Ethanol Recovery from Low-Concentration Aqueous Solutions Using Membrane Contactors with Ionic Liquids

Abstract Recovery of alcohols from diluted aqueous solutions is highly energy-intensive. In order to reduce the costs of concentration of alcohols, membrane processes (including membrane extraction) are used. This paper reports the results of ethanol concentration from diluted aqueous solutions using a hollow fiber membrane contactor with ionic liquid. The studies were performed using a contactor with microporous hollow fiber membranes. The membrane creates a barrier between the feed and extracting solvent, also providing a large mass transfer area. In the process, selected ionic liquid presenting different selectivity towards ethanol was used as extractant. The experiments were performed with feed concentrations of ethanol ranging from 1 to 5 wt.% and various feed flow rates ranging from 1 to 8 dm3/h.