Synthesis and Characterization of Antibacterial Chitosan Films with Ciprofloxacin in Acidic Conditions.

This work presents the results of research on obtaining chitosan (CS) films containing on their surface ciprofloxacin (CIP). A unique structure was obtained that not only gives new properties to the films, but also changes the way of coverage and structure of the surface. The spectroscopic test showed that in the process of application of CIP on the surface of CS film, CIP was converted from its crystalline form to an amorphic one, hence improving its bioavailability. This improved its scope of microbiological effect. The research was carried out on the reduction of CIP concentration during the process of CIP adhesion to the surface of chitosan films. The antibacterial activity of the CS films with and without the drug was evaluated in relation to Escherichia coli and Staphylococcus aureus, as well as Candida albicans and Penicillium expansum. Changes in the morphology and roughness of membrane surfaces after the antibacterial molecule adhesion process were tested with atomic force microscopy (AFM) and scanning electron microscopy (SEM). Structural analysis of CS and its modifications were confirmed with Fourier-transform spectroscopy in the infrared by an attenuated total reflectance of IR radiation (FTIR-ATR) and solid-state nuclear magnetic resonance (NMR).

Evaluation of Polysaccharide-Peptide Conjugates Containing the RGD Motif for Potential Use in Muscle Tissue Regeneration.

New scaffold materials composed of biodegradable components are of great interest in regenerative medicine. These materials should be: stable, nontoxic, and biodegrade slowly and steadily, allowing the stable release of biodegradable and biologically active substances. We analyzed peptide-polysaccharide conjugates derived from peptides containing RGD motif (H-RGDS-OH (1), H-GRGDS-NH2 (2), and cyclo(RGDfC) (3)) and polysaccharides as scaffolds to select the most appropriate biomaterials for application in regenerative medicine. Based on the results of MTT and Ki-67 assays, we can state that the conjugates containing calcium alginate and the ternary nonwoven material were the most supportive of muscle tissue regeneration. Scanning electron microscopy imaging and light microscopy studies with hematoxylin-eosin staining showed that C2C12 cells were able to interact with the tested peptide-polysaccharide conjugates. The release factor (Q) varied depending on both the peptide and the structure of the polysaccharide matrix. LDH, Alamarblue®, Ki-67, and cell cycle assays indicated that peptides 1 and 2 were characterized by the best biological properties. Conjugates containing chitosan and the ternary polysaccharide nonwoven with peptide 1 exhibited very high antibacterial activity against Staphylococcus aureus and Klebsiella pneumoniae. Overall, the results of the study suggested that polysaccharide conjugates with peptides 1 and 2 can be potentially used in regenerative medicine.

Antibacterial and Antifungal Properties of Modified Chitosan Nonwovens.

Chitosan acquires bacteriostatic properties via protonation of its amino groups. However, much of the literature assumes that chitosan itself inhibits the growth of bacteria. This article presents a comparative study of chitosan nonwovens modified with various acids, including acetic, propionic, butyric, and valeric organic acids, as well as hydrochloric acid. The aim was to determine which acid salts influence the antibacterial and antifungal activity of chitosan-based materials. Two methods were used to modify (formation of ammonium salts) the chitosan nonwovens: First, acid vapors (gassing process) were used to find which salt of chitosan had the best antibacterial properties. Based on the results, the most effective acid was prepared in a solution in ethanol. The influence of the acid concentration in ethanol, the time of treatment of chitosan materials with acid solution, and the rinsing process of modified nonwovens on the antimicrobial activity of the modified materials was investigated. The modified materials were subjected to microbiological tests. Each of the modified materials was placed in bacterial inoculum. The cultures were tested on agar to observe their microbial activity. Toxicity to human red blood cells was also investigated. A reduction in the number of bacterial cells was observed for the S. aureus strain with chitosan salt modified with 10% acetic acid in ethanol. The antibacterial activity of the chitosan salts increased with the percentage of acid salts formed on the surface of the solid material (decreasing numbers of bacterial colonies or no growth). No reduction in growth was observed for the E. coli strain. The chitosan samples were either inactive or completely eliminated the bacterial cells. Antimicrobial activity was observed for chitosan salts with hydrochloric acid and acetic acid. Finally, 1H-NMR spectroscopy and FTIR spectroscopy were used to confirm the incorporation of the acid groups to the amino groups of chitosan.

The Kinetics of Chitosan Degradation in Organic Acid Solutions.

This paper presents a comparative study on chitosan degradation in organic acid solutions according to their different dissociation characteristics. More precisely, the aim of the study was to determine the kinetics of the degradation process depending on the different acid dissociation constants (pKa values). The scientists involved in chitosan to date have focused mainly on acetic acid solutions. Solutions of lactic, acetic, malic, and formic acids in concentrations of 3% wt. were used in this research. The progress of degradation was determined based on the intrinsic viscosity measurement, GPC/SEC chromatographic analysis, and their correlation. Changes in the viscosity parameters were performed at a temperature of 20 °C ± 1 °C and a timeframe of up to 168 h (7 days). The chemical structure and DDA of the initial chitosan were analyzed using 1H-NMR spectroscopy analysis. The results of this study can be considered of high importance for the purpose of electrospinning, production of micro- and nano-capsules for drug delivery, and other types of processing. Understanding the influence of the dissociation constant of the solvent on the kinetics of chitosan degradation will allow the selection of an appropriate medium, ensuring an effective and stable spinning process, in which the occurrence of polymer degradation is unfavorable.