Enhancing Chitosan Fibers: A Dual Approach with Tripolyphosphate and Ursolic Acid.

Chitosan, a well-established biomaterial known for its biocompatibility, biodegradability, and bioactivity, has been the focus of extensive research in recent years. This study explores the enhancement of chitosan fibers' properties through wet impregnation with either ursolic acid (UA) or cross-linking with tripolyphosphate (TPP). In the first experiment, chitosan fibers were treated with UA, for varying immersion set points (1, 2, 4, 6, and 8 h). FTIR, SEM, and UV-Vis spectroscopy analyses demonstrated a chemical reaction between chitosan and UA, with stability reached after 2 h of immersion. Antibacterial testing revealed that chitosan fibers impregnated with UA exhibited significant antibacterial activity against Gram-positive bacteria, notably Staphylococcus aureus. The second experiment involved modifying chitosan fibers' surfaces with a 1% w/v TPP solution for the same periods of time (1, 2, 4, 6, and 8 h). Subsequently, the investigation involved FTIR, SEM, and dynamometry analyses, which revealed successful cross-linking between chitosan and TPP ions, resulting in improved tensile strength after 2 h of immersion. This dual-approach study highlights the potential of chitosan fibers for diverse applications, from wound-healing dressings to antibacterial materials against Gram-positive bacteria.

Anti-bacterial materials based on hyaluronic acid: Selection of research methodology and analysis of their anti-bacterial properties.

In the frame of the presented research, highly-porous structures made of hyaluronic acid modified with bioactive compounds were prepared. The method of microbiological testing of hygroscopic materials has been elaborated by verification of the JIS L 1902:2002 and ASTM E2149-13a test methods. The research has shown that the method developed in accordance with ASTM E2149-13a is suitable for testing the activity of hyaluronic acid samples against bacteria. E. coli and S. aureus. In the case of E. coli it is preferred to use as a medium the phosphoric buffer and for S. aureus NaCl solution from NB. By analysing the results of the antibacterial properties, it is important to note that the introduction of a small amount of zinc and zinc oxide in the matrix from the hyaluronic acid (in the amount of 3% by weight of the polymer) makes it possible to obtain a material with a strong activity against the bacterial strains. It enables to use this type of material as a treatment for hard-to-treat, infected wounds. On the other hand, using a relatively small dose of the cephalosporin antibiotic did not result in high levels of activity against the bacteria Gram "+" and Gram "-".

Swarming growth and resistance of Proteus penneri and Proteus vulgaris strains to normal human serum.

BACKGROUND: Proteus sp. strains isolated from patients with urinary tract infection (UTI) are often insensitive to the bactericidal action of normal human serum (NHS) which poses a clinical problem. The swarming phenomenon is an especially important factor in cases of UTIs gained through the ascending route. Both these virulence factors are connected with the cell surface components of bacteria, including lipopolysaccharide (LPS). OBJECTIVES: The resistance of Proteus bacilli to the bactericidal activity of NHS and the swarming phenomenon were investigated as well as the possible relationships between these virulence factors and the chemical structure of LPS. MATERIAL AND METHODS: The research was carried out on P. penneri and P. vulgaris species. Two preparations of sera were tested with respect to the bactericidal action of NHS. The ability of bacteria to swarm was checked on broth agar plates. The length of the O-specific part of LPS was estimated after poliacrylamide gel electrophoresis (PAGE) and staining with silver nitrate. RESULTS: Among the 62 tested Proteus strains, over 62% of Proteus vulgaris and 50% of Proteus penneri strains were sensitive to the bactericidal action of NHS. However, the number of resistant strains grew dramatically when serum with blocked complement activation via the alternative pathway was used. From 102 of the Proteus sp. Strains, only few were unable to swarm over the solid surface of the media. The remaining showed diverse ability to translocate. CONCLUSIONS: There was no definite correlation between the chemical structure of the O-specific chains of lipopolysaccharides and sensitivity or resistance of the Proteus sp. strains to NHS. Also, no significant relationships were found between the length or the chemical structure of the O-specific chains of the bacterial LPSs and the swarming phenomenon.

Square wave adsorptive stripping voltammetric determination of famotidine in urine.

Electrochemical studies of famotidine were carried out using voltammetric techniques: cyclic voltammetry, linear sweep and square wave adsorptive stripping voltammetry. The dependence of the current on pH, buffer concentration, nature of the buffer, and scan rate was investigated. The best results for the determination of famotidine were obtained in MOPS buffer solution at pH 6.7. This electroanalytical procedure enabled to determine famotidine in the concentration range 1x10(-9)-4x10(-8)molL(-1) by linear sweep adsorptive stripping voltammetry (LS AdSV) and 5x10(-10)-6x10(-8)molL(-1) by square wave adsorptive stripping voltammetry (SW AdSV). Repeatability, precision and accuracy of the developed methods were checked. The detection and quantification limits were found to be 1.8x10(-10) and 6.2x10(-10)molL(-1) for LS AdSV and 4.9x10(-11) and 1.6x10(-10)molL(-1) for SW AdSV, respectively. The method was applied for the determination of famotidine in urine.

Application of iodine-azide reaction for detection of amino acids in thin-layer chromatography.

The iodine-azide reaction was employed to TLC detection of sulphur-containing derivatives of protein and some non-protein amino acids. The derivatization reaction with phenyl isothiocyanate (PITC) took place directly on the plate before the developing step. Subsequently, the plates were sprayed with a mixture of sodium azide and starch solution in NP-TLC and in the case of RP-TLC sodium azide solution with starch incorporated into mobile phase and then exposed to iodine vapour. The spots became visible as white spots on violet-grey background. The obtained detection limits of PTC-derivatives have been compared with other visualizing techniques commonly used in TLC practice (UV254 and iodine vapour). The iodine-azide system has been proved to be the most favourable and enabled to detect quantities per spot in the range of 1-60 pmol (HPTLC) and 3-100 pmol (TLC).