Poly(octamethylene citrate) Modified with Glutathione as a Promising Material for Vascular Tissue Engineering.

One of the major goals of vascular tissue engineering is to develop much-needed materials that are suitable for use in small-diameter vascular grafts. Poly(1,8-octamethylene citrate) can be considered for manufacturing small blood vessel substitutes, as recent studies have demonstrated that this material is cytocompatible with adipose tissue-derived stem cells (ASCs) and favors their adhesion and viability. The work presented here is focused on modifying this polymer with glutathione (GSH) in order to provide it with antioxidant properties, which are believed to reduce oxidative stress in blood vessels. Cross-linked poly(1,8-octamethylene citrate) (cPOC) was therefore prepared by polycondensation of citric acid and 1,8-octanediol at a 2:3 molar ratio of the reagents, followed by in-bulk modification with 0.4, 0.8, 4 or 8 wt.% of GSH and curing at 80 °C for 10 days. The chemical structure of the obtained samples was examined by FTIR-ATR spectroscopy, which confirmed the presence of GSH in the modified cPOC. The addition of GSH increased the water drop contact angle of the material surface and lowered the surface free energy values. The cytocompatibility of the modified cPOC was evaluated in direct contact with vascular smooth-muscle cells (VSMCs) and ASCs. The cell number, the cell spreading area and the cell aspect ratio were measured. The antioxidant potential of GSH-modified cPOC was measured by a free radical scavenging assay. The results of our investigation indicate the potential of cPOC modified with 0.4 and 0.8 wt.% of GSH to produce small-diameter blood vessels, as the material was found to: (i) have antioxidant properties, (ii) support VSMC and ASC viability and growth and (iii) provide an environment suitable for the initiation of cell differentiation.

Advancements in structure-property correlation studies of cross-linked citric acid-based elastomers from the perspective of medical application.

Herein, a renewed prominence towards the synthesis of poly(alkylene citrate) (PAC) biomaterials and their detailed chemical, structural and mechanical characterization has been reported. Based on the modifications to the PAC synthesis protocol introduced in this study, the fabrication process was significantly streamlined, the reaction yields were increased, and the homogeneity of the final materials was found to be substantially improved. Comprehensive nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) studies of the fabricated prepolymers shed light on the mechanism of the PAC cross-linking process and supported the design of materials with enhanced biocompatibility. Therefore, the initial molar ratio of the reagents involved in the synthesis of PAC materials was found to be pivotal to both the biological and mechanical properties of the final products. Moreover, cell viability and proliferation assays revealed enhanced biocompatibility of the materials formulated with a molar ratio of diol over citric acid (3 : 2 mol/mol) in comparison to the most commonly described 1 : 1 analogue without affecting the possibility of further functionalization. Furthermore, this work creates a new paradigm for prospective studies on the properties of modified PAC materials and their application in medicine and tissue engineering.

Fluorescence assay for the determination of glutathione based on a ring-fused 2-pyridone derivative in dietary supplements.

Herein, a novel fluorescent method for the determination of GSH levels in aqueous solutions involving the utilization of citric acid as a derivatization reagent was developed. Therefore, the crucial parameters of the derivatization process were established from what has resulted in the development of a sensitive, reproducible, and accurate GSH assay. The method was validated, and its applicability in the characterization of the GSH concentration in dietary supplements concerning the selectivity in the determination of GSH over GSSG was both confirmed. The chemical structure of the new fluorophore 3-[(carboxymethyl)carbamoyl]-5-oxo-2,3-dihydro-5H-[1,3]thiazolo[3,2-a]pyridine-7-carboxylic acid - CTPC was elucidated using detailed NMR: one-dimensional (1H, 13C), as well as two-dimensional NMR spectra (1H-1H COSY, 1H-13C HSQC, 1H-13C HMBC, 1H-15N HSQC, 1H-15N HMBC) experiments. Besides, the essential optical, biological and antioxidative properties of CTPC were investigated.

Fluorescence Assay for the Determination of d-Panthenol Based on Novel Ring-Fused 2-Pyridone Derivative.

Herein, a novel fluorescent method for the determination of d-panthenol (DP) level in solutions with no separate hydrolysis step has been revealed based on the utilization of citric acid (CA) as a derivatizing agent. Consequently, the essential parameters of the derivatization process were established, resulting in the development of sensitive, repeatable, and accurate determination of panthenol. The method was approved, and its usefulness in characterizing the concentration of DP in pharmaceutical formulations and selectivity in the determination of DP were validated. The chemical structure of the new fluorophore formulating in the reaction in DP with CA, i.e., 6-oxo-3,4-dihydro-2H,6H-pyrido[2,1-b][1,3]oxazine-8-carboxylic acid (ODPC), was elucidated using detailed NMR experiments: one-dimensional (1H, 13C) as well as two-dimensional NMR spectra (1H-1H COSY, 1H-13C HSQC, 1H-13C HMBC, 1H-15N HSQC, 1H-15N HMBC).