New Amphiphilic Lactic Acid Oligomer−Hyaluronan Conjugates: Synthesis and Physicochemical Characterization

Abstract

The "grafting onto" strategy was used to conjugate DL-lactic acid oligomers (OLA) to hyaluronan (HA) for the sake of developing novel degradable HA-based self-assembling polymeric systems. Grafting was achieved by reacting COCl-terminated OLA with cetyltrimethylammonium hyaluronate (CTA-HA) in dimethyl sulfoxide (DMSO). The resulting CTA-HAOLA conjugates were purified and turned to sodium form (Na-HAOLA) by dissolution in a phosphate buffer-DMSO mixture and successive dialyses against DMSO, ethanol, and water. In contrast, when the same protocol was applied to CTA-HAOLA, phase separation with gel formation was observed. The solution phase was composed of Na-HAOLA whereas the gel phase was made of mixed CTA-Na-HAOLA salt with ca. 25% of the carboxyl groups neutralized by CTA. Gelation was assigned to intramolecular hydrophobic associations between OLA and cetyl alkyl chains that complemented electrostatic interactions between CTA and HA COO- groups synergistically. Therefore, the corresponding stabilized CTA ions required more drastic conditions to be released. Under the selected dialysis conditions, the CTA-Na-HAOLA gels formed tiny tubes. Na-HAOLA and CTA-Na-HAOLA were characterized by FTIR, one-dimensional 1H and two-dimensional 1H NMR. The extent of grafting was ca. 5% per disaccharidic repeating unit, regardless of the molecular weight, as determined by NMR and capillary zone electrophoresis. Amphiphilic Na-HAOLA molecules were aggregated and formed spherical species in water according to size exclusion chromatography combined with multiangle laser light scattering detection. The critical aggregation concentration ranged between 0.2 and 0.35% (w/v), depending of the molecular weight of the parent hyaluronan.

Structural analysis of an acidic polysaccharide isolated from white tea

“…Peaks at 1,149.01 cm −1 suggested the presence of C-O-C link bonds. FTIR characterization of WTPS showed the typical absorption patterns of polysaccharides (23)(24)(25). Absorption peaks at 1,149.01, 939.13, and 816.64 cm −1 and comparisons with previous results indicated that the polysaccharide consisted of pyranoside (26).…”

Extraction of hyaluronic acid (HA) from rooster comb and characterization using flow field‐flow fractionation (FlFFF) coupled with multiangle light scattering (MALS)

“…For relatively small HA derivatives or fragments, HPLC [8][9][10][11][12] or HPLC-MS [13,14] have been employed. For large underivatized HA, size-exclusion chromatography (SEC) [15][16][17][18][19][20][21][22], SEC combined with viscometry [23][24][25], SEC combined with light scattering (LS) detection (SEC-LS) [23][24][25][26][27][28][29][30][31][32], SEC combined with MALDI-MS (SEC-MALDI-MS) [33][34][35] have been used.…”

Hyaluronic Acid in the 3^rd Millennium

“…Alternatively, HA can be converted into a DMSO-soluble salt which can undergo esterification with activated compounds such as acylchloride carboxylates [164].…”