Andrea Francescangeli

Hyaluronan networking via Ugi's condensation using lysine as cross-linker diamine

Abstract A new type of hyaluronan based polymeric network has been prepared applying the well known cross-linking processes based on aqueous Ugi condensation reactions. In this study lysine has been used as a cross-linking agent. The structural and physico-chemical properties of the resulting hydrogels have been studied using solid state NMR spectroscopy and measurements of swelling in water and in aqueous NaCl solution.

NMR structural study of hydrogels based on partially deacetylated hyaluronan

Hydrogels have been prepared using two partially deacetylated hyaluronan (deHA) samples having a molar ratio of free amino groups to total initial N-acetamido groups equal to 23 and 33%, respectively. Taking advantage of such primary amino functionalities, polymeric networks could be easily obtained in aqueous media by means of two different crosslinking procedures, namely: a) Ugi multicomponent reactions and, more simply, b) glutaraldehyde reticulation. In this paper, we wish to report on the synthesis of deHA based hydrogels and, in particular, on their structural elucidation as obtained by NMR studies. Structure of HA (R = COCH3) and de-HA (R = H) repeat units.

HYALURONAN LINEAR AND CROSSLINKED DERIVATIVES AS POTENTIAL/ACTUAL BIOMATERIALS

ABSTRACT The synthetic routes leading to a few novel hyaluronic acid 1 (HA) derivatives – recently obtained in our laboratories - and their main physical properties and potential or actual applications in the biomedical sector are briefly described. HA derivatives considered include linear, water soluble species and hydrophilic networks and membranes. The latter are biomaterials particularly suitable for controlled drug release formulations and for avoiding post-surgical adherence phenomena, respectively.

Note: Biological Activity of C6-Oxidized Hyaluronic Acid: Antibacterial Properties of the Zn(II) Salt

Partially oxidized hyaluronan sodium and zinc salts and hyaluronan zinc salts were prepared. The antibacterial activity of hyaluronic acid and of C(6)-oxidized hyaluronic acid zinc salts (HAZn+2 and HAOXZn+2) were evaluated against Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli bacterial strains. HAOXZn+2 showed a higher antibacterial effect than HAZn+2 with E. coli and S. aureus; however, neither zinc salt was not able to promote any antiseptic activity against P. aeruginosa.