In situ forming hydrogels of new amino hyaluronic acid/benzoyl-cysteine derivatives as potential scaffolds for cartilage regeneration

A new chemical strategy is described to link ethylenediamino (EDA) groups to primary hydroxyl groups of hyaluronic acid (HA) and the obtained derivatives have been characterized by 1H-NMR and 13C-NMR analyses. Such HA–EDA derivatives have been exploited to control the functionalization degree in benzoyl-cysteine (BC) groups, chosen as moieties able to allow both self-assembling in aqueous media and an oxidative crosslinking. In particular, the kinetics of oxidation of thiol groups in HA–EDA–BC derivatives has been studied in Dulbecco's Phosphate Buffer Solution (DPBS) pH 7.4 by colorimetric assays and rheological measurements. Mechanical properties of chemical hydrogels obtained after oxida…

Sintesi di nuovi copolimeri graft di acido ialuronico,polietilenglicole ed acido lattico

Self-assembling and auto-crosslinkable hyaluronic acid hydrogels with a fibrillar structure

Abstract A hyaluronic acid derivative bearing pendant l -benzoyl-cysteine portions (with a derivatization degree equal to 10 mol.%) was synthesized by linking N,N′-dibenzoyl- l -cystine to the polysaccharide and then reducing its disulfide bridge to thiol groups. The formation of π–π stacking interactions between the benzoyl moieties was studied by fluorescence spectroscopy as a function of polymer concentration and oxidation time. The efficiency of oxidation of thiol groups to disulfide bridges occurring in phosphate buffer pH 7.4, was determined by colorimetric assays. The hydrogel formed by means of oxidative crosslinking has shown the presence of fibrillar aggregates as detected by ligh…

NEW AMPHIPHILIC HYALURONIC ACID COPOLYMERS BEARING PEG AND PLA CHAINS

SYNTHESIS OF NOVEL GRAFT COPOLYMERS OF HYALURONAN, POLYETHYLENEGLYCOL AND POLYLACTIC ACID

PRELIMINARY ANALYSES FROM A HOSPITAL BASED STUDY ON 3154 WESTERN SICILIAN PATIENTS WITH ORAL MUCOSAL LESIONS

Objectives: Diagnosis of the wide variety of lesions that occur in the oral cavity is an essential part of dental practice. The objective of this study was to explore the demographic and behavioural profiles of patients affected by oral cavity diseases on a wide spectrum. Methods: Demographic and behavioural data of 3154 patients with at least one oral cavity disease among those consecutively visited between 2004 and 2009 at the Unit of Oral Medicine, were recorded: gender, age, smoking status, alcohol consumption, drugs use. Analysis was restricted to the eleven more frequent oral cavity diseases. Firstly, Multiple Correspondence Analysis (MCA) was applied as a descriptive tool to geometri…

MODIFIED PEPTIDE RELEASE FROM NEW IN SITU GEL FORMING COPOLYMERS BASED ON POLYLACTIDE AND POLYASPARTAMIDE

Mechanical Characterization of Polysaccharide/polyaminoacid Hydrogels as Potential Scaffolds for Tissue Regeneration

The mechanical properties of hydrogel scaffolds based on hyaluronic acid (HA) that were chemically crosslinked with α,β-poly(N-2-hydroxyethyl)(2-aminoethylcarbamate)-D,L-aspartamide (PHEA-EDA) were investigated. Variation of these properties as a function of three different PHEA-EDA amounts used to crosslink HA has been related to the reaction efficiency evaluated using a colorimetric assay. Moreover, the amount of unreacted amino groups that was still present in the hydrogels was related to the attachment behavior of human dermal fibroblasts to the hydrogel surface. The mechanical data and biological results suggest the suitability of the investigated hydrogels as scaffolds for the regener…

COMPOSITE BIOMATERIALS OF HYALURONIC ACID AND A PROTEIN-LIKE POLYMER FOR TISSUE ENGINEERING

NEW IN SITU FORMING HYALURONIC ACID SCAFFOLDS WITH A FIBRILLAR STRUCTURE

FIBRILLAR SCAFFOLD BASED ON ELECTROSPUN alpha,beta-POLY(N-2-HYDROXYETHYL)-DL-ASPARTAMIDE-GRAFT-POLYLACTIC ACID COPOLYMER.

COMPOSITE SCAFFOLD FOR TISSUE ENGINEERING

MICELLES OF AMPHYPHLIC HYALURONIC ACID DERIVATIVES FOR TARGETED DELIVERY OF DOXORUBICIN

Mono- and polynuclear complexes of Pt(II) with polypyridyl ligands. Synthesis, spectroscopic and structural characterization and cytotoxic activity.

Abstract An array of poly- and mononuclear complexes of Pt(II) with polypyridyl ligands is reported. The framework complexes [(PtCl 2 ) 2 (bpp) 2 (μ-PtCl 2 )](H 2 O) 2 [bpp = 2,3-bis(2-pyridyl)pyrazine], [PtCl 2 (μ-tptz)PtClNCPh]Cl [tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine], and mononuclear PtCl 2 (NH 2 dpt) [NH 2 dpt = 4-amino-3,5-bis(2-pyridyl)-1,2,4-triazole] have been prepared and structurally characterized. Both neutral and ionic complexes are present, with bifunctional and monofunctional Pt(II) moieties, whose size and shape enable them to behave as novel scaffolds for DNA binding. Pt(II) complexes were tested for their biological activity. Cell viability assay and flow cytometric …

SELF-ASSEMBLED AMPHIPHILIC HYALURONIC ACID GRAFT COPOLYMERS FOR TARGETED RELEASE OF ANTITUMORAL DRUG

Polymeric micelles obtained by self-assembling of amphiphilic hyaluronic acid (HA) graft copolymers have been prepared and characterized. In particular, hyaluronic acid (HA) has been grafted to polylactic acid (PLA) and polyethylenglycol chains (PEG), then the copolymers able to form micelles in aqueous medium have been chosen to entrap the antitumoral drug Doxorubicin. The critical aggregation concentration of HA-g-PLA or HA-g-PLA-g-PEG micelles has been determined by using pyrene as a fluorescent probe, whereas their shape and size have been evaluated by light scattering measurements, scanning and transmission electron microscopies. The selective cytotoxicity of drug loaded micelles towar…

SELF ASSEMBLED AND CROSSLINKED FIBRILLAR SCAFFOLDS FOR CARTILAGE REGENERATION.

In situ gel forming graft copolymers of a polyaspartamide and polylactic acid: Preparation and characterization

Abstract In situ gel forming systems have been prepared by linking polylactic acid (PLA) to a water soluble and polyfunctional polymer, such as α,β-poly( N -2-hydroxyethyl)- d , l -aspartamide (PHEA). Three graft copolymers PHEA–PLA with a different derivatization degree in PLA, have been synthesized and characterized. PHEA–PLA graft copolymer with the highest amount in PLA has been used to prepare solutions in organic solvents able to give rise to gel-like matrices when injected into phosphate buffered saline solution. The chemical degradation of these gels has been evaluated and in vitro tests have been performed to evaluate the cell compatibility of the hydrolysis products. The possibili…