Search

The paper focusses on the synthesis of novel hydrogels by joining natural biodegradable compounds with the aim to achieve biocompatible materials for bio related applications. The hydrogels were prepared from chitosan and citral by constitutional dynamic chemistry, incorporating both molecular and supramolecular dynamic features. The hydrophobic flexible citral has been reversible immobilized onto the hydrophilic chitosan backbone via imine bonds to form amphiphilic glycodynamers, which further self-ordered through supramolecular interactions into a 3D-network of biodynameric hydrogel. The synthetic pathway has been demonstrated by NMR and FTIR spectroscopy, X-ray diffraction and polarized light microscopy. Studies of the hydrogel morphology revealed a 3D porous microstructure, whose pores size correlated with the crosslinking degree. Rheological investigations evidenced high elasticity, thermo-responsiveness and thixotropic behavior. As a proof of the concept, the hydrogels proved in vivo biocompatibility on laboratory mice. The paper successfully implements the constitutional dynamic chemistry in generation of chitosan high performance hydrogels. [ABSTRACT FROM AUTHOR]

Chitosan based hydrogels are a class of cross-linked materials intensely studied for their biomedical, industrial and environmental application, but their biomedical use is limited because of the toxicity of different organic crosslinkers. To overcome this disadvantage, a new strategy to produce supramolecular chitosan hydrogels using low molecular weight compounds able to form covalent linkages and H-bonds to give a dual crosslinking is proposed. For this purpose we used 2-formylphenylboronic acid, which brings the advantage of imine stabilization via iminoboronate formation and potential antifungal activity due to the presence of boric acid residue. FTIR and NMR spectroscopy indicated that the gelling process took place by chemo-physical crosslinking forming a dual iminoboronate-chitosan network. Further, X-ray diffraction demonstrated a three-dimensional nanostructuring of the iminoboronate network with consequences on the micrometer-scale morphology and on the improvement of mechanical properties, as demonstrated by SEM and rheological investigation. The hydrogels proved strong antifungal activity against Candida planktonic yeasts and biofilms, promising to be a friendly treatment of the recurrent vulvovaginitis infections. [ABSTRACT FROM AUTHOR]

The present study reports the synthesis and characterization of 12 drug delivery systems (DDS) for the co-delivery of antifungal and antiviral agents. The systems were obtained by an in situ hydrogelation method of 6 chitosan oligomers with values of the polymerization degree between 14 and 51, with 2-formylphenylboronic acid, in the presence of tenofovir. The structural characterization by NMR and FTIR spectroscopy demonstrated the formation of imine linkages, while WXRD revealed the 3D layered architecture of the systems. SEM and POM images demonstrated the uniform distribution of tenofovir into the matrix, while the Zeta potential measurements revealed the strong interactions which develop between system components. The obtained DDSs presented biodegradability, hemocompatibility and in vivo biocompatibility, which along with their ability to release both the drug and the antifungal aldehyde make them promising materials for the treatment of HIV infection and its associated co-infections' symptoms. [Display omitted] [ABSTRACT FROM AUTHOR]

• Urea controlled release systems based on chitosan and salicyladehyde were prepared. • They showed porous structure, good water absorbency and hydrolytic stability. • Urea has been anchored into the hydrogel walls as micrometric crystals by H-bonds. • The in vivo release study revealed a prolonged urea delivery during 35 days. • The new formulations are promising candidates as multifunctional soil conditioners. The paper reports new soil conditioner systems obtained by in situ hydrogelation of chitosan with salicylaldehyde in the presence of urea fertilizer, designed to address both fertilization and water retention of the soil. The new systems were structural, supramolecular and morphological characterized by FTIR spectroscopy, XRD diffraction, POM and SEM microscopy. The rate of urea release has been investigated by NMR analysis and the release mechanism has been assessed by fitting five mathematical models. The formulations showed high water absorbency of 68 g/g, and they induced water holding capacity in soil up to 154% and an increment of the nitrogen content in soil to almost double, leading to a growth of plants with almost 70% higher compared to the reference soil. All these data revealed the new systems as new multifunctional soil conditioner ecoproducts capable to address both fertilizing and water retention issues, with high potential of application for sustainable agriculture. [ABSTRACT FROM AUTHOR]