Temperature- and pH-sensitive nanohydrogels of poly(N-Isopropylacrylamide) for food packaging applications: modelling the swelling-collapse behaviour.

Temperature-sensitive poly(N-isopropylacrylamide) (PNIPA) nanohydrogels were synthesized by nanoemulsion polymerization in water-in-oil systems. Several cross-linking degrees and the incorporation of acrylic acid as comonomer at different concentrations were tested to produce nanohydrogels with a wide range of properties. The physicochemical properties of PNIPA nanohydrogels, and their relationship with the swelling-collapse behaviour, were studied to evaluate the suitability of PNIPA nanoparticles as smart delivery systems (for active packaging).

Water soluble folate-chitosan nanogels crosslinked by genipin.

Folate-chitosan conjugates were prepared by a concurrent functionalization and crosslinking reaction with the natural crosslinker genipin. Genipin molecule was employed simultaneously as crosslinker agent and spacer molecule in order to allow the functionalization with folic acid for active tumor targeting. The reaction was carried out in reverse microemulsion which provided colloidal size and monodisperse particle size distribution.

Biodegradable chitosan nanogels crosslinked with genipin.

Chitosan nanoparticles crosslinked with genipin were prepared by reverse microemulsion that allowed to obtain highly monodisperse (3-20 nm by TEM) nanogels. The incorporation of genipin into chitosan was confirmed and quantitatively evaluated by UV-vis and (1)H NMR. Loosely crosslinked chitosan networks showed higher water solubility at neutral pHs than pure chitosan.

Use of poly(N-isopropylacrylamide) nanohydrogels for the controlled release of pimaricin in active packaging.

Unlabelled: We propose here a delivery drug-polymer system using poly(N-isopropylacrylamide) (PNIPA) nanohydrogels that enables pimaricin to be protected from hostile environments and allows the controlled release of the antifungal through environmental stimuli. We synthesized 2 nanohydrogels, 1 with 100% N-isopropylacrylamide (PNIPA(5)) and 1 with 80% N-isopropylacrylamide copolymerized and 20% acrylic acid (PNIPA-20AA(5)). Both were then, loaded with a pimaricin aqueous solution.

In vitro transdermal and biological evaluation of ALA-loaded poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide-co-acrylic acid) microgels for photodynamic therapy.

Poly(N-isopropylacrylamide) (PNIPA) and Poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPA-co-AA)) microgels loaded with 5-aminolevulinic acid (ALA) were prepared by the spray-drying method. The amount of drug loaded was 290 µg ALA/mg microgel for PNIPA and 244 µg ALA/mg microgel for P(NIPA-co-AA) microgels. Maximum in vitro drug release took place within 15-30 min for PNIPA and 1-1.