Hydrogels of carboxymethylcellulose (CMC) with 2.5%, 25%, 50%, and 100% cross-linking were prepared. Cross-linking and stoichiometry was controlled by appropriate addition of CMPJ and determined by potentiometric titration. The cross-linked polymer was then sulfated using a sulfur trioxidepyridine complex (SO 3-Py) in a heterogeneous mixture. Water uptake of the gels was studied in relation to cross-linking, pH, and sulfation. FT-IR spectra of the gels were recorded at different pHs to evidence the hydrogen bonds. Hydrogen bonds formation between the chains may explain the correlation found between water uptake properties and the chemical composition of the gels.

We describe a novel parallel method for the patterning of proteins with nanoscale resolution. Combining nanoimprint lithography (NIL) and molecular assembly patterning by lift-off (MAPL), we produced streptavidin patterns with feature sizes in the order of 100 nm. A stamp is imprinted into a heated PMMA film followed by a dry etching step that converts the topography into a PMMA/Nb 2 O 5 contrast. A biotin functionalized copolymer, poly(L-lysine)-graft-poly(ethylene glycol)-biotin (PLL-g-PEG/PEG-biotin), spontaneously adsorbs on the oxide surfaces. After PMMA lift-off, the background is backfilled with protein-resistant PLL-g-PEG. We show that streptavidin selectively adsorbs on the biotin areas and thus can be used as a universal platform for immobilization of biotin-tagged molecules. This novel process is a parallel patterning method that is fast, reproducible, and economic. The PEG-copolymer can be functionalized with a variety of bioactive groups and thus allows a great flexibility in terms of surface chemistry.

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Different hydrogels were prepared starting from natural or semi-synthetic polysaccharides (carboxymethylcellulose, hyaluronic acid and chitosan) which were cross-linked by the addition of a cross-linking agent chosen according to the chemical groups present along the polymer chains. The cross-linking reaction allows for the formation of a three-dimensional network made of covalent bonds between the polymer chains, which is stable under physiological conditions. The presence of a substantial amount of water within the polysaccharide matrices makes such systems unique among hydrophilic gels. Water itself is responsible for some of their peculiar characteristics, one of which is their injectability which makes these hydrogels suitable for using as matrices for mini-invasive surgery and localized therapy.

An efficient strategy is employed for the preparation of magnetic hybrid hydrogels consisting of functionalized CoFe 2 O 4 magnetic nanoparticles covalently bound to a carboxymethylcellulose (CMC) polymer. The method involves the formation of an amide bond between the carboxylic groups of CMC and the amine groups of functionalized nanoparticles, which work as the crosslinking agents of the polymer chains. The hybrid hydrogels were chemically and morphologically characterized. The rheological properties of the hydrogels were also investigated with the aim to verify their behavior under an applied mechanical stress. The hybrid hydrogel turns out to be thixotropic. Thanks to the presence of magnetic nanoparticles, the hydrogel is capable of responding to an external magnetic field. Preliminary data show the possibility of loading the hydrogel with a dye, which can be considered as a drug model, to squeeze it through a syringe and to drive the material by the application of an external magnetic field.

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Natural bone is a complex inorganic-organic nanocomposite material, in which hydroxyapatite (HA) nanocrystals and collagen fibrils are well organized into hierarchical architecture over several length scales. In this work, we reported a new hybrid material (CMC-HA) containing HA drown in a carboxymethylcellulose (CMC)-based hydrogel. The strategy for inserting HA nanocrystals within the hydrogel matrix consists of making the freeze-dried hydrogel to swell in a solution containing HA microcrystals. The composite CMC-HA hydrogel has been characterized from a physicochemical and morphological point of view by means of FTIR spectroscopy, rheological measurements, and field emission scanning electron microscopy (FESEM). No release of HA was measured in water or NaCl solution. The distribution of HA crystal on the surface and inside the hydrogel was determined by time of flight secondary ion mass spectrometry (ToF-SIMS) and FESEM. The biological performance of CMC-HA hydrogel were tested by using osteoblast MG63 line and compared with a CMC-based hydrogel without HA. The evaluation of osteoblast markers and gene expression showed that the addition of HA to CMC hydrogel enhanced cell proliferation and metabolic activity and promoted the production of mineralized extracellular matrix.

Anticoagulant polymer sulfated hyaluronic acid was patterned immobilized on a poly(ethylene terephthalate) (PET) film in a specific pattern by photolithography. Hyaluronic acid was sulfated by a sulfur trioxide-pyridine complex. The polymer was coupled with azidoaniline. The derivatized polymer was cast on a PET film from aqueous solution. After drying, the film was photoirradiated in the presence or absence of a photomask. The micropatterning was confirmed by staining with a dye, brilliant green. Since the anticoagulant polymer has negative charges, the cationic dye was adsorbed on the regions where the anticoagulant polymer was immobilized. Platelet adhesion was reduced on the sulfated hyaluronic acid-immobilized areas. The immobilized sulfated hyaluronic acid significantly reduced thrombus formation.