RGD-mimic polyamidoamine-montmorillonite composites with tunable stiffness as scaffolds for bone tissue-engineering applications.

This paper reports on the development of montmorillonite (MMT)-reinforced hydrogels, based on a peptidomimetic polyamidoamine carrying guanidine pendants (AGMA1), as substrates for the osteo-induction of osteoblast precursor cells. AGMA1 hydrogels of various degrees of crosslinking responded favourably to MMT reinforcement, giving rise to composite hydrogels with shear storage modulus G', when fully swollen in water, up to 200 kPa, i.e.

Chitosan nanoparticles loaded with the antimicrobial peptide temporin B exert a long-term antibacterial activity in vitro against clinical isolates of Staphylococcus epidermidis.

Nowadays, the alarming rise in multidrug-resistant microorganisms urgently demands for suitable alternatives to current antibiotics. In this regard, antimicrobial peptides (AMPs) have received growing interest due to their broad spectrum of activities, potent antimicrobial properties, unique mechanisms of action, and low tendency to induce resistance. However, their pharmaceutical development is hampered by potential toxicity, relatively low stability and manufacturing costs.

Mg- and/or Sr-doped tricalcium phosphate/bioactive glass composites: synthesis, microstructure and biological responsiveness.

Presently, there is an increasing interest towards the composites of calcium phosphates, especially β-tricalcium phosphate (TCP), and bioactive glasses. In the present contribution, the recently developed BG_Ca/Mix glass has been used because its low tendency to crystallize allows to sinter the composites at relatively low temperature (i.e.

Additive manufacturing of poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] scaffolds for engineered bone development.

A wide range of poly(hydroxyalkanoate)s (PHAs), a class of biodegradable polyesters produced by various bacteria grown under unbalanced conditions, have been proposed for the fabrication of tissue-engineering scaffolds. In this study, the manufacture of poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] (or PHBHHx) scaffolds, by means of an additive manufacturing technique based on a computer-controlled wet-spinning system, was investigated. By optimizing the processing parameters, three-dimensional scaffolds with different internal architectures were fabricated, based on a layer-by-layer approach.

Amphoteric, prevailingly cationic L-arginine polymers of poly(amidoamino acid) structure: synthesis, acid/base properties and preliminary cytocompatibility and cell-permeating characterizations.

A linear amphoteric poly(amidoamino acid), L-ARGO7, is prepared by Michael-type polyaddition of L-arginine with N,N'-methylenebisacrylamide. Chain-extension of acrylamide end-capped L-ARGO7 oligomers with piperazine leads to high-molecular-weight copolymers in which L-arginine maintains its absolute configuration. Acid/base properties of L-ARGO7 polymers show isolectric points of ≈ 10 and positive net average charges per repeating unit at pH = 7.

Preparation, physical-chemical and biological characterization of chitosan nanoparticles loaded with lysozyme.

A commercially available chitosan (CS) was employed in the formulation of nanoparticles loaded with lysozyme (LZ) as antimicrobial protein drug model. Due to the variability of commercially available batches of chitosans and to the strict dependence of their physical and biological properties to the molecular weight (Mw) and deacetylation degree (DD) of the material, the CS was fully characterized resulting in weight-average molecular weight of 108,120g/mol and DD of 92%. LZ-loaded nanoparticles (LZ-NPs) of 150nm diameter were prepared by inotropic gelation.

A new hydroxyapatite-based biocomposite for bone replacement.

Since the 1970s, various types of ceramic, glass and glass-ceramic materials have been proposed and used to replace damaged bone in many clinical applications. Among them, hydroxyapatite (HA) has been successfully employed thanks to its excellent biocompatibility. On the other hand, the bioactivity of HA and its reactivity with bone can be improved through the addition of proper amounts of bioactive glasses, thus obtaining HA-based composites.

Magnetism and spin dynamics of novel encapsulated iron oxide superparamagnetic nanoparticles.

Encapsulated Fe3O4 nanoparticles of average diameters d = 12 nm are obtained by coprecipitation, in the presence of 2-methoxyethanol hemiester of poly(maleic anhydride-alt-butyl vinyl ether) 5% grafted with poly(ethylene glycol) (VP-MAG nanoparticles). A complete characterization of nude and encapsulated nanoparticles through structural techniques (namely XRD, TEM, SEM), Raman spectroscopy and magnetic measurements has been performed. These nanoparticles compared with commercial compounds (ENDOREM®) present superparamagnetic behavior and nuclear relaxivities that make them promising as magnetic resonance imaging (MRI) contrast agents (CAs).

Additive manufacturing of wet-spun polymeric scaffolds for bone tissue engineering.

An Additive Manufacturing technique for the fabrication of three-dimensional polymeric scaffolds, based on wet-spinning of poly(ε-caprolactone) (PCL) or PCL/hydroxyapatite (HA) solutions, was developed. The processing conditions to fabricate scaffolds with a layer-by-layer approach were optimized by studying their influence on fibres morphology and alignment. Two different scaffold architectures were designed and fabricated by tuning inter-fibre distance and fibres staggering.

A novel method for the preparation of retinoic acid-loaded nanoparticles.

The goal of present work was to investigate the use of bioerodible polymeric nanoparticles as carriers of retinoic acid (RA), which is known to induce differentiation of several cell lines into neurons. A novel method, named "Colloidal-Coating", has been developed for the preparation of nanoparticles based on a copolymer of maleic anhydride and butyl vinyl ether (VAM41) loaded with RA. Nanoparticles with an average diameter size of 70 nm and good morphology were prepared.

Bioactive polymeric materials for targeted administration of active agents: synthesis and evaluation.

Bioerodible polymers displaying both stealth and targeting properties for the preparation of nanosystems for targeted and controlled delivery of fibrinolytic drugs to the thrombus were prepared by straightforward synthetic routes and characterized. Poly[(maleic anhydride)-alt-(butylvinyl ether)]s were synthesized in the presence of dodecyl mercaptan as chain transfer agent allowing for the preparation of copolymers with tunable molecular weight. 2-Methoxyethanol hemiesters containing antiopsonizing molecules of poly(ethylene glycol) were prepared and further biofunctionalized with a Fab fragment by a two-step reaction.