Current Trend and New Opportunities for Multifunctional Bio-Scaffold Fabrication via High-Pressure Foaming.

Biocompatible and biodegradable foams prepared using the high-pressure foaming technique have been widely investigated in recent decades as porous scaffolds for in vitro and in vivo tissue growth. In fact, the foaming process can operate at low temperatures to load bioactive molecules and cells within the pores of the scaffold, while the density and pore architecture, and, hence, properties of the scaffold, can be finely modulated by the proper selection of materials and processing conditions. Most importantly, the high-pressure foaming of polymers is an ideal choice to limit and/or avoid the use of cytotoxic and tissue-toxic compounds during scaffold preparation.

Tuning the three-dimensional architecture of supercritical CO foamed PCL scaffolds by a novel mould patterning approach.

In tissue engineering, the use of supercritical CO foaming is a valuable and widespread choice to design and fabricate porous bioactive scaffolds for cells culture and new tissue formation in three dimensions. Nevertheless, the control of scaffold pores size, shape and spatial distribution with foaming technique remains, to date, a critical limiting step. To mimic the biomimetic structure of tissues like bone, blood vessels and nerve tissues, we developed a novel supercritical CO-foaming approach for the preparation of dual-scale, dual-shape porous polymeric scaffolds with pre-defined arrays of micro-channels within a foamed porosity.

In Vitro Human Umbilical Vein Endothelial Cells Response to Ionic Dissolution Products from Lithium-Containing 45S5 Bioactive Glass.

Since lithium (Li⁺) plays roles in angiogenesis, the localized and controlled release of Li⁺ ions from bioactive glasses (BGs) represents a promising alternative therapy for the regeneration and repair of tissues with a high degree of vascularization. Here, microparticles from a base 45S5 BG composition containing (wt %) 45% SiO₂, 24.5% Na₂O, 24.

Functionalization of polycaprolactone/hydroxyapatite scaffolds with Usnea lethariiformis extract by using supercritical CO2.

Investigation of an integrated supercritical fluid extraction and supercritical solvent impregnation process for fabrication of microporous polycaprolactone-hydroxyapatite (PCL-HA) scaffolds with antibacterial activity is presented. The HA content and particle size as well as the operating conditions of the integrated process is optimized regarding the amount of impregnated antibacterial agent (Usnea lethariiformis extract) in the PCL-HA matrix, scaffold morphology and antibacterial activity against methicillin resistant Staphylococcus aureus (MRSA) strains. High pressure differential scanning calorimetry (HP-DSC) assay reveals that an increasing amount of HA results in decreasing melting temperature as well as crystallinity at an operating pressure of 17 MPa.

Functionalized bridged silsesquioxane-based nanostructured microspheres: ultrasound-assisted synthesis and in vitro cytotoxicity characterization.

Different kinds of polymers have been employed in medicine as biomaterials for different purposes. In recent years, considerable attention has been focused on the development of new drug-delivery systems in order to increase bio-availability, sustain, localize and target drug action in the human body. The versatility of the sol-gel processing to synthesize nanostructured materials and the possibility of incorporating organic molecules into the matrix of the final hybrid material, represent a novel and attractive path to the synthesis of new functionalized hybrid biomaterials with advanced properties.

Functionalized bridged silsesquioxane-based nanostructured microspheres: performance as novel drug-delivery devices in bone tissue-related applications.

Two kinds of functionalized nanostructured hybrid microspheres, based on the bridged silsesquioxane family, were synthesized by employing the sol-gel method via self-assembly of two different organic-inorganic bridged monomers. The architecture reached at molecular level allowed the incorporation of acetylsalicylic acid (ASA) as an anti-inflammatory model drug. The ASA-functionalized microspheres were characterized as delivery devices in simulated body fluid (SBF).

Application of impedance spectroscopy to evaluate the effect of different setting accelerators on the developed microstructures of calcium phosphate cements.

The main goal of the present study was to evaluate the effect of different setting accelerator agents on the developed microstructures of calcium phosphate cements (CPCs) by employing the impedance spectroscopy (IS) technique. Six compositions of CPCs were prepared from mixtures of commercial dicalcium phosphate anhydrous (DCPA) and synthesized tetracalcium phosphate (TTCP) as the solid phases. Two TTCP/DCPA molar ratios (1/1 and 1/2) and three liquid phases (aqueous solutions of Na(2)HPO(4), tartaric acid (TA) and oxalic acid (OA), 5% volume fraction) were employed.

Synthesis of tetracalcium phosphate from mechanochemically activated reactants and assessment as a component of bone cements.

The aim of this work was to gain a better understanding about the synthesis of tetracalcium phosphate (TTCP, Ca(4)(PO(4))(2)O) through a solid-state reaction from mechanochemically activated CaCO(3)-(NH(4))(2)HPO(4) mixtures. The evolution of the reaction was followed by DTA, XRD, FTIR and SEM techniques. An enhanced reactivity of the mixtures was detected as the mechanochemical treatment times increased.

Influence of temperature and additives on the microstructure and sintering behaviour of hydroxyapatites with different Ca/P ratios.

Sintering of two hydroxyapatite (HA) samples with different Ca/P ratios was studied as a function of thermal pretreatments, sintering temperature and additives (0-0.6 ion % Li+ or 0-5 ion % Mg2+). The samples were sintered in air and characterized by density measurements, scanning electron microscopy, differential thermal analysis, X-ray diffraction and dilatometry.

Hydrolytic stability of experimental hydroxyapatite-filled dental composite materials.

Objectives: The purpose of this study was to analyze the behavior in water, related to mechanical properties, of experimental composites for dental restoration.

Methods: The studied materials were composed of a visible-light-curing monomer mixture (Bis-GMA and TEGDMA or HEMA) and micrometric, nanometric or a mixture of both sizes hydroxyapatite particles as a reinforcing filler. Filler particles were modified with a coupling agent (citric, hydrosuccinic, acrylic or methacrylic acid or silane).

Mechanical properties of visible light-cured resins reinforced with hydroxyapatite for dental restoration.

Objectives: The purpose of this study was to measure and analyze the mechanical properties of several composite materials designed for dental restoration.

Methods: The materials were composed of a visible light-curing monomer mixture (either Bis-GMA+TEGDMA or Bis-GMA+HEMA) as a matrix and hydroxyapatite (either microscopic or nanoscopic particles) as a reinforcing filler. The surface of the hydroxyapatite particles was modified by using a coupling agent (citric, malic, acrylic or methacrylic acid).

Dental composites reinforced with hydroxyapatite: mechanical behavior and absorption/elution characteristics.

The purpose of this study was to analyze the behavior in water as well as the mechanical and surface properties of experimental composites designed for dental restoration. Studied materials were composed of a visible-light-cured monomer mixture as a matrix (bisphenol-alpha-glycidyl methacrylate with triethyleneglycol dimethacrylate or hydroxyethyl methacrylate) and either micrometric or nanometric hydroxyapatite (HA) particles as a reinforcing filler. The surface of the filler particles was modified by using different coupling agents (citric, hydroxysuccinic, acrylic, or methacrylic acid).

Polymethylmethacrylate-based bone cement modified with hydroxyapatite.

A commercial acrylic bone cement was modified by the incorporation of different weight fractions of polycrystalline hydroxyapatite (HA), and the modified formulation was investigated. The influence of the filler proportion on the flow characteristics and the mechanical behavior of the resultant composite was evaluated. The residual monomer present in the cured materials was measured by gas chromatography.