In the last 30 days

• Open/close Stem cells in bone tissue engineering

  Jeong Min Seong et al 2010 Biomed. Mater. 5 062001 Tag this article

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  Bone tissue engineering has been one of the most promising areas of research, providing a potential clinical application to cure bone defects. Recently, various stem cells including embryonic stem cells (ESCs), bone marrow-derived mesenchymal stem cells (BM-MSCs), umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs), adipose tissue-derived stem cells (ADSCs), muscle-derived stem cells (MDSCs) and dental pulp stem cells (DPSCs) have received extensive attention in the field of bone tissue engineering due to their distinct biological capability to differentiate into osteogenic lineages. The application of these stem cells to bone tissue engineering requires inducing in vitro differentiation of these cells into bone forming cells, osteoblasts. For this purpose, efficient in vitro differentiation towards osteogenic lineage requires the development of well-defined and proficient protocols. This would reduce the likelihood of spontaneous differentiation into divergent lineages and increase the available cell source for application to bone tissue engineering therapies. This review provides a critical examination of the various experimental strategies that could be used to direct the differentiation of ESC, BM-MSC, UCB-MSC, ADSC, MDSC and DPSC towards osteogenic lineages and their potential applications in tissue engineering, particularly in the regeneration of bone.

• Open/close Stimuli-responsive polymers and their applications in drug delivery

  Priya Bawa et al 2009 Biomed. Mater. 4 022001 Tag this article

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  Interest in stimuli-responsive polymers is steadily gaining increasing momentum especially in the fields of controlled and self-regulated drug delivery. Delivery systems based on these polymers are developed to closely resemble the normal physiological process of the diseased state ensuring optimum drug release according to the physiological need. Also termed 'environmental-sensitive' or 'smart', these polymers experience rapid changes in their microstructure from a hydrophilic to a hydrophobic state triggered by small changes in the environment. The changes are reversible; therefore, the polymer is capable of returning to its initial state as soon as the trigger is removed. Stimuli may occur internally (e.g. a change in pH in certain organs or diseased states, a change in temperature or the presence of specific enzymes or antigens). External stimuli include magnetic or electric fields, light, ultrasound, etc. This review will delve into the various internally and externally stimuli-responsive polymers and the drug delivery systems that exploit them.

• Open/close Quantification of growth and differentiation of C2C12 skeletal muscle cells on PSS–PAH-based polyelectrolyte layer-by-layer nanofilms

  Leonardo Ricotti et al 2011 Biomed. Mater. 6 031001 Tag this article

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  Polyelectrolyte layer-by-layer (LbL) nanofilms are interesting polymeric structures, built by alternating adsorption of positively and negatively charged polyelectrolytes. They consist of multilayer sheets with nanometric overall thickness, and they can be used as supports and surface coatings for in vitro and in vivo cell and tissue growth and regeneration. The present study focuses on nanofilms based on alternated layers of poly(sodium-4-sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) fabricated using spin-assisted LbL assembly (SA-LbL). The fabrication process used to assemble polyelectrolyte nanofilms made of up to 60 bilayers is described, and the influence of different surface charges (i.e. changing the terminal layer) and of different film composition (e.g. varying PSS molecular weight) on cell behaviour is investigated. In particular, C2C12 skeletal muscle cells' viability, proliferation and differentiation on six different typologies of polyelectrolyte nanofilms are evaluated and quantified, giving a reference for skeletal muscle regeneration capabilities on such kind of structures.

• Open/close Fabrication of a nanofibrous scaffold with improved bioactivity for culture of human dermal fibroblasts for skin regeneration

  Arun Richard Chandrasekaran et al 2011 Biomed. Mater. 6 015001 Tag this article

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  Engineering dermal substitutes with electrospun nanofibres have lately been of prime importance for skin tissue regeneration. Simple electrospinning technology served to produce nanofibrous scaffolds morphologically and structurally similar to the extracellular matrix of native tissues. The nanofibrous scaffolds of poly(l-lactic acid)-co-poly(ε-caprolactone) (PLACL) and PLACL/gelatin complexes were fabricated by the electrospinning process. These nanofibres were characterized for fibre morphology, membrane porosity, wettability and chemical properties by FTIR analysis to culture human foreskin fibroblasts for skin tissue engineering. The nanofibre diameter was obtained between 282 and 761 nm for PLACL and PLACL/gelatin scaffolds; expressions of amino and carboxyl groups and porosity up to 87% were obtained for these fibres, while they also exhibited improved hydrophilic properties after plasma treatment. The results showed that fibroblasts proliferation, morphology, CMFDA dye expression and secretion of collagen were significantly increased in plasma-treated PLACL/gelatin scaffolds compared to PLACL nanofibrous scaffolds. The obtained results prove that the plasma-treated PLACL/gelatin nanofibrous scaffold is a potential biocomposite material for skin tissue regeneration.

• Open/close Poly(lactic acid) (PLA) based nanocomposites—a novel way of drug-releasing

  Chen Chen et al 2007 Biomed. Mater. 2 L1 Tag this article

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  In this communication, poly(lactic acid) nanofibers have been fabricated by electrospinning and then poly(lactic acid) (PLA) based nanocomposites have been prepared by accumulating anticancer drug daunorubicin on PLA nanofibers combined with TiO ₂ nanoparticles. Our atomic force microscopy (AFM) and laser-scanning confocal microscope (LSCM) studies demonstrate that the respective drug molecules could be readily self-assembled on the surface of the blends of nano-TiO ₂ with PLA polymer nanocomposites, which could further efficiently facilitate the drug permeation and accumulation on the target leukemia K562 cells. Besides, the respective new nanocomposites have good biocompatibility, ease of surface chemistry modification and very high surface area, which may afford the possibility for their promising application in pharmacology and biomedical engineering areas.

• Open/close Novel scaffold design with multi-grooved PLA fibers

  Sangwon Chung et al 2011 Biomed. Mater. 6 045001 Tag this article

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  A novel prototype nonwoven textile structure containing polylactide (PLA) multigrooved fibers has been proposed as a possible scaffold material for superior cell attachment and proliferation. Grooved cross-sectional fibers with larger surface area were obtained by a bi-component spinning system and the complete removal of the sacrificial component was confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and x-ray photon spectroscopy (XPS) analysis. These PLA nonwoven scaffolds containing the grooved fibers exhibited enhanced wettability, greater flexibility and tensile properties, and a larger surface area compared to a traditional PLA nonwoven fabric containing round fibers. To evaluate cellular attachment on the two types of PLA nonwoven scaffolds, NIH 3T3 fibroblasts were cultured for up to 12 days. It was evident that the initial cellular attachment was superior on the scaffold with grooved fibers, which was confirmed by MTT viability assay ( p < 0.01) and SEM analysis. In the future, by modulating the size of the grooves on the fibers, such a scaffold material with a large surface area could serve as an alternative matrix for culturing different types of cells.

• Open/close Electrospun gelatin/polyurethane blended nanofibers for wound healing

  Sung Eun Kim et al 2009 Biomed. Mater. 4 044106 Tag this article

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  In this study, we prepared a blended nanofiber scaffold using synthetic and natural polymers, polyurethane (PU) and gelatin respectively, using the electrospinning method to prepare a material for wound dressing. In order to confirm the properties of this gelatin/PU blended nanofiber scaffold, we performed scanning electron microscopy, atomic force microscopy, attenuated total reflectance Fourier-transform infrared spectroscopy, thermal gravimetric analysis, contact angle, water uptake, mechanical property, recovery, and degradation tests, and cellular response. The results obtained indicate that the mean diameter of these nanofibers was uniformly electrospun and ranged from 0.4 to 2.1 µm. According to the results, when the amount of gelatin in the blended solution decreased, the contact angle increased and water uptake of the scaffold decreased concurrently. In the mechanical tests, the blended nanofibrous scaffolds were elastic, and elasticity increased as the total amount of PU increased. Moreover, as the total amount of gelatin increased, the cell proliferation increased with the same amount of culture time. Therefore, this gelatin/PU blended nanofiber scaffold has potential application for use as a wound dressing.

• Open/close Current investigations into carbon nanotubes for biomedical application

  Xiaoming Li et al 2010 Biomed. Mater. 5 022001 Tag this article

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  The nano-dimensionality of nature has logically given rise to the interest in using nanomaterials in the biomedical field. Currently, a lot of investigations into carbon nanotubes (CNTs), as one of the typical nanomaterials, are being made for biomedical application. In this review, five parts, such as cellular functions induced by CNTs, apatite formation on CNTs, CNT-based tissue engineering scaffold, functionalized CNTs for the delivery of genes and drugs and CNT-based biosensors, are stated, which might indicate that CNTs, with a range of unique properties, appear suited as a biomaterial and may become a useful tool for tissue engineering. However, everything has two parts and CNTs is not an exception. There are still concerns about cytotoxicity and biodegradation of CNTs. Chemical fictionalization may be one of the effective ways to improve the 'disadvantages' and utilize the 'advantages' of CNTs. One of their 'disadvantages', unbiodegradable property, may be utilized by creating monitors in in vivo-engineered tissues or nanosized CNT-based biosensors. Other promising research points, for example proteins adsorbed on CNTs, use of CNTs in combination with other biomaterials to achieve the goals of tissue engineering, mineralization of CNTs and standard toxicological tests for CNTs, are also described in the conclusion and perspectives part.

• Open/close Synthetical bone-like and biological hydroxyapatites: a comparative study of crystal structure and morphology

  Smilja Marković et al 2011 Biomed. Mater. 6 045005 Tag this article

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  Phase composition, crystal structure and morphology of biological hydroxyapatite (BHAp) extracted from human mandible bone, and carbonated hydroxyapatite (CHAp), synthesized by the chemical precipitation method, were studied by x-ray powder diffraction (XRD), Fourier transform infrared (FTIR) and Raman (R) spectroscopy techniques, combined with transmission electron microscopy (TEM). Structural and microstructural parameters were determined through Rietveld refinement of recorded XRD data, performed using the FullProf computing program, and TEM. Microstructural analysis shows anisotropic extension along the [0 0 l] crystallographic direction (i.e. elongated crystallites shape) of both investigated samples. The average crystallite sizes of 10 and 8 nm were estimated for BHAp and CHAp, respectively. The FTIR and R spectroscopy studies show that carbonate ions substitute both phosphate and hydroxyl ions in the crystal structure of BHAp as well as in CHAp, indicating that both of them are mixed AB-type of CHAp. The thermal behaviour and carbonate content were analysed using thermogravimetric and differential thermal analysis. The carbonate content of about 1 wt.% and phase transition, at near 790 °C, from HAp to β-tricalcium phosphate were determined in both samples. The quality of synthesized CHAp powder, particularly, the particle size distribution and uniformity of morphology, was analysed by a particle size analyser based on laser diffraction and field emission scanning electron microscopy, respectively. These data were used to discuss similarity between natural and synthetic CHAp. Good correlation between the unit cell parameters, average crystallite size, morphology, carbonate content and crystallographic positions of carbonate ions in natural and synthetic HAp samples was found.

• Open/close The effect of fluoride surface modification of ceramic TiO₂ on the surface properties and biological response of osteoblastic cells in vitro

  H Tiainen et al 2011 Biomed. Mater. 6 045006 Tag this article

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  This study investigates the effect of fluoride surface modification on the surface properties of polycrystalline ceramic TiO ₂ and the biological response of murine osteoblast cells to fluoride-modified TiO ₂ in vitro. Fluoride concentrations up to 9 at.% were detected and the fluoride was found to bind to the surface in a ligand exchange reaction between surface hydroxyl groups and the fluoride anions from the HF. No significant changes in the surface topography were detected. In vitro experiments were performed in order to evaluate the biological response of the MC3T3-E1 cells to the fluoride-modified ceramic TiO ₂ surfaces. No difference in the lactate dehydrogenase (LDH) activity was seen in comparison to unmodified samples, apart from the highest fluoride concentration (~9 at.%) which was found to be more toxic to the cells. Real-time PCR analysis showed no conclusive evidence for the fluoride-induced promotion of osteoblast differentiation as no significant increase in the collagen-1, osteocalcin, or BMP-2 mRNA levels was detected on the fluoride-modified ceramic TiO ₂ surfaces apart from one group, which showed an elevated osteocalcin level and higher number of cells. Since the observed grain boundary corrosion is also anticipated to reduce the mechanical properties of ceramic TiO ₂, this surface modification method may not be an ideal method for improving the osteogenic response of ceramic TiO ₂ scaffolds.