Use of genetically modified muscle and fat grafts to repair defects in bone and cartilage

We report a novel technology for the rapid healing of large osseous and chondral defects, based upon the genetic modification of autologous skeletal muscle and fat grafts. These tissues were selected because they not only possess mesenchymal progenitor cells and scaffolding properties, but also can be biopsied, genetically modified and returned to the patient in a single operative session. First generation adenovirus vector carrying cDNA encoding human bone morphogenetic protein-2 (Ad.BMP-2) was used for gene transfer to biopsies of muscle and fat. To assess bone healing, the genetically modified (“gene activated”) tissues were implanted into 5mm-long critical size, mid-diaphyseal, stabilized defects in the femora of Fischer rats. Unlike control defects, those receiving gene-activated muscle underwent rapid healing, with evidence of radiologic bridging as early as 10 days after implantation and restoration of full mechanical strength by 8 weeks. Histologic analysis suggests that the grafts rapidly differentiated into cartilage, followed by efficient endochondral ossification. Fluorescence in situ hybridization detection of Y-chromosomes following the transfer of male donor muscle into female rats demonstrated that at least some of the osteoblasts of the healed bone were derived from donor muscle. Gene activated fat also healed critical sized defects, but less quickly than muscle and with more variability. Anti-adenovirus antibodies were not detected. Pilot studies in a rabbit osteochondral defect model demonstrated the promise of this technology for healing cartilage defects. Further development of these methods should provide ways to heal bone and cartilage more expeditiously, and at lower cost, than is presently possible.

Bisphenol A degradation enhanced by air bubbles via advanced oxidation using in situ generated ferrous ions from nano zero-valent iron/palygorskite composite materials

Novel nano zero-valent iron/palygorskite composite materials prepared by evaporative and centrifuge methods are tested for the degradation of bisphenol A in an aqueous medium. A systematic study is presented which showed that nano zero-valent iron material has little effect on bisphenol A degradation. When hydrogen peroxide was added to initiate the reaction, some percentage of bisphenol A removal (∼20%) was achieved; however, with the aid of air bubbles, the percentage removal can be significantly increased to ∼99%. Compared with pristine nano zero-valent iron and commercial iron powder, nano zero-valent iron/palygorskite composite materials have much higher reactivity towards bisphenol A and these materials are superior as they have little impact on the solution pH. However, for pristine nano zero-valent iron, it is difficult to maintain the reaction system at a favourable low pH which is a key factor in maintaining high bisphenol A removal. All materials were characterized by X-ray diffraction, scanning electron microscopy, elemental analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. The optimum conditions were obtained based on a series of batch experiments. This study has extended the application of nano zero-valent iron/palygorskite composites as effective materials for the removal of phenolic compounds from the environment.

Identification of phospholipids in human meibum by nano-electrospray ionisation tandem mass spectrometry

Meibum is believed to be the major source of tear film lipids, which are vital in the prevention of excess evaporation of the aqueous phase. The complete lipid composition of meibum has yet to be established. While earlier studies reported the presence of phospholipids in human meibum, recent mass spectrometric studies have not detected them. In this study we use electrospray ionisation tandem mass spectrometry to investigate the presence of phospholipids in meibum and provide comparison to the phospholipid profile of tears.Lipids were extracted from human meibum and tear samples using standard biphasic methods and analysed by nano-electrospray ionisation tandem mass spectrometry using targeted ion scans. A total of 35 choline-containing phospholipids were identified in meibum and the profile of these was similar to that observed in tears, suggesting tear lipids are derived from meibum. The results shown here highlight the need for a combination of optimised techniques to enable the identification of the large range of lipid classes in meibum. © 2011 Elsevier Ltd.

Comparison of mechanical and ultrasound elastic modulus of ovine tibial cortical bone

Finite element models of bones can be created by deriving geometry from anx-ray CT scan. Material properties such as the elastic modulus can then be applied using either a single or set of homogeneous values, or individual elements can have local values mapped onto them. Values for the elastic modulus can be derived from the CT density values using an elasticityversus density relationship. Many elasticity–density relationships have been reported in the literature for human bone. However, while ovine in vivo models are common in orthopaedic research, no work has been done to date on creating FE models of ovine bones. To create these models and apply relevant material properties, an ovine elasticity-density relationship needs to be determined. Using fresh frozen ovine tibias the apparent density of regions of interest was determined from a clinical CT scan. The bones were the sectioned into cuboid samples of cortical bone from the regions of interest. Ultrasound was used to determine the elastic modulus in each of three directions – longitudinally, radially and tangentially. Samples then underwent traditional compression testing in each direction. The relationships between apparent density and both ultrasound, and compression modulus in each directionwere determined. Ultrasound testing was found to be a highly repeatable non-destructive method of calculating the elastic modulus, particularly suited to samples of this size. The elasticity-density relationships determined in the longitudinal direction were very similar between the compression and ultrasound data over the density range examined.A clear difference was seen in the elastic modulus between the longitudinal and transverse directions of the bone samples, and a transverse elasticity-density relationship is also reported.

Hyperbranched polymer-gold nanoparticle assemblies : role of polymer architecture in hybrid assembly formation and SERS activity

Plasmonic gold nano-assemblies that self-assemble with the aid of linking molecules or polymers have the potential to yield controlled hierarchies of morphologies and consequently result in materials with tailored optical (e.g. localized surface plasmon resonances (LSPR)) and spectroscopic properties (e.g. surface enhanced Raman scattering (SERS)). Molecular linkers that are structurally well-defined are promising for forming hybrid nano-assemblies which are stable in aqueous solution and are increasingly finding application in nanomedicine. Despite much ongoing research in this field, the precise role of molecular linkers in governing the morphology and properties of the hybrid nano-assemblies remains unclear. Previously we have demonstrated that branched linkers, such as hyperbranched polymers, with specific anchoring end groups can be successfully employed to form assemblies of gold NPs demonstrating near-infrared SPRs and intense SERS scattering. We herein introduce a tailored polymer as a versatile molecular linker, capable of manipulating nano-assembly morphologies and hot-spot density. In addition, this report explores the role of the polymeric linker architecture, specifically the degree of branching of the tailored polymer in determining the formation, morphology and properties of the hybrid nano-assemblies. The degree of branching of the linker polymer, in addition to the concentration and number of anchoring groups, is observed to strongly influence the self-assembly process. The assembly morphology shifts primarily from 1D-like chains to 2D plates and finally to 3D-like globular structures, with increase in degree of branching. Insights have been gained into how the morphology influences the SERS performance of these nano-assemblies with respect to hot-spot density. These findings supplement the understanding of the morphology determining nano-assembly formation and pave the way for the possible application of these nano-assemblies as SERS bio-sensors for medical diagnostics.

Lithium release from ß-tricalcium phosphate inducing cementogenic and osteogenic differentiation for both hPDLCs and hBMSCs

It is accepted that the accelerated differentiation of tissue cells on bioactive materials is of great importance to regenerate the lost tissues. It was previously reported that lithium (Li) ions could enhance the in vitro proliferation and differentiation of retinoblastoma cells and endometrium epithelia by activating the Wnt canonical signalling pathway. It is interesting to incorporate Li ions into bioactive ceramics, such as β-tricalcium phosphate (Li-β-TCP), in order to stimulate both osteogenic and cementogenic differentiation of different stem cells for the regeneration of bone/periodontal tissues. Therefore, the aim of this study was to investigate the interactions of human periodontal ligament cells (hPDLCs) and human bone marrow stromal cells (hBMSCs) with Li-β-TCP bioceramic bulks and their ionic extracts, and further explore the osteogenic and cementogenic stimulation of Li-β-TCP bioceramics and the possible molecular mechanisms. The results showed that Li-β-TCP bioceramic disks supported the cell attachment and proliferation, and significantly enhanced bone/cementum-related gene expression, Wnt canonical signalling pathway activation for both hPDLCs and hBMSCs, compared to conventional β-TCP bioceramic disks without Li. The release of Li from Li-β-TCP powders could significantly promote the bone/cementum-related gene expression for both hPDLCs and hBMSCs compared to pure β-TCP extracts without Li release. Our results suggest that the combination of Li with β-TCP bioceramics may be a promising method to enhance bone/cementum regeneration as Li-β-TCP possesses excellent in vitro osteogenic and cementogenic stimulation properties by inducing bone/cementum-related gene expression in both hPDLCs and hBMSCs.

Self assembly of plasmonic core-satellite nano-assemblies mediated by hyperbranched polymer linkers

The morphology of plasmonic nano-assemblies has a direct influence on optical properties, such as localised surface plasmon resonance (LSPR) and surface enhanced Raman scattering (SERS) intensity. Assemblies with core-satellite morphologies are of particular interest, because this morphology has a high density of hot-spots, while constraining the overall size. Herein, a simple method is reported for the self-assembly of gold NPs nano-assemblies with a core-satellite morphology, which was mediated by hyperbranched polymer (HBP) linkers. The HBP linkers have repeat units that do not interact strongly with gold NPs, but have multiple end-groups that specifically interact with the gold NPs and act as anchoring points resulting in nano-assemblies with a large (~48 nm) core surrounded by smaller (~15 nm) satellites. It was possible to control the number of satellites in an assembly which allowed optical parameters such as SPR maxima and the SERS intensity to be tuned. These results were found to be consistent with finite-difference time domain (FDTD) simulations. Furthermore, the multiplexing of the nano-assemblies with a series of Raman tag molecules was demonstrated, without an observable signal arising from the HBP linker after tagging. Such plasmonic nano-assemblies could potentially serve as efficient SERS based diagnostics or biomedical imaging agents in nanomedicine.

Characterisation of the micro-architecture of direct writing melt electrospun tissue engineering scaffolds using diffusion tensor and computed tomography microimaging

This article describes the first steps toward comprehensive characterization of molecular transport within scaffolds for tissue engineering. The scaffolds were fabricated using a novel melt electrospinning technique capable of constructing 3D lattices of layered polymer fibers with well - defined internal microarchitectures. The general morphology and structure order was then determined using T 2 - weighted magnetic resonance imaging and X - ray microcomputed tomography. Diffusion tensor microimaging was used to measure the time - dependent diffusivity and diffusion anisotropy within the scaffolds. The measured diffusion tensors were anisotropic and consistent with the cross - hatched geometry of the scaffolds: diffusion was least restricted in the direction perpendicular to the fiber layers. The results demonstrate that the cross - hatched scaffold structure preferentially promotes molecular transport vertically through the layers ( z - axis), with more restricted diffusion in the directions of the fiber layers ( x – y plane). Diffusivity in the x – y plane was observed to be invariant to the fiber thickness. The characteristic pore size of the fiber scaffolds can be probed by sampling the diffusion tensor at multiple diffusion times. Prospective application of diffusion tensor imaging for the real - time monitoring of tissue maturation and nutrient transport pathways within tissue engineering scaffolds is discussed.

Tunable “Nano-Shearing” : A physical mechanism to displace nonspecific cell adhesion during rare cell detection

We report a tunable alternating current electrohydrodynamic (ac-EHD) force which drives lateran fluid motion within a few nanometers of an electrode surface. Because the magnitude of this fluid shear force can be tuned externally (e.g., via the application of an ac electric field), it provides a new capability to physically displace weakly (nonspecifically) bound cellular analytes. To demonstrate the utility of the tunable nanoshearing phenomenon, we present data on purpose-built microfluidic devices that employ ac-EHD force to remove nonspecific adsorption of molecular and cellular species. Here, we show that an ac-EHD device containing asymmetric planar and microtip electrode pairs resulted in a 4-fold reduction in nonspecific adsorption of blood cells and also captured breast cancer cells in blood, with high efficiency (approximately 87%) and specificity. We therefore feel that this new capability of externally tuning and manipulating fluid flow could have wide applications as an innovative approach to enhance the specific capture of rare cells such as cancer cells in blood.

Lanthanum oxide nanostructured films synthesized using hot dense and extremely non-equilibrium plasma for nanoelectronic device applications

Lanthanum oxide (La2O3) nanostructured films are synthesized on a p-type silicon wafer by ablation of La2O3 pellet due to interaction with hot dense argon plasmas in a modified dense plasma focus (DPF) device. The nanostructured films are investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) spectra. SEM study shows the formation of nano-films having nano-size structures with the average nanostructures size ~25, ~53, and ~45 nm for one, two, and three DPF shots, respectively. The nanostructures sizes and morphology of nano-films are consistent between the AFM and SEM analyses. XRD spectra confirms nano-sized La2O3 with an average grain size ~34, ~51, and ~42 nm for one, two, and three DPF shots, respectively. The electrical properties such as current-voltage and capacitance-voltage (C-V) characteristics of the Al-La2O3-Si metal-oxide- semiconductor (MOS) capacitor structure are measured. The current conduction mechanism of the MOS capacitors is also demonstrated. The C-V characteristics are further used to obtain the electrical parameters such as the dielectric constant, oxide thickness, flat-band capacitance, and flat-band voltage of the MOS capacitors. These measurements demonstrate significantly lower leakage currents without any commonly used annealing or doping, thereby revealing a significant improvement of the MOS nanoelectronic device performance due to the incorporation of the DPF-produced La2O3 nano-films.

Plasma nanoscience : from nano-solids in plasmas to nano-plasmas in solids

The unique plasma-specific features and physical phenomena in the organization of nanoscale soild-state systems in a broad range of elemental composition, structure, and dimensionality are critically reviewed. These effects lead to the possibility to localize and control energy and matter at nanoscales and to produce self-organized nano-solids with highly unusual and superior properties. A unifying conceptual framework based on the control of production, transport, and self-organization of precursor species is introduced and a variety of plasma-specific non-equilibrium and kinetics-driven phenomena across the many temporal and spatial scales is explained. When the plasma is localized to micrometer and nanometer dimensions, new emergent phenomena arise. The examples range from semiconducting quantum dots and nanowires, chirality control of single-walled carbon nanotubes, ultra-fine manipulation of graphenes, nano-diamond, and organic matter to nano-plasma effects and nano-plasmas of different states of matter. © 2013 Taylor and Francis Group, LLC.

Core-leaf onion-like carbon/MnO2 hybrid nano-urchins for rechargeable lithium-ion batteries

A hybrid nano-urchin structure consisting of spherical onion-like carbon and MnO2 nanosheets is synthesized by a facile and environmentally-friendly hydrothermal method. Lithium-ion batteries incorporating the hybrid nano-urchin anode exhibit reversible lithium storage with superior specific capacity, enhanced rate capability, stable cycling performance, and nearly 100% Coulombic efficiency. These results demonstrate the effectiveness of designing hybrid nano-architectures with uniform and isotropic structure, high loading of electrochemically-active materials, and good conductivity for the dramatic improvement of lithium storage.

Plasma functionalization of SiO2 nanoparticles for the synthesis of polymer nano-dielectrics

In this study, we improve the insulation performance of polymeric nano-dielectrics by using plasma pre-treatment on the filled nanoparticles. Non-equilibrium atmospheric-pressure plasma is employed to modify a commercial type of silane-coated SiO2 nanoparticles. The treated nanoparticles and the synthesized epoxy-based nanocomposites are characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The plasma-treated SiO2 nanoparticles can disperse uniformly and form strong covalent bonds with the molecules of the polymer matrix. Moreover, the electrical insulation properties of the synthesized nanocomposites are investigated. Results show that the nanocomposites with plasma-treated SiO2 nanoparticles obtain improved dielectric breakdown strength and extended endurance under intense electrical ageing process.