Targeting Calcium Magnesium Silicates for Polycaprolactone/Ceramic Composite Scaffolds

Amikacin sulphate loaded chitosan-diopside nanoparticles composite scaffold for infectious wound healing

A wound dressing material should inhibit infections that may occur at the wound site, and at the same time, it should enhance the healing process. In this study, we developed an amikacin sulphate (AK) incorporated chitosan (Ch) and Diopside nanoparticles composite dressing (Ch-nDE-AK) for controlling wound infection and healing. The diopside nanoparticles (nDE) were prepared using sol-gel synthesis and characterized using XRD, FT-IR, and FESEM. nDE shows a size range of 142 ± 31 nm through FESEM analysis. Later, the developed composite dressing was characterized using SEM, EDS, and FT-IR analysis. Ch-nDE-AK dressing possesses a porous nature that will aid in easy cell infiltration and proliferation. The swelling studies indicated the expansion capability of the scaffold when applied to the injured site. Ch-nDE-AK scaffold showed a 69.6 ± 8.2 % amikacin sulphate release up to 7 days, which indicates the sustained release of the drug from Ch-nDE-AK scaffold. The drug release data was subjected to various kinetics models and was observed to follow the Higuchi model. The scaffold showed antibacterial activity against ATCC strains of S. aureus and E. coli for 7 days by in vitro. Ch-nDE-AK scaffold also showed antibacterial activity against S. aureus and E. coli clinical strains in vitro. The ex vivo antibacterial study confirmed the antibacterial ability of Ch-nDE-AK scaffold against S. aureus and E. coli. Ch-nDE-AK scaffold also exhibits anti-biofilm activity against S. aureus and E. coli. The Ch-nDE-AK scaffold showed cytocompatibility and cell attachment to fibroblast cells. Additionally, the scratch assay using fibroblast cells confirmed the role of the nDE in the scaffold, helping in cell migration. Thus, the developed Ch-nDE-AK dressing can potentially be used to treat infectious wound healing.

Processing of Calcium Magnesium Silicates by the Sol–Gel Route

In this work, calcium magnesium silicate ceramics were processed through the sol–gel method in order to study the crystalline and morphological properties of the resulting materials in correlation with the compositional and thermal parameters. Tetraethyl orthosilicate and calcium/magnesium nitrates were employed as sources of cations, in ratios specific to diopside, akermanite and merwinite; they were further subjected to gelation, calcination (600 °C) and thermal treatments at different temperatures (800, 1000 and 1300 °C). The properties of the intermediate and final materials were investigated by thermal analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction and Rietveld refinement. Such ceramics represent suitable candidates for tissue engineering applications that require porosity and bioactivity.

Antibacterial biomaterials in bone tissue engineering

Bone infection is a devastating disease characterized by recurrence, drug-resistance, and high morbidity, that has prompted clinicians and scientists to develop novel approaches to combat it. Currently, although numerous biomaterials that possess excellent biocompatibility, biodegradability, porosity, and mechanical strength have been developed, their lack of effective antibacterial ability substantially limits bone-defect treatment efficacy. There is, accordingly, a pressing need to design antibacterial biomaterials for effective bone-infection prevention and treatment. This review focuses on antibacterial biomaterials and strategies; it presents recently reported biomaterials, including antibacterial implants, antibacterial scaffolds, antibacterial hydrogels, and antibacterial bone cement types, and aims to provide an overview of these antibacterial materials for application in biomedicine. The antibacterial mechanisms of these materials are discussed as well.

An Image-Guided Intrascaffold Cell Assembly Technique for Accurate Printing of Heterogeneous Tissue Constructs

For tissue engineering and regenerative medicine, creating thick and heterogeneous scaffold-based tissue constructs requires deep and precise multicellular deposition. Traditional cell seeding strategies lack the ability to create multicellular tissue constructs with high cell penetration and distribution, while emerging strategies aim to simultaneously combine cell-laden tissue segments with scaffold fabrication. Here we describe a technique that allows for three-dimensional (3D) intrascaffold cell assembly in which scaffolds are prefabricated and pretreated, followed by accurate cell distribution within the scaffold using an image-guided technique. This two-step process yields less limitation in scaffold material choice as well as additional treatments, provides accurate cell distribution, and has less potential to harm cells. The image processing technique captures a 2D geometric image of the scaffold, followed by a series of processes, mainly including grayscale transformation, threshold segmentation, and boundary extraction, to ultimately locate scaffold macropore centroids. Coupled with camera calibration data, accurate 3D cell assembly pathway plans can be made. Intrascaffold assembly parameter optimization and complex intrascaffold gradient, multidirectional, and vascular structure assembly were studied. Demonstration was also made with path planning and cell assembly experiments using NIH3T3-cell-laden hydrogels and collagen-coated poly(lactic-co-glycolic acid) (PLGA) scaffolds. Experiments with CellTracker fluorescent monitoring, live/dead staining, and phalloidin-F-actin/DAPI immunostaining and comparison with two control groups (bioink manual injection and cell suspension static surface pipetting) showed accurate cell distribution and positioning and high cell viability (>93%). The PrestoBlue assay showed obvious cell proliferation over seven culture days in vitro. This technique provides an accurate method to aid simple and complex cell colonization with variant depth within 3D-scaffold-based constructs using multiple cells. The modular method can be used with any existing printing platform and shows potential in facilitating direct spatial organization and hierarchal 3D assembly of multiple cells and/or drugs within scaffolds for further tissue engineering studies and clinical applications.

Carbon nanotube, graphene and boron nitride nanotube reinforced bioactive ceramics for bone repair

The high brittleness and low strength of bioactive ceramics have severely restricted their application in bone repair despite the fact that they have been regarded as one of the most promising biomaterials. In the last few years, low-dimensional nanomaterials (LDNs), including carbon nanotubes, graphene and boron nitride nanotubes, have gained increasing attention owing to their favorable biocompatibility, large surface specific area and super mechanical properties. These qualities make LDNs potential nanofillers in reinforcing bioactive ceramics. In this review, the types, characteristics and applications of the commonly used LDNs in ceramic composites are summarized. In addition, the fabrication methods for LDNs/ceramic composites, such as hot pressing, spark plasma sintering and selective laser sintering, are systematically reviewed and compared. Emphases are placed on how to obtain the uniform dispersion of LDNs in a ceramic matrix and maintain the structural stability of LDNs during the high-temperature fabrication process of ceramics. The reinforcing mechanisms of LDNs in ceramic composites are then discussed in-depth. The in vitro and in vivo studies of LDNs/ceramic in bone repair are also summarized and discussed. Finally, new developments and potential applications of LDNs/ceramic composites are further discussed with reference to experimental and theoretical studies.

STATEMENT OF SIGNIFICANCE

Despite bioactive ceramics having been regarded as promising biomaterials, their high brittleness and low strength severely restrict their application in bone scaffolds. In recent years, low-dimensional nanomaterials (LDNs), including carbon nanotubes, graphene and boron nitride nanotubes, have shown great potential in reinforcing bioactive ceramics owing to their unique structures and properties. However, so far it has been difficult to maintain the structural stability of LDNs during fabrication of LDNs/ceramic composites, due to the lengthy, high-temperature process involved. This review presents a comprehensive overview of the developments and applications of LDNs in bioactive ceramics. The newly-developed fabrication methods for LDNs/ceramic composites, the reinforcing mechanisms and the in vitro and in vivo performance of LDNs are also summarized and discussed in detail.

Fabrication and characterization of cell sheets using methylcellulose and PNIPAAm thermoresponsive polymers: A comparison Study

Culturing cells on thermoresponsive polymers enables cells to be harvested as an intact cell sheet without disrupting the extracellular matrix or compromising cell-cell junctions. Previously, cell sheet fabrication methods using methylcellulose (MC) gel and PNIPAAm were independently demonstrated. In this study, MC and PNIPAAm fabrication methods are detailed and the resulting cell sheets characterized in parallel studies for direct comparison of human adipose derived stromal/stem cell (hASCs) sheet formation, cell morphology, viability, proliferation, and osteogenic potential over 21 days. A cell viability study revealed that hASCs in MC and PNIPAAm cell sheets remained viable for 21 days and proliferated until confluency. Osteogenic cell sheets exhibited upregulation of alkaline phosphatase (ALP) at day 7, as well as calcium deposition at 21 days. Additionally, expression of osteocalcin (OCN), a late-stage marker of osteogenesis, was quantified at days 14 and 21 using RT-PCR. OCN was upregulated in MC cell sheets at day 14 and PNIPAAm cell sheets at days 14 and 21. These results indicate that hASCs formed into cell sheets commit to an osteogenic lineage when cultured in osteogenic conditions. Cell sheets composed of hASCs may be used for further studies of hASC differentiation or surgical delivery of undifferentiated cells to defect sites. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1346-1354, 2017.

45S5 Bioglass analogue reinforced akermanite ceramic favorable for additive manufacturing mechanically strong scaffolds

Mechanically strong akermanite-based porous bioceramic scaffolds with appreciable bioactivity and biodegradation were developedviaextrusion 3D-printing followed by a low-melt bioactive glass-assisted pressureless sintering process.