Weizhong Yang

Preparation, in vitro degradability, cytotoxicity, and in vivo biocompatibility of porous hydroxyapatite whisker-reinforced poly(L-lactide) biocomposite scaffolds

Abstract Biodegradable and bioactive scaffolds with interconnected macroporous structures, suitable biodegradability, adequate mechanical property, and excellent biocompatibility have drawn increasing attention in bone tissue engineering. Hence, in this work, porous hydroxyapatite whisker-reinforced poly(L-lactide) (HA-w/PLLA) composite scaffolds with different ratios of HA and PLLA were successfully developed through compression molding and particle leaching. The microstructure, in vitro mineralization, cytocompatibility, hemocompatibility, and in vivo biocompatibility of the porous HA-w/PLLA were investigated for the first time. The SEM results revealed that these HA-w/PLLA scaffolds possessed interconnected pore structures. Compared with porous HA powder-reinforced PLLA (HA-p/PLLA) scaffolds, HA-w/PLLA scaffolds exhibited better mechanical property and in vitro bioactivity, as more formation of bone-like apatite layers were induced on these scaffolds after mineralization in SBF. Importantly, in vitro cytotoxicity displayed that porous HA-w/PLLA scaffold with HA/PLLA ratio of 1:1 (HA-w1/PLLA1) produced no deleterious effect on human mesenchymal stem cells (hMSCs), and cells performed elevated cell proliferation, indicating a good cytocompatibility. Simultaneously, well-behaved hemocompatibility and favorable in vivo biocompatibility determined from acute toxicity test and histological evaluation were also found in the porous HA-w1/PLLA1 scaffold. These findings may provide new prospects for utilizing the porous HA whisker-based biodegradable scaffolds in bone repair, replacement, and augmentation applications.

Nano-hydroxyapatite reinforced polyphenylene sulfide biocomposite with superior cytocompatibility and in vivo osteogenesis as a novel orthopedic implant

The design of novel functional biomaterials that possess similar mechanical attributes as human bones, accompanied with admirable osteogenesis to replace conventional metallic implants would be an intriguing accomplishment, especially in the orthopedic, craniomaxillofacial and dental fields where biointerfaces with outstanding osseointegration are in high demand. Guided by this purpose, in the current study, nano-hydroxyapatite reinforced polyphenylene sulfide (PPS/nano-HA) biocomposites via a process of compounding and injection-molding, in an attempt to elevate the bioactivity and osteogenic properties of PPS, were successfully developed for the first time. The resultant binary composites were characterized in terms of topological structure, chemical composition, hydrophilicity, and water uptake capacity. Mechanical property evaluation revealed that the elastic modulus of the PSS/nano-HA composites was closer to that of natural bones. Besides, in vitro cytotoxicity, cell proliferation, alkaline phosphatase activity, osteocalcin expression and calcium mineral deposition all disclosed that the PSS/nano-HA bioactive composites evoked better cell viability and osteo-differentiation of osteoblasts on account of the contribution of the doped nano-HA. To our delight, in vivo assessment of the calvarial defect model by means of soft X-ray, histological observation, and real-time PCR analysis after 8 weeks confirmed the dramatically accelerated osteogenesis and osteointegration. Overall, our findings demonstrated that the nano-HA enriched PPS biocomposites with impressive cytocompatibility and osteogenic functions hold large potential in load-bearing orthopedic and dental applications. In addition, this work will, as expected, offer a crucial scientific basis and experimental fundamentals to support the adoption of PPS-based biomaterials as new hard tissue repair materials for further clinical therapy.

Poly(N-isopropyl acrylamide)/chitosan composite membrane with smart thermoresponsive performance

Abstract In this study, poly(N-isopropylacrylamide)/chitosan (PNIPAAm/CS) composite membranes with different weight ratios were fabricated using a one-step method, in which PNIPAAm was directly synthesised using NIPAAm monomers by means of free radical polymerisation. Fourier transform infrared spectroscopy and X-ray diffraction were employed to characterise the interactions. The lower critical solution temperature (LCST) of the swollen membrane was determined by differential scanning calorimetry. The morphologies of the obtained membranes were observed using SEM. The results showed that there was hydrogen bonding formed between CS and PNIPAAm. The LCST of the PNIPAAm/CS membranes was about 31·3–31·8°C. Obvious phase conversion and shape change of the composite membrane can occur below and above the LCST, indicating that when the weight ratio of PNIPAAm to CS is 7 : 3 to 5 : 5, the composite membranes have the potential to be used as a smart artificial skin or wound dressings.

Preparation and characterisation of nanohydroxyapatite–sodium alginate–polyvinyl alcohol composite scaffold

Abstract In this study, novel porous composite scaffolds for bone tissue engineering and drug delivery system were prepared from nanohydroxyapatite, biodegradable Ca crosslinked sodium alginate (SA) and polyvinyl alcohol (PVA) by the method of coprecipitation. The properties of the composite were characterised by the means of burning test, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, mechanical test and cell experiment. The results show that the nanohydroxyapatite component could disperse uniformly in SA–PVA copolymer matrix. Excellent miscibility existed among the three phases and inter- or intrahydrogen bonding could be formed among the three phases. The entrance of PVA matrix in the composite enhanced the mechanical properties of the composite scaffold. The scaffold exhibited highly porous structure with a pore size of 50–250 μm and porosity up to 75%. When the porous scaffold contained 50% PVA, its compressive strength reached 8·29 MPa. Preliminary cell experiment testified that the composite scaffold was no cytotoxicity. This triphasic composite scaffold shows good prospects for bone tissue engineering and controlled drug delivery system.

Enhanced antibacterial property and osteo-differentiation activity on plasma treated porous polyetheretherketone with hierarchical micro/nano-topography

Abstract Implantable polyetheretherketone (PEEK) has great biomedical potential as hard tissue substitute in orthopedic application due to its outstanding mechanical properties and excellent biological stability. However, the poor osseointegration and bacteriostatic ability of implantable PEEK become the major barrier for its wide clinic application. In this study, a hierarchically micro/nano-topographic PEEK with specific functional groups (amino and COOH/COOR) has been fabricated using facile sulfonation combined with argon plasma treatment. The new developed hierarchically micro/nano-topographic PEEK have enhanced hydrophilicity, surface roughness, as well as the high ability of apatite-layer forming. Antibacterial assessment shows that as-treated samples exhibit better antibacterial activity. The cellular responses in osteoblast-like MG-63 cells culturing experiment reveal that the micro/nano-topography accompanied with specific functional groups improves the cell adhesion at the initial stage, further ameliorates proliferation and osteogenic differentiation of MG-63. This study proposes a promising approach to increase osteo-differentiation activity and bacteriostasis of PEEK via synergistic effects involving surface topologic structure and chemical modification, which shows great potential in developing advanced implantable materials.

Preparation of nano-sized titanium carbide particles via a vacuum carbothermal reduction approach coupled with purification under hydrogen/argon mixed gas

In the present work, nano-sized titanium carbide (TiC) particles were successfully synthesized through a process of producing carbon coated titanium precursors, heating these precursors under vacuum conditions at 1450xa0°C for 2 h, and treating the products in hydrogen/argon (1:1) mixed gas or hydrogen gas. The effects of carbon content, pressure and temperature of removing excess carbon on the TiC products were examined by using XRD, SEM, TEM and DTA-TG analysis. Experimental results demonstrated that TiC powders with a single phase were obtained when the molar ratio of Ti to C ranged from 1:2 to 1:4. With changing the molar ratio of Ti/C in the precursors, the particle size of the synthetized TiC powders varied from 30 to 200 nm. After treatment in the hydrogen/argon mixed gas at 830 °C for 3 h, the TiC product accounted for a high TiC purity of 99.36% and possessed a small grain size of about 20 nm. The vacuum calcination method coupled with the hydrogen/argon mixed gas process applied in this work would be an efficient way to obtain nano-sized and purified TiC particles, which hold great promising for industrial purposes.

Effect of lanthanum doping on the far-infrared emission property of vanadium–titanium slag ceramic

In the present study, a series of far-infrared ceramics were successfully synthesized using vanadium–titanium slag solid waste and some ordinary minerals as main raw materials with lanthanum (La) as an additive. The phase composition and microstructure of the prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM). Besides, the far-infrared emission and absorption properties of the ceramics were determined via Fourier transform infrared spectroscopy (FT-IR). The results indicated that the doped La3+ could efficiently promote the transformation of Fe2+ to Fe3+, which decreased crystallite size and increased lattice strain in the orthopyroxene-like structure. When doped with 9 wt% La, the vibration absorption intensities of Si–O–Mg and Si–O–Fe in orthopyroxenes irregular polyhedron and inerratic octahedron sites were strongest, which consequently contributed to enhanced far-infrared emissivity in 8–14 μm wavebands, reaching as high as 0.927. Moreover, the product exhibited a high bending strength of 30.45 ± 0.54 MPa for the La-doped groups, satisfying the requirement of ISO 13006 standard (>18 MPa). These results indicated that our prepared La3+-doped vanadium–titanium slag ceramics hold great promise for practical infrared applications due to their high far-infrared emissivity and excellent physical performances.

Preparation and in vitro degradation study of the porous dual alpha/beta-tricalcium phosphate bioceramics

The ideal bone tissue engineering scaffolds are long-cherished with the properties of suitable three-dimensional structure, controlled biodegradability and acceptable biocompatibility. Here, the porous biphasic α/β-tricalcium phosphate (α/β-TCP) bioceramics with different two phase ratios of α-tricalcium phosphate (α-TCP) and β-tricalcium phosphate (β-TCP) were successfully synthesised by heating an amorphous calcium phosphate (ACP) precursor containing pore-forming agent. The crystalline and morphological characterisation revealed that α- and β-TCP phases co-existed in the α/β-TCP bioceramics and they had interconnected pore structures with size between 200 and 500u2009μm. The degradation behaviours of the biphasic α/β-TCPs were also probed in physiological saline solution under static and dynamic environments for the first time. The results showed that dissolution rate of α/β-TCP bioceramics in dynamic environment was higher than that under static conditions. Compared with monophasic TCP ceramics, these porous α/β-TCP bioceramics displayed a tailored dissolution rate through tuning the proportion of each TCP phases (α and β) in the materials, and the Ca degradation concentration correlated with the circulating flow velocity. Further, the degradation profile of porous α/β-TCPs was well-described by Johnson–Mehl–Avrami (JMA) method. The porous biphasic α/β-TCP bioceramics with controllable degradation performance hold great potential to be applied in bone tissue engineering.

Dual Ag/ZnO‐Decorated Micro‐/Nanoporous Sulfonated Polyetheretherketone with Superior Antibacterial Capability and Biocompatibility via Layer‐by‐Layer Self‐Assembly Strategy

Polyetheretherketone is attractive for dental and orthopedic applications due to its mechanical attributes close to that of human bone; however, the lack of antibacterial capability and bioactivity of polyetheretherketone has substantially impeded its clinical applications. Here, a dual therapy implant coating is developed on the 3D micro-/nanoporous sulfonated polyetheretherketone via layer-by-layer self-assembly of Ag ions and Zn ions. Material characterization studies have indicated that nanoparticles consisting of elemental Ag and ZnO are uniformly incorporated on the porous sulfonated polyetheretherketone surface. The antibacterial assays demonstrate that Ag-decorated sulfonated polyetheretherketone and Ag/ZnO-codecorated sulfonated polyetheretherketone effectively inhibit the reproduction of Gram-negative and Gram-positive bacteria. Owing to the coordination of micro-/nanoscale topological cues and Zn induction, the Ag/ZnO-codecorated sulfonated polyetheretherketone substrates are found to enhance biocompatibility (cell viability, spreading, and proliferation), and hasten osteodifferentiation and -maturation (alkaline phosphate activity (ALP) production, and osteogenesis-related genetic expression), compared with the Ag-decorated sulfonated polyetheretherketone and the ZnO-decorated sulfonated polyetheretherketone counterparts. The dual therapy Ag/ZnO-codecorated sulfonated polyetheretherketone has an appealing bacteriostatic performance and osteogenic differentiation potential, showing great potential for dental and orthopedic implants.

Graphene‐Oxide‐Decorated Microporous Polyetheretherketone with Superior Antibacterial Capability and In Vitro Osteogenesis for Orthopedic Implant

Due to its similar elastic modulus of human bones, polyetheretherketone (PEEK) has been considered as an excellent cytocompatible material. However, the bioinertness, poor osteoconduction, and weak antibacterial activity of PEEK limit its wide applications in clinics. In this study, a facile strategy is developed to prepare graphene oxide (GO) modified sulfonated polyetheretherketone (SPEEK) (GO-SPEEK) through a simple dip-coating method. After detailed characterization, it is found that the GO closely deposits on the surface of PEEK, which is attributed to the π-π stacking interaction between PEEK and GO. Antibacterial tests reveal that the GO-SPEEK exhibits excellent suppression toward Escherichia coli. In vitro cell attachment, growth, differentiation, alkaline phosphatase activity, quantitative real-time polymerase chain reaction analyses, and calcium mineral deposition all illustrate that the GO-SPEEK substrate can significantly accelerate the proliferation and osteogenic differentiation of osteoblast-like MG-63 cells compared with those on PEEK and SPEEK groups. These results suggest that the GO-SPEEK has an improved antibacterial activity and cytocompatibility in vitro, showing that the developed GO-SPEEK has a great potential as the bioactive implant material in bone tissue engineering.