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To improve the fixations of the implant and implant-bone integration after joint arthroplasty from locally preventing inflammation and promoting the bone regeneration, we design a multifunctional biomaterial consisting of recombinant human bone morphogenetic protein 2 (rhBMP-2) and antibiotic loaded nano-hydroxyapatite with an alginate/gelatin sticky gel. We investigate its role for the prevention of the inflammation and possibility of inducing a new bone growth along with its adhesive ability. The stickiness exists in the composite, which may help to fix itself on the bone fracture surface. The composite sustains the antibacterial effect and promotes the proliferation and differentiation of MG63 cells in vitro. In vivo experimentation also shows that the composite gel has a role for the reduction of inflammation. It enhances the formation of new bone and blood vessels compared to both the sole rhBMP-2 and non-rhBMP-2/antibiotic loaded composite gels. The multifunctional composite provides a promising material for the prosthetic and bone tissue regeneration. [ABSTRACT FROM AUTHOR]

Porous microspheres fabricated from bioceramics have great potential for cell delivery in injectable tissue engineering application. The size and structure of pores in the microspheres are important for the effective protection and transportation of cells. In this study, porous hydroxyapatite microspheres are fabricated through the water-in-oil emulsion method followed by a calcination treatment at the high temperature. Both self-made resorcinol-formaldehyde (RF) composite spheres and camphene are used as pore-forming agents to produce big pores corresponding to the size of RF spheres and connected channel among big pores in hydroxyapatite matrix. The properties of the microspheres are characterized using X-ray diffraction, thermogravimetry analysis, universal material machine, field emission scanning electron microscopy. Cell assays are carried out to evaluate the cellular compatibility of the microspheres. The results showed that the hydroxyapatite microspheres with controllable pore structure and high porosity could be fabricated by this method, which have better strength to resist the compressive force. The microspheres are conducive to support adhesion, proliferation and differentiation of MC3T3-E1 cells. The results indicate that the obtained porous hydroxyapatite microspheres can be a permeable microenvironment for cell delivery in injectable tissue engineering. [ABSTRACT FROM AUTHOR]

Despite superior clinical handling, excellent biocompatibility, biodegradation property of calcium phosphate needs to be improved to coincide with the rate of new bone formation. In this study, spherical CaCO 3 are fabricated in the presence of the silk sericin and then transformed into porous hydroxyapatite (HAP) microspheres via hydrothermal method. The degradation behavior of obtained CaCO 3 , HAP and their mixture is first investigated in vitro . The result demonstrates that the weight loss of HAP microspheres are almost 24.3% after immersing in pH 7.40 Tris-HCl buffer solution for 12 weeks, which is far slower than that of spherical CaCO 3 (97.5%). The degradation speed of the mixtures depends on the proportion of CaCO 3 and HAP. The mixture with higher content of CaCO 3 possesses a quicker degradation speed. The obtained CaCO 3 and HAP microspheres are injected into subcutaneous tissue of ICR mice with the assistance of sodium alginate. The result in vivo also shows an obvious difference of degradation speed between the obtained CaCO 3 and HAP microspheres, implying it is feasible to modulate the degradation property of the mixture through changing the proportion of CaCO 3 and HAP The good cytocompatibility of the two kinds of microspheres is proved and a mild inflammation response is observed only at early stage of implantation. The job offers a simple method to modify the degradation properties of biomaterial for potential use in bone tissue engineering. [ABSTRACT FROM AUTHOR]

To fabricate hard tissue implants with bone-like structure using a biomimetic mineralization method is drawing much more attentions in bone tissue engineering. The present work focuses in designing 3D silk fibroin hydrogel to modulate the nucleation and growth of hydroxyapatite crystals via a simple ion diffusion method. The study indicates that Ca 2+ incorporation within the hydrogel provides the nucleation sites for hydroxyapatite crystals and subsequently regulates their oriented growth. The mineralization process is regulated in a Ca 2+ concentration- and minerlization time-dependent way. Further, the compressive strength of the mineralized hydrogels is directly proportional with the mineral content in hydrogel. The orchestrated organic/inorganic composite supports well the viability and proliferation of human osteoblast cells; improved cyto-compatibility with increased mineral content. Together, the present investigation reports a simple and biomimetic process to fabricate 3D bone-like biomaterial with desired efficacy to repair bone defects. [ABSTRACT FROM AUTHOR]

Abstract: Deep infection of prosthesis is one of the most frequent complications after joint replacement. One of the most effective ways is to introduce directly some antibiotics in the local site of the surgery. In the present study, an antimicrobial composite has been fabricated using nano-hydroxyapatite particles as carriers for the antimicrobial drug of vancomycin hydrochloride (VAN) and the mixture of oxidation sodium alginate (OSA) and gelatin (GT) as a sticky matrix. Samples have been characterized using X-ray diffraction instrument (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM) and Fourier transform infrared (FTIR) spectra, Brunauer–Emmett–Teller (BET) methods, the rotational rheometer and the texture analyzer. The release of VAN from nano-hydroxyapatite (nHAP) particles was detected by the ultraviolet–visible (UV–vis) spectrophotometer and then bactericidal property of the composite was evaluated using the Staphylococcus aureus (S. aureus) as a bacterial model. Experimental results showed that the composite possessed an adhesive property derived from the gel of OSA and GT, which implied that the composite could bond directly to the fracture surface of bones in surgery. Furthermore, VAN was loaded efficiently on the surface of nHAP particles and could be released slowly from these particles, which endowed the composite with an obvious and continuous antimicrobial performance. The sticky and antimicrobial composite may has a potential application in arthroplasty to overcome deep infection in a simple and direct manner. [Copyright &y& Elsevier]

Abstract: The influence of soluble silk sericin (SS) protein on the formation of CaCO3 particles was investigated and the CaCO3 particles were then used as a template to synthesize the hydroxyapatite microspheres. The SS showed a strong preference to the mineralization of vaterite and the fine controls over the shape, size and uniformity of vaterite were carried out by the variation of pH value and reaction time in the presence of SS. Using the vaterites as a template, the homogeneous and monodispersed hydroxyapatite microspheres, copying faithfully the shape and size of original vaterites, were fabricated under the assistance of microwave irradiation. The research may provide a feasible method for the fabrication of hydroxyapatite-based biomaterials with controllable configuration. [Copyright &y& Elsevier]

Abstract: The injectable chitosan/β-glycerophosphate (CS/GP) hydrogels were prepared with dexamethasone (Dex)/recombinant human bone morphogenetic protein (rhBMP-2) loaded hydroxyapatite nanoparticles (nHAP). The obtained samples were characterized by TEM, SEM, XRD and nitrogen adsorption tests, and the effect of Dex and rhBMP-2 on the mesenchymal stem cells (MSCs) was evaluated. The results showed that nHAP could be dispersed homogeneously in the matrix of injectable CS/GP hydrogels and the combination of Dex and rhBMP-2 could promote the proliferation and osteoblastic differentiation of MSCs, indicating that the prepared injectable CS/GP hydrogels with Dex and rhBMP-2 loaded nHAP have great potential in different orthopedic regenerative applications. [Copyright &y& Elsevier]

Abstract: Hydroxyapatite-modified titanate nanowire scaffolds as alternative materials for tissue engineering have been developed via a titanate nanowire matrix assisted electrochemical deposition method. The macroporous titanate nanowire matrix on Ti metal was fabricated by a hydrothermal method, and then followed by an electrochemical synthesis of hydroxyapatite nanoparticles on titanate nanowire. The incorporation of titanate nanowire matrix with high oriented hydroxyapatite nanoparticles generates hierarchical scaffolds with highly osteogenic, structural integrity and excellent mechanical performance. As-prepared porous three dimensional interconnected hydroxyapatite-modified titanate nanowire scaffolds, mimicking the nature’s extracellular matrix, could provide a suitable microenvironment for tissue cell ingrowth and differentiation. The ceramic titanate nanowire core with HA nanoparticle sheath structure displays superhydrophilicity, which facilitates the cell attachment and proliferation, and induces the in vitro tissue-engineered bone. Human osteoblast-like MG63 cells were cultured on the hydroxyapatite-modified titanate nanowire scaffolds, and the results showed that the scaffolds highly promote the bioactivity, osteoconductivity and osteoblast differentiation. [Copyright &y& Elsevier]

Abstract: Plenty of techniques have been developed to modify the surface character of titanium (Ti) and its alloys in order to realize their biological bond to natural bone. In this work, a biomimetic process was employed to form a hydroxyapatite (HAp) coating on the alkali-heat treated Ti substrate in 1.5 times simulated body fluid (1.5×SBF) with the addition of a recombinant collagen-like protein. The coating was characterized using SEM-EDX, FESEM, and XRD. Results showed that the recombinant collagen-like protein could accelerate the preferential nucleation and directional growth along c axis of HAp on the pretreated Ti substrates. The investigation of in vitro cell cultivation showed that the existence of recombinant collagen-like protein in coating could improve the initial cell adhesion, proliferation and differentiation of MG-63 cells, which implied the materials possessed excellent biocompatibility and had a wide potential in biomedical application. [Copyright &y& Elsevier]

Abstract: Novel composite films of Bombyx mori silk fibroin (SF) and hydroxyapatite (HA) composite films, with glycerin as an additive, were fabricated by means of co-precipitation, where the theoretical HA content was varied from 2 (w/w)% to 31 (w/w)%. The structure and properties of the composite films were investigated by SEM, XRD, AFM, TGA and tensile testing. The results showed that the composite films were smooth and transparent with the uniform distribution of HA into the composites when the final HA content was lower than 21 (w/w)%. XRD and TGA data showed that the silk fibroin in the composites was predominantly in a β-sheet crystalline structure, which was induced not only by the addition of glycerin, also by the HA crystal growth during the composite fabrication, leading to the thermal stable composite films. On the other hand, the HA crystals had the anisotropic growth with high extent of lattice imperfection and the preferential orientation along c-axis, probably promoted by the silk fibroin. The mechanical testing results showed that both break strain and stress were declined with the increase of HA content in the composites, presumably due to the original brittleness of HA compound. [Copyright &y& Elsevier]

Abstract: Bombyx mori silk fibroin is of practical interest for its excellent intrinsic properties utilizable in the biotechnological and biomedical fields. Here, the silk fibroin films were pretreated with different methods and then used as the template for the hydroxyapatite (HA) crystal growth. To study the effect of silk films’ surface structure on the protein biomineralization, the films were immersed into 1.5 times simulated body fluid (1.5×SBF) to induce the HA deposition at 37°C. The results showed that an anisotropic growth of HA crystals was observed on the different films as judging from XRD, TEM and HRTEM data. This was thought that the positions and density of carboxyl groups, Cno groups on the surface of SF films may be different, which play the key effect on HA crystal growth. [Copyright &y& Elsevier]

Abstract: Porous 3D silk fibroin (SF) scaffolds were prepared directly from the SF solution with the addition of methanol and glutaraldehyde by a freeze-drying method. The scaffolds were then soaked in the simulated body fluid (SBF) for the deposition of hydroxyapatite (HA) crystals. The XRD and FTIR results showed that the SF were in β-sheet structure, resulting in the high thermal stability and mechanical properties of scaffolds. The XRD and AAS data revealed that the SF scaffolds could induce the continuous growth and enrichment of HA crystals onto the scaffolds with the extension of soaking time. The mechanical properties of scaffolds increased first with the HA-deposition within 3d of soaking, then it declined. During the full soaking period, no significant change was observed on the porosity and water-binding ability, which were kept at about 84% and 800%, respectively. The cell cultivation results showed that the scaffolds have the satisfied cell biocompatibility, which was promoted after the HA-deposition. This work suggests that the porous 3D SF scaffolds may be a potential candidate in the bone engineering. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to investigate the effect of amino acid on the morphology and crystallinity of nano-sized hydroxyapatite (HAP) crystals via a chemical precipitation method in the presence of l-lysine and l-tyrosine at different concentrations. The products were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. The results showed the effect of l-lysine and l-tyrosine on the crystal growth of HAP was at opposite poles, i.e., the crystal growth was inhibited by l-lysine but promoted by l-tyrosine depending on the amino acid content. The mechanism of HAP crystal growth was also proposed. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to investigate the effect of silk sericin (SS) on the morphology and crystallinity of hydroxyapatite (HAp) crystals synthesized at the pH 7.4–12 and 50°C via a biomimetic method. Using X-ray diffraction (XRD), transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM), it was revealed that a homogeneous assembly could be obtained in the presence of SS, which held a highly ordered microstructure and poor crystallinity. But in the absence of SS, an oriented aggregate could be prepared at 50°C and pH 10, which held more confused crystal lattice lines. The results proved that the biomimetic structure of HAp could be constructed under the controlled reaction conditions, which may offer a new clue on the understanding of the process of biomineralization. [ABSTRACT FROM AUTHOR]