-
[show abstract]
[hide abstract]
ABSTRACT: Hydroxyapatite (HA) with highly ordered three-dimensional pores, whose size is about 300nm, was prepared by colloidal template
method. The effect of the surface modification of silica spheres on the order degree of porous structure was investigated
by field emission scanning electron microscopy (FESEM). Then, superparamagnetic Fe3O4 nanoparticles were fabricated via redox reaction, followed by coating with silica via a sol–gel process, in which a certain
amount of TEOS was used in order to control the thickness of the silica shell. X-ray diffraction (XRD), transmission electron
microscopy (TEM), and magnetometry were applied to characterize the properties. Finally, Fe3O4 magnetic nanoparticles coated with silica were adsorbed in the mesopores of HA with highly ordered three-dimensional pores
by capillarity. The influence of dispersing agent on the adsorption results has been studied. Magnetometry was applied to
characterize the magnetic properties of superparamagnetic HA. The quantities of adsorbed SiO2/Fe3O4 nanoparticles with core–shell have been compared by variation of saturation magnetization before and after adsorption.
Journal of Materials Science 04/2012; 44(15):4020-4025. · 2.02 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Borate bioactive glasses are receiving increasing attention as scaffold materials for bone repair and regeneration. In this
study, the kinetics and mechanisms of converting three groups of sodium–calcium–borate glasses with varying CaO:B2O3 ratio to hydroxyapatite (HA) in 0.25M K2HPO4 solution were investigated at 10–70°C. Glass disks with the composition 2Na2O·(2−x)CaO·(6+x)B2O3 (x=0, 0.5, and 1.0) were immersed for up to 8days in the potassium phosphate solution. The conversion kinetics to HA were
monitored by measuring the weight loss of the glass, while X-ray diffraction, scanning electron microscopy, and Fourier transform
infrared spectroscopy were used to study structural and compositional changes. All three groups of glasses formed HA on their
surfaces, showing that the glasses were bioactive. At 10–37°C, the conversion kinetics was well fitted by the contracting
sphere model. Also, the contracting sphere model has a good fit for the early stage of conversion at 70°C, whereas a three-dimensional
(3D) diffusion model provided a good fit to the data of the later stage. The results of this study provide kinetic and structural
data for the design of borate bioactive glasses for potential applications in bone tissue engineering.
Journal of Materials Science 04/2012; 46(1):47-54. · 2.02 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The bioactive borosilicate scaffolds (R2O-RO-B2O3-SiO2-P2O5) with four different contents of borate were fabricated by replication technique. The bioactivity, degradability and the
cytotoxicity of the scaffolds were studied in this paper. The porosity of the scaffolds was found to be 73%–80%, and the pore
size was in the range of 200–300 μm. The porous scaffolds immersed in 0.02 mol·L−1 K2HPO4 solution were transformed into hydroxyapatite. And it is notable that the D-Alk-2B, D-Alk-3B-scaffolds were covered by hydroxyapatite
layers after 7 h-immersion, which proved their high bioactivity. In the cell adhesion test, cells could be seen growing well
on the scaffolds, showing stretched morphology and obvious pseudopodia, and only the high cumulative concentration of B ions
released from the D-Alk-3B-scaffold samples had an inhibition effect on cell proliferation. But the inhibition effect could
be alleviated by diluting the extract solution to a certain concentration (dilution ratio: 1:8). Therefore, after suitable
pretreatment, the porous borosilicate bioactive glass scaffold can be a desirable candidate for bone tissue engineering.
Chinese Science Bulletin 04/2012; 54(18):3181-3186. · 1.32 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Bioactive glasses and ceramics have been widely investigated for bone repair because of their excellent bioactive characteristics.
However, these biomaterials undergo incomplete conversion into a bone-like material, which severely limits their biomedical
application. In this paper, borosilicate bioactive glasses were prepared by traditional melting process. The results showed
that borosilicate glasses possessed high biocompatibility and bioactivity. In addition, when immersed in a 0.02 mol/L K2HPO4 solution, particles of a borate glass were fully converted to HA. The desirable conversion rate to HA may be achieved through
the adjustment of the B2O3/SiO2 ratio. The results of XRD and FTIR analysis indicated that the degradation product was carbonate-substituted hydroxyapatite,
which was similar to the inorganic component of bone
Chinese Science Bulletin 04/2012; 52(2):272-276. · 1.32 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The temperature-responsive magnetic composite particles were synthesized by emulsion-free polymerization of N-isopropylacrylamide (NIPAAm) and acrylamide (Am) in the presence of oleic acid-modified Fe(3)O(4) nanoparticles. The magnetic properties and heat generation ability of the composite particles were characterized. Furthermore, temperature and alternating magnetic field (AMF) triggered drug release behaviors of vitamin B(12)-loaded composite particles were also examined. It was found that composite particles enabled drug release to be controlled through temperature changes in the neighborhood of lower critical solution temperature. Continuous application of AMF resulted in an accelerated release of the loaded drug. On the other hand, intermittent AMF application to the composite particles resulted in an "on-off", stepwise release pattern. Longer release duration and larger overall release could be achieved by intermittent application of AMF as compared to continuous magnetic field. Such composite particles may be used for magnetic drug targeting followed by simultaneous hyperthermia and drug release.
Journal of Materials Science Materials in Medicine 08/2011; 22(10):2239-47. · 2.32 Impact Factor
-
07/2011: pages 297 - 321; , ISBN: 9781118075647
-
Weibin Zhang,
Yuhui Shen,
Haobo Pan,
Kaili Lin,
Xiaoguo Liu,
Brian W Darvell,
William W Lu,
Jiang Chang,
Lianfu Deng, Deping Wang,
Wenhai Huang
[show abstract]
[hide abstract]
ABSTRACT: Strontium (Sr) plays a special role in bone remodelling, being associated with both the stimulation of bone formation and a reduction in bone resorption. Thus, the modification of biomaterials by partial or full substitution by Sr is expected to increase both bioactivity and biocompatibility. However, such effects have to be studied individually. Although no phase transition was found in Sr-substituted hydroxyapatite (Sr-HA), Sr-containing calcium silicate (Sr-CS) or Sr-containing borosilicate (Sr-BS), their biological performance was substantially affected by changes in the physico-chemical properties and Sr content of the materials. Three distinct outcomes were found for the presence of Sr: (1) increased HA solubility; (2) no significant effect on the degradation rate of CS; (3) apparent inhibition of the otherwise rapid degradation of BS. In each case the released Sr affected osteoblast proliferation and alkaline phosphatase activity, with clear evidence that an optimum Sr dose exists. Such chemical and biological variations must be disentangled for the behaviour to be properly understood and materials design to be advanced.
Acta biomaterialia 02/2011; 7(2):800-8. · 3.98 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The goal of this study was to synthesize use of hydroxyapatite as a high-efficiency adsorbent for Ni(II) ions, and to study its adsorption behavior. Three tests--Fourier-transform infrared spectroscopy, transmission electron microscopy, and Brunauer-Emmett-Teller were carried out to determine the chemical functionality of the hydroxyapatite powders, to observe its crystal morphology, and to measure the specific surface area. Results indicate that proves the n-HA synthesized by chemical precipitation is an effective adsorbent for the removal of Ni(II) ions from water solution. The synthesized, needle-like nano-hydroxyapatite (n-HA) have a uniform average size of 31.9 X 21.3nm, a large specific surface area (135 m2/g), and typically is a weak crystal with a broad pore distribution. The adsorption isotherm shows the Langmuir model is applicable only when the initial Ni2+ concentration is lower than 0.1 mol/L. Multilayer adsorption was attributed to uneven pore distribution that occurred at higher Ni2+ concentration. The adsorption of Ni2+ onto n-HA was attributed to electrostatic attraction, ion exchange, and dissolution-precipitation reaction. As the result, Ni2+ substitutes Ca2+ and binds with the oxygen atom on the surface, which resulted from the change in crystal-phase composition and in the binding energy of surface elements of n-HA before and after adsorption.
Water Environment Research 11/2010; 82(11):2279-84. · 0.88 Impact Factor
-
Xin Zhang,
Weitao Jia,
Yifei Gu,
Wei Xiao,
Xin Liu, Deping Wang,
Changqing Zhang,
Wenhai Huang,
Mohamed N Rahaman,
Delbert E Day,
Nai Zhou
[show abstract]
[hide abstract]
ABSTRACT: The treatment of chronic osteomyelitis (bone infection) remains a clinical challenge. In this work, pellets composed of a chitosan-bonded mixture of borate bioactive glass particles (<50microm) and teicoplanin powder (antibiotic), were evaluated in vitro and in vivo for treating chronic osteomyelitis induced by methicillin-resistant Staphylococcus aureus (MRSA) in a rabbit model. When immersed in phosphate-buffered saline, the pellets showed sustained release of teicoplanin over 20-30 days, while the bioactive glass converted to hydroxyapatite (HA) within 7 days, eventually forming a porous HA structure. Implantation of the teicoplanin-loaded pellets in a rabbit tibia osteomyelitis model resulted in the detection of teicoplanin in the blood for about 9 days. The implants converted to a bone-like HA graft, and supported the ingrowth of new bone into the tibia defects within 12 weeks of implantation. Microbiological, histological and scanning electron microscopy techniques showed that the implants provided a cure for the bone infection. The results indicate that the teicoplanin-loaded borate bioactive glass implant, combining sustained drug release with the ability to support new bone ingrowth, could provide a method for treating chronic osteomyelitis.
Biomaterials 08/2010; 31(22):5865-74. · 7.40 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Bioactive borosilicate glass scaffolds with the pores of several hundred micrometers and a competent compressive strength were prepared through replication method. The in vitro degradation and bioactivity behaviors of the scaffolds have been investigated by immersing the scaffolds statically in diluted phosphate solution at 37 degrees C, up to 360 h. To monitor the degradation progress of the scaffolds, the amount of leaching elements from the scaffolds were determined by ICP-AES. The XRD and SEM results reveal that, during the degradation of scaffolds, the borosilicate scaffolds converted to hydroxyapatite. The compressive strength of the scaffolds decreased during degradation, in the way that can be well predicted by the degradation products, or the leachates, from the scaffolds. MTT assay results demonstrate that the degradation products have little, if any, inhibition effect on the cell proliferation, when diluted to a certain concentration ([B] <2.690 and pH value at neutral level). The study shows that borosilicate glass scaffold could be a promising candidate for bone tissue engineering material.
Journal of Materials Science Materials in Medicine 01/2009; 20(6):1237-43. · 2.32 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The effect of replacing varying amounts (0-2.5 mol.%) of B2O3 with Al2O3 in a borate glass on (1) the conversion of the glass to HA in an aqueous phosphate solution and (2) the compressive strength of the as-formed HA product was investigated. Samples of each glass (10 x 10 x 8 mm) were placed in 0.25 M K2HPO4 solution at 60 degrees C, and the conversion kinetics to HA were determined from the weight loss of the glass and the pH of the solution. The structure and composition of the solid reaction products were characterized using X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. While the conversion rate of the glass to HA decreased considerably with increasing Al2O3 content, the microstructure of the HA product became denser and the compressive strength of the HA product increased. The addition of SiO2 to the Al2O3-containing borate glass reversed the deterioration of the conversion rate, and produced a further improvement in the strength of the HA product. The compressive strength of the HA formed from the borate glass with 2.5 mol.% Al2O3 and 5 mol.% SiO2 was 11.1 +/- 0.2 MPa, which is equal to the highest strengths reported for trabecular bone. The results indicated that simultaneous additions of Al2O3 and SiO2 could be used to control the bioactivity of the borate glass and to enhance the mechanical strength of the HA product. Furthermore, the HA product formed from the glass containing both SiO2 and Al2O3 could be applied to bone repair.
Acta biomaterialia 01/2009; 5(4):1265-73. · 3.98 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Three-dimensional macroporous scaffolds with the pore size of 200-500 mum were fabricated by replication method using bioactive borosilicate glass from Na(2)O-K(2)O-MgO-CaO-SiO(2)-P(2)O(5)-B(2)O(3) system. The effects of the strength of the strut in reticulated scaffold, as well as the geometrical parameter of the scaffold on the strength of reticulated scaffold were investigated. Scanning electron microscope (SEM) and X-ray diffraction (XRD) results show that the solidified glass struts in the reticulated scaffold could be obtained through a sufficient vicious flow of glass, during the fabrication. By increasing the solid content in slurries, from which the scaffold was made, the load-bearing units of the reticulated scaffold switch from struts to the walls between the pores, and the compressive strength dramatically climbs higher than the theoretical strength calculated by Gibson model. In particular, the compressive strength of the reticulated scaffold, as high as approximately 10 MPa with the porosity of approximately 70%, is close to the reported compressive values of human cancellous bone. This indicates the bioactive borosilicate glass-based scaffold is a promising candidate for bone tissue engineering.
Journal of Materials Science Materials in Medicine 10/2008; 20(1):365-72. · 2.32 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The synthesis of CdSe/ZnS core/shell nanocrystals though aqueous phase using the coprecipitation method was reported. The
influences of factors such as injection methods and dosages of precursors, reaction duration of water-bathing and the initial
CdSe:ZnS molar ratio were discussed. In comparison to the CdSe plain core nanocrystals, the CdSe/ZnS core/shell nanocrystals
show much brighter photoluminescence demonstrated by the photoluminescence spectra. The epitaxial growth of the core/shell
structures was verified by TEM and XRD.
Journal of Wuhan University of Technology-Mater Sci Ed 09/2008; 23(5):600-605. · 0.35 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Hydroxyapatite (HA) is widely used in filling of bone defects and coating on metal parts of prosthetic implants due to its excellent biocompatibility, bioactivity, and bone-bonding properties. It has been demonstrated that micro-sized HA particles cause inflammatory reaction, especially for the needle shaped particles. However, little effort has been concentrated on the cell responses of the spherical HA nanoparticles. The aim of the present work is to chemically and physically characterize the synthesized HA nanoparticles and to investigate the in vitro cell responses. X-ray diffraction, electron microscopy, nitrogen adsorption, and Fourier transform infrared spectroscopy revealed that the particles consisted of nearly spherical crystallites of carbonate-substituted HA with size of 20-40 nm and specific surface area of 75 m(2)/g. L929 cell proliferation experiments demonstrate that the spherical HA nanoparticles is more biocompatible than commercially available HA. On the other hand, U2-OS cell test results show that the inhibition rate of the spherical HA nanoparticles increases with time and concentration. The half effective inhibitory concentration (IC50) of the nanoparticles was determined to be 50.8 mug/mL at 72 h. All these data indicated that the synthesized spherical nanocrystalline HA particles can function as an effective biomaterial for bone tumorectomy repair, while having little adverse effect.
Journal of Biomaterials Applications 08/2008; 23(1):37-50. · 2.08 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Hollow HAP microspheres in sub-millimeter size were prepared and investigated as a drug delivery vehicle. The LCB (lithium-calcium
borate) glass microspheres, which were made through flame spray process, were chosen as precursor for hollow HAP microspheres.
The LCB glass microspheres reacted with phosphate buffer (K2HPO4) solution for 5 days at 37 °C. During the reaction the Ca-P-OH compound precipitated on the surface of LCB glass microspheres
and formed porous shells. Then the microspheres turned to be hollow ones with the same diameter as the glass microspheres
after LCB glass run out in the chemical reaction. After heat-treated at 600 ° for 4 h, the Ca-P-OH compound became HAP, thus
the hollow HAP microspheres were produced. The mechanism of forming hollow HAP microspheres through the chemical reaction
between phosphate buffer and LCB glass was confirmed by the XRD analysis. The microstructure characteristics of the hollow,
porous microspheres were observed by SEM.
Journal of Wuhan University of Technology-Mater Sci Ed 01/2007; 22(1):174-177. · 0.35 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Silicate-based bioactive glasses undergo incomplete conversion to a calcium phosphate material after in vivo implantation, which severely limits their biomedical application. In this communication, novel borate-based glasses with controllable degradation behavior were developed and their bioactive potential was investigated in vitro. When immersed in a 0.02M K2HPO4 solution at 37°C, these glasses reacted to form a carbonate-substituted hydroxyapatite (c-HA) on their surfaces, indicating their bioactive potential. The conversion rate to c-HA was controlled by adjusting the B2O3/SiO2 ratio in the glass composition. The results indicate the potential application of the borate-based bioactive glass as scaffold materials for bone tissue engineering.
Journal of the American Ceramic Society 12/2006; 90(1):303 - 306. · 2.27 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The preparation of hollow hydroxyapatite (HA) microspheres as potential drug-delivery vehicles was investigated. A lithium-calcium-borate (10Li(2)O-15CaO-75B(2)O(3)) (mol%) glass, made by fusing the components at 1100 degrees C for 1 h, was ground to a powder and passed through a flame at approximately 1400 degrees Celsius to spheroidize the particles. The resulting glass microspheres (106-125 microm in diameter) were reacted in 0.25 M K(2)HPO(4) solution for 5 days at 37 degrees Celsius and pH 10-12, resulting in the formation of porous, hollow microspheres of a calcium phosphate (Ca-P) material with external diameters similar to those of the original glass particles. Heat treatment at 600 degrees Celsius for 4 h partially converted the Ca-P material to HA, as confirmed by X-ray diffraction, and also increased the strength of the hollow microspheres.
Journal of Materials Science Materials in Medicine 08/2006; 17(7):641-6. · 2.32 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A novel type of glass-based nanoscale hydroxyapatite (HAP) bioactive bone cement (designed as GBNHAPC) was synthesized by adding nanoscale hydroxyapatite crystalline (20-40 nm), into the self-setting glass-based bone cement (GBC). The inhibition rate of nanoscale HAP and micron HAP on osteosarcoma U2-OS cells was examined. The effects of nanoscale HAP on the crystal phase, microstructure and compressive strength of GBNHAPC were studied, respectively. It was concluded that nanoscale HAP could inhibit the cell proliferation, whereas micron HAP could not, and that nanoscale HAP could be dispersed in the cement evenly and the morphology did not change significantly after a longer immersion time. XRD and FTIR results show nanoscale HAP did not affect the setting reaction of the cement. Furthermore, GBNHAPC had a higher compressive strength (92.6 +/- 3.8 MPa) than GBC (80.1 +/- 3.0 MPa). It was believed that GBNHAPC might be a desirable biomaterial that could not only fill bone defects but also inhibit cancer cell growth.
Journal of Biomedical Materials Research Part A 09/2005; 74(2):156-63. · 2.63 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A novel type of glass-based nanoscale hydorxypatite (HAP) bioactive bone cement (designed as GBNHAPC) was synthesized by adding nanoscale hydroxyapatite (HAP) crystalline (20-40 nm), into the self-setting glass-based bone cement (GBC). The inhibition rate of nanoscale HAP and micron HAP on osteosarcoma U2-OS cells was examined. The effects of nanoscale HAP on the crystal phase, microstructure and compressive strength of GBNHAPC were studied respectively. It was concluded that nanoscale HAP could inhibit the cell proliferation, while micron HAP could not, and that nanoscale HAP could be dispersed in the cement evenly and the morphology did not change significantly after a longer immersion time. XRD and FTIR results show nanoscale HAP did not affect the setting reaction of the cement. Furthermore, GBNHAPC had a higher compressive strength (92 MPa) than GBC. It was believed that GBNHAPC might be a desirable biomaterial that could not only fill bone defects but also inhibit cancer cell growth.
Journal of Materials Science Materials in Medicine 01/2005; 15(12):1333-8. · 2.32 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Three-dimensional, highly ordered macroporous frame of hydroxyapatite has been fabricated via a template-assisted colloidal processing technique. In the present method, colloidal template was first prepared with SiO2 spheres by gravitational sedimentation, which was then infiltrated with hydroxyapatite precursor prepared by the sol–gel process. The resulting hydroxyapatite replicated the three-dimensionally ordered macroporous structure of SiO2 template. Modified by H2O2, the SiO2 spheres could be packed into better ordered templates. After removal of the template by immersing in NaOH solution, the well-ordered macroporous frame made from HA was obtained. The arrangement of the pore structure was hexagonal close-packed and pore sizes could be controlled by changing the sizes of SiO2 spheres. The resulting highly ordered macroporous frame of hydroxyapatite could have potential applications in the biomedical field.
Materials Research Bulletin. 44(2):259-262.
