Porous agarose/Gd-hydroxyapatite composite bone fillers with promoted osteogenesis and antibacterial activity

Artificial bone fillers are essentially required for repairing bone defects, and developing the fillers with synergistic biocompatibility and anti-bacterial activity persists as one of the critical challenges. In this work, a new agarose/gadolinium-doped hydroxyapatite filler with three-dimensional porous structures was fabricated. For the composite filler, agarose provides three-dimensional skeleton and endows porosity, workability, and high specific surface area, hydroxyapatite (HA) offers the biocompatibility, and the rare earth element gadolinium (Gd) acts as the antibacterial agent. X-ray photoelectron spectroscopy detection showed the doping of Gd in HA lattice with the formation of Gd-HA interstitial solid solution. Attenuated total reflection Fourier transform infrared spectroscopy imaging suggested chemical interactions between agarose and Gd-HA, and the physical structure of agarose was tuned by the Gd-doped HA. Cytotoxicity testing and alizarin red staining experiments using mouse pro-osteoblasts (MC3T3-E1) revealed remarkable bioactivity and osteogenic properties of the composite fillers, and proliferation and growth rates of the cells increased in proportion to Gd content in the composites. Antibacterial testing using the gram-positive bacteria S. aureus and the gram-negative bacteria E. coli indicated promising antibacterial properties of the fillers. Meanwhile, the antibacterial properties of composite filles were enhanced with the increase of Gd content. The antibacterial fillers with porous structure and excellent physicomechanical properties show inspiring potential for bone defect repair.     

Biocompatibility and electron microscopy studies of epitaxial nanolaminate (Al0·5Ti0.5)N/ZrN coatings deposited by Arc-PVD technique

The ability to combine layers with high mechanical strength and additional physicochemical properties, such as biocompatibility, makes the use of multilayer coatings attractive for various applications. The transition from single layer to nanolaminate architecture can improve the mechanical performance of the coatings by increasing the number of interfaces and decreasing the modulation period of the layers. The microstructural study of the nanolaminate (Al_0·5Ti_0.5)N/ZrN coating with a modulation period λ of ≃ 20 nm was carried out using the TEM-HRTEM method. It was found that the coatings of (Al_0·5Ti_0.5)N/ZrN series consisted of two phases: the fcc-(Ti,Al)N solid solution obtained by isomorphic substitution of Ti atoms with Al ones in the TiN crystal lattice and the cubic ZrN phase. ZrN layers had a high texture structure with [111]-preferred growth texture and made a dominant effect on the nucleation and growth of (Al_0·5Ti_0.5)N layers. The epitaxial growth process was the most pronounced for fcc-(Ti,Al)N (111)||fcc-(ZrN) (111) and fcc-(Ti,Al)N (200)||fcc-(ZrN) (200) grains. Finally, the new coating demonstrated high biocompatibility, failure to toxicity and supported U2OS osteogenic cells proliferation within 7 days of cultivation.     

Manufacturing and characterization of mechanical,biological and dielectric properties of hydroxyapatite-barium titanate nanocomposite scaffolds

In this research, hydroxyapatite (HA)-based ceramics were produced as suitable ceramic implants for orthopedic applications. To improve the physical, mechanical, electrical and biological properties of pure HA, we developed composite scaffolds of HA-barium titanate (BT) by cold isostatic pressing and sintering. Microstructure, crystal phases, and molecular structure were analyzed by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), respectively. Bulk density values were measured using the Archimedes method. The effect of different percentages of BT on cell proliferation, viability, and ALP activity of dental pulp stem cells (DPSCs) was assessed by ProstoBlue assay, Live/Dead staining, and p-NPP assay. The obtained results indicate that the HA-BT scaffolds possess higher compressive strength, toughness, density, and hardness compared with pure HA scaffolds. After immersing the scaffold in SBF solution, more deposited apatite appeared on the HA-BT, which results in rougher surface on this scaffold thanpure HA. Electrical properties of HA in the presence of BT are improved. Based on the results of cell culture experiments, composites containing 40, 50 and 60 %wt of BT have excellent biocompatibility, with the best results occurring for the sample with 50 %wt BT.     

抗感染重组合异种骨的生物相容性研究

目的 检测抗感染重组合异种骨（ARBX）产品的生物相容性,确保ARBX产品在临床上安全、有效。方法 根据卫生部制定的《生物材料和制品的生物学评价标准》及《相关生物材料和制品的企业标准 Q/JGY001-94》,进行了ARBX急性毒性试验、过敏性试验、熟原试验、骨内埋植试验、肌内埋植试验、溶血试验及细胞毒性试验。结果ARBX未引起小鼠急性毒性反应、豚鼠过敏反应及家兔热原反应。在兔骨内和小鼠肌内埋植,既未产生纤维包膜,也未引起淋巴细胞及炎性细胞浸润。对家兔红细胞溶血率为1.2％,无溶血现象。体外细胞毒性反应指标R=0.25/0,无细胞毒性。结论ARBX的生物相容性符合国家规定的生物材料和制品的生物学标准及企业标准,可试用于临床治疗相关疾病。     

光化学固定法表面改性医用高分子材料研究进展

综述了光化学固定法表面改性医用高分子材料方面的研究进展,介绍了光化学固定法的原理和优点。     

Spectroscopic and SEM studies of SWNTs: Polymer solutions and films

Raman spectra of SWNTs suspended in aqueous solutions containing fragmented single-stranded DNA (SWNT:DNA), and films obtained from this suspension have been obtained. SEM study of the dried films indicated that the nanotubes tend to aggregate into bundles which results in the enhancement of the Raman intensity of the G⁻ tangential band, and an upshift and broadening of the G⁺ band. The intensity of radial breathing modes of metallic SWNTs is higher in the SWNT:DNA films as compared to that of the SWNT:DNA solution. The Raman spectra of SWNT:PVP and SWNT:agaroza samples exhibit similar changes as the SWNT:DNA samples when films are cast from the corresponding solutions. Both films and the solution forms of SWNT:DNA yield luminescence spectra which indicates the presence of individual tubes or small bundles in the films. The luminescence bands of SWNT:DNA films are relatively wider and is attributed to the interaction of DNA with the nanotube surface in the solid state.     

Multiwalled carbon nanotubes grafted chitosan nanobiocomposite: A prosperous functional nanomaterials for glucose biosensor application

Multiwalled carbon nanotubes (MWNTs) grafted chitosan (CS) nanowire (NW) was prepared by phase separation method. Glucose oxidase (GOx) was sequentially immobilized into MWNT-CS-NW to obtain MWNT-CS-NW/GOx biosensor. Field emission scanning electron microscopy (FESEM) images of MWNT-CS-NW/GOx reveals the existence of MWNT and CS. Cyclic voltammetry and amperometry were used to evaluate the electrochemical determination of glucose. The MWNT-CS-NW/GOx biosensor shows an excellent performance for glucose at +0.34 V with a high sensitivity (5.03 μA/mM) and lower response time (3 s) in a wide concentration range of 1-10 mM (correlation coefficient of 0.9988). In addition, MWNT-CS-NW/GOx biosensor possesses better reproducibility, storage stability and there is negligible interference from other electroactive components.     

A MEMS affinity glucose sensor using a biocompatible glucose-responsive polymer

We present a MEMS affinity sensor that can potentially allow long-term continuous monitoring of glucose in subcutaneous tissue for diabetes management. The sensing principle is based on detection of viscosity changes due to affinity binding between glucose and poly(acrylamide-ran-3-acrylamidophenylboronic acid) (PAA-ran-PAAPBA), a biocompatible, glucose-specific polymer. The device uses a magnetically driven vibrating microcantilever as a sensing element, which is fabricated from Parylene and situated in a microchamber. A solution of PAA-ran-PAAPBA fills the microchamber, which is separated from the surroundings by a semi-permeable membrane. Glucose permeates through the membrane and binds reversibly to the phenylboronic acid moiety of the polymer. This results in a viscosity change of the sensing solution, which is obtained by measuring the damped cantilever vibration using an optical lever setup, allowing determination of the glucose concentration. Experimental results demonstrate that the device is capable of detecting glucose at physiologically relevant concentrations from 27 mg/dL to 324 mg/dL. The glucose response time constant of the sensor is approximately 3 min, which can be further improved with device design optimization. Excellent reversibility and stability are observed in sensor responses, as highly desired for long-term, stable continuous glucose monitoring.     

A high strength,wear and corrosion-resistant,antibacterial and biocompatible Nb-5 at.％ Ag alloy for dental and orthopedic implants

Refractory metal niobium (Nb) incorporated with a small amount of silver (Ag),the resulting Nb-Ag two-phase alloys,were fabricated by mechanical alloying and spark plasma sintering.The microstructure,mechanical properties,wear resistance,corrosion behavior,in vitro and in vivo antibacterial properties and biocompatibility of the Nb-Ag alloys were systematically investigated.The results show that the mechanical properties,wear resistance,corrosion resistance and antibacterial ability were significantly enhanced after addition of 5 at.％ Ag.The fabricated Nb-5 at.％ Ag alloy demonstrates high yield strength of up to ～ 1486 MPa and fracture strain of ～ 35 ％.The precipitated Ag particles could reduce friction and wear.The enhanced corrosion resistance was attributed to the higher relative density of the sintered alloys and the formation of a stable and dense passive film of niobium and silver oxides.In vitro and in vivo evaluations show that the Nb-5 at.％ Ag alloy also has strong antibacterial activity and good biocompati-bility and osteointegration ability.These results demonstrate great potential of the nanostructured Nb-Ag alloys for dental and orthopedic implants.