Biomedical subjects

Changjian Lin

Publications and source records attributed to Changjian Lin.

6 recordsLinked to original sources

PubMed2006

Selective heterogeneous nucleation and growth of size-controlled metal nanoparticles on carbon nanotubes in solution.

We present a novel approach to the in situ deposition of size-controlled platinum nanoparticles on the exterior walls of carbon nanotubes (CNTs). The reduction of metal ions in ethylene glycol (EG), by the addition of a salt such as sodium dodecyl sulfate (SDS), p-CH3C6H4SO3Na, LiCF3SO3, or LiClO4, results in high dispersions and high loadings of platinum nanoparticles on CNTs without aggregation. We have performed controlled experiments to elucidate the mechanism. By exploiting the salt effect, our method effectively depresses homogeneous nucleation, leading to selective heterogeneous metal nucleation and growth, even on unmodified CNTs. In the 2.3-9.6 nm size range, the size of platinum nanoparticles, at 50% loading, can be controlled by changing the concentration of metal ions, the reaction temperature, the reducing reagent or the means by which reactive solutions are added. Our method provides a flexible route towards the preparation of novel one-dimensional hybrid materials, for which a number of promising applications in a variety of fields can be envisioned.

Crystallization↗

PubMed2005

Proton diffusion determination and dual structure model for nickel hydroxide based on potential step measurements on single spherical beads.

Potential step measurement is carried out on single beads of spherical nickel hydroxide to determine the proton diffusion coefficient (D) and concentration of the effective proton vacancies (C). The semi-infinite diffusion equation for the initial stage and the finite diffusion equation for the long-term of the current response to potential step are used for deducing the D and C values. The diffusion coefficients deduced from short and long-term current responses are in the order of magnitude 10(-7) and 10(-10) cm2 s(-1), respectively. The sum of the effective proton vacancy concentrations associated with the two D values comes out to be equal within experimental error to the effective proton vacancy concentration converted from the released electricity during discharge. A dual structure model is proposed to interpret the above-mentioned findings, featuring densely packed grains within which proton diffusion is slow and an inter-grain matrix where proton diffusion is fast. With this model the huge difference (about 6 orders of magnitude) in D values reported in the literature as well as the controversy of the dependence of diffusion coefficient on the state of charge can be largely rationalized. This dual structure model is supported by SEM and AFM observations.

Journal Article↗

PubMed2005

[Surface biochemical modification for the titanium implants].

This paper reviews the progress in biochemical design and modification for the surfaces of titanium implants in recent years, the emphasis being laid on the introduction of the surface molecular construction, self-assembly technique and its application in biomedical materials.

Biocompatible Materials↗

PubMed2003

Electrochemical deposition of hydroxyapatite with vinyl acetate on titanium implants.

A novel approach to electrochemical processing of hydroxyapatite (HA) coating was explored. Vinyl acetate was added in the electrolytes of calcium and phosphorous in order to improve the adhesion between HA coating and titanium substrate. X-ray powder diffractometer (XRD) spectra indicated that the vinyl acetate did not interfere with the deposition of HA on the surface of titanium cathodes. X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) results revealed that both vinyl acetate and HA were deposited on the titanium cathodes. The vinyl acetate changed the HA crystalline morphology in the deposition layer. The shape and growth direction of the HA crystals in the coating with vinyl acetate differed from those of HA deposition along. The addition of vinyl acetate increased the coating strength considerably, even though further improvement is needed for clinical applications. Moreover, a preliminary study of the bioactivity showed that osteoblastic cells exhibited higher cell proliferation potential on the HA/vinyl acetate coating than on that of pure HA.

Adhesiveness↗

PubMed2003

[An investigation of HAP/organic polymer composite coatings prepared by electrochemical co-deposition technique].

An electrochemical co-deposition technique has been developed to prepare a hydroxyapatite (HAP)/organic polymer composite coatings on Ti surface as new biomaterial of hard tissue. The composite coating of organic polymer and calcium phosphate is formed by adding a water soluble polymer of the ethylene series to NH4H2PO4-Ca (NO3)2 solution when conducting an appropriate electrochemical co-deposition experiment. The XRD, SEM, XPS, SIMS and nano indent measurements were performed to characterize the morphology, composition, structure and surface stiffness of the composite coating. It was found that the morphology and surface hardness of the coatings showed a remarkable modification when introducing a minor polymer to HAP coating, and the bonding force between the coating and metal substrate was distinctly increased. The incorporation of minor organic polymer into the HAP compound at molecular level will improve the mechanical properties and morphology of the composite coatings, and this may be helpful to raising its bio-activity.

Coated Materials, Biocompatible↗

PubMed2003

[An investigation of HAP/organic polymer composite coating prepared by electrochemical co-deposition technique (II) characterization of XRD, SEM and mechanic properties].

Electrodeposition hydroxyapatite(HAP) coatings of ceramics were studied by Nano Indent. The bonding force between the coating and metal substrate was distinctly increased. The experiments about XPS and SIMS showed that there is the act of organic polymer enriching at negative. It ensues that minor organic polymer is compounded to HAP coatings at molecular level and forms that HAP/Organic polymer compound coating.

Coated Materials, Biocompatible↗