Papers by Author: Sheng Min Zhang

Abstract: Skin wounds, burns and scars represent a major burden upon world healthcare costs. The successful creation in vitro of skin substitutes has been the focus of a concentrated research activity for the last 30 or more years, culminating in some success for its translation into the clinical setting. In this paper, a novel artificial skin of bacterial cellulose has been biosynthesized by Acetobacter xylinum and modified by chitosan. BC is thought as an optimal substrate material of artificial skin. It is thought to be an interesting material for using as a substratum of artificial skin because it could provide moist environment to a wound resulting in a better wound healing. But BC has no antimicrobial activity to reduce the probability of wound infection. To achieve antimicrobial activity of BC, it was modified by chitosan due to its antibiotic activity. The structure and components were characterized by FTIR and ESEM. The results indicated the nano-composites of BC and chitosan are promising and potential for wound dressings.

Abstract: Crucumin (diferuloylmethane) is a major active component of turmeric, but its bioavailability of oral administration is very low. In order to improve its pharmaceutical efficiency in oral use, poly (d,l-lactide) (PDLLA) nanospheres containing curcumin are successfully fabricated using a modified spontaneous emulsification solvent diffusion (SESD) method. The morphology, size and distribution of the resulting nanospheres are characterized by TEM and laser light scattering method. Drug contents in the nanospheres are calculated through UV spectrophotometer method. As a result, regular spherical PDLLA nanospheres containing curcumin are obtained and their effective diameters are 289 nm with narrow distribution (Pd=0.118)

Abstract: Nano-sized zinc-substituted hydroxyapatite (nano-ZnHA) has stimulatory effect on bone formation and inhibitory effect on osteoclastic bone resorption in vivo. Nano-ZnHA with serial zinc fractions (0, 2, 5, 10 mol%) were synthesized by an improved precipitation method based on dialysis process. Transmission electron microscopy observation indicated that the increase of Zn fraction led to smaller crystallite. X-ray diffraction of the products revealed that some typical characteristic peaks of HA displayed when the Zn fraction was below 10%. Fourier transform infrared spectroscopy showed that the bending peaks of the group-OH in HA became wider with the increase of Zn fraction and it disappeared at 10 mol%. The current work demonstrated that zinc could substitute for calcium into hydroxyapatite in the limited range of composition by using dialysis process.

Abstract: In our previous work the nano-sized hydroxyapatite (nano-HAP) with uniform morphology has been firstly synthesized by a wet chemical method based on dialysis, but the dialysis efficiency was not investigated in detail. In this paper, the removal efficiency of impurity ions such as NH4 + and NO3 - was respectively evaluated by calculating the concentration of the representative irons between the inner slurry and outer distilled water. Results showed that 99% NO3 - ions and 96.9% NH4 + - ions in the slurry has been eliminated. In the first dialysis time, the NH4 + ions diffuse faster than the NO3 - ions due to their smaller size. In the following dialysis times, the dialysis efficiency of NO3 - ions is higher than that of the NH4 + ions because of the presence of higher NO3 - ions concentration gradient. The final nano-HAP is also characterized by XRD, TEM, and FT-IR. It is revealed that the products are stick-like with a length of about 150nm and a diameter of about 20-50 nm. Current work suggests that dialysis is an efficient purified method for nano-HAP production and especially can be applied to industrial preparation of fine nano-sized HAP powders.

Abstract: Nano-sized β-tricalcium phosphate (nano-sized β-TCP) was synthesized by dialysis process using Ca(NO3)2·4H2O and (NH4)2HPO4 as starting materials. The time needed for the whole process is much shorter than other reported methods. In this new synthesis, dialysis was used to remove the unwanted ions, and the removal efficiency of impurity ion was evaluated by comparing the representative ion NH4 + between the original slurries and deionized water outside of the dialysis tube. The resulting powders were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), and chemical analysis. Results showed the final products are pure β-TCP. The pictures of high resolution-transmission electron microscope (HR-TEM) further indicated that β-TCP crystals are around 100nm in diameter.

Abstract: A novel synthesis of nano-fluoride-substituted hydroxyapatite (nano-F-HAP) was successfully realized through dialysis process within 4 h, which required much shorter time than the methods reported so far. In new preparation, a dialysis was employed to purify unwanted ions. The removal efficiency of impurity ions in dialysis was evaluated by calculating the concentration of the representative irons NH4 + between the inner slurry and outer distilled water. Results showed that total dialysis efficiency came to 94.5%. The final products were characterized by XRD, HR-TEM, and FT-IR. The XRD and FT-IR results strongly supported substitution of F- for OH-, and the TEM pictures further indicated that the final crystals are about 100nm in length and about 20 nm in diameter without obvious aggregation. Therefore, comparing with traditional purifying processing, such a new synthesis provides a promising application for scale preparation of fine nano-F-HAP crystals.

Abstract: In this paper, three different scale HA/PDLLA porous scaffolds, nano-HA/PDLLA, micro-HA/PDLLA and pure PDLLA were successfully fabricated using solvent casting/particulate leaching method. Chondrocytes adhesion and proliferation on these scaffolds were investigated. In detail, the cells attachment rate and proliferation on nano-HA/PDLLA, micro-HA/PDLLA and pure PDLLA were quantitatively evaluated by cytometry. The interaction between the scaffolds and chondrocytes were observed by optical microscope with HE staining and FE-SEM. The results exhibited that nano-HA/PDLLA scaffold has a modified cell adhesion property, and cells on the nano-scaffold grow much better both in biological and morphological characteristics than on the micro-HA/PDLLA and pure PDLLA scaffolds. This work suggested that nano-HA/PDLLA composite scaffold can significantly improved cell adhesion and proliferation tendency with the existing of nano-effects，and could be used as a potential scaffold material for bone defect repair.

Abstract: Six silane-modified hydroxyapatite (HA) / poly(lactic acid) (PLA) composites at 20% volume HA are prepared through absorption in liquid phase, volatilization, milling, and hot-press molding. Bending testing results indicate that their bending strengths are higher than that of control HA composite (unmodified HA composite) and the maximum strength enhances 27.8%. Calcium precipitation and calcium release experiments are designed to examine the bioactivity of the modified HA. The results show that the presence of the modification coating does not really impair the bioactivity and mineralization tendency of HA particles. Relationship of swelling property of the composites as function of time is investigated. Swelling equilibriums of silane-modified HA / PLA composites are reached after 48 h or 72 h, but the equilibrium of the unmodified HA / PLA composite is reached within 24 h. The swelling experiment also suggests that the desired swelling property of the composites could be achieved by changing modification molecules of HA according to necessity. Finally, SEM micrographs show that there is an improved interfacial binding between the modified HA and PLA matrix.

Abstract: The regular spherical poly-D, L-lactic acid (PDLLA) nanoparticles containing DNR are produced using a double-emulsion solvent evaporation process. The products morphology is characterized by a laser light-scattering particle size analyzer and scanning electron microscopy. Results show a mean diameter in 546.9 nm with narrow size distribution and homogeneous particle production. The encapsulation efficiency is evaluated by UV spectra. The results indicate that drug contents and loading efficiency are 14.34% and 72.9% respectively, and the drug release profile shows a biphasic phenomenon.