The Influence of Surface Morphology of Dense Ca-P Ceramics on Apatite Formation in Dynamic SBF

This study aimed at exploring the effect of surface morphology of dense phosphate calcium （Ca-P） ceramics upon the formation of bone-like apatite in static or dynamic simulated body fluid （SBF）. Dense and sandblasted calcium phosphate ceramics were immersed into dynamic SBF flowing at normal physiological speed of body fluid of skeletal muscle.The changes were characterized using SEM, XPS, IR and XRD. Changes can be observed after the sandblasted surface of dense calcium phosphate ceramics had been immersed in SBF for 14 days. XPS analysis results showed that the flake-like structure was composed of Ca, P, C, O; IR analysis result of surface structure of samples showed that there were specific peaks for CO 2- <sub>3; XRD results indicated the decrease in crystallinity and the increase in amorphous structure. The rough surface was advantageous for the formation of bone-like apatite. Increasing the Ca 2+ , HPO 2- <sub>4 concentration of SBF could also enhance the bone-like apatite formation. All the results demonstrated that local concentration is a key factor affecting nucleation.

Maturation of Osteoblast-Like Saos-2 on Hydroxyapatite Ceramics

Hydroxyapatite ceramics (HA) has been proved to be excellent in biocompatibility and bioactivity. However, limited information is available concerning how HA ceramics affects the maturation of osteoblasts in molecular biological level in vitro. This study examines the mRNA expression and protein production of bone-related genes in osteoblast-like cell line (Saos-2) cultured on HA disks. Saos-2 cells are seeded onto the substrates and cultured for 18 days. Harvested cells are tested for the cell growth rate, expression of mRNAs for osteocalcin and alkaline phosphatase, and protein production of bone sialoprotein and osteocalcin. MTS assay shows that cell proliferates well on HA ceramic substrate. After 9d, bone sialoprotein and osteocalcin protein production in SaPS-2 increases more on HA surfaces than on control material. As bone sialoprotein and osteocalcin are the genes to be highly expressed at the late stage of osteoblast differentiation, this study reveals that after long time culture in HA, HA can induce Saos-2 maturation. The behavior of Saos-2 on HA surfaces revealed in this study provides valuable information for the understanding of the biocompatibility and bioactivity of HA ceramics.

A study on the biocompatibility of ramie fibre for medical dressing application

In order to explore the potential application of Ramie fibre(RF)in medical dressing,the absorbency ratio of ramie fibre cloth,medical gauze and natural cotton fibre cloth was tested,and the factors affecting the absorbency ratio of materials were analysed.Meanwhile,the hemocompatibility of the three fibre materials were also studied.The results showed that the RF cloth had good moisture absorption and hemocompatibility.Therefore,RF is a potential material for medical dressing.

Bioactive Titanium Surfaces with the Effect of Inhibiting Biofilm Formation

Titanium metals and its alloy have been widely used in hard tissue repairing fields due to their good biocampatibility and mechanical properties. However, bioinert response and biomaterial associated infections are the main problems for their clinical application. In this study, we chose titanium plates treated with anodic oxidation （AO-Ti）, alkali-heat （AH-Ti） and acid-alkali （AA-Ti） methods, which have been proved to be bioactive in vivo, to culture with Staphylococcus aureus and Escherichia coli to investigate the interaction between bioactive titanium surfaces and biofilm. We used X-ray diffraction （XRD）, Scanning Electron Microscope （SEM）, roughness measurement to study the physical-chemical properties of the as-received bioactive titanium surfaces, and Confocal Laser Scanning Microscope （CLSM） was employed to study the properties of biofilm formed on the biomaterial surfaces. The results indicate that the titanium surface subjected to anodic oxidation treatment is unfavorable for the formation ofbiofilm in vitro because the titania （TiO2） coating formed by anodizing has superior antimicrobial property than the other surfaces. Therefore, anodic oxidation surface modification is effective to endow titanium surface with bioactivity and antimicrobial property, which has the potential to improve the successful rate of the clinical application of titanium implants.

Integrated printed BDNF/collagen/chitosan scaffolds with low temperature extrusion 3D printer accelerated neural regeneration after spinal cord injury

Recent studies have shown that 3D printed scaffolds integrated with growth factors can guide the growth of neurites and promote axon regeneration at the injury site.However,heat,organic solvents or cross-linking agents used in conventional 3D printing reduce the biological activity of growth factors.Low temperature 3D printing can incorporate growth factors into the scaffold and maintain their biological activity.In this study,we developed a collagen/chitosan scaffold integrated with brain-derived neurotrophic factor(3D-CC-BDNF)by low temperature extrusion 3D printing as a new type of artificial controlled release system,which could prolong the release of BDNF for the treatment of spinal cord injury(SCI).Eight weeks after the implantation of scaffolds in the transected lesion of T10 of the spinal cord,3D-CC-BDNF significantly ameliorate locomotor function of the rats.Consistent with the recovery of locomotor function,3D-CC-BDNF treatment could fill the gap,facilitate nerve fiber regeneration,accelerate the establishment of synaptic connections and enhance remyelination at the injury site.

A Study on the Biocompatibility of MgO Coating Prepared by Anodic Oxidation Method on Magnesium Metal

Magnesium(Mg),is widely used for the bone repair in oral and orthopedic application due to excellent bioactivity,degradation and biocompatibility.However,the range of application is greatly limited because of the rapid degradation of Mg metal in the body.Surface modification is an effective method to enhance the corrosion resistance and reduce the degradation rate of Mg metal.In the present study,pure Mg metal(P-Mg)was subjected to alkali-heat treatment(AT-Mg)or anodic oxidation-heat treatment(AO-HT-Mg).Both AT-Mg and AO-HT-Mg had a layer of MgO on their surfaces after treatment.Then the effects of MgO coating on corrosion resistance,bioactivity,Mesenchymal Stem Cells’(MSCs)proliferation,adhesion and osteogenic differentiation,and the bone repair capability of Mg metal were investigated.We found both AT-Mg and AO-HT-Mg had stronger corrosion resistance than P-Mg.MSCs on both AT-Mg and AO-HT-Mg had higher expression of proteins and genes of ALP,OCN,Col-I and Runx2 than those on P-Mg.They also showed better bone repair property than P-Mg in vivo.In general,MgO layer formed by anodic oxidation-heat treatment had better resistance and biocompatibility than that produced by alkali-heat treatment.This study indicated the MgO coating not only improved the corrosion resistance of Mg metal,but also promoted the osteogenic differentiation of MSCs and bone regeneration.

CdS magic-size clusters exhibiting one sharp ultraviolet absorption singlet peaking at 361 nm

We report,for the first time,the synthesis of CdS magic-size clusters (MSCs) which exhibit a single sharp absorption peaking at ~ 361 nm,along with sharp band edge photoemission at ~ 377 nm and broad trap emission peaking at ~ 490 nm.These MSCs are produced in a singleensemble form without the contamination of conventional quantum dots (QDs) and/or other-bandgap clusters.They are denoted as MSC-361.We present the details of several controlled syntheses done in oleylamine (OLA),using C,d(NO3)2 or C,d(OAc)2 as a C,d source and thioacetamide (TAA) or elementary sulfur (S) as a S source.A high synthetic reproducibility of the reaction of Cd(NO3)2 and TAA to single-ensemble MSC-361 is achieved,the product of which is not contaminated by other bandgap clusters and/or QDs.In some cases,the reaction product exhibits an additional absorption peak at ~ 322 nm.We demonstrate that the two peaks,at 361 and 322 nm,do not evolve synchronously.Therefore,the 322 nm peak is not a higher order electronic transition of MSC-361,but due to the presence of another ensemble,namely MSC-322.The present study suggests that there is an outstanding need for the development of a physical model to narrow the knowledge gap regarding the electronic structure in these colloidal semiconductor CdS MSCs.

Size matters:Steric hindrance of precursor molecules controlling the evolution of CdSe magic-size clusters and quantum dots

Little is known about how to precisely promote the selective production of either colloidal semiconductor metal chalcogenide(ME),magic-size clusters(MSCs),or quantum dots(QDs).Recently,a two-pathway model has been proposed to comprehend their evolution;here,we reveal for the first time that the size of precursors plays a decisive role in the selected evolution pathway of MSCs and QDs.With the reaction of cadmium myristate(Cd(MA)2)and tri-n-octylphosphine selenide(SeTOP)in 1-octadecene(ODE)as a model system,the size of Cd precursors was manipulated by the steric hindrance of carboxylic acid(RCOOH)additive.Without RCOOH,the reaction produced both CdSe MSCs and QDs(from 100 to 240℃).With RCOOH,the reaction produced MSCs or QDs when R was small(such as CH3−)or large(such as C6H5−),respectively.According to the twopathway model,the selective evolution is attributed to the promotion and suppression of the self-assembly of Cd and Se precursors,respectively.We propose that the addition of carboxylic acid may occur ligand exchange with Cd(MA)2,causing the different sizes of Cd precursor.The results suggest that the size of Cd precursors regulates the self-assemble behavior of the precursors,which dictates the directed evolution of either MSCs or QDs.The present findings bring insights into the two-pathway model,as the size of M and E precursors determine the evolution pathways of MSCs or QDs,the understanding of which is of great fundamental significance toward mechanism-enabled design and predictive synthesis of functional nanomaterials.

生物可降解镁植入物——骨肿瘤患者的潜在支架

骨癌患者切除术后可能发生复发和转移.传统的金属支架可以对骨缺损部位提供力学支撑,但无法有效清除复发的肿瘤细胞.本文中,我们介绍了一种可以抑制骨肉瘤生长的生物可降解镁丝植入物.简而言之,镁丝释放镁离子激活锌指蛋白Snail1从胞浆到细胞核的转运,通过下游的miRNA-181d-5p/TIMP3和miRNA-181c-5p/NLK两条平行的抗肿瘤信号通路诱导骨肉瘤细胞凋亡,抑制骨肉瘤细胞增殖.同时,镁丝释放出的氢气消除了细胞内过多的活性氧,从而抑制了骨肿瘤细胞的生长.裸鼠骨肉瘤细胞皮下荷瘤实验进一步证实镁丝能有效抑制肿瘤生长,延长荷瘤小鼠生存期.此外,镁丝对正常细胞和组织无毒性,揭示了镁植入物是骨肉瘤患者潜在的抗肿瘤支架材料.

Bioactive titanium metal surfaces with antimicrobial properties prepared by anodic oxidation treatment

In order to endow titanium metals with bioactivity and antimicrobial properties, titanium plates were subjected to anodic oxidation treatment in NaCl solutions in this study. The treated titanium metals could induce apatite formation in the fast calcification solution, and osteoblasts on the treated titanium surfaces proliferated well as those on the untreated titanium metal surfaces. The treated metals could inhibit S. aureus growth in the microbial culture experiments. It was assumed that Ti-OH groups and Ti-Cl groups formed on the treated titanium surface were responsible for the bioactivity and antimicrobial properties of the metals. The anodic oxidation treatment was an effective way to prepare bioactive titanium surfaces with antimicrobial properties.

Precursor compound enabled formation of aqueous-phase CdSe magic-size clusters at room temperature

The formation pathway of aqueous-phase colloidal semiconductor magic-size clusters(MSCs)remains unrevealed.In the present work,we demonstrate,for the first time,a precursor compound(PC)-enabled formation pathway of aqueous-phase CdSe MSCs exhibiting a sharp absorption peaking at about 420 nm(MSC-420).The CdSe MSC-420 is synthesized with CdCl2 and selenourea as the respective Cd and Se sources,and with 3-mercaptopropionic acid or L-cysteine as a ligand.Absorption featureless CdSe PCs form first in the aqueous reaction batches,which transform to MSC-420 in the presence of primary amines.The coordination between primary amine and Cd^(2+)on PCs may be responsible to the PC-to-MSC transformation.Upon increasing the reactant concentrations or decreasing the CdCl_(2)-ligand feed molar ratios,the Cd precursor self-assembles into large aggregates,which may encapsulate the resulting CdSe PCs and inhibit their transformation to MSC-420.The present study sheds essential light on the syntheses and formation mechanisms of nanocrystals.

Regulation of the Macrophage Phenotype on Titanium Metal by Surface Modification

The regulation of macrophage phenotype(M1/M2)is very important for tissue repair.The macrophage phenotypes could be affected by the physical and chemical parameters of implant surface.The aim of this study was to investigate the effects of surface modifications of titanium metals on macrophage phenotype.The medical pure titanium metals(PT-Ti)subjected to Anodic Oxidation(AO-Ti),Sand Blasting/acid etching(SLA-Ti)and Plasma-sprayed HA coating(HA coating-Ti)were used for regulating the phenotype of macrophage.The results showed that the Raw264.7 cells of AO-Ti groups had no obvious pseudopodia and could spread evenly in all directions.The levels of IL-1βand TNF-α,which belong to pro-inflammatory genes,expressed by the cells on AO-Ti groups were the lowest among all of the modified titanium groups.But,the levels of IL-10 and TGF-β,which belong to anti-inflammatory genes,expressed on AO-Ti groups were much higher than those on the other groups.Furthermore,the AO-Ti could regulate the expression of SOCS-1 and SOCS-3 to affect the active of NF-κB signaling.The gene expression results of macrophages showed that the AO-Ti was more conductive to inhibit the expression of M1-related genes and promote the expression of M2-related genes in an inflammatory environment.The AO-Ti was more beneficial to tissue repair than other modified titanium metals.The results showed that the anodic oxidation is an effective method to regulate the phenotype of macrophages.

The precursor compound of two types of ZnSe magic-sized clusters

Precursor compounds(PCs)link quantum dots(QDs)and magic-sized clusters(MSCs),which is pivotal in the conversion between QDs and MSCs.Here,for the first time,we report the transformation,synthesis,and composition of a type of ZnSe PCs.ZnSe PCs can be directly transformed to two different MSCs with the assistance of octylamine and acetic acid at room temperature.The two types of MSCs exhibit sharp absorption peaks at 299 and 328 nm which are denoted as MSC-299 and MSC-328.In the preparation of ZnSe PCs,diphenylphosphine(DPP)as an additive plays a key role which not only inhibits the thermal decomposition of Zn precursor,but also acts as a reducing agent to reduce the by-products produced in the reaction.The composition was explored by X-ray photoelectron spectroscopy,energy dispersive spectrometer,matrix-assisted laser desorption/ionization time-of-flight mass spectra with ZnSe PC powder appeared as white powder after purifying by toluene(Tol)and methanol(MeOH).The results indicate that the molar ratio of Zn/Se is 2:1 with a molecular of〜3,350 Da.Therefore,we propose that the molecular formula of ZnSe PCs is Zn_(32)Se_(16).In addition,at the molecular level,the covalent bond of Zn-Se is formed in ZnSe PCs.This study offers a deeper understanding of the transformation from PCs to MSCs and for the first time proposes the composition of PCs.Meanwhile,this research provides us with a new understanding of the role of DPP in the synthesis of colloidal semiconductor nanoparticles.