Sensitive electrochemical measurement of nitric oxide released from living cells based on dealloyed PtBi alloy nanoparticles.

Nitric oxide (NO), as a vital signaling molecule related to different physiological and pathological processes in living systems, is closely associated with cancer and cardiovascular disease. However, the detection of NO in real-time remains a difficulty. Here, PtBi alloy nanoparticles (NPs) were synthesized, dealloyed, and then fabricated to NP-based electrodes for the electrochemical detection of NO. Transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and nitrogen physical adsorption/desorption show that dealloyed PtBi alloy nanoparticles (dPtBi NPs) have a porous nanostructure. Electrochemical impedance spectroscopy and cyclic voltammetry results exhibit that the dPtBi NP electrode possesses unique electrocatalytic features such as low charge transfer resistance and large electrochemically active surface area, which lead to its excellent NO electrochemical sensing performance. Owing to the higher density of catalytical active sites formed PtBi bimetallic interface, the dPtBi NP electrode displays superior electrocatalytic activity toward the oxidation of NO with a peak potential at 0.74 V vs. SCE. The dPtBi NP electrode shows a wide dynamic range (0.09-31.5 µM) and a low detection limit of 1 nM (3σ/k) as well as high sensitivity (130 and 36.5 µA µM-1 cm-2). Moreover, the developed dPtBi NP-based electrochemical sensor also exhibited good reproducibility (RSD 5.7%) and repeatability (RSD 3.4%). The electrochemical sensor was successfully used for the sensitive detection of NO produced by live cells. This study indicates a highly effective approach for regulating the composition and nanostructures of metal alloy nanomaterials, which might provide new technical insights for developing high-performance NO-sensitive systems, and have important implications in enabling real-time detection of NO produced by live cells.

Electrochemically Switchable Circularly Polarized Photoluminescence within Self-Assembled Conducting Polymer Helical Microfibers.

Achieving electrically and/or electrochemically controlled circularly polarized photoluminescence (CPL) is challenging due to the non-electroactive characteristics of most chiral materials and the non-electrosensitive feature of materials' chiroptical signals. Here we found that the CPL of self-assembled conducting polyaniline (PANI) helical microfibers could be reversibly switched by applying an alternating electrical bias. The conducting polymer is not the fluorophore but can transfer its chirality to the coassembled aggregation-induced emission (AIE) fluorescent molecules. The electrochemically switchable CPL is derived from the reversible transformation of the chirality of the polyaniline microfibers, which is probably due to the change in the molecular interchain distance upon doping/dedoping. Subsequently, we have demonstrated double-layer information encryption based on the electrochemically reversible CPL and conductance.

Synthesis, Characterization, and Application of Core-Shell Co0.16Fe2.84O4@NaYF4(Yb, Er) and Fe3O4@NaYF4(Yb, Tm) Nanoparticle as Trimodal (MRI, PET/SPECT, and Optical) Imaging Agents.

Multimodal nanoparticulate materials are described, offering magnetic, radionuclide, and fluorescent imaging capabilities to exploit the complementary advantages of magnetic resonance imaging (MRI), positron emission tomography/single-photon emission commuted tomography (PET/SPECT), and optical imaging. They comprise Fe3O4@NaYF4 core/shell nanoparticles (NPs) with different cation dopants in the shell or core, including Co0.16Fe2.84O4@NaYF4(Yb, Er) and Fe3O4@NaYF4(Yb, Tm). These NPs are stabilized by bisphosphonate polyethylene glycol conjugates (BP-PEG), and then show a high transverse relaxivity (r2) up to 326 mM(-1) s(-1) at 3T, a high affinity to [(18)F]-fluoride or radiometal-bisphosphonate conjugates (e.g., (64)Cu and (99m)Tc), and fluorescent emissions from 500 to 800 nm under excitation at 980 nm. The biodistribution of intravenously administered particles determined by PET/MR imaging suggests that negatively charged Co0.16Fe2.84O4@NaYF4(Yb, Er)-BP-PEG (10K) NPs cleared from the blood pool more slowly than positively charged NPs Fe3O4@NaYF4(Yb, Tm)-BP-PEG (2K). Preliminary results in sentinel lymph node imaging in mice indicate the advantages of multimodal imaging.

Fabricating biodegradable calcium phosphate/calcium sulfate cement reinforced with cellulose: in vitro and in vivo studies.

Osteoporosis is a growing public health concern worldwide. To avoid extra surgeries, developing biodegradable bone cement is critical for the treatment of osteoporosis. Herein, we designed calcium phosphate/calcium sulfate cement reinforced with sodium carboxymethyl cellulose (CMC/OPC). It presents an appropriate physicochemical performance for clinical handling. Meanwhile, CMC/OPC bone cement promotes osteogenic differentiation in vitro. Results of the immune response in vitro and in vivo confirmed that increasing the cellulose content triggered macrophage switching into the M2 phenotype and CMC/OPC exhibited significant anti-inflammation. Furthermore, in vitro and in vivo degradation demonstrated that cellulose tailors the degradation rate of composite bone cement, which achieved a linear degradation process and could degrade by more than 90% for 12 weeks. In summary, the composite bone cement CMC/OPC is a promising candidate for bone repair applications.

Preparation of high concentration polyaluminum chloride by chemical synthesis-membrane distillation method with self-made hollow fiber membrane.

A method of direct contact membrane distillation (DCMD) with a self-made hollow polyvinylidene fluoride membrane was applied to prepare high concentration polyaluminum chloride (PACl) with high A1b content based on chemical synthesis. The permeate flux and A1 species distribution were investigated. The experimental results showed that the permeate flux decreased from 14 to 6 kg/(m2 x hr) at the end of the DCMD process, which can be mainly attributed to the formation of NaCl deposits on the membrane surface. The Alb content decreased slightly, only from 86.3% to 84.4%, when the DCMD experiment finished, correspondingly the A1c content increased slightly from 7.2% to 8.5%, and the A1a content remained at 7% during the whole DCMD process. A PACl with A1b content of 84% at total aluminum concentration 2.2 mol/L was successfully prepared by the chemical synthesis-DCMD method.

Efficacy evaluation of True Lift®, a nonsurgical facial ligament retightening injection technique: Two case reports.

BACKGROUND: With aging, four major facial retaining ligaments become elongated, leading to facial sagging and wrinkling. Even though synthetic fillers are popular, however, it cannot address the problems of soft tissue descent alone, and injection of these fillers requires knowledge of the injection technique including the selection of injection sites, the amount of filler, and the dosage used per injection site. CASE SUMMARY: This report aimed to assess the safety and efficacy of a nonsurgical retightening technique to lift and tighten the true ligaments of the face, to improve age-related skin sagging and wrinkling. We objectively quantified the aesthetic lifting effect of a nonsurgical facial retightening procedure that strategically injected high G' fillers into the base of the true retaining ligaments of the face in two female patients. Facial images were recorded with a three-dimensional facial imaging system for comparison of the clinical outcome. The primary efficacy outcome was the change in facial anthropometric measurements obtained prior to and after injection. The patients were followed for 6 mo after the procedure. Skin retightening was observed, with an evident lift in the orbital, zygomatic, and mandibular regions, and the lifting effect was still observable at the 6-mo follow-up. Few mild adverse events, such as mild-to-moderate pain, tenderness, and itching, occurred during the 1st week after the procedure. No adverse events were reported 1 mo post-procedure. CONCLUSION: The results of this study demonstrated that our nonsurgical retightening procedure with strategically placed high G' fillers achieved quantifiable aesthetic improvements in the orbital, zygomatic, and mandibular regions of two patients. Future research with a larger sample could provide a more in-depth evaluation and validation of the aesthetic improvements observed in this study.

Fluidity-Guided Assembly of Au@Pt on Liposomes as a Catalase-Powered Nanomotor for Effective Cell Uptake in Cancer Cells and Plant Leaves.

The fluidity of the liposomes is essential to nanoparticle-membrane interactions. We herein report a liposomal nanomotor system by controlling the self-assembly behavior of gold core-platinum shell nanoparticles (Au@Pt) on liposomes. Au@Pt can aggregate immediately on fluid-phase dioleoyl-sn-glycero-3-phosphocholine (DOPC) liposomes, forming an uneven distribution. By control of the lipid phase and fluidity, either using pure 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) above its phase transition temperature or adding cholesterol as an adjuvant to DPPC lipids, we precisely control the assembly of Au@Pt on liposomes. Au@Pt maintained high catalase-like activity on the liposomal surface, promoting the decomposition of H2O2 and the movement of the liposomal nanomotors. Finally, we demonstrate that liposomal nanomotors are biocompatible and they can speed up the cellular uptake in mammalian HepG2 cancer cells and Nicotiana tabacum (Nb) plant leaves. This liposomal nanomotor system is expected to be further investigated in biomedicine and plant nanotechnology.

Changes in degree of conversion and microhardness of dental resin cements.

There are few studies available on the post-light activation or post-mix polymerization of dental resin cements as a function of time. This in vitro study evaluated the successive changes in the degree of conversion (DC) and microhardness during polymerization of six commercial resin cements (light-cured [Choice 2, RelyX Veneer], chemical-cured [Multilink, C&B Cement] and dual-cured [Calibra, RelyX ARC]) within the first 24 hours and up to seven days. Resin specimens were prepared for Fourier transform infrared (FTIR) spectroscopy and microhardness testing to determine the DC and Vickers hardness (VH), respectively. The light-cured materials or mixed pastes of the dual-cured materials were irradiated with a light-curing unit (Elipar TriLight) through a precured composite overlay for 40 seconds. The FTIR spectra and microhardness readings were taken at specified times: 1, 2, 5, 10, 15, 30 and 60 minutes; 24 hours and after two days and seven days. According to the FTIR study, most of the curing reaction of Choice 2 and RelyX Veneer occurred within 10 and 30 minutes, respectively. Multilink, C&B Cement and Calibra exhibited gradual increases in the DC up to 24 hours, with no further statistically significant increase (p > 0.05). RelyX ARC attained a DC value within five minutes, similar to that at seven days (p > 0.05). Choice 2 and RelyXARC showed gradual increases in the VH, up to 15 minutes, with no further significant change over the remaining observation time (p > 0.05). For RelyX Veneer, Multilink, C&B Cement and Calibra, there were no significant increases in the VH value after 24 hours (p > 0.05). The light-cured materials produced significantly higher DC values than the chemical-cured materials (p < 0.05). The DC values of the two dual-cured resin cements were significantly different from each other (p < 0.001). The results suggest that the significant polymerization reaction was finished within 24 hours post-mix or post-light activation for all resin cements tested.

Synthesis and in vivo evaluation of PEG-BP-BaYbF5 nanoparticles for computed tomography imaging and their toxicity.

Computed tomography (CT) is one of the most widespread imaging techniques in clinical use worldwide. CT contrast agents are administered to improve soft tissue contrast and highlight blood vessels. However, the range of CT contrast agents available in the clinic is limited and they suffer from short-circulation times and low k-edge values that result in the need for high doses for in vivo applications. Nanomaterials containing a mixture of electron-dense elements, such as BaYbF5 nanoparticles, have shown promise as more efficient CT contrast agents, but they require biocompatible coatings for biomedical applications. Here, we explore the use of a bifunctional PEG polymer (5 kDa) containing a terminal bisphosphonate (BP) anchor for efficient binding to the surface of BaYbF5 nanomaterials. The resulting PEG(5)-BP-BaYbF5 nanoparticles were synthesized and characterized using TEM, DLS, TGA, XRD and Z-potential measurements. Their in vitro stability was verified and their ability to produce CT contrast in a wide range of X-ray energies, covering preclinical and clinical scanners, was demonstrated. In vitro toxicity studies with PEG(5)-BP-BaYbF5 in the phagocytic pro-monocytic human cell line U937 did not identify toxic effects, even at high concentrations (30 mM). In vivo, PEG(5)-BP-BaYbF5 exhibited efficient CT contrast for angiography imaging, highlighting blood vessels and vascular organs, and long circulation times as expected from the PEG coating. However, at late time points (48 h), in vivo toxicity was observed. While the causes could not be completely elucidated, in vitro studies suggest that decomposition and release of Yb3+ and/or Ba2+ metal ions after decomposition of PEG(5)-BP-BaYbF5 may play a role. Overall, despite the promising CT contrast properties, our results suggest that BaYbF5 nanomaterials may suffer from significant long-term toxicities.

[Biocompatibility of combined deproteinized bone coated with hepatocyte growth factor as scaffold for osteoblasts in vitro in fetal rabbits].

OBJECTIVE: To determine the cellular compatibility of combined deproteinized bone(DPB) coated with hepatocyte growth factor (HGF), and to observe the adherent effect of osteoblasts in response to HGF. METHODS: Osteoblasts were isolated from fetal rabbits. Osteoblasts were cultured with DPB coated with HGF and deproteinized bone as experimental group and contral group, respectively. The proliferation and alkalinephosphatase activity were tested. Their growth was examined by inverted phase contrast microscope and scanning electronmicroscope. RESULTS: The osteoblasts were attached to the outside and inside surfaces and grew well. HGF/DPB could stimulate the alkalinephosphatase activity of the osteoblasts and improve the proliferation of the osteoblasts. CONCLUSION: HGF/DPB has good biocompatibility and bone induction. HGF could improve the adherent effect of DPB on osteoblasts, and it could be used as scaffold material for the bone tissue engineering.

Development and Application of A Duplex Real-Time RT-PCR Assay for Simultaneous Detection of Coxsackievirus A6 and Coxsackievirus A10.

Hand, foot and mouth disease (HFMD) is a serious public health problem. Generally, it is considered that HFMD is mainly caused by enterovirus 71 (EV71) and coxsackievirus A16 (CVA16). Nevertheless, the incidence of HFMD caused by coxsackievirus A6 (CVA6) and coxsackievirus A10 (CVA10) has increased significantly and CVA6 and CVA10 have become major causes of HFMD epidemic. This study develops a duplex real-time reverse transcript polymerase chain reaction (RT-PCR) assay for simultaneous detection of CVA 6 and CVA 10. The specificity, sensitivity, and reproducibility of this assay were analyzed. No cross-reactions with other viruses or false positives were observed. The detection limit of this assay was as low as 11.935 copies for CVA6 and 17.591 copies for CVA10 per reaction (concentration giving a positive duplex real-time RT-PCR result in 95% of samples). The coefficients of variation of the intra- and inter-assay reproducibility for CVA 6 and CVA 10 were both lower than 2%. Our results showed that this duplex real-time RT-PCR assay was a simple, rapid, and cost-effective method for simultaneous identification of CVA6 and CVA10.

A Near Infrared Light Triggered Hydrogenated Black TiO2 for Cancer Photothermal Therapy.

White TiO2 nanoparticles (NPs) have been widely used for cancer photodynamic therapy based on their ultraviolet light-triggered properties. To date, biomedical applications using white TiO2 NPs have been limited, since ultraviolet light is a well-known mutagen and shallow penetration. This work is the first report about hydrogenated black TiO2 (H-TiO2 ) NPs with near infrared absorption explored as photothermal agent for cancer photothermal therapy to circumvent the obstacle of ultraviolet light excitation. Here, it is shown that photothermal effect of H-TiO2 NPs can be attributed to their dramatically enhanced nonradiative recombination. After polyethylene glycol (PEG) coating, H-TiO2 -PEG NPs exhibit high photothermal conversion efficiency of 40.8%, and stable size distribution in serum solution. The toxicity and cancer therapy effect of H-TiO2 -PEG NPs are relative systemically evaluated in vitro and in vivo. The findings herein demonstrate that infrared-irradiated H-TiO2 -PEG NPs exhibit low toxicity, high efficiency as a photothermal agent for cancer therapy, and are promising for further biomedical applications.

[Effects of collagen I coating on the porous poly-lactide-co-glycolid on adhesion, proliferation, and differentiation of mesenchymal stem cells].

OBJECTIVE: To investigate the effects of collagen I on the adhesion, proliferation, and differentiation of MSCs on PLGA. METHODS: Collagen I was added onto the surface of pores in pieces of 3-D porous poly-lactide-co-glycolid (PLGA). Bone marrow-derived mesenchymal stem cells (MSCs) were obtained from New Zealand rabbits and were cultured for 3 generations, inoculated into the pores of PLGA pieces with the volume of 0.3 cm x 1.2 cm x 2.0 cm, and then cultured in solution with [(3)H]-thymidine deoxyribose (TdR). PLGA pieces not coated by collagen I were used as controls. The incorporation rate of [(3)H]-TdR was detected 2, 4, 6, and 8 hours, and 7, 14, and 21 days after culture, shown in count per minute (CPM) value, to determine the adhesion and proliferation of the MSCs. RT-POCR was used to examine the expressions of mRNA of the osteoblast markers: osteocalcin (OCN), alkaline phosphatase (ALP), and osteopontin (OPN). Scanning electron microscopy (SEM) was used to observe the morphology of MSCs. RESULTS: The CPM value since 6 hours after culture between the experimental group and control group began to be significantly different (both P < 0.05) The CPM values 7, 14, and 21 days after culture between the experimental group and control groups (P < 0.05 or P < 0.01). OCN, ALP, and OPN mRNA were expressed in MSCs of the experimental group and only ALP mRNA was weakly expressed in the control group. SEM showed the distribution of spindle and polygonal cells in the pores of the 3-D PLGA pieces and distribution of cylindrical or round cells in the control group. CONCLUSION: Collagen I is effective in promoting the adhesion, proliferation, and differentiation of MSCs on PLGA.

Star-shaped poly(L-lactide)-b-poly(lactobionamidoethyl methacrylate) with porphyrin core: synthesis, self-assembly, singlet oxygen research and recognition properties.

Star-shaped porphyrin-cored poly(L-lactide)-b-poly(lactobionamidoethyl methacrylate) block copolymers (SPPLA-b-PLAMA) were synthesized via RAFT of unprotected Lactobionamidoethyl methacrylate (LAMA) in 1-methyl-2-pyrrolidinone (NMP) solution at 70 °C. The structure of this as-synthesized SPPLA-b-PLAMA block copolymer was thoroughly studied by nuclear magnetic resonance spectroscopy, gel permeation chromatography (GPC), and Fourier transforms infrared. Moreover, under the irradiation, such SPPLA-b-PGAMA copolymer exhibits efficient singlet oxygen generation (0.17) and indicates high fluorescence quantum yields (0.20). Notably, with UV-vis investigation, SPPLA-b-PLAMA showed a very specific recognition with RCA120 lectin. This will not only provide potentially prophyrin-cored star-shaped SPPLA-b-PLAMA block copolymers for targeted photodynamic therapy, but also improve the physical, biodegradation, biocompatibility properties of PLA-based biomaterials.

Biomimetic layer-by-layer Co-mineralization approach towards TiO2/Au nanosheets with high rate performance for lithium ion batteries.

We fabricated a sandwich-like branched-polyethyleneimine (b-PEI)/TiO2/Au/graphene oxide (GO) nanocomposite through a biomimetic layer-by-layer co-mineralization approach, and the polymer b-PEI was believed to act as both an inducing agent for the hydrolysis of titanium bis(ammonium lactato)-dihydroxide (Ti-BALDH) and a reducing agent for the reduction of HAuCl4 in the synthetic procedure. Upon organic pyrolysis in air at 500 °C, a TiO2/Au nanosheet was formed; and gold nanocrystals were observed uniformly dispersed on TiO2 nanosheet. Moreover, the obtained TiO2/Au nanosheets demonstrated an enhanced lithium storage performance when they are used as anode materials for lithium ion batteries (LIBs), particularly, a high capacity of 205 mA h g(-1) and 189 mA h g(-1) was obtained at 5 C and 10 C rate, respectively, indicating the high rate capability of the material. The greatly improved rate performance might be attributed from both the sheet-like nanostructure and the existence of uniformly dispersed gold nanocrystals, which facilitate electron transfer and lithium ions diffusion in the material. The result suggests that the TiO2 electrode performance can be improved through a design of sheet-like nanocomposites using a bio-inspired route, which is desirable for both "green synthesis" and application for high power LIBs, moreover, such a benign bio-inspired route can be developed into a general pathway to synthesize many other TiO2 based nanocomposites for broad applications in the fields of batteries, photoelectrochemistry, photocatalysis and dye-sensitized solar cells.

Bio-inspired synthesis of titania with polyamine induced morphology and phase transformation at room-temperature: insight into the role of the protonated amino group.

Poly(allylamine hydrochloride) (PAAH), a mimic of biopolyamines, was used to induce the mineralization of titania at room-temperature, hollow spheres with a mixed phase (anatase and rutile) were obtained, and the fine anatase and rutile nanocrystals were observed mixing at the sub-10 nm scale on the hollow spheres. The structural information about the precipitated titania gained by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy revealed a distinct dependence of the polymorph and morphology of the titania precipitates on the molecular structure of the polyamines and titanium precursors. Moreover, we have observed the phase transformation from anatase to rutile in the formation process of hollow spheres, and it was suggested that the protonated amino groups on PAAH played key roles in the transformation of both polymorphs and morphologies of titania. Additionally, poly(diallyldimethylammonium chloride) (PDDA), a long chain quaternary ammonium polymer, was used as another catalytic template for the synthesis of titania, which also led to a hollow structure with a mixture of anatase and TiO2-B.

Bisphosphonate-anchored PEGylation and radiolabeling of superparamagnetic iron oxide: long-circulating nanoparticles for in vivo multimodal (T1 MRI-SPECT) imaging.

The efficient delivery of nanomaterials to specific targets for in vivo biomedical imaging is hindered by rapid sequestration by the reticuloendothelial system (RES) and consequent short circulation times. To overcome these two problems, we have prepared a new stealth PEG polymer conjugate containing a terminal 1,1-bisphosphonate (BP) group for strong and stable binding to the surface of ultrasmall-superparamagnetic oxide nanomaterials (USPIOs). This polymer, PEG(5)-BP, can be used to exchange the hydrophobic surfactants commonly used in the synthesis of USPIOs very efficiently and at room temperature using a simple method in 1 h. The resulting nanoparticles, PEG(5)-BP-USPIOs are stable in water or saline for at least 7 months and display a near-zero ζ-potential at neutral pH. The longitudinal (r(1)) and transverse (r(2)) relaxivities were measured at a clinically relevant magnetic field (3 T), revealing a high r(1) of 9.5 mM(-1) s(-1) and low r(2)/r(1) ratio of 2.97, making these USPIOs attractive as T1-weighted MRI contrast agents at high magnetic fields. The strong T1-effect was demonstrated in vivo, revealing that PEG(5)-BP-USPIOs remain in the bloodstream and enhance its signal 6-fold, allowing the visualization of blood vessels and vascular organs with high spatial definition. Furthermore, the optimal relaxivity properties allow us to inject a dose 4 times lower than with other USPIOs. PEG(5)-BP-USPIOs can also be labeled using a radiolabeled-BP for visualization with single photon emission computed tomography (SPECT), and thus affording dual-modality contrast. The SPECT studies confirmed low RES uptake and long blood circulation times (t(1/2) = 2.97 h). These results demonstrate the potential of PEG(5)-BP-USPIOs for the development of targeted multimodal imaging agents for molecular imaging.

[A clinical study on the stability of miniscrew anchorage in orthodontics].

PURPOSE: The aim of this retrospective study was to summarize the cases who used miniscrew anchorage and to evaluate the clinical factors influencing the stability of miniscrew. METHODS: The sample comprised 13 patients with 32 miniscrews, in whom the design, occlusogingival position, alveolar position, loading opportunity, gingival condition were investigated to assess the factors related to stability. The data was analyzed by univariate analysis and multivariate analysis using SAS 10.0 software package. RESULTS: The overall success rate was 90.6%. There was significant relationship between the patients' age and the stability of miniscrews (P=0.04). The success rate was 75% in adolescent patients, and 100% in adult patients. The osseointegration was affected by initial over-loading, but the long-term orthodontic loading (200g) was safe, if osseointegration was achieved. Perio-implant gingivitis, even the suppurative gingivitis (2 cases) didn't destroy the bone-implant interface. The success rate was independent on gender, occlusogingival position, jaw positioning, inserting times of the same miniscrew, and early loading. CONCLUSIONS: The primary stability is the crucial factor for long-term stability of the miniscrews.

[A study on the stability of miniscrew on different loading time as orthodontic anchorage].

PURPOSE: To evaluate the stability of the miniscrew on different loading time as orthodontic anchorage. METHODS: 2 healthy adult male Beagle dogs were used in this study. 48 mini-implants were implanted into the maxilla and mandible of the dogs. The miniscrews were divided into 8 different groups,1 group was loaded 0g as control group and the others were loaded 200g forces as experimental groups. 200g forces were loaded on the corresponding mini-implant anchorages immediately after implantation and at the time of 1w,2w,3w,4w,5w and 6w after implantation. The dogs were sacrificed at 12w after implantation. Histological progresses of implant-bone interfaces was examined with light microscope. Blue deposition and contact ratio were calculated and analyzed using SPSS13.0 software package. RESULTS: Fibrous and osseous-integration was noted in the interface, there was no significant difference in bone deposition ratio and bone contact ratio. CONCLUSION: Different force loading time does not affect the stability of the mini-implant anchorage.