Immunomodulatory activity of polycaprolactone nanoparticles with calcium phosphate salts against Leishmania infantum infection

Objective:To prepare and characterize polycaprolactone(PCL)nanoparticles loaded with sonicator fragmented(SLA)and freeze-thaw Leishmania antigens(FTLA)and to investigate the in vitro immunogenicity of antigen-encapsulated nanoparticles with calcium phosphate adjuvant.Methods:The water/oil/water binary emulsion solvent evaporation method was used to synthesize antigen-loaded PCL nanoparticles.Particles were characterized by scanning electron microscopy and zeta potential measurements.Their cytotoxicity in J774 macrophages in vitro was determined by MTT analysis.In addition,the amount of nitric oxide and the level of cytokines produced by macrophages were determined by Griess reaction and ELISA method,respectively.The protective effect of the developed formulations was evaluated by determining the infection index percentage in macrophages infected with Leishmania infantum.Results:Compared to the control group,SLA PCL and FTLA PCL nanoparticles with calcium phosphate adjuvant induced a 6-and 7-fold increase in nitric oxide,respectively.Additionally,the vaccine formulations promoted the production of IFN-γand IL-12.SLA PCL and FTLA PCL nanoparticles combined with calcium phosphate adjuvant caused an approximately 13-and 11-fold reduction in infection index,respectively,compared to the control group.Conclusions:The encapsulation of antigens obtained by both sonication and freeze-thawing into PCL nanoparticles and the formulations with calcium phosphate adjuvant show strong in vitro immune stimulating properties.Therefore,PCL-based antigen delivery systems and calcium phosphate adjuvant are recommended as a potential vaccine candidate against leishmaniasis.

Effect of Fluoride on the Ion-association of Calcium Phosphate and Crystallization of Hydroxyapatite

Using a titration setup to accurately control the reaction conditions and in situ monitor the reaction,we showed that fluoride exhibited negligible effects on the ion association process of calcium and phosphate and the formation of ACP nanospheres in a buffer solution with constant ionic strength.However,the stability of ACP increased with increasing fluoride concentration,which was ascribed to the inhibitory effect of fluoride on the aggregation of ACP nanospheres and the nucleation of nanocrystals on the surface of ACP nanospheres.Furthermore,fluoride could inhibit the lateral growth of HAP nanosheets and promote the formation of rod-like crystals.These results further improve our understanding of the crystallization pathway of HAP crystals and the regulatory effects of fluoride.

Phosphate,calcium,and vitamin D signaling,transport,and metabolism in the endometria of cyclic ewes

Background Recent evidence suggests important roles for progesterone(P4)and interferon tau in the regulation of calcium,phosphate,and vitamin D signaling in the uteri of pregnant sheep.However,the effects of P4 and estradiol(E2),with respect to the expression of their receptors PGR and ESR1,respectively,in uterine epithelia on mineral signaling during the estrous cycle has not been investigated.Estrous cycles of mature Suffolk ewes were synchronized,prostaglandin F2αwas administered,and ewes were observed for estrus(designated as Day 0)in the presence of vasectomized rams.On Days 1,9,or 14 of the estrous cycle,hysterectomies were performed.Results 25-hydroxyvitamin D was more abundant in plasma from ewes on Day 14 than Day 1(P<0.05).Expression of fibroblast growth factor receptor 2(FGFR2),a disintegrin and metalloprotease 17(ADAM17),and parathyroid hormone-related protein(PTHrP)mRNAs was greater in endometria on Day 9 compared to Days 1 and 14(P<0.01).Similarly,expression of transient receptor potential cation channel subfamily V member 6(TRPV6)mRNA was greater in endometria on Day 9 than Day 1(P<0.05).ATPase plasma membrane Ca^(2+)transporting 4(ATP2B4)and S100 calcium binding protein G(S100G)mRNA expression was greater in endometria on Day 14 than on Days 1 and 9(P<0.01).In contrast,endometrial expression of vitamin D receptor(VDR)mRNA was lower on Days 9 and 14 than Day 1(P<0.01).Expression of klotho(KL)(P<0.05)and cytochrome P450 family 24 subfamily A member 1(CYP24)(P<0.01)mRNAs was lower on Day 14 than Days 1 and 9.ADAM17,FGF23,CYP2R1,CYP27B1,KL,and VDR proteins immunolocalized to the uterine myometrium,blood vessels,and uterine luminal(LE),superficial glandular(sGE),and glandular(GE)epithelia.S100A9 protein was weakly expressed in the uterine myometrium,LE,sGE,and GE.Immunoreactivity of CYP2R1 and KL proteins in uterine LE and sGE was less on Day 1 than on Days 9 and 14.In contrast,S100G protein was expressed exclusively by GE,and immunoreactive S100G protein was less on Day 9.S100A12 protein localized to stromal cells of the uterine stratum spongiosum and blood vessels,but not by uterine epithelial cells.Conclusion Collectively,these results implicate E2,P4,and PGR in the regulation of phosphate,calcium,and vitamin D signaling in cyclic ewes.

Optimization by the Taguchi Method of a Robust Synthesis Protocol of Calcium Carbonate Phosphate

The experimental processes are difficult to model by physical laws, because a multitude of factors can intervene simultaneously and are responsible for their instabilities and their random variations. Two types of factors are to be considered;those that are easy to manipulate according to the objectives, and those that can vary randomly (uncontrollable factors). These could eventually divert the system from the desired target. It is, therefore, important to implement a system that is insensitive to fluctuations in factors that are difficult to control. The aim of this study is to optimize the synthesis of an apatitic calcium carbonate phosphate characterized with a Ca/P ratio equal to 1.61 by using the experimental design method based on the Taguchi method. In this process, five factors are considered and must be configured to achieve the previously defined objective. The temperature is a very important factor in the process, but difficult to control experimentally, so considered to be a problem factor (noise factor), forcing us to build a robust system that is insensitive to the last one. Therefore, a much simpler model to study the robustness of a synthetic solution with respect to temperature is developed. We have tried to parameterize all the factors considered in the process within a wide interval of temperature variation (60˚C - 90˚C). Temperature changes are no longer considered as a problem for apatitic calcium carbonate phosphate synthesis. In this finding, the proposed mathematical model is linear and efficient with very satisfactory statistical indicators. In addition, several simple solutions for the synthesis of carbonate phosphate are proposed with a Ca/P ratio equal to 1.61.

Corrosion resistance of cerium-doped zinc calcium phosphate chemical conversion coatings on AZ31 magnesium alloy

Zinc calcium phosphate （Zn-Ca-P） coating and cerium-doped zinc calcium phosphate （Zn-Ca-Ce-P） coating were prepared on AZ31 magnesium alloy. The chemical compositions, morphologies and corrosion resistance of coatings were investigated through energy-dispersive X-ray spectroscopy （EDS）, X-ray photoelectron spectroscopy （XPS）, X-ray diffraction （XRD）, electron probe micro-analysis （EPMA） and scanning electron microscopy （SEM） together with hydrogen volumetric and electrochemical tests. The results indicate that both coatings predominately contain crystalline hopeite （Zn3（PO4）2·4H2O）, Mg3（PO4）2 and Ca3（PO4）2, and traces of non-crystalline MgF2 and CaF2. The Zn-Ca-Ce-P coating is more compact than the Zn-Ca-P coating due to the formation of CePO4, and displays better corrosion resistance than the Zn-Ca-P coating. Both coatings protect the AZ31 Mg substrate only during an initial immersion period. The micro-galvanic corrosion between the coatings and their substrates leads to an increase of hydrogen evolution rate （HER） with extending the immersion time. The addition of Ce promotes the homogenous distribution of Ca and formation of hopeite. The Zn-Ca-Ce-P coating has the potential for the primer coating on magnesium alloys.

Highly Efficient and Selective Removal of Pb（II） ions by Sulfur-Containing Calcium Phosphate Nanoparticles

A facile one-step co-precipitation method was demonstrated to fabricate amorphous sulfurcontaining calcium phosphate （SCP） nanoparticles, in which the sulfur group was in-situ introduced into calcium phosphate. The resulting SCP exhibited a noticeable enhanced performance for Pb（II） removal in comparison with hydroxyapatite （HAP）, being capable of easily reducing 20 ppm of Pb（II） to below the acceptable standard for drinking water within less than 10 min. Remarkably, the saturated removal capacities of Pb（II） on SCP were as high as 1720.57 mg/g calculated by the Langmuir isotherm model, exceeding largely that of the previously reported absorbents. Significantly, SCP displayed highly selective removal ability toward Pb（II） ions in the presence of the competing metal ions （Ni（II）, Co（II）, Zn（II）, and Cd（II））. Further investigations indicated that such ultra-high removal efficiency and preferable affinity of Pb（II） ions on SCP may be reasonably ascribed to the formation of rodlike hydroxypyromorphite crystals on the surface of SCP via dissolution-precipitation and ion exchange reactions, accompanied by the presence of lead sulfide precipitates. High removal efficiency, fast removal kinetics and excellent selectivity toward Pb（II） made the obtained SCP material an ideal candidate for Pb（II） ions decontamination in practical application.

Effect of humic substances on the precipitation of calcium phosphate

For phosphorus （P） recovery from wastewater, the effect of humic substances （HS） on the precipitation of calcium phosphate was studied. Batch experiments of calcium phosphate precipitation were undertaken with synthetic water that contained 20 mg/L phosphate （as P） and 20 mg/L HS （as dissolved organic carbon, DOC） at a constant pH value in the range of 8.0-10.0. The concentration variations of phosphate, calcium （Ca） and HS were measured in the precipitation process; the crystalline state and compositions of the precipitates were analysed by powder X-ray diffraction （XRD） and chemical methods, respectively. It showed that at solution pH 8.0, the precipitation rate and removal efficiency of phosphate were greatly reduced by HS, but at solution pH ≥9.0, the effect of HS was very small. The Ca consumption for the precipitation of phosphate increased when HS was added; HS was also removed from solution with the precipitation of calcium phosphate. At solution pH 8.0 and HS concentrations ≤3.5 mg/L, and at pH ≥ 9.0 and HS concentrations ≤ 10 mg/L, the final precipitates were proved to be hydroxyapatite （HAP） by XRD. The increases of solution pH value and initial Ca/P ratio helped reduce the influence of HS on the precipitation of phosphate.

Effects of quaternary ammonium chain length on the antibacterial and remineralizing effects of a calcium phosphate nanocomposite

Composites containing nanoparticles of amorphous calcium phosphate （NACP） remineralize tooth lesions and inhibit caries. A recent study synthesized quaternary ammonium methacrylates （QAMs） with chain lengths （CLs） of 3-18 and determined their effects on a bonding agent. This study aimed to incorporate these QAMs into NACP nanocomposites for the first time to simultaneously endow the material with antibacterial and remineralizing capabilities and to investigate the effects of the CL on the mechanical and biofilm properties. Five QAMs were synthesized： DMAPM （CL3）, DMAHM （CL6）, DMADDM （CL12）, DMAHDM （CL16）, and DMAODM （CL18）. Each QAM was incorporated into a composite containing 20% NACP and 50% glass fillers. A dental plaque microcosm biofilm model was used to evaluate the antibacterial activity. The flexural strength and elastic modulus of nanocomposites with QAMs matched those of a commercial control composite （n = 6; P 〉 0.1）. Increasing the CL from 3 to 16 greatly enhanced the antibacterial activity of the NACP nanocomposite （P 〈 0.05）; further increasing the CL to 18 decreased the antibacterial potency. The NACP nanocomposite with a CL of 16 exhibited biofilm metabolic activity and acid production that were 10-fold lesser than those of the control composite. The NACP nanocomposite with a CL of 16 produced 2-log decreases in the colony-forming units （CFU） of total microorganisms, total streptococci, and mutans streptococci. In conclusion, QAMs with CLs of 3-18 were synthesized and incorporated into an NACP nanocomposite for the first time to simultaneously endow the material with antibacterial and remineralization capabilities. Increasing the C/reduced the metabolic activity and acid production of biofilms and caused a 2-log decrease in CFU without compromising the mechanical properties. Nanocomposites exhibiting strong anti-biofilm activity, remineralization effects, and mechanical properties are promising materials for tooth restorations that inhibit caries.

Utility of tricalcium phosphate and osteogenic matrix cell sheet constructs for bone defect reconstruction

AIM: To determine the effects of transplanting osteogenic matrix cell sheets and beta-tricalcium phosphate(TCP) constructs on bone formation in bone defects.METHODS: Osteogenic matrix cell sheets were prepared from bone marrow stromal cells(BMSCs), and a porous TCP ceramic was used as a scaffold. Three experimental groups were prepared, comprised of TCP scaffolds(1) seeded with BMSCs;(2) wrapped with osteogenic matrix cell sheets; or(3) both. Constructs were implanted into a femoral defect model in rats and bone growth was evaluated by radiography, histology, biochemistry, and mechanical testing after 8 wk. RESULTS: In bone defects, constructs implanted with cell sheets showed callus formation with segmentalor continuous bone formation at 8 wk, in contrast to TCP seeded with BMSCs, which resulted in bone nonunion. Wrapping TCP constructs with osteogenic matrix cell sheets increased their osteogenic potential and resulting bone formation, compared with conventional bone tissue engineering TCP scaffolds seeded with BMSCs. The compressive stiffness(mean ± SD) values were 225.0 ± 95.7, 30.0 ± 11.5, and 26.3 ± 10.6 MPa for BMSC/TCP/Sheet constructs with continuous bone formation, BMSC/TCP/Sheet constructs with segmental bone formation, and BMSC/TCP constructs, respectively. The compressive stiffness of BMSC/TCP/Sheet constructs with continuous bone formation was significantly higher than those with segmental bone formation and BMSC/TCP constructs.CONCLUSION: This technique is an improvement over current methods, such as TCP substitution, and is useful for hard tissue reconstruction and inducing earlier bone union in defects.

One-year water-ageing of calcium phosphate composite containing nano-silver and quaternary ammonium to inhibit biofilms

Dental composites are commonly used restorative materials; however, secondary caries due to biofilm acids remains a major problem. The objectives of this study were （1） to develop a composite containing quaternary ammonium dimethacrylate （QADM）, nanoparticles of silver （NAg）, and nanoparticles of amorphous calcium phosphate （NACP）, and （2） to conduct the first investigation of the mechanical properties, biofilm response and acid production vs water-ageing time from 1 day to 12 months. A 4 x 5 design was utilized, with four composites （NACP-QADM composite, NACP-NAg composite, NACP-QADM-NAg composite, and a commercial control composite）, and five water-ageing time periods （1 day, and 3, 6, 9, and 12 months）. After each water- ageing period, the mechanical properties of the resins were measured in a three-point flexure, and antibacterial properties were tested via a dental plaque biofilm model using human saliva as an inoculum. After 12 months of water-ageing, NACP-QADM- NAg had a flexural strength and elastic modulus matching those of the commercial control （P〉 0.1）. Incorporation of QADM or NAg into the NACP composite greatly reduced biofilm viability, metabolic activity and acid production. A composite containing both QADM and NAg possessed a stronger antibacterial capability than one with QADM or NAg alone （P〈0.05）. The anti-biofilm activity was maintained after 12 months of water-ageing and showed no significant decrease with increasing time （P〉0.1）. In conclusion, the NACP-QADM-NAg composite decreased biofilm viability and lactic acid production, while matching the load- bearing capability of a commercial composite. There was no decrease in its antibacterial properties after 1 year of water-ageing. The durable antibacterial and mechanical properties indicate that NACP-QADM-NAg composites may be useful in dental restorations to combat caries.

Novel rechargeable calcium phosphate nanoparticle-containing orthodontic cement

White spot lesions （WSLs）, due to enamel demineralization, occur frequently in orthodontic treatment. We recently developed a novel rechargeable dental composite containing nanoparticles of amorphous calcium phosphate （NACP） with long-term calcium （Ca） and phosphate （P） ion release and caries-inhibiting capability. The objectives of this study were to develop the first NACP- rechargeable orthodontic cement and investigate the effects of recharge duration and frequency on the efficacy of ion re-release. The rechargeable cement consisted of pyromellitic glycerol dimethacrylate （PMGDM） and ethoxylated bisphenol A dimethacrylate （EBPADMA）. NACP was mixed into the resin at 40% by mass. Specimens were tested for orthodontic bracket shear bond strength （SBS） to enamel, Ca and P ion initial release, recharge and re-release. The new orthodontic cement exhibited an SBS similar to commercial orthodontic cement without CaP release （P〉 0.1）. Specimens after one recharge treatment （e.g., 1 min immersion in recharge solution repeating three times in one day, referred to as ＂1 min 3 times＂） exhibited a substantial and continuous re-release of Ca and P ions for 14 days without further recharge. The ion re-release did not decrease with increasing the number of recharge/re-release cycles （P〉 0.1）. The ion re-release concentrations at 14 days versus various recharge treatments were as follows： 1 min 3 times〉3 min 2 times〉 1 min 2 times〉6 min 1 time〉3 min 1 time〉 1 min 1 time. In conclusion, although previous studies have shown that NACP nanocomposite remineralized tooth lesions and inhibited caries, the present study developed the first orthodontic cement with Ca and P ion recharge and long-term release capability. This NACP-rechargeable orthodontic cement is a promising therapy to inhibit enamel demineralization and WSLs around orthodontic brackets.

Porous Calcium Phosphate Ceramic Scaffolds for Tissue Engineering

This study examined the biological response of two porous calcium phosphate ceramics, hydroxyapntite （ HA ） and hydroxyapaptite/β-tricalcium phosphate （ HA/β- TCP ） scaffolds. Three different cell types , a human osteoblastic cell line （ HOS ） , primary human osteoblasts （HOB） and human mesenehymal stem cells （MSCs）, were used to examine biocompatibility and osteoinductive capacity. The experimental results showed both materials were highly biocompatible and proliferation was significantly greater on pure HA （ P 〈 0.01 ）, with a peak in proliferation at day 7. Protein levels were significantly higher （ P 〈 0.05） than the control Thermanox（ TMX （ tm） ） for both test materials. Osteoinduction of MSCs was observed on both test materials, with cells seeded on HA/ β-TCP showing greater alkaline phosphatase activity compared to HA alone, indicating an enhancement in osteoinductive property. Both materials show good potential for use as tissue engineered scaffolds.

Microwave assisted synthesis & properties of nano HA-TCP biphasic calcium phosphate

Biphasic calcium phosphate （BCP） nanopowders were synthesized by using microwave and non-microwave irradiation assisted processes. The synthesized powders were pressed under a pressure of 90 MPa, and then were sintered at 1000-1200℃ for 1 h. The mechanical properties of the samples were investigated. The formed phases and microstructures were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results showed that the synthesis time was shorter, along with a more homogeneous microstructure, when the microwave irradiation assisted method was applied. The compression strength and the Young＇s modulus of the samples synthesized with microwave irradiation were about 60 MPa and 3 GPa, but those of the samples synthesized without microwave irradiation were about 30 MPa and 2 GPa, respectively. XRD patterns of the microwave irradiation assisted and non-microwave irradiation assisted nanopowders showed the coexistence of hydroxyapatite （HA） and lricalcium phosphate （TCP） phases in the system.

Preparation of calcium phosphate coating on pure titanium substrate by electrodeposition method

The influences of pH value, electrolyte temperature and loading time on depositing calcium phosphate coating on pure titanium substrate by electrodeposition process were investigated. The process was carried out with an electrochemical work-station supplying a direct current power at potential of -0.8V （vs SCE）. The electrolyte consists of 7 mmol·L-1 CaCl2·2H2O, 3 mmol·L-1 Ca（H2PO4）2·H2O and 2.5% H2O2. NaOH and HCl solutions were used to adjust pH value. The deposited samples were characterized by X-ray diffraction and scanning electron microscope. The comparison of the deposits obtained at lower and higher pH values demonstrates that the crystallization process at the interface is favoured by high pH value. With temperature increasing, the deposited hydroxyapatite is occasionally of plate-like shape, and the width and the length of the deposited calcium phosphates at 65 ℃ are larger than those at 55 ℃. Therefore, it is confirmed that the morphology and microstructure of electrochemically deposited calcium phosphates can be regulated. Additionally, the coating formed in electrolyte with H2O2 additive is homogeneous and the evolution of H2 bubble can be eliminated.

Preparation of Laminin-apatite-polymer Composites Using Metastable Calcium Phosphate Solutions

A synthetic polymer with a laminin-apatite composite layer on its surface would be useful as a percutaneous device. The preparation of such a composite was attempted in the present study using poly（ ethylene terephthalate ） （PET） and polyethylene （PE） as the synthetic polymer. PET and PE plates and those pretreated with an oxygen plasma were alternately dipped in calcium and phosphate ion solutions, and then immersed in a metastable calcium phosphate solution supplemented with laminin （ LCP solution ）. The PET and PE plates pretreated with an oxygen plasma formed a uniform and continuous layer of a laminin-apatite composite on their surfaces. In contrast, the PET and PE plates that had not been pretreated with an oxygen plasma did not form a continuous layer of a laminin-apatite composite on their surfaces. The hydrophilic functional groups on the PET and PE surfaces introduced by the plasma treatment were responsible for the successful laminin-apatite coruposite coating.

Facile Approach to Synthesize Gold Nanorod@Polyacrylic Acid/Calcium Phosphate Yolk–Shell Nanoparticles for Dual-Mode Imaging and pH/NIR-Responsive Drug Delivery

A facile strategy to fabricate gold nanorod@polyacrylic acid/calcium phosphate(Au NR@-PAA/Ca P) yolk–shell nanoparticles(NPs) composed with a PAA/Ca P shell and an Au NR yolk is reported. The asobtained Au NR@PAA/Ca P yolk–shell NPs possess ultrahigh doxorubicin(DOX) loading capability(1 mg DOX/mg NPs), superior photothermal conversion property(26%)and p H/near-infrared(NIR) dual-responsive drug delivery performance. The released DOX continuously increased due to the damage of the Ca P shell at low p H values. When the DOX-loaded Au NR@PAA/Ca P yolk–shell NPs wereexposed to NIR irradiation, a burst-like drug release occurs owing to the heat produced by the Au NRs. Furthermore,Au NR@PAA/Ca P yolk–shell NPs are successfully employed for synergic dual-mode X-ray computed tomography/photoacoustic imaging and chemo-photothermal cancer therapy. Therefore, this work brings new insights for the synthesis of multifunctional nanomaterials and extends theranostic applications.

Calcium phosphate cements for bone engineering and their biological properties

Calcium phosphate cements （CPCs） are frequently used to repair bone defects. Since their discovery in the 1980s, extensive research has been conducted to improve their properties, and emerging evidence supports their increased application in bone tissue engineering. Much effort has been made to enhance the biological performance of CPCs, including their biocompatibility, osteoconductivity, osteoinductivity, biodegradability, bioactivity, and interactions with cells. This review article focuses on the major recent developments in CPCs, including 3D printing, injectability, stem cell delivery, growth factor and drug delivery, and pre- vascularization of CPC scaffolds via co-culture and tri-culture techniques to enhance angiogenesis and osteogenesis.

In Situ Laser Coating of Calcium Phosphate on TC4 Surface for Enhancing Bioactivity

Titanium alloy has been a successful implant material owing to its excellent ratio of strength to weight, toughness, and bio-inert oxide surface. Significant progress has been made in improving the bioactivity of titanium alloy by coating its oxide surface with calcium phosphates. In the present study, in situ coating was reported on Ti6Al4V（TC4） surface with calcium phosphate （Ca-P） bioceramics synthesized and synchronously cladded by laser beam. This coating was grown by first preplacing directly the raw powders, which contain 80% of CaHPO4 · 2H2O, 20% of CaCO3, and dram of rare earth （RE）, on the TC4 surfaces, and then exposing the surfaces to the laser beam with a power density of 12. 73-15.27 MW · m^-2 and a scanning velocity of 10.5 m/s. The resultant coating was characterized using scanning electron microscopy （SEM）, X-ray diffraction （XRD）, thermogravimetric analysis and Different-thermal Scanning （TG-DSC）, and Energy Dispersive X-ray Detection （EDX）. The results show that these laser ceramics include hydroxyapatite （HA）, tricalcium phosphate （TCP）, Ca2 P2 O7, and other Ca-P phases, and the interface between the coating and the TC4 substrate has tighter fixation, in which the chemical bonding is approved. These laser hybrid coatings are useful in enhancing the bioactivity of titanium alloy surfaces.

3D printing of calcium phosphate bioceramic with tailored biodegradation rate for skull bone tissue reconstruction

The bone regenerative scaffold with the tailored degradation rate matching with the growth rate of the new bone is essential for adolescent bone repair.To satisfy these requirement,we proposed bone tissue scaffolds with controlled degradation rate using osteoinductive materials(Ca-P bioceramics),which is expected to present a controllable biodegradation rate for patients who need bone regeneration.Physicochemical properties,porosity,compressive strength and degradation properties of the scaffolds were studied.3D printed Ca-P scaffold(3DS),gas foaming Ca-P scaffold(FS)and autogenous bone(AB)were used in vivo for personalized beagle skull defect repair.Histological results indicated that the 3DS was highly vascularized and well combined with surrounding tissues.FS showed obvious newly formed bone tissues.AB showed the best repair effect,but it was found that AB scaffolds were partially absorbed and degraded.This study indicated that the 3D printed Ca-P bioceramics with tailored biodegradation rate is a promising candidate for personalized skull bone tissue reconstruction.

Dental remineralization via poly(amido amine) and restorative materials containing calcium phosphate nanoparticles

Tooth decay is prevalent,and secondary caries causes restoration failures,both of which are related to demineralization.There is an urgent need to develop new therapeutic materials with remineralization functions.This article represents the first review on the cutting edge research of poly(amido amine)(PAMAM) in combination with nanoparticles of amorphous calcium phosphate (NACP).PAMAM was excellent nucleation template,and could absorb calcium (Ca) and phosphate (P) ions via its functional groups to activate remineralization.NACP composite and adhesive showed acid-neutralization and Ca and P ion release capabilities.PAMAM +NACP together showed synergistic effects and produced triple benefits: excellent nucleation templates,superior acidneutralization,and ions release.Therefore,the PAMAM+NACP strategy possessed much greater remineralization capacity than using PAMAM or NACP alone.PAMAM+NACP achieved dentin remineralization even in an acidic solution without any initial Ca and P ions.Besides,the long-term remineralization capability of PAMAM+NACP was established.After prolonged fluid challenge,the immersed PAMAM with the recharged NACP still induced effective dentin mineral regeneration.Furthermore,the hardness of predemineralized dentin was increased back to that of healthy dentin,indicating a complete remineralization.Therefore,the novel PAMAM+NACP approach is promising to provide long-term therapeutic effects including tooth remineralization,hardness increase,and caries-inhibition capabilities.