Abstract: Various dicarboxylate ions can be incorporated into the crystal structure of octacalcium phosphate (OCP). This unique property can be applied to develop functional bone substitute materials. However, there are many unclear points regarding the chemistry of OCP with incorporated dicarboxylate ions. In this review, we discuss the following three topics regarding the fundamental properties of OCP with incorporated dicarboxylate ions: the incorporation of two types of dicarboxylate ions into the OCP interlayer, the precise control of the interplanar spacing for OCP with dicarboxylate ions having a side chain, and the chirality recognition of guest molecules during OCP incorporation phenomena.
Abstract: The self-hardening calcium phosphate cement (CPC) has widely been used in bone defect repairs. CPC tends to decay or disintegrate upon early contact with blood or body fluids, and the gelation of CPC paste using sodium alginate, chitosan, or collagen may overcome such a wash-out property. The incorporation of chitosan in CPC paste increased the compressive strength and work-of-fracture. However, the viscosity of CPC paste increased with an increase of chitosan content, and acidic liquid is not favorable, as chitosan must be dissolved in an acidic solution. The CPC paste using the liquid prepared from freeze-dried chitosan powder was easily push out from the syringe, but the content of chitosan was reduced. An addition of polyol-phosphate salt to chitosan solution produces a transparent liquid at physiological pH, and the chitosan content was found to be increased. Chitosan content of liquid was increased from 0.09% to 0.54 % by adding polyol to liquid, and the compressive strength of CPC was also increased.
Abstract: The mechanical strength of pulp capping material based on carbonate apatite and silica calcium-phosphate composite (CO3Ap-SCPC) is one of the key factors for the success of the material in protecting the vitality of the pulp during the formation of apatite and dentin reparative. Modifying the material in the powder phase was known to increase the mechanical strength. The purpose of this study was to determine whether the addition of SCPC and calcium hydroxide in pulp capping materials based on CO3Ap-SCPC would affect the compressive strength of this pulp capping material. In this study, three cement groups were used, each group consisted of dicalcium phosphate anhydrous and vaterite which added by SCPC concentration 0%, 5% and 10% and calcium hydroxide concentration 0%, 5% and 10%, respectively. All groups were tested by a compressive strength test and X-Ray diffraction (XRD) for phase analysis. The mean value of compressive strength with addition of 0% SCPC and 10% Ca(OH)2 was 16.54 ± 1.35 MPa, addition of 5% SCPC and 5% Ca(OH)2 of 18.55 ± 2.81 MPa, addition of 10% SCPC and 0% Ca(OH)2 was 9.22 ± 1.21 MPa. The addition of SCPC and Ca(OH)2 show statistically significant difference in compressive strength (p<0.05). The XRD analysis of the highest compressive strength revealed that the apatite crystal was successfully formed. It can be concluded that incorporated specific amount of SCPC and Ca(OH)2 could improve the mechanical strength and the apatite formation of the CO3Ap-SCPC pulp capping material.
Abstract: We prepared hydroxyapatite (HA) capsules encapsulating maghemite particles. In order to evaluate enzyme immobilization behavior of the HA capsules under alkaline condition, we immobilized five kinds of enzymes with different isoelectric point in carbonate/bicarbonate buffer (CBB, pH 10.0). When the enzymes in CBB were moderately charged, immobilization efficiency on the HA capsules showed the highest value. It was suggested that immobilization efficiency was affected according to both pI of enzyme and pH of the surrounding solution and that enzyme immobilized on the HA capsules by not only electrical double layer interactions but also ion interaction and other interactions.
Abstract: Appropriate biomaterial and controlled size particle are the important component to achieve effective delivery system. Reducing size of the particle is recommended because it can overcome the barriers during cellular uptake. Biomimetic carbonate apatite (CHA) is now considered as candidate for protein delivery because it has high affinity to protein, high biocompatibility and biodegradibility, and increases protein stability. In this study, nano-CHA was prepared and ovalbumin (OVA) protein was incorporated into the CHA particles.
Abstract: The carbonate apatite (CO3Ap) cement as an endodontic sealer play an essential role for endodontics treatment due to its potential to obturate root canal system as one of the most important part in endodontic treatment. Moreover, the CO3Ap has probability of similarities with composition of root dentin. Recently, the setting time of commercial endodontic sealer has 4 hours to 1 day. Therefore, the aim of this present study is to evaluate setting time and to determine the functional group of the new material composition for endodontic sealer. CO3Ap cement sealer was prepared by mixing dicalcium phosphate anhydrous (DCPA), vaterite and calcium hydroxide [Ca (OH)2] with 0.2 mol/L Na2HPO4 containing 1% sodium carboxymethylcellulose (NaCMC) and 32 μg thymoquinone, with liquid to powder ratio of 0.6. The setting time was evaluated by Vicat needle method as describe on modification ISO 1566 for zinc phosphate cement. Five compositions of powder ratio were prepared in this study. The set CO3Ap cement sample was evaluated by Fourier Transform Infrared Spectroscopy (FTIR) to define the functional group of the sample. Setting time evaluation indicated that the average setting time of CO3Ap cement was 21 minutes of five compositions. The FTIR analyses revealed that the CO32- groups were detected, so the results could determine as B-type CO3Ap.The CO3Ap cement was considered fast setting as an endodontic sealer compared to sealers made from other base and proven to have similarities with the components of root dentin.
Abstract: We synthesized the inorganic/organic hybrid nanocrystal (EHA) by hydroxyapatite (HA) nanocrystal growth under the existence of tris(2,2,6,6-tetramethyl-3,5-heptanedionato)europium(III) (EuTH) complex. Then, folic acid derivative (FA-NHS: folate N-hydroxysuccinimidyl ester) as the targeting ligand for the HeLa cancer cells was immobilized on the EHA by the mediation of 3-aminopropyltriethoxysilane (APTES) and methyltriethoxysilane (MTES). When the FA-NHS molecular occupancy ratio on the EHA surface is around 3 to 5 %, the strong luminescence from the f-f transition of the Eu3+ ion and luminescence associated with energy transfer between the EuTH-FA monomer near 518 nm were observed. Moreover, the dispersibility in phosphate buffer saline was confirmed with immobilizing the positively-charged FA-NHS. The affinity and non-cytotoxicity between the nanocrystals and HeLa cancer cells were confirmed for 3 days. The red luminescence from the cells could be observed by fluorescence microscopy and the luminescence spectra.
Abstract: 60CaO-30P2O5-(10 ̶ x)Nb2O5-xTiO2 (x = 0 ~ 10, mol%) glasses were prepared in order to obtain biomaterials with high chemical durability and therapeutic ions releasability. Dissolution test of these glasses using Tris buffer solution showed the controlled release of niobate ions from Nb2O5-containing glasses and the formation of calcium titanate in some of them. These behavior might induce positive effects for bone regeneration.
Abstract: Cotton-wool-like bioresorbable bone void fillers consisting of β-tricalcium phosphate (β-TCP), siloxane-containing vaterite (SiV) and poly (L-lactic acid) (PLLA) was prepared by an electrospinning method. The fibers, which were 50 ~ 150 μm-width with 10 ~ 30 μm-thickness, were entwined. The resulting cotton-wool-like material showed mechanical flexibility and excellent shapability; it showed easy, excellent mechanical-fixation in defects. The in vivo performance of this material was examined in the distal femur in New Zealand white rabbits. It was evaluated using micro CT and histologic analyses at time points of 6 and 12 weeks. These analyses of the defect sites verified normal healing response and new bone formation. The in vivo testing with rabbits showed good biocompatibility and excellent osteogenic ability.