Controllable Degradation Behavior Research Articles

Three-dimensional porous polycaprolactone/chitosan/bioactive glass scaffold for bone tissue engineering

Three-dimensional (3D) porous scaffolds based on polycaprolactone (PCL)/chitosan (CS)/bioactive glass (BG) nanoparticle composites were fabricated by the freeze-drying technique for bone tissue engineering. The physiochemical properties of the developed PCL/CS/BG scaffolds were studied using FTIR, XRD, EDX and SEM. Furthermore, the swelling degree, porosity, water retention ability, compression strength, in vitro biodegradation, bioactivity and biocompatibility of the scaffolds were examined. The PCL/CS/BG scaffolds with 4 wt. % of BG content presented adequate pore size (106 μm), porosity (156%), water swelling degree (128%), water retention ability (179%), compressive strength (3.7 MPa) and controlled degradation behavior, which could be ideal for bone tissue engineering. The PCL/CS/BG composite scaffolds showed good antimicrobial activity against both test bacteria and fungi. The MTT assay demonstrated the biocompatibility of PCL/CS/BG scaffolds against C3H10T1/2 cell line. The Alizarin red staining assay confirmed the osteogenic activity of the PCL/CS/BG scaffolds.

ROS-responsive thermosensitive polypeptide hydrogels for localized drug delivery and improved tumor chemoimmunotherapy.

In this study, we developed a ROS-responsive thermosensitive poly(ethylene glycol)-polypeptide hydrogel loaded with a chemotherapeutic drug, doxorubicin (Dox), an antiviral imidazoquinoline, resiquimod (R848), and antibody targeting programmed cell death protein 1 (aPD-1) for local chemoimmunotherapy. The hydrogel demonstrated controllable degradation and sustained drug release behavior according to the concentration of ROS in vitro. Following intratumoral injection into mice bearing B16F10 melanoma, the Dox/R848/aPD-1 co-loaded hydrogel effectively inhibited tumor growth, prolonged animal survival time and promoted anti-tumor immune responses with low systemic toxicity. In the postoperative model, the Dox/R848/aPD-1 co-loaded hydrogel exhibited enhanced tumor recurrence prevention and long-term immune memory effects. Thus, the hydrogel-based local chemoimmunotherapy system demonstrates potential for effective anti-tumor treatment and suppression of tumor recurrence.

Additive manufacturing a novel bioceramic bone scaffold with MgO/Ca3(PO4)2: Microstructure, mechanical property and controllable degradation behavior

Biodegradable bone grafts have gained considerable attention in the field of clinical research as they can be used to avoid re-surgery to remove scaffolds. We fabricated biodegradable composite ceramic scaffolds using magnesium oxide and calcium phosphate following the vat photopolymerization technology. We studied the effects of different magnesium oxide content on the process of in vitro degradation of the composite scaffolds and discussed the degradation process by comparing the extent of degradation realized in Tris-HCl buffer and simulated body fluids. We also explored the variations in the mechanical properties of the scaffolds during degradation. The results revealed that the composite scaffolds maintained the strength standard for spongy bone (compressive strength σ: 2–20 MPa) even after 28 d of degradation. Additionally, the strength of the composite scaffold containing 80 wt% magnesium oxide was comparable to the strength standard recommended for cortical bones (σ: 100–200 MPa). Controllable degradation rates were recorded, and acceptable mechanical properties were observed for these scaffolds during degradation. The results reported herein can be potentially used to expand the application prospects of biodegradable scaffolds.

Development and preclinical evaluation of multifunctional hydrogel for precise thermal protection during thermal ablation

Image-guided thermal ablation (TA), which is less invasive, has been widely applied for treating various kinds of tumors. However, TA still poses the potential risk of thermal damage to sensitive tissue nearby. Therefore, an adjunctive thermoprotective hydrodissection technique with constant injection of 5% glucose (5% Glu) has currently been adopted for clinical application, but this may be hazardous to humans. In this study, a multifunctional hyaluronic acid-based hydrogel (HA-Dc) was developed for hydrodissection. Compared with 5% Glu (the most clinically used solution) and the previously reported F127 hydrogel, the HA-Dc hydrogel was studied in vitro in a porcine liver model and in vivo in a rabbit model and showed good injectability and better tissue retention, stability, and thermoprotective properties throughout the TA procedure. Furthermore, in the preclinical evaluation in a Macaca fascicularis (M. fascicularis) model, HA-Dc showed excellent performance in terms of stricter neuroprotection compared with 5% Glu. In addition, the HA-Dc hydrogel with good biocompatibility and controllable degradation behavior in vivo could be a promising platform for thermal protection during clinical TA procedures.

Hydrogels as Potential Controlled Drug Delivery System: Drug Release Mechanism and Applications

Abstract: Hydrogels are one of the most extensively studied novel drug delivery dosage forms owing to their satisfactory results in drug delivery in various conditions, including pain management, immunomodulation, carcinomas, healing of wounds, and cardiology. A crosslinked polymeric network and an optimum amount of water combine to form hydrogels. Due to their specific properties such as biocompatibility, biodegradability, hydrophilicity, and non-toxic to biological tissues, hydrogels are demanding biomaterials. Furthermore, due to their programmable physical characteristics, controlled degradation behavior, and capability to preserve unstable medicines from degradation, hydrogels serve as an advanced drug delivery system in which diverse physiochemical interactions with the polymeric matrix containing embedded medications control their release. Despite significant challenges remaining, there has been significant progress in recent years in overcoming the clinical and pharmacological constraints of hydrogels for drug delivery applications This review covers various hydrogel-forming polymers, strategies for crosslinking of gelling agents, and release mechanisms from the hydrogel. Moreover, the current work includes a few marketed hydrogel preparations and patent rights associated with it, describing its mechanism of action against the underlying diseases.

Controllable degradation behavior of Mg-Sr-Y alloys for the bio-applications

The biodegradation behavior and mechanical properties of Mg-Sr-Y alloys were systematically investigated for the medical application. The alloy (Mg-0.3Sr-0.5Y) exhibits a comparable UTS as 111.53 MPa and shows a general uniform degradation behavior with low corrosion rate as only 0.823 mm y−1 in Hanks’ solution. The simultaneous solid solution of Y in α-Mg phase and in Mg17Sr2 phase reduces the micro-galvanic corrosion. Additionally, the formation of a compact composite film of Mg(OH)2, Y2O3 and Sr-substituted phosphate (Sr-HA) delivers the protection for the matrix. Low corrosion rate, fine precipitates and dispersed Y rich-zones, which hinder the corrosion propagation, further guarantees a uniform degradation behavior. While, with increasing Sr content, the corrosion resistance is deteriorated because of the formed continuous distribution of Mg17Sr2 along grain boundaries. By tailoring composition and structure, Mg-Sr-Y alloys with balanced mechanical and bio-degradation properties can be promising for the bio-applications.

Nanofibrous hybrid scaffolds based on PCL-borosilicate system by a green sol-gel process

Tissue regeneration is yet a critical issue, and to mimic the natural extracellular matrix (ECM) innovative scaffolds need to be developed to ensure the functional and safe repair of the damaged organs or tissues. Hybrid biomaterials based on the combination of a biodegradable polymer and bioactive glasses (BGs) are potential candidates for tissue engineering (TE), since they exhibit tailored physical, biological, and mechanical properties, as well as controlled degradation behavior. Thus, the main purpose of this research was to develop by electrospinning (ES) a hybrid nanofibrous membrane composed of a synthetic polymeric matrix (PCL) and a boron and calcium silicate glass, formed via in situ sol-gel, and based on a non-aqueous and green fabrication route. Formic acid (FA) and glacial acetic acid (AA) were used as green solvents to dissolve the PCL. Different compositions were prepared: neat PCL and PCL/SiO2–B2O3–CaO with different sol-gel aging times and green solvent systems. All prepared hybrid solutions, except the composition with only AA, were spinnable. Structural features of the hybrids were assessed by ATR-FTIR spectroscopy, which confirmed the presence of siloxane (Si–O–Si) bonds of silica and carbonyl (CO) bonds characteristic of PCL polymer as well as intermolecular hydrogen-bonding interactions between the carbonyls of PCL and the silanol hydroxyls (Si–OH) of silica networks. Boron (B–O–B) and borosiloxane (B–O–Si) bonds were not visible due to the overlapping of PCL bands in the spectra. Only the solid state 11B NMR technique allowed to find peaks assigned to trigonal BO3 and tetrahedral BO4 groups, which evidence the boron linkages to silica. Thermal analysis showed a change in the crystallinity of PCL with the incorporation of inorganic domains, confirming the formation of chemical interactions between the polymer and the inorganic part. Microstructure and chemical analysis, by SEM/EDS, showed a homogenous distribution of Ca and Si elements into the fibers, as well as an increase of the fiber diameter with the incorporation of boron and calcium silicate glass in the PCL. The developed compositions of PCL/boron and calcium-containing silicate were feasible to electrospin into fibrous meshes, proving its potential for further design of multicomponent nanofibrous microstructures closer to extra cellular matrix architectures.

Multifunctional magnetocaloric bone cement with a time-varying alkaline microenvironment for sequential bacterial inhibition, angiogenesis and osteogenesis.

Repairing infected bone defects remains a severe challenge due to antibiotic abuse and recurrence. Hence, we modified magnetocaloric Fe3O4 nanoparticles and added them to magnesium calcium phosphate bone cement (MCPC) to fabricate multifunctional magnetic composites for sequential bacterial inhibition, angiogenesis and osteogenesis. Nevertheless, high doses of Mg ions and Fe ions were released from MCPC, which adversely affected osteogenesis. Thus, Fe3O4 was modified using gelatin according to the emulsification crosslinking method, which exhibited a controllable magnetocaloric effect and degradation behavior, and favorable anti-bacterial ability under the action of an alternating magnetic field (AMF). In the early stage, the residual MgO created a local strong alkaline microenvironment by hydrolysis, which inhibited the function and activity of S. aureus and E. coli. At the later stage, the MCPC composites were controllably degraded under the function of gelatin and maintained a long-term local slight alkaline microenvironment that promoted the osteogenic differentiation and mineralization of BMSCs. In vivo subcutaneous implantation experiments further indicated that MCPC composites showed good biocompatibility and facilitated angiogenesis, presenting a promising future in magnetic materials design and infectious bone defect repair.

Assessment of chitosan:gum tragacanth cryogels for tissue engineering applications

AbstractGum tragacanth is one of the most widely used natural gums in food, medicine, cosmetics and personal care products, and its use as polysaccharide‐based scaffolds in tissue engineering applications has attracted great attention in recent years. The fabrication of pure gum tragacanth as a scaffold poses many challenges because of the high viscosity, poor mechanical properties and repulsive interaction between the polyanions. To overcome these, facilitate the formation of scaffolds and improve their final properties, chitosan and gum tragacanth were used together as natural, biocompatible and biodegradable polysaccharides. The scaffolds based on chitosan and gum tragacanth were successfully fabricated through cryotropic gelation and were characterized using different chemical, morphological, mechanical and biocompatibility analyses. All cryogel scaffolds exhibited a porous structure with an average diameter of 96.56–30.21 μm, exhibiting high liquid absorption capacity, appropriate mechanical stability and controlled degradation behavior. According to the biocompatibility results, mouse embryonic fibroblast cells adhered well to the scaffolds and achieved high viability. The results are also discussed in the light of their potential usefulness as a scaffold for tissue engineering applications. © 2022 Society of Industrial Chemistry.

Hydrolytically degradable Poly (β-amino ester) resins with tunable degradation for 3D printing by projection micro-stereolithography.

Applications of 3D printing that range from temporary medical devices to environmentally responsible manufacturing would benefit from printable resins that yield polymers with controllable material properties and degradation behavior. Towards this goal, poly(β-amino ester) (PBAE)-diacrylate resins were investigated due to the wide range of available chemistries and tunable material properties. PBAE-diacrylate resins were synthesized from hydrophilic and hydrophobic chemistries and with varying electron densities on the ester bond to provide control over degradation. Hydrophilic PBAE-diacrylates led to degradation behaviors characteristic of bulk degradation while hydrophobic PBAE-diacrylates led to degradation behaviors dominated initially by surface degradation and then transitioned to bulk degradation. Depending on chemistry, the crosslinked PBAE-polymers exhibited a range of degradation times under accelerated conditions, from complete mass loss in 90 min to minimal mass loss at 45 days. Patterned features with 55 μm resolution were achieved across all resins, but their fidelity was dependent on PBAE-diacrylate molecular weight, reactivity, and printing parameters. In summary, simple chemical modifications in the PBAE-diacrylate resins coupled with projection microstereolithography enables high resolution 3D printed parts with similar architectures and initial properties, but widely different degradation rates and behaviors.

Identification of main influencing factors on the protein corona composition of PLGA and PLA nanoparticles

Poly(DL-lactic-co-glycolic acid) and poly(DL-lactic acid) are widely used for the preparation of nanoparticles due to favorable characteristics for medical use like biodegradability and controllable degradation behavior. The contact with different media like human plasma or serum leads to the formation of a protein corona that determines the NP’s in vivo processing.In this study, the impact of surface end group identity, matrix polymer hydrophobicity, molecular weight, and incubation medium on the protein corona composition was evaluated. Corona proteins were quantified using Bradford assay, separated by SDS-PAGE, and identified via LC-MS/MS. The acquired data revealed that surface end group identity had the most profound effect on corona composition in both quantitative and qualitative terms. Regarding matrix polymer hydrophobicity, adsorption profiles on NP systems with similar physicochemical characteristics resembled each other. The molecular weight of the matrix polymers proved to impact quantity, but not quality of corona bound proteins. The corona of plasma incubated NP showed adsorption of incubation medium-specific proteins but resembled those of serum incubated NP in terms of protein function, average mass and isoelectric point. Overall, the NP physicochemical properties proved to be easily adjustable determining factors of protein corona formation in physiological environments.

Injectable sericin based nanocomposite hydrogel for multi-modal imaging-guided immunomodulatory bone regeneration

• An injectable alginate/sericin/graphene oxide (Alg/Ser/GO) hydrogel was fabricated. • The released sericin of Alg/Ser/GO hydrogel promoted macrophage M2 polarization. • Synergistic effects on bone regeneration between sericin and GO were demonstrated. • The injected Alg/Ser/GO hydrogels with BMSCs promptly repaired bone defect in rats. Irregular bone defects, where the inflammation and immune microenvironment confronted with implanted biomaterials, remain a prominent challenge for bone regeneration. In this study, we fabricated an injectable alginate/sericin/graphene oxide (Alg/Ser/GO) hydrogel based on the Alg–Tyramine framework with HRP/H 2 O 2 enzymatic crosslinking. This hydrogel exhibited bioimaging property and controlled degradation behavior upon releasing sericin and GO. Importantly, synergistic effects on bone regeneration between sericin and GO were demonstrated. GO significantly enhanced the spreading, osteogenic differentiation, and mineralization of encapsulated rat BMSCs, whereas the released sericin promoted M2 polarization and migration via the NF-κB and MAPK pathways. The M2 polarization of macrophages induced osteogenic differentiation of BMSCs via several secreted cytokines. Both in vivo and in vitro experiments showed that the Alg/Ser/GO hydrogel induced macrophage infiltration into the surrounding tissues and inhibited inflammation and fibrous capsule thickening. Last, the injected Alg/Ser/GO hydrogels with BMSCs promptly repaired established distal femoral defects in rats. Therefore, the fabricated Alg/Ser/GO hydrogel, along with macrophages and BMSCs, is a promising biomaterial for bone healing, especially the irregular bone defects.

Engineering microstructure of hydroxyapatite by electron beam irradiation to induce controllable in vitro degradation

Controllable degradation behavior of hydroxyapatite (HA) plays a crucial role in successful long-term implantation of a bone tissue substitute. In this study, electron beam irradiation (EBI) was carried out as an efficient strategy to modify HA structure. The degradation characteristics, bioactivity and cell response of the irradiated HA were comprehensively evaluated. The results showed that EBI with absorbed dose of 3.42, 10.27 and 20.54 Gy did not introduce newly-formed phase or impurity, but created crystal defects and nanovoids, which were formed from oxygen deficiencies, into HA lattice with irradiation dose-dependence. The dissolution rate of the irradiated HA enhanced continuously with increasing irradiation dose, as a result of constantly increasing crystal defects and enlarging voids, where the main reactive sites for the degradation of HA formed. The Ca2+ and PO43- releasing of HA with the highest irradiation dose enhanced by 92.75% and 138.85% respectively compared to that of the pristine HA after 28 days’ immersion. SBF immersion results suggested the irradiated HA with raising EBI doses exhibited preferable performance in bioactivity as well. Moreover, the results from CCK-8 assay and SEM observation showed that the irradiated HA were beneficial to the proliferation and attachment of osteoblasts.

Anti-CD34-Grafted Magnetic Nanoparticles Promote Endothelial Progenitor Cell Adhesion on an Iron Stent for Rapid Endothelialization.

Iron stents, with superior mechanical properties and controllable degradation behavior, have potential for use as feasible substitutes for nondegradable stents in the treatment of coronary artery occlusion. However, corrosion renders the iron surface hard to modify with biological molecules to accelerate endothelialization and solve restenosis. The objective of this study is to demonstrate the feasibility of using endothelial progenitor cells (EPCs) to rapidly adhere onto iron surfaces with the assistance of anti-CD34-modified magnetic nanoparticles. Transmission electron microscopy, Fourier transform infrared spectroscopy, Thermogravimetric analysis, XRD, and anti-CD34 immunofluorescence suggested that anti-CD34 and citric acid were successfully modified onto Fe3O4, and Prussian blue staining demonstrated the selectivity of the as-prepared nanoparticles for EPCs. Under an external magnetic field (EMF), numerous nanoparticles or EPCs attached onto the surface of iron pieces, particularly the side of the iron pieces exposed to flow conditions, because iron could be magnetized under the EMF, and the magnetized iron has an edge effect. However, the uniform adhesion of EPCs on the iron stent was completed because of the weakening edge effect, and the sum of adherent EPCs was closely linked with the magnetic field (MF) intensity, which was validated by the complete covering of EPCs on the iron stent upon exposure to a 300 mT EMF within 3 h, whereas almost no cells were observed on the iron stent without an EMF. These results verify that this method can efficiently promote EPC capture and endothelialization of iron stents.

Novel controllable degradation behavior and biocompatibility of segmented poly–ε–caprolactone in rats

Bioresorbable polymers have multiple clinical applications; however, the reaction methods required for their synthesis generally require harsh reaction conditions and long reaction times. This study uses a new conceptual molecular control method that links poly–ε–caprolactone (PCL) diols of differing molar mass with an aliphatic diisocyanate as a coupling agent for polymerization to develop a new type of segmented polycaprolactone (SM-PCL) material. Relative to the polymerization of typical high molecular weight polyester materials, this polymerization process only requires ordinary pressure and low temperature to yield product with sufficiently high molecular weight. The results of in vitro cytotoxicity and in vivo implantation assays show that the newly synthesized SM-PCL exhibits excellent biocompatibility. In addition, in vivo degradation analyses demonstrate that the porous SM-A material was nearly completely degraded at 6 months after implantation in rat tissue (P < 0.01), whereas porous PCL homopolymer was only degraded to 53.25% of the initial molecular weight even after 12 months. The study indicated that the degradation rates of porous and solid thin film SM-PCL were higher than those of PCL homopolymer and that its degradation behavior could be controlled. Moreover, the material did not result in significant adverse pathological reactions and has good tissue compatibility. For clinical application, this material may therefore be suitable as a carrier for controlled drug release or as an artificial material for soft tissue repair.

Solvent-Free Strategy To Encapsulate Degradable, Implantable Metals in Silk Fibroin.

Implantable electronics hold enormous clinical potential for diagnosis and treatment of neurodegenerative and cardiac diseases and abnormalities. Transient devices are attractive alternatives to conventional silicon electrodes, as they can provide short-term electrical stimulation/recording followed by complete device degradation, mitigating the need for removal surgeries. Packaging transient metals is inherently challenging as they degrade upon contact with aqueous conditions. Development of new transient metal packaging strategies is a critical step toward transient device development. In this fundamental work, a solvent-free compression molding approach to encapsulate magnesium, a resorbable metal, in silk fibroin protein is reported. Silk fibroin was selected because of its processing versatility, desirable mechanical properties, compatibility with biological environments, and controllable degradation behavior in aqueous environments. The silk/magnesium composites were fabricated via compression molding, followed by water annealing to modify the secondary structure of the silk protein matrix to tune physical properties. Transient composite properties as a function of water annealing time are presented, which elucidate synergies between silk physical properties and degradation kinetics of the encapsulated magnesium, information useful in the design of multifunctional, transient metal-based constructs.

Precise Synthesis of PS-PLA Janus Star-Like Copolymer.

In this work, an efficient strategy is designed for the precise synthesis of novel Janus star-like copolymer (polystyrene)8 -b-(poly(l-lactide))8 , (PLLA)8 -b-(PS)8 , consisting of two types of chemically distinct polymer arms, PS and PLLA, in an asymmetric structure. During the synthesis, PLLA hemisphere carrying protected hydroxyl groups at the focal point was first synthesized via a combined reactions of esterification, light-induced "Click" chemistry, and ring opening polymerization (ROP) using a specially designed dendron as initiator. After removing the protecting moiety, the terminal hydroxyl groups on the dendron segment is increased fourfold and further modified into bromopropionate-based macroinitiator through a two-step end group transformation reaction, followed by atom transfer radical polymerization (ATRP) of styrene to obtain the desired (PLLA)8 -b-(PS)8 Janus star-like copolymer. The versatility and efficiency of the designed synthetic strategy are demonstrated by the well-defined molecular characteristics and high yields of the targeted product. In addition to the controlled degradation behavior of the PLLA segments, the remaining bromide groups located at the distal end of PS arms could allow for further fabrication of diverse building blocks through consecutive ATRP of various monomers. This work signifies the first time for facile and precise synthesis of Janus star-like copolymer with unique biphasic structure and function control.

In vitro degradation of chitosan composite foams for biomedical applications and effect of bioactive glass as a crosslinker

Abstract In tissue engineering applications, 3D scaffolds with adequate structure and composition are required to provide durability that is compatiblewith the regeneration of native tissue. In the present study, the degradation of novel flexible 3D composite foams of chitosan (CH) combined with bioactive glass (BG)was evaluated, focusing on the role of BG as a physical crosslinker in the composites, and its effect on the degradation process. Highly porous CH/BG composite foams were obtained, and an elevated degradation temperature and lower degradation rate compared with pure chitosan were observed, probably as a result of greater intermolecular interaction between CH and BG. The Fourier transform infrared spectroscopy (FTIR) data suggest that hydrogen bonds were responsible for the physical crosslinking between CH and BG. The results confirm that CH/BG foams can combine controllable bioactivity and degradation behavior and, therefore, could be useful for tissue regeneration matrices.

In vivo immuno-reactivity analysis of the porous three-dimensional chitosan/SiO2 and chitosan/SiO2 /hydroxyapatite hybrids.

Inorganic/organic hybrid silica-chitosan (CS) scaffolds have promising potential for bone defect repair, due to the controllable mechanical properties, degradation behavior, and scaffold morphology. However, the precise in vivo immuno-reactivity of silica-CS hybrids with various compositions is still poorly defined. In this study, we fabricated the three-dimensional (3D) interconnected porous chitosan-silica (CS/SiO2 ) and chitosan-silica-hydroxyapatite (CS/SiO2 /HA) hybrids, through sol-gel process and 3D plotting skill, followed by the naturally or freeze drying separately. Scanning electron microscopy demonstrated the hybrids possessed the uniform geometric structure, while, transmission electron microscopy displayed nanoscale silica, or HA nanoparticles dispersed homogeneously in the CS matrix, or CS/silica hybrids. After intramuscular implantation, CS/SiO2 and CS/SiO2 /HA hybrids triggered a local and limited monocyte/macrophage infiltration and myofiber degeneration. Naturally dried CS/SiO2 hybrid provoked a more severe inflammation than the freeze-dried ones. Dendritic cells were attracted to invade into the implants embedded-muscle, but not be activated to prime the adaptive immunity, because the absence of cytotoxic T cells and B cells in muscle received the implants. Fluorescence-activated cell sorting (FACS) analysis indicated the implanted hybrids were incapable to initiate splenocytes activation. Plasma complement C3 enzyme linked immunosorbent assay (ELISA) assay showed the hybrids induced C3 levels increase in early implanting phase, and the subsequent striking decrease. Thus, the present results suggest that, in vivo, 3D plotted porous CS/SiO2 and CS/SiO2 /HA hybrids are relatively biocompatible in vivo, which initiate a localized inflammatory procedure, instead of a systematic immune response. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1223-1235, 2018.

Preparation, characterization and in vitro dissolution behavior of porous biphasic α/β-tricalcium phosphate bioceramics

The ideal bone tissue engineering scaffolds are long-cherished with the properties of interconnected macroporous structures, adjustable degradation and excellent biocompatibility. Here, a series of porous α/β-tricalcium phosphate (α/β-TCP) biphasic bioceramics with different phase ratios of α-TCP and β-TCP were successfully synthesized by heating an amorphous calcium phosphate precursor. The chemical and morphological characterization showed that α- and β-TCP phases co-existed in the α/β-TCP bioceramics and they had interconnected pore structures with size between 200 and 500μm. The in vitro dissolution behavior and bioactivity of the dual α/β-TCP were also probed in static and dynamic SBF for the first time. The results revealed that α/β-TCP scaffolds had good in vitro bioactivity, as the formation of bone-like apatite layers was induced on the scaffolds after mineralization in SBF. Moreover, dissolution rate of α/β-TCP bioceramics in dynamic environment was higher than that under static condition. Compared with monophasic TCP ceramics, these porous α/β-TCP bioceramics displayed a tailored dissolution rate proportionate to the TCP content (α and β) in the materials. Further, the degradation profile of porous α/β-TCP was well-described by Avrami equation. The porous dual α/β-TCP bioceramics with controllable degradation behavior hold great potential to be applied in bone tissue engineering as bone substitutes.