Calcium Phosphate Cement Research Articles

Enhanced biological activity of ACPs/cc/cs/PVA composite bone cement: a study on degradation, mineralization, and bone repair properties

The application of calcium phosphate cement in bone repair is often limited by its restricted degradation and mineralization capabilities. Here, we developed a novel composite material integrating amorphous calcium phosphates (ACPs) and calcium citrate (CC) to enhance biological activity. The composite was combined with powdered chitosan (CS) and liquid polyvinyl alcohol (PVA) to formulate the ACPs/CC/CS/PVA bone cement. We investigated the influence of varying PVA concentrations (0.3%, 0.6%, 1.0%, and 1.5%) on the cement’s setting time, hydrophilicity, compressive strength, pH, calcium release rate, and degradation rate. We find the ACPs/CC/CS/PVA bone cement demonstrates favorable injectability and anti-washout characteristics within the PVA concentration range of 0.3–1.5%. An elevated PVA concentration is correlated with enhanced anti-washout properties and improved compressive strength, reaching 42.8 MPa, which is essential for maintaining mechanical stability at the defect site. Additionally, the 1.5% PVA cement formulation ensures an adequate calcium ion concentration (6.5–9.5 mg/L) for the beginning of bone repair. Furthermore, in vivo animal studies have confirmed the biocompatibility of the ACPs/CC/CS/PVA bone cement. Controlled release of Ca2+ and PO4 3− ions from ACPs is suggested to facilitate osteoconduction and osteogenesis, highlighting the material’s prospect in bone repair applications.

Enhanced compressive strength and in vitro degradation of porous pectin/ calcium phosphate cement scaffolds by freeze casting without sintered

Enhanced compressive strength and in vitro degradation of porous pectin/ calcium phosphate cement scaffolds by freeze casting without sintered

Magnesium-Based Composite Calcium Phosphate Cement Promotes Osteogenesis and Angiogenesis for Minipig Vertebral Defect Regeneration.

Calcium phosphate cement (CPC) is an injectable bone cement with excellent biocompatibility, widely used for filling bone defects of various shapes. However, its slow degradation, insufficient mechanical strength, and poor osteoinductivity limit its further clinical applications. In this study, we developed a novel composite magnesium-based calcium phosphate cement by integrating magnesium microspheres into PLGA fibers obtained through wet spinning and incorporating these fibers into CPC. The inclusion of magnesium-based PLGA fibers enhanced the compressive strength and degradation rate of CPC, with the degradation rate of the magnesium microspheres being controllable to allow for the sustained release of magnesium ions. In vitro experiments showed that magnesium-based CPC enhanced the proliferation and migration of MC3T3-E1 and HUVECs. Additionally, the magnesium-based composite CPC not only enhanced osteogenic differentiation of MC3T3-E1 cells but also promoted angiogenesis in HUVECs. In vivo experiments using a vertebral bone defect model in Bama miniature pigs showed that the magnesium-based composite CPC significantly increased new bone formation. Additionally, compared to the CPC group, this composite exhibited significantly higher levels of osteogenic and angiogenic markers, with no inflammation or necrosis observed in the heart, liver, or kidneys, indicating good biocompatibility. These results suggest that magnesium-based composite CPC, with its superior compressive strength, biodegradability, and ability to promote vascularized bone regeneration, holds promise as a minimally invasive injectable material for bone regeneration.

The Effectivity of Acemannan Sponge and Calcium Phosphate Cement-Calcium Sulfate Hemihydrate (CPC-CSH)-Diode Laser-Assisted Method on the Direct Pulp Capping

Dental caries, the decay of tooth, affects approximately 2.3 billion people worldwide and reaches 88.8% of the total Indonesians. Caries reaching the pulp requires direct pulp capping (DPC) therapy to preserve pulp vitality. Ca(OH)2 is the golden standard DPC material, but its adhesion and mechanical properties are poor. Therefore, an alternative therapy is needed to improve the success of DPC using acemannan sponge and calcium phosphate cement-calcium sulfate hemihydrate (CPC-CSH)-diode laser. Acemannan, polymannose extracted from aloe vera gel, plays a role in reparative dentin formation that is immunomodulatory, antimicrobial, biocompatible, and accelerates wound healing. Calcium Phosphate Cement (CPC), bioactive material used in tissue engineering. Calcium sulfate hemihydrate (CSH), inorganic component and biocompatible. The combination of CPC-CSH can shorten the setting time, maintain compressive strength, and has good handling properties. Low level diode laser (LLDL) plays a role in reparative dentin formation by altering growth factors expression to stimulate cell proliferation and fibroblast development. LLDL is applied before pulp capping material application between the pulp-dentin so that aggregated collagen fibrils are collected and stimulate the formation of odontoblasts. This paper aims to describe The Effectiveness of Acemannan Sponge and Calcium Phosphate Cement-Calcium Sulfate Hemihydrate (CPC-CSH)-Diode Laser Assisted Method in Direct Pulp Capping Therapy. Article searching uses the Preferred Reporting Items for Systematic Reviews and Meta-analyses with keywords (MeSH): "DPC and Acemannan", "DPC and CPC-CSH", and "DPC and Diode Laser" from Pubmed, ScienceDirect, and Google Scholar databases in 2019-2024. Acemannan Sponge and Calcium Phosphate Cement-Calcium Sulfate Hemihydrate (CPC-CSH)-Diode Laser Assisted Method are effective as Alternative Direct Pulp Capping Therapy.

Optimizing α-tricalcium phosphate bone cement composite formulations: The critical role of bioactive glass particle size

Calcium phosphate cements (CPCs) have been extensively utilized as bone grafting material due to their inherent osteoconductive properties, although they often lacked sufficient biological performance for effective bone healing at the defect site. Incorporating mesoporous bioactive glass (MBG) into CPCs offers a solution by improving porosity, promoting degradation and increasing the available surface area. In the scope of this study, we integrated MBG into CPCs and assessed the impact of varying MBG particle sizes (<20 µm, <38 µm, <100 µm) on the setting characteristics, microstructure, mechanical strength, and preliminary cell response of CPCs. Investigations revealed that < 20 µm MBG particles significantly improved the setting characteristics and compressive strength of CPCs, while < 38 µm particles promoted degradation and ion release, facilitating apatite formation. MBG incorporation was found to promote microstructural homogeneity and facilitate apatite formation, with particle size directly affecting these outcomes. Biocompatibility assessments indicated no cytotoxic effects, supported by the favorable cellular responses (> 92 % viability compared to control group). These findings underscore the critical impact of MBG particle size on developing advanced CPCs for biomedical applications, guiding future design and optimization strategies.

Gluing osteochondral fragments: development of a novel strategy for dual adhesive application in a preclinical model

This study proposes a novel dual adhesive approach for fixing osteochondral fractures, aiming to address the limitations of current fixation methods by incorporating both a bone adhesive (phosphoserine modified calcium phosphate cement PM-CPC) and a cartilage adhesive (methacrylated phosphoserine-containing gelatin MePGa hydrogel). The feasibility and efficacy of this approach were investigated using an ex vivo bovine knee model. Results indicate successful gluing of osteochondral cylinders with both adhesives, with no significant difference in adhesion strength between the groups (adhesion strength mean of 1211.6 kPa, SD 602.4 kPa, and mean of 1299.6 kPa, SD 850.9 kPa for groups 1 and 2 respectively). Importantly, the inclusion of the hydrogel component in the dual adhesive system aims to enhance cartilage repair potential, complementing the mechanical support provided by the bone adhesive. Each adhesive offers distinctive benefits: PM-CPC for mechanical support and bone repair, and MePGa hydrogel for cartilage repair. The study demonstrates the potential of the dual adhesive strategy for osteochondral repair, though further refinement and in vivo validation are needed.

In vivo validation of osteoinductivity and biocompatibility of BMP-2 enriched calcium phosphate cement alongside retrospective description of its clinical adverse events

PurposeAlthough bone morphogenetic protein-2 (BMP-2) possesses potent osteoinductivity, there have been some concerns on the safety of BMP-2 and BMP-2-incorporated bone substitutes used for bone formation. On the other hand, BMP-2-loaded calcium phosphate cement (BMP-2@CPC) has been developed and used for bone regeneration in oral implantology. Therefore, this study aims to investigate this product's biocompatibility and clinical safety after being used in maxillofacial surgery.Materials and methodsA rat model was employed to assess the osteoinduction and biocompatibility of BMP-2@CPC. Further, a retrospective investigation was carried out: 110 patients who received BMP-2@CPC treatment after their maxillofacial surgery were recruited to describe relative adverse events.ResultsIn vivo, BMP-2@CPC showed a significantly higher mean bone volume density and osteoblasts volume density (15 ± 2% and 3 ± 1%)than those of the CPC group (p < 0.05) after being implanted in the dorsal area of rats. Regarding biocompatibility, the mean fibrous tissue volume density was significantly lower in the BMP-2@CPC group (20 ± 5% compared to 31 ± 6%, p = 0.026). The retrospective clinical study showed that only five mild/moderate adverse events were identified in four patients based on the medical records of 110 patients, including swelling, bony mass, and wound dehiscence. This adverse event occurrence was not affected by gender, age, the dose of filled materials, and operations in the study (p > 0.05).ConclusionsBMP-2-loaded CPC has osteoinductivity and more promising biocompatibility than pure CPC. However, its degradation is slower than CPC. The safety of BMP-2-loaded CPC with 0.5 or 1 mg BMP-2 is promising in oral maxillofacial surgery.Clinical implicationsThis study confirmed the promising safety of this BMP-2 incorporated CPC used in dental clinical practice, which can promote its reassuring application for dental implant placement in bone insufficient areas.Graphical

Compositional Variations in Calcium Phosphate Cement and Poly(Lactic-Co-Glycolic-Acid) Porogens Do Not Affect the Orthotopic Performance of Calcium Phosphate Cement/Poly(Lactic-Co-Glycolic-Acid) Cements.

Calcium phosphate cement (CPC) has evolved as an appealing bone substitute material, especially since CPCs were combined with poly(lactic-co-glycolic acid) (PLGA) porogens to render the resulting CPC/PLGA composite degradable. In view of the multiple variables of CPC and PLGA used previously, the effect of CPC composition and PLGA porogen morphology (i.e., microspheres versus microparticles) on the biological performance of CPC/PLGA has not yet been investigated. Consequently, we here aimed to evaluate comparatively various CPC/PLGA formulations varying in CPC composition and PLGA porogen morphology on their performance in a rabbit femoral condyle bone defect model. CPCs with a composition of 85 wt% α-TCP, 15 wt% dicalcium phosphate anhydrate (DCPA) and 5 wt% precipitated hydroxyapatite (pHA), or 100 wt% α-TCP were combined with spherical or irregularly shaped PLGA porogens (CPC/PLGA ratio of 60:40 wt% for all formulations). All CPC/PLGA formulations were applied via injection in bone defects, as created in the femoral condyle of rabbits, and retrieved for histological evaluation after 6 and 12 weeks of implantation. Descriptive histology and quantitative histomorphometry (i.e., material degradation and new bone formation) were used for analyses. Descriptively, all CPC/PLGA formulations showed material degradation at the periphery of the cement within 6 weeks of implantation. After 12 weeks, bone formation was observed extending into the defect core, replacing the degraded CPC/PLGA material. Quantitatively, similar material degradation (up to 87%) and new bone formation (up to 28%) values were observed, irrespective of compositional variations of CPC/PLGA formulations. These data prove that neither the CPC compositions nor the PLGA porogen morphologies as used in this work affect the biological performance of CPC/PLGA formulations in a rabbit femoral condyle bone defect model.

Injectable calcium phosphate cement integrated with BMSCs-encapsulated microcapsules for bone tissue regeneration

Injectable calcium phosphate cement (CPC) offers significant benefits for the minimally invasive repair of irregular bone defects. However, the main limitations of CPC, including its deficiency in osteogenic properties and insufficient large porosity, require further investigation and resolution. In this study, alginate-chitosan-alginate (ACA) microcapsules were used to encapsulate and deliver rat bone mesenchymal stem cells (rBMSCs) into CPC paste, while a porous CPC scaffold was established to support cell growth. Our results demonstrated that the ACA cell microcapsules effectively protect the cells and facilitate their transport into the CPC paste, thereby enhancing cell viability post-implantation. Additionally, the ACA + CPC extracts were found to stimulate osteogenic differentiation of rBMSCs. Furthermore, results from a rat cranial parietal bone defect model showed that ACA microcapsules containing exogenous rBMSCs initially improved thein situosteogenic potential of CPC within bone defects, providing multiple sites for bone growth. Over time, the osteogenic potential of the exogenous cells diminishes, yet the pores created by the microcapsules persist in supporting ongoing bone formation by recruiting endogenous cells to the osteogenic sites. In conclusion, the utilization of ACA loaded stem cell microcapsules satisfactorily facilitate osteogenesis and degradation of CPC, making it a promising scaffold for bone defect transplantation.

Injectable double-crosslinked bone cement with enhanced bone adhesion and improved osteoporotic pathophysiological microenvironment for osteoregeneration in osteoporosis

The osteoporotic bone defect caused by excessive activity of osteoclasts has posed a challenge for public healthcare. However, most existing bioinert bone cement fails to effectively regulate the pathological bone microenvironment and reconstruct bone homeostasis in the presence of osteoclast overactivity and osteoblast suppression. Herein, inspired by natural bone tissue, an in-situ modulation system for osteoporotic bone regeneration is developed by fabricating an injectable double-crosslinked PEGylated poly(glycerol sebacate) (PEGS)/calcium phosphate cement (CPC) loaded with sodium alendronate (ALN) (PEGS/CPC@ALN) adhesive bone cement. By incorporating ALN, the organic-inorganic interconnection within PEGS/CPC@ALN results in a 100 % increase in compression modulus and energy dissipation efficiency. Additionally, PEGS/CPC@ALN effectively adheres to the bone by bonding with amine and calcium ions present on the bone surface. Moreover, this in-situ regulation system comprehensively mitigates excessive bone resorption through the buffering effect of CPC to improve the acidic microenvironment of osteoporotic bone and the release of ALN to inhibit hyperactive osteoclasts, and facilitates stem cell proliferation and differentiation into osteoblasts through calcium ion release. Overall, the PEGS/CPC@ALN effectively regulates the pathological microenvironment of osteoporosis while promoting bone regeneration through synergistic effects of drugs and materials, thereby improving bone homeostasis and enabling minimally invasive treatment for osteoporotic defects.

The Effect of SiO&lt;sub&gt;2&lt;/sub&gt; Addition to the Hydroxyapatite/Curcumin Composite Properties

Hydroxyapatite/curcumin composites have been studied as a calcium phosphate cement candidate. In this research, the effects of adding SiO2 to the hydroxyapatite/curcumin composite on the characteristics of the cement, such as the crystal and surface properties, as well as the release behavior of curcumin in Ringer's solution media, were studied. The composite preparation with and without SiO2 was carried out using a Na2HPO4 2.5% solution. The results showed that the addition of 25% SiO2 to the hydroxyapatite/curcumin composite did not change the crystal properties of hydroxyapatite but produced a more homogenous distribution of the ingredients. The behavior of the composite in Ringer's solution also changes, which is proven by the change in the crystal growth direction and Ca/P ratio. Adding SiO2 produced a composite with a platter and larger particles, as well as a higher Ca/P ratio on the surface. The presence of SiO2 inhibited the release of curcumin in which the ratio of HA: curcumin changed from 77.7%:22.3% to 69.6%:30.4% after 5 d of immersion in Ringer's solution. Thus, besides increasing calcium phosphate deposition on the cement surface, SiO2 also prevents curcumin from being released from the composite.

Carvacrol-loaded premixed calcium phosphate bone cements with exceptional osteogenic and antibacterial properties to heal infected bone defects

The healing of infected bone fractures represents a significant clinical challenge in orthopedic surgery. Calcium phosphate cements (CPCs) are attractive materials, highly applicable in bone healing due to their satisfactory biological properties and chemical similarity to bone minerals. However, manual mixing is often required before localized application of conventional CPCs, increasing the risk of infection. Moreover, their antibacterial properties are often insufficient for treating infected fractures. In this study, antimicrobial two-paste premixed CPCs loaded with carvacrol were developed. The influence of the carvacrol on the setting properties and mechanical strength of the cement was studied. In vitro studies demonstrated the biocompatibility, osteogenic potential, and broad-spectrum antimicrobial efficacy of the premixed bone cements, including effectiveness against gram-positive, gram-negative, and drug-resistant bacteria. Notably, in vivo studies revealed exceptional antimicrobial and osteogenic properties of the carvacrol-loaded cements, confirming the promising potential of the premixed cements for the healing of infected bone defects.

Design of porous calcium phosphate cement composed of spherical porous granules based on precipitation of octacalcium phosphate

Design of porous calcium phosphate cement composed of spherical porous granules based on precipitation of octacalcium phosphate

Development of calcium phosphate cement composed of silica-modified hydroxyapatite, cerium oxide, and silica as an osteoporotic bone filler

Calcium phosphate cement (CPC), composed of silica-modified hydroxyapatite (HA-SiO2), cerium oxide (CeO2), and silica (SiO2), was developed as an osteoporosis bone filler. The effect of CeO2 and SiO2 content on the CPC's properties, such as crystal parameters, surface properties, antibacterial activity, and toxicity properties, were studied. HA-SiO2 was prepared using the sol-gel method, while CeO2 was prepared using the precipitation method. HA in HA-SiO2 has crystal properties similar to pure HA. Synthesized CeO2 contains Ce3+ and Ce4+ ions with Ce3+/Ce4+ = 0.34. Computational calculation predicted that the CeO2 (111) surface and glycine molecule interaction was categorized as chemisorption. Moreover, CeO2 has antibacterial activity toward Escherichia coli and Staphylococcus aureus. Combining HA-SiO2 and CeO2 did not change the adsorption-desorption isotherm curve type, but slightly decreased the surface area, total pore volume, and average pore. Increasing the percentage of CeO2 and adding 10 % SiO2 (w/w) affected the particle's size and CeO2 distribution. However, CPC lost antibacterial activity toward Staphylococcus aureus but adding 10 % SiO2 (w/w) increases the bacterial activity toward Escherichia coli close to that of pure CeO2. The MTT assay using pre-osteoblast MC3T3E1 cells showed that the CPC has IC50 = 4227 μg/ml or is nontoxic.

Design of bioresorbable calcium phosphate cement with high porosity via the addition of bioresorbable polymers.

Novel calcium phosphate cements (CPCs) that can be resorbed into the human body need to be developed. One approach for improving bioresorbability is reducing the content of calcium phosphate in CPCs; however, this may induces difficulties in setting the cement and increases the risk of decay. Adding bioresorbable polymers to a liquid solution can shorten the setting time and inhibit decay during setting. A novel bioresorbable polymer, phosphorylated pullulan (PPL), was recently reported. The effect of adding PPL to α-tricalcium phosphate (α-TCP)-based CPCs was examined and compared to that of adding bioresorbable polymers such as collagen, chitosan, and alginate. Collagen did not significantly inhibit the conversion of α-TCP to hydroxyapatite (HA), and its combination with calcium phosphate decreased the setting time and suppressed decay; chitosan decreased the setting time when combined with calcium phosphate; and alginate inhibited the conversion of α-TCP to HA and contributed to suppressing the decay. In contrast, PPL slightly inhibited the conversion of α-TCP to HA; however, its combination with calcium phosphate decreased the setting time. Thus, selecting bioresorbable polymers can help effectively control the properties of CPCs.

Incorporation of calcium phosphate cement into decellularized extracellular matrix enhances its bone regenerative properties

Decellularized extracellular matrix (dECM) hydrogels are engineered constructs that are widely-used in the field of regenerative medicine. However, the development of ECM-based hydrogels for bone tissue engineering requires enhancement in its osteogenic properties. For this purpose, we initially employed bone-derived dECM hydrogel (dECM-Hy) in combination with calcium phosphate cement (CPC) paste to improve the biological and structural properties of the dECM hydrogel. A decellularization protocol for bovine bone was developed to prepare dECM-Hy, and the mechanically-tuned dECM/CPC-Hy was built based on both rheological and mechanical characteristics. The dECM/CPC-Hy displayed a double swelling ratio and compressive strength. An interconnected structure with distinct hydroxyapatite crystals was evident in dECM/CPC-Hy. The expression levels of Alp, Runx2 and Ocn genes were upregulated in dECM/CPC-Hy compared to the dECM-Hy. A 14-day follow-up of the rats receiving subcutaneous implanted dECM-Hy, dECM/CPC-Hy and mesenchymal stem cells (MSCs)-embedded (dECM/CPC/MSCs-Hy) showed no toxicity, inflammatory factor expression or pathological changes. Radiography and computed tomography (CT) of the calvarial defects revealed new bone formation and elevated number of osteoblasts-osteocytes and osteons in dECM/CPC-Hy and dECM/CPC/MSCs-Hy compared to the control groups. These findings indicate that the dECM/CPC-Hy has substantial potential for bone tissue engineering.

Reinforcement of hydroxyapatite bone cement via thin glycerol-citrate polyester infiltration: Microstructural, mechanical and in-vitro evaluation

The development of calcium phosphate cements (CPCs) incorporating biopolymers, such as thermoplastic polylactides, is known as an efficient strategy to enhance the physico-chemical, biological, and mechanical properties of CPCs. However, the use of thermosetting polyol citrates as fillers in CPCs has rarely been reported. Hence, the main goal of the present work was to produce composite CPCs based on tetracalcium phosphate–monetite cement matrix (C) and glycerol-citrate polyester (GCA) and to thoroughly study the effect of GCA addition on microstructural, micro, and nano-mechanical as well as in-vitro cellular properties of final cement composites. The GCA polymer was synthesized by esterification of glycerol with citric acid and coated on the C cement powder matrix at a concentration of 2.5 wt% by infiltration in ethanol solution. Two systems were prepared, by drying the composite powder at 105 and 170 °C (denoted as GCA/C105 and GCA/C170), while the respective composite cements were produced by mixing the powders with the 2 wt% of NaH2PO4 liquid phase. The results showed that the GCA polyester had no significant effect on the hydrolysis and transformation of the original cement matrix, and the nanocrystalline hydroxyapatite (Hap) was found as the main hydration product in all types of cement. The cement setting time decreased slightly with the GCA addition. On the other hand, a significant increase in mechanical properties was reached by introducing the GCA polyester into the CPC matrix, achieving more than a 70 % increase in the compressive strength, and about 50 % and 20 % in micro and nanohardness values compared to that obtained for the original C cement sample. The nanoindentation analysis revealed that the improved compressive strength and hardness were due to the stronger boundaries between the platelet-like hydroxyapatite particles in GCA-doped cements and partially caused by the denser, less porous, and more compact microstructures. The results of in-vitro cytotoxicity testing revealed high proliferation activity of the osteoblastic cells in all cement extracts, providing useful information for designing novel composite cements with the potential to be applied as bone substitute materials.

Assessment of Novel Surgical Procedures Using Bone Morphogenic Protein-7 Infused Into Decellularised Muscle and Bioactive Ceramic: A Histological Analysis.

Reconstruction of critical bone defects is considered a challenge due to vascular reperfusion injury that may occur. The present study hypothesized that the use of decellularized muscle scaffold (DMS) and bone morphogenic protein-7 (BMP-7), along with resorbable bioactive ceramic silica calcium phosphate cement (SCPC) seeded with human bone marrow stromal cells, can expedite bone formation and maturation. Surgical bone defects were created in 20 nude transgenic mice. In experimental group 1 (n = 10), a critical-size (4mm) calvarial defect was made and grafted with DMS-BMP-7/SCPC. In situ human bone marrow stromal cells [human mesenchymal stromal cells (hMSC)] were seeded thereafter. As a control, group 2 (n = 10) was treated with DMS/SCPC seeded with hMSCs. After 8 weeks, bone regeneration was evaluated using histology and histomorphometry for both groups. Histological examination showed bone regeneration crossing the gap (experimental group 1), bone regeneration was noted at the defect periphery, and scattered islands of bone at the canters of the defects (control group 2). New bone formation and maturation were superior in the groups treated with the DMS/BMP-7/SCPC/hMSC constructs. The quantitative histological assessment revealed that the average bone surface area was 255 ± 25mm2, which was 1.5 times the surface area of group 2, which was reported at 170 ± 35mm2. The reported difference was considered statistically significant (P < 0.05). The DMS-BMP-7/SCPC scaffold induced bone regeneration and neovascularization in critical-size defects.

Preparation of composite calcium phosphate cement scaffold loaded with Hedysarum polysaccharides and its efficacy in repairing bone defects

It’s imperative to create a more ideal biological scaffold for bone defect repair. Calcium phosphate bone cements (CPC) could be used as a scaffold. Some ingredients and osteogenic factors could be added to improve its poor mechanical properties and biological activity. As a macromolecule extracted from traditional Chinese medicine, Hedysarum polysaccharides (HPS) would significantly promote the osteogenic activity of bone biomaterials. Zirconium oxide and starch were added to the solid phase and citric acid was added to the liquid phase to optimize CPC. HPS was loaded onto the scaffold as an osteogenic factor, and the prepared CPS + HPS was characterized. Further, the cytocompatibility of CPS + HPS was assessed according to activity, differentiation, and calcification in neonatal rat calvarial osteoblasts, and the biosafety of CPS + HPS was evaluated according to acute toxicity, pyrogen, sensitization, and hemolysis. The success of CPS + HPS in repairing bone defects was evaluated by using a rabbit femur implantation experiment. After optimization, CPS-20-CA-5 containing 10% starch and 5% citric acid displayed the highest mechanical strength of 28.96 ± 0.03 MPa. HPS-50 was demonstrated to exert the best osteogenic effect. The combination of CPS + HPS achieved HPS-loaded CPC. Material characterization, cytocompatibility, biosafety, and femoral implantation experiments indicated that CPS + HPS possessed better pressure resistance and improved osteogenic ability in bone defect repair.CPS + HPS demonstrated effective pressure resistance and superior osteogenic ability, which may be of great significance for bone defects and bone tissue engineering to promote bone regeneration and repair.Graphical The composite CPS loaded with HPS-50 is an excellent scaffold with fine load-bearing ability and sustained release of osteogenic factors to repair bone defects.

Proposing a new sustainable approach for sand improvement using biologically-derived calcium phosphate cement

Bio-mediated soil improvement methods keep on gaining the attention of geotechnical engineers and researchers globally due to their nature-based elegance and eco-friendliness. Most prevalent bio-mediated soil improvement methods include microbial induced carbonate precipitation (MICP) and enzyme induced carbonate precipitation (EICP). During their processes, the bacteria/ free urease hydrolyzes the urea into ammonium and carbonic acid, which is accompanied by a considerable increase of alkalinity (about pH 9.0). The major problem associated with the above techniques is the release of gaseous ammonia that is extremely detrimental. Therefore, this study aims to propose a new sustainable approach involving lactic acid bacteria to facilitate the calcium phosphate mineralization for the strengthening of sand matrix. The major objectives of this investigation are (i) to evaluate the urease activity of the lactic acid bacteria under different temperatures, pH conditions and additions of metal ions, (ii) to assess the treated sand matrix, (iii) to perform cost analysis. The outcomes indicated that Limosilactobacillus sp. could effectively facilitate the urea hydrolysis, hence increase in pH from acidic to neutral, and provided a desirable environment for the calcium phosphate to mineralize within the voids of the sand. The addition of 0.01% Ni2+ in culture media was found to enhance the urease activity by 38.8% and compressive strength over 40%. A combined formation of amorphous- and whisker-like precipitates could bridge a larger area at particle-particle contact points, facilitated a strong force-network in sand matrix. The mineralized calcium phosphate compound was found to be brushite. The cost herein for producing 1L treatment solution was estimated to be about 2.5-folds and 11.8-folds lower compared to that of MICP and EICP treatment solutions, respectively. Moreover, since the treatment pH could potentially be regulated between acidic – neural range, it would greatly control the release of gaseous ammonia. With several environmental and economical benefits, the study has disclosed a new sustainable direction for sand improvement via the use of lactic acid bacteria.