Collagen-calcium Phosphate Research Articles

Bone Regenerative Effects of Biphasic Calcium Phosphate Collagen, Bone Morphogenetic Protein 2, Mesenchymal Stem Cells, and Platelet-Rich Plasma in an Equine Bone Defect Model

Bone Regenerative Effects of Biphasic Calcium Phosphate Collagen, Bone Morphogenetic Protein 2, Mesenchymal Stem Cells, and Platelet-Rich Plasma in an Equine Bone Defect Model

Fast Construction of Biomimetic Organic-Inorganic Interface by Crosslinking of Calcium Phosphate Oligomers: A Strategy for Instant Regeneration of Hard Tissue.

The organic-inorganic structure in biological hard tissues ensures their marvelous characteristics but these hybrids are easily destroyed by the demineralization of inorganic components, e.g., the damage of dentin. Current clinical materials for hard tissue regeneration commonly act as "fillers" and their therapeutic effect is limited by the failures of biological-linked organic-inorganic interface reconstruction. Herein, a fast in situ crosslinking of calcium phosphate oligomers (CPOs) on collagen matrixes for efficient organic-inorganic interface re-construction, which can result in a biomimetic hybrid, is demonstrated. By using damaged dentin as an example, the inorganic ionic crosslinking can instantly infiltrate into the dentin matrix to rebuild a dense and continuous calcium phosphate-collagen hybrid within only 5min, where the structurally integrated organic-inorganic interface is identical to natural dentin. As a result, the damaged dentin can be fully recovered to a healthy one, which is superior to any current dentin treatments. The fast construction of biomimetic hybrid by inorganic ionic crosslinking provides a promising strategy for hard tissue repair and follows great potentials of CPOs as advanced biomedical materials in future.

ToF-SIMS Analysis of Demineralized Dentin Biomodified with Calcium Phosphate and Collagen Crosslinking: Effect on Marginal Adaptation of Class V Adhesive Restorations

This study aimed to assess the effect of biomodification before adhesive procedures on the tooth-restoration interface of class V restorations located in caries-simulated vs. sound dentin, and the quality of dentin surface by time-of-flight secondary ion mass spectrometry (ToF-SIMS). Class V cavities located on cervical dentin were prepared on the buccal surfaces of extracted human molars under the simulation of intratubular fluid flow. Two dentin types, i.e., sound and demineralized by formic-acid, were biomodified with 1% riboflavin and calcium phosphate (CaP) prior to the application of a universal adhesive (Clearfil Universal Bond) in etch and rinse or self-etch mode, and a conventional micro hybrid composite (Clearfil APX). Restorations were subjected to thermo mechanical fatigue test and percentages of continuous margins (% CM) before/after fatigue were compared. Bio modification of dentin surfaces at the molecular level was analyzed by Time-of-Flight Secondary Mass Spectometry (ToF-SIMS). % CM were still significantly higher in tooth-restoration interfaces on sound dentin. Meanwhile, biomodification with riboflavin and CaP had no detrimental effect on adhesion and in carious dentin, it improved the % CM both before and after loading. Etching carious dentin with phosphoric acid provided with the lowest results, leading even to restoration loss. The presence of molecule fragments of riboflavin and CaP were detected by ToF-SIMS, evidencing dentin biomodification. The adhesive interface involving carious dentin could be improved by the use of a collagen crosslinker and CaP prior to adhesive procedures.

P1. Efficacy of a calcium phosphate collagen matrix bone graft with needle-shaped submicron surface topography in a rabbit posterolateral lumbar spine fusion model

<h3>BACKGROUND CONTEXT</h3> Synthetic bone grafts are a promising alternative for the treatment of degenerative spine conditions and are available without the added drawbacks associated autografts including limited availability and donor-site morbidity. Of these synthetic materials, calcium phosphate (CaP) with a characteristic needle-shaped submicron surface topography (BCP<µm) has attracted much attention due to its unique bone-forming ability which is essential for repairing critical-size bone defects such as those found in the posterolateral spine [1,2]. Previous in vitro and ex-vivo data presented by van Dijk LA [3] and Yuan H [4] at NASS, 2020 demonstrated that these specific surface characteristics drive a favorable response from the innate immune system. <h3>PURPOSE</h3> This study was to evaluate the efficacy of a novel synthetic bone graft using a clinically-relevant "Boden" rabbit posterolateral spine fusion model. The synthetic bone graft comprised of CaP granules with a needle-shaped submicron surface structure (BCP<µm) embedded in a highly porous and fibrillar bovine type I collagen matrix (col-BCP<µm). The fibrillar collagen was introduced as a carrier, designed to facilitate admixing of the graft with biological fluids perioperatively and to minimize graft migration postoperatively. <h3>STUDY DESIGN/SETTING</h3> The novel synthetic bone graft was first mixed in a 1:1 volume ratio with autologous bone (ABG). Subsequently, grafts were implanted in the rabbit posterolateral spine environment for 3 days, 6, 9 and 12 weeks. An autologous bone graft group was used as a positive control in this study. Outcomes for the test article were additionally compared to historical data for the same material (BCP<µm) implanted alone, without the fibrillar collagen carrier. <h3>OUTCOME MEASURES</h3> Spinal fusion was determined by manual palpation (MP), X-ray and µCT imaging (based on the Lenke scale), mechanical testing (range of motion testing at 12 weeks only) and histology (decalcified and undecalcified). <h3>METHODS</h3> Forty skeletally mature New Zealand white rabbits were divided into two groups and underwent single-level bilateral posterolateral intertransverse process spine arthrodesis at L4-5. Animals were euthanized after 3 days, 6, 9 and 12 weeks. <h3>RESULTS</h3> Based on all endpoints, the test group and positive control group showed an equivalent and gradual progression in bone formation and implant resorption over time, leading to mature fusion masses at 12 weeks. No adverse reactions were observed in any of the groups. Bilateral fusion rates by MP were consistent with the literature (0-40% at 6 weeks; 60-70% at 12 weeks) and similar trends were seen by histological and radiographic assessment (both X-ray and µCT). Flexion-extension and lateral bending results at 12 weeks demonstrated fusion of the treated level consistent with the MP results. The results observed for the test group were consistent with those seen historically for the same material implanted without the fibrillar collagen carrier. <h3>CONCLUSIONS</h3> These results show that BCP with needle-shaped submicron-scale surface topography (BCP<µm) combined with a fibrillar collagen matrix (col-BCP<µm) could achieve equivalent fusion rates to ABG when used as a bone graft extender in a clinically relevant single level rabbit intertransverse process posterolateral lumbar fusion model. Over time, a progression in bone healing, graft resorption and remodeling were seen with all experimental endpoints, with equivalency between the groups. The results for col-BCP<µm were consistent with those previously seen for BCP<µm alone, confirming that the fibrillar collagen carrier improved handling properties but was not detrimental to the bone-forming capacity of the BCP<µm. <h3>FDA DEVICE/DRUG STATUS</h3> Col-BCP<µm (Investigational/Not approved)

Porous calcium phosphate-collagen composite microspheres for effective growth factor delivery and bone tissue regeneration.

Microspheres are beneficial for filling defects of various shapes and provide a large surface area for cell attachment. Porous microspheres have attracted particular attention because they can deliver cells and bioactive molecules such as growth factors. In this study, BCP-collagen composite microspheres were developed for growth factor delivery in bone regeneration. Firstly, porous biphasic calcium phosphate (BCP) microspheres were fabricated by applying a water-in-oil emulsion technique using camphene as a pore generator. Then, porous BCP-collagen composite microspheres were fabricated by repetitively dip coating the microspheres in a collagen solution to effectively deliver growth factor to bone defects. Characterization of the microspheres and in vitro studies were conducted to investigate the effect of collagen infiltration on bone regeneration. In addition, in vitro evaluation demonstrated the sustained bone morphogenetic protein-2 (BMP-2) delivery of the microspheres and the effect of cell differentiation, and in vivo assessment with rabbits revealed that the microspheres filled the defect well and that bone could be regenerated through the microspheres. Moreover, the composite system was more effective for bone regeneration than the bare BCP microspheres because of the drug retention of collagen. These findings indicate that the porous microspheres are effective for tissue regeneration by continuous growth factor delivery.

Use of tendon to produce decellularized sheets of mineralized collagen fibrils for bone tissue repair and regeneration.

With demand for alternatives to autograft and allograft materials continuing to rise, development of new scaffolds for bone tissue repair and regeneration remains of significant interest. Engineered collagen‐calcium phosphate (CaP) constructs can offer desirable attributes, including absence of foreign body response and possession of inherent osteogenic potential. Despite their promise, current collagen‐CaP constructs are limited to nonload‐bearing applications. In this article, we describe a process for creating decellularized sheets of highly aligned, natively cross‐linked, and mineralized collagen fibrils, which may be useful for developing multilaminate collagen‐CaP constructs with improved mechanical properties. Decellularized bovine tendons were cryosectioned to produce thin sheets of aligned collagen fibrils. Mineralization of the sheets was then performed using an alternate soaking method incorporating a polymer‐induced liquid precursor (PILP) process to promote intrafibrillar mineralization, along with incorporation of physiologically relevant amounts of citrate, Mg, and carbonate. Characteristics of the produced scaffolds were assessed using energy‐dispersive X‐ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Scaffolds were also compared with both native bovine cortical bone and pure hydroxyapatite using X‐ray powder diffraction (XRD), and Fourier transform infrared spectroscopy attenuated total reflection (FTIR‐ATR). Structural and chemical analyses show that the scaffold preparation process that we described is successful in creating mineralized collagen sheets, possessing a mineral phase similar to that found in bone as well as a close association between collagen fibrils and mineral plates.

Biomimetic Collagen/Zn2+-Substituted Calcium Phosphate Composite Coatings on Titanium Substrates as Prospective Bioactive Layer for Implants: A Comparative Study Spin Coating vs. MAPLE.

Synthesis of biomimetic materials for implants and prostheses is a hot topic in nanobiotechnology strategies. Today the major approach of orthopaedic implants in hard tissue engineering is represented by titanium implants. A comparative study of hybrid thin coatings deposition was performed by spin coating and matrix-assisted pulsed laser evaporation (MAPLE) onto titanium substrates. The Collagen-calcium phosphate (Coll-CaPs) combination was selected as the best option to mimic natural bone tissue. To accelerate the mineralization process, Zn2+ ions were inserted by substitution in CaPs. A superior thin film homogeneity was assessed by MAPLE, as shown by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) microscopy. A decrease of P-O and amide absorbance bands was observed as a consequence of different Zn2+ amounts. A variety of structural modifications of the apatite layer are then generated, which influenced the confinement process towards the collagen template. The in-vitro Simulated Body Fluid (SBF) assay demonstrated the ability of Coll/Zn2+-CaPs coatings to stimulate the mineralization process as a result of synergic effects in the collagen-Zn2+ substituted apatite. For both deposition methods, the formation of droplets associated to the growth of CaPs particulates inside the collagen matrix was visualized. This supports the prospective behavior of MAPLE biomimetic coatings to induce mineralization, as an essential step of fast implant integration with vivid tissues.

Clinical and experimental Study to evaluate the effect of Biphasic calcium phosphate collagen composite (cpcc) on healing of bone defects after oral surgical procedures

Background: A recent discoveries used for reconstruction in maxillofacial surgery is the composite bone graft materials. The availability of collagen I matrix make our choice to use this material in surgery .It is biomaterials that its structure could be modified by simple techniques. Studies to find a new materials use for bone reconstruction is to overcome the disadvantages of autogenous bone and the synthetic resorbable bone substitutes.&#x0D; Objectives: This study was done to evaluate the effect of biphasic calcium phosphate collagen composite (ccpc) on healing of bone defects after oral surgical procedures.&#x0D; Type of the study: A cross sectional study.&#x0D; Method: It involved 60 patients, 35 male and 25 female, age (15-40) yearsand experimental animals study involved sixty rabbits.The study was done in Department of Maxillofacial surgery in Al anbarCollege of Dentistry (2015-2016).These patients were received tooth extraction, and other minor surgical procedures .Clinical and radiographical examination and patients consents are done before surgery. The surgery was done under local anesthesia.The resulting bone cavities are filled with composite bone graft material composed from combination of lyophilized hydrolysed collagen sponge (Hemospon),Brasil and Osteon II bone graft material,Korea .The area is closed with 3/0 block silk suture .Antibiotic cover (Ampicillin 500mg ×4) for 1 week was prescribed. The patients were followed up by careful clinical examination with radiograph 15-30 days after surgery. .Sixty New Zeleandi White rabbit were used in our study for histopathologicalexamination.Intraperitoneal injection of ketamine 10 mg with XYL-M2 solution 20 mg xylazine base used to anesthetize the animals. (5mm diameter) bone defects were made using straight surgical hand piece and bur in anterior mandibular region and filled with each material. The study design involve the following groups: group 1( involve 15 rabbit; the defect was made and filled with blood clot only (control group),group 2( involve 15 rabbit, the defect was made and filled with collagen sponge only),group 3(Involve 15 rabbit, the defect was made and filled with Osteon II bone graft only),group4( involve 15 rabbit, the defect was made and filled with Osteon II bone graft +collagen (Composite bone graft).The flap were closed 3/0 black silk suture. The rabbits were killed after 30 days. 10 cmexcisional biopsy specimen was taken from the paramandibular area and placed in 10%formalin then send histopathologicalexamination.&#x0D; Results: Clinically, the treated area show good healing with absence of infection .Radiographs during follow up period show radiopacity indicating new bone formation .The results of experimental animals (Rabbits) indicategrowth new bone . In group 1 and group2, the center of the defects was depressed by surrounding tissues Eung et al, While, in group 3&amp;group 4, the graft materials maintained the space and the center of the defect did not depress. Statistical analysis indicates that during 4 th week ,the highest healing % is (100%) in group 3 &amp;group4 in compared to control group (50%)..A significant difference in healing % was found among the treated groups.&#x0D; Conclusion:The result indicates that biphasic calcium phosphate collagen composite can be efficiently utilized clinically.

Calcium Phosphate-Collagen Scaffold with Aligned Pore Channels for Enhanced Osteochondral Regeneration.

This study reports the development of a bilayered scaffold with aligned channels produced via a sequential coextrusion and unidirectional freezing process to facilitate upward bone-marrow stem-cell migration. The biomimetic scaffold with collagen and biphasic calcium phosphate (BCP) layers is successfully fabricated with matching of the cartilage and bone layers. The aligned structure results in an enhancement of the compressive strength, and the channels enable tight anchoring of the collagen layers on the BCP scaffolds compared with a randomly structured porous scaffold. An in vitro evaluation demonstrates that the aligned channels guide the cells to attach on the surface in highly stretched shapes and migrate upward faster than the random structure. In addition, in vivo assessment reveals that the aligned channels yield superior osteochondral tissue regeneration compared with the random structure. Moreover, the channel diameter greatly affects the tissue regeneration, and the scaffold with a channel diameter of ≈270 µm exhibits the optimal regeneration because of sufficient nutrient supply and adequate tissue ingrowth. These findings indicate that the introduction of aligned channels to a bilayered scaffold provides an effective approach for osteochondral tissue regeneration.

Selective preparation and characterization of nano-hydroxyapatite/collagen coatings with three-dimensional network structure

Nano hydroxyapatite/collagen (HA/COL) coatings were prepared on the surface of carbon/carbon (C/C) composites by a two-step process, i.e. electrochemically assisted co-deposition of calcium phosphate/collagen (CaP/COL) coatings and subsequent soaking CaP/COL coated C/C composites in Ca(OH)2 aqueous solution. Both CaP/COL and HA/COL coatings on the C/C composites exhibit three-dimensional network structure consisting of collagen fibers and uniform CaP covered on the surface of collagen fibers. CaP in the composite coatings was deposited into different forms depending on the concentration, Ca/P molar ratio and pH value of initial electrolyte. The concentration and pH value of initial electrolyte have little impact on the shape of CaP though they significantly influence the size of CaP. Higher Ca/P molar ratio of initial electrolyte leads to spherical amorphous calcium phosphate (ACP)/COL coatings. Plate-like octacalcium phosphate (OCP)/COL coatings were prone to form with low Ca/P molar ratios in the electrolyte. After Ca(OH)2-treatment as the second processing step, OCP/COL coatings on C/C were converted to HA/COL coatings. Their structure and compositions are similar to those of human bone tissue. SBF immersion tests indicate that HA/COL coated C/C composites have better in vitro bioactivity. In vitro cellular biocompatibility tests indicate OCP/COL and HA/COL coated C/C composites have almost the same biocompatibility.

Healing of experimental femoral defects in rats after implantation of collagen-calcium phosphate biocomposites

Healing of experimental femoral defects in rats after implantation of collagen-calcium phosphate biocomposites

Biocompatibility of calcium phosphate bone cement with optimised mechanical properties: an in vivo study.

This work establishes the in vivo performance of modified calcium phosphate bone cements for vertebroplasty of spinal fractures using a lapine model. A non-modified calcium phosphate bone cement and collagen-calcium phosphate bone cements composites with enhanced mechanical properties, utilising either bovine collagen or collagen from a marine sponge, were compared to a commercial poly(methyl methacrylate) cement. Conical cement samples (8 mm height × 4 mm base diameter) were press-fit into distal femoral condyle defects in New Zealand White rabbits and assessed after 5 and 10 weeks. Bone apposition and tartrate-resistant acid phosphatase activity around cements were assessed. All implants were well tolerated, but bone apposition was higher on calcium phosphate bone cements than on poly(methyl methacrylate) cement. Incorporation of collagen showed no evidence of inflammatory or immune reactions. Presence of positive tartrate-resistant acid phosphatase staining within cracks formed in calcium phosphate bone cements suggested active osteoclasts were present within the implants and were actively remodelling within the cements. Bone growth was also observed within these cracks. These findings confirm the biological advantages of calcium phosphate bone cements over poly(methyl methacrylate) and, coupled with previous work on enhancement of mechanical properties through collagen incorporation, suggest collagen-calcium phosphate bone cement composite may offer an alternative to calcium phosphate bone cements in applications where low setting times and higher mechanical stability are important.

Bone regenerative efficacy of biphasic calcium phosphate collagen composite as a carrier of rhBMP‐2

This study compared the bone regenerative effects of a recombinant human bone morphogenetic protein 2 (rhBMP-2)-loaded collagen-based biphasic calcium phosphate composite (BCPC) and rhBMP-2-loaded biphasic calcium phosphate (BCP). The in vitro release profiles of rhBMP-2-loaded BCP and BCPC were measured. The animal surgery was performed on ten rabbits. Four 8-mm-diameter circular calvarial defects were made and filled with BCP, BCPC, rhBMP-2-loaded BCP (BMP+BCP) and rhBMP-2-loaded BCPC (BMP+BCPC). The animals were euthanized either 2 or 8weeks after surgery. The initial burst release of rhBMP-2 was greater for BCP than for BCPC, and both presented a slow release pattern thereafter. In rabbit calvarial defects, the space maintaining capability and graft resorption of all experimental groups did not show statistical differences at 2 and 8weeks. New bone formation in the rhBMP-2-loaded groups was greater than in the non-loaded groups at both weeks, but the amount of new bone was comparable between both rhBMP-2-loaded groups at both weeks. There was a distinct histologic difference between the BMP+BCP and BMP+BCPC groups at 2weeks; the new bone formation occurred more in the intergranular spaces and the BCP-to-bone contact was greater in the BMP+BCPC group, but these differences were no longer discernible at 8weeks. BCP- and BCPC-loaded rhBMP-2 significantly improved bone regeneration and BCPC led to a dense network of new bone and bone particles during the early healing period. BCPC can therefore be considered as a promising candidate for carrying rhBMP-2.

Comparative evaluation of biphasic calcium phosphate and biphasic calcium phosphate collagen composite on osteoconductive potency in rabbit calvarial defect.

BackgroundThe aim of this study was to determine the osteoconductivity of biphasic calcium phosphate collagen composite (BCPC) in rabbit calvarial defect model by comparing with biphasic calcium phosphate (BCP). Four 8 mm diameter bicortical calvarial defects were made in ten rabbits. Each of the defects was randomly assigned and filled with 1) collagen sponge, 2) BCP, 3) BCPC, and 4) nothing as control. The animals were sacrificed at either 2 weeks (n = 5) or 8 weeks (n = 5) healing period.ResultsAll groups showed wedge shaped new bone formation limited to the area of the defect margin at both healing periods. The amounts of new bone and defect closure were similar among all groups. In the control and collagen sponge group, the center of the defect was depressed by surrounding tissues. In contrast, in BCP and BCPC group, the center of the defect did not depressed and the grafted materials maintained the space. And the augmented area was significantly higher in BCP and BCPC group compared to the control and collagen sponge group at both healing periods (p < 0.05).ConclusionsThe BCPC and BCP demonstrated proper space maintaining capacity and osteoconductive property, suggesting BCPC can be efficiently utilized in various clinical situations.

Electrically conducting collagen and collagen–mineral composites for current stimulation

Electrochemical aggregation of (a) collagen–PEDOT:PSS and (b) collagen–calcium phosphate–PEDOT:PSS.

Effects of different crosslinking methods on the properties of collagen–calcium phosphate composite materials

The purpose of this study is the preparation and characterization of porous collagen/calcium phosphates (Col/CaP) composites. Collagen scaffolds with high porosity were prepared by freeze–drying technique. Col/CaP scaffold were created by new method – by deposition of calcium phosphate within collagen matrix in two steps using freeze–drying process before immersing samples in calcium solution. To find the optimal preparative method, we prepared diverse Col/CaP scaffolds using different collagen concentration and various crosslinking method: crosslinking with carbodiimide (EDC/NHS) and dehydrothermal treatment (DHT).This study explores the effect of the different crosslinking method on the properties of scaffolds, such as: microstructure (porosity and density), dissolution, water uptake, mechanical properties and collagenase degradation. The results obtained showed that crosslinking the scaffolds by either EDC/NHS or DHT have good mechanical and morphological properties compatible with their potential application in bone regeneration. The results demonstrated that properties of Col/CaP scaffolds changed significantly with different crosslinking method. However, while EDC/NHS increased the scaffolds’ resistance to dissolution and degradation by collagenase, DHT decreased the swelling ratio and resistance to dissolution in PBS solution.Based on our study, 2% collagen concentration and EDC/NHS as crosslinking reagent are recommended to design the scaffold for use in bone engineering.

Surface modification of porous polycaprolactone/biphasic calcium phosphate scaffolds for bone regeneration in rat calvaria defect.

In this study, polycaprolactone scaffolds fabricated by a salt-leaching process were loaded with biphasic calcium phosphate successfully to improve the osteoconductivity in bone regeneration. The surface of polycaprolactone/biphasic calcium phosphate scaffolds was aminolyzed by 1,6-hexamethylenediamine to introduce amino groups onto the surface, which was verified qualitatively by ninhyrin staining. Collagen was further immobilized on the aminolyzed porous polycaprolactone via N-ethyl-N'-(3-dimethylaminopropy) carbodiimide hydrochloride/hydroxy-2,5-dioxopyrolidine-3-sulfonic acid sodium cross-linking. The pore size of polycaprolactone/biphasic calcium phosphate-collagen scaffolds was 200-300 µm, which was suitable for bone in-growth. The X-ray photoelectron spectroscopy confirmed the coupling of collagen immobilized on the surface of polycaprolactone/biphasic calcium phosphate. In vitro results demonstrated that the spreading and viability of MC3T3-E1 cells were remarkably improved in the polycaprolactone/biphasic calcium phosphate-collagen scaffolds. The in vivo study was carried out by implanting the porous polycaprolactone, polycaprolactone/biphasic calcium phosphate, and polycaprolactone/biphasic calcium phosphate-collagen to the skulls of rats. Although the addition of biphasic calcium phosphate particles in the polycaprolactone scaffolds does not have a strong effect on the new bone formation, the immobilization of collagen on the polycaprolactone/biphasic calcium phosphate scaffolds significantly improved the bone regeneration even though the implantation time was short, 6 weeks. The present results provide more evidence that functionalizing polycaprolactone with biphasic calcium phosphate and collagen may be a feasible way to improve the osteoconduction in bone regeneration.

3D printing of composite calcium phosphate and collagen scaffolds for bone regeneration

Low temperature 3D printing of calcium phosphate scaffolds holds great promise for fabricating synthetic bone graft substitutes with enhanced performance over traditional techniques. Many design parameters, such as the binder solution properties, have yet to be optimized to ensure maximal biocompatibility and osteoconductivity with sufficient mechanical properties. This study tailored the phosphoric acid-based binder solution concentration to 8.75 wt% to maximize cytocompatibility and mechanical strength, with a supplementation of Tween 80 to improve printing. To further enhance the formulation, collagen was dissolved into the binder solution to fabricate collagen-calcium phosphate composites. Reducing the viscosity and surface tension through a physiologic heat treatment and Tween 80, respectively, enabled reliable thermal inkjet printing of the collagen solutions. Supplementing the binder solution with 1–2 wt% collagen significantly improved maximum flexural strength and cell viability. To assess the bone healing performance, we implanted 3D printed scaffolds into a critically sized murine femoral defect for 9 weeks. The implants were confirmed to be osteoconductive, with new bone growth incorporating the degrading scaffold materials. In conclusion, this study demonstrates optimization of material parameters for 3D printed calcium phosphate scaffolds and enhancement of material properties by volumetric collagen incorporation via inkjet printing.

The effect of magnetic field on electrochemically deposited calcium phosphate/collagen coatings.

Nanostructured calcium phosphate/collagen (CaP/COL) coatings were deposited on the carbon/carbon (C/C) composites through electrochemical deposition (ECD) under magnetic field. The effect of magnetic fields with different orientations on the morphology and composition was investigated. Both the morphology and composition of the coatings could be altered by superimposed magnetic field. Under zero magnetic field and magnetic field, three-dimensional network structure consisting of collagen fibers and CaP were formed on the C/C substrate. The applied magnetic field in the electric field helped to form nanostructured and plate-like CaP on collagen fibers. For the ECD under magnetic field, the Ca/P molar ratio of the coatings was lower than the one under B=0. This may be contributed to the decreased electrical resistance or the increased electrical conductivity of electrolyte solutions under magnetic field. The nanosized CaP/COL coatings exhibited the similar morphology to the human bone and could present excellent cell bioactivity and osteoblast functions.

In vitro study of vancomycin release and osteoblast-like cell growth on structured calcium phosphate-collagen

A drug delivery vehicle consisting of spherical calcium phosphate-collagen particles covered by flower-like (SFCaPCol) blossoms composed of nanorod building blocks and their cellular response is studied. The spherical structure was achieved by a combination of sonication and freeze-drying. The SFCaPCol blossoms have a high surface area of approximately 280m2g−1. The blossom-like formation having a high surface area allows a drug loading efficiency of 77.82%. The release profile for one drug, vancomycin (VCM), shows long term sustained release in simulated body fluid (SBF), in a phosphate buffer saline (PBS, pH 7.4) solution and in culture media over 2weeks with a cumulative release ~53%, 75% and 50%, respectively, over the first 7days. The biocompatibility of the VCM-loaded SFCaPCol scaffold was determined by in vitro cell adhesion and proliferation tests of rat osteoblast-like UMR-106 cells. MTT tests indicated that UMR-106 cells were viable after exposure to the VCM loaded SFCaPCol, meaning that the scaffold (the flower-like blossoms) did not impair the cell's viability. The density of cells on the substrate was seen to increase with increasing cultured time.