Papers by Keyword: Injectable

Abstract: The study aimed to synthesize alginate hydrogel-based composites which could be injected for medical purpose and can be cured in situ gelling after the injection process. The effect of reduced graphene oxide (r-GO) addition on Alginate /poly (vinyl alcohol) (PVA) hydrogel to physical properties were evaluated. Synthesis of hydrogel Alginate/PVA/r-GO composite was previously performed by production of r-GO using Hummer method. The composition of r-GO used in composite hydrogel was 0.4, 0.8, 1.2 and 1.6% wt. The sample was then characterized using XRD, FTIR, and analyzed perform with its curing time, injectable performance, swelling ratio, and water content.

Abstract: An ideal injectable bone cement should be able to fill fully the fractures gap and provide good mechanical support. In the present work, the mineralized collagen and calcium sulphate dehydrate (CSD) was incorporated into α-calcium sulphate hemihydrates (α-CSH) to explore an injectable composite cement. The injectability, the setting time and the biomechanics properties were investigated. A porcine thoracolumbar burst fracture model was used to evaluate the biomechanical performance of composite cements. The porcine thoracolumbar burst fracture models in vitro were prepared. A half of models was made by the vertebroplasty of the composite cements, the other half of models was used as control. Imaging analysis showed the composite cements distributed uniformly and solidified well. Biomechanical test showed the ability of the composite cements to repair spinal burst fractures was significant.

Abstract: To explore a new type of injectable composite cements similar to the natural bone in both composition and hierarchical structure, the mineralized collagen and calcium sulphate dihydrate（CSD）were incorporated into α-calcium sulphate hemihydrate (α-CSH).The mineralized collagen was synthesized biomimetically by nanohydroxyapatite/collagen. We investigated the injectability, the setting time and the biomechanics properties to find an ideal combination of them to prepare the composite cements. SEM analysis showed biphasic cements consisting of an entanglement of calcium sulfate dihydrate and calcium-deficient hydroxyapatite crystals. We prepared porcine thoracolumbar burst fracture models and made the vertebroplasty for them by the composite cements. Imaging analysis showed the composite cements distributed uniformly and solidified well. Biomechanical test showed the ability of composite cements to repair spinal burst fractures was significant.

Abstract: Injectable hydroxyapatite/collagen nanocomposite (HAp/Col) artificial bone was prepared utilizing gelation of sodium alginate (Na-Alg). Mass ratio of the HAp/Col powder, with or without Ca adsorption treatment and Na-Alg (80-120, 300-400, 500-600 cP in viscosity at 10 g/dm³) was fixed at 90/10. Injectable HAp/Col was prepared by mixing the HAp/Col powder with Na-Alg solution at several powder (HAp/Col)/liquid (Na-Alg solution) ratios (P/L ratio, g/cm³). The result of consistency measurement suggested that the operability of injectable HAp/Col paste could be controlled by both the P/L ratio and the viscosity of Na-Alg solution. According to the consistency measurement and practical feelings during mixing, P/L=1/1.67 (80-120 cP) and 1/1.89 (300-400, 500-600 cP) were considered to be the highest P/L ratio allowed to mix the HAp/Col paste with a spatula. At the P/L=1/2.33 (80-120 cP), the paste prepared with the non-treated HAp/Col powder, placed in an incubator (37 °C,relative humidity 100%) for 24h, demonstrated gel-like property, while the paste prepared with Ca-treated HAp/Col powder did putty-like property. The difference in their property might be caused by the initial bonding behavior between Alg and Ca²⁺ after mixing. The setting time measurement with Gillmore needle was impossible because they were toosoft for this method. Even though, their operability and coalescence/settingproperty could be used as the injectable bone filler.

Abstract: The aim of this study was to develop a novel injectable hydroxyapatite for bone repair materials. This study was based on the in situ setting properties of calcium phosphate cement (CPC), which properties were improved. The solid phase consisted of tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCPA). The liquid phase was the weak acidic solution of chitosan. The CPC powder was mixed with the chitosan solution to form a paste that could conform to the bone cavity even for irregularly shaped cavities. All the by-production disappeared by neutralization reaction. The CPC paste could then set in situ to form hydroxyapatite (HA) as the final product. The chemical process of CPC hydration was studied. The process was controlled by dissolution and precipitation chemical reaction. The kinetic model of hydration reaction was established. The effects of preparing conditions, such as powder to liquid ratio and particle size, on setting time and compressive strength were investigated systematically. The optimal condition was that the liquid phase contained 3% chitosan, 5% citric acid and 15% glucose (wt%), powder to liquid ratio was 0.8 g/ml, and powders were respectively ground for 40 hours.

Abstract: The aim of this study was to analyze the effect of starting powder granulometry and sintering conditions on the morphological structure and mechanical properties of injectable hydroxyapaptite (HAp) microspheres. The mechanical properties of the microspheres were evaluated, to investigate if their integrity could be maintained during the injection process. To obtain microspheres, HAp powders were dispersed in a sodium alginate solution and spherical particles were prepared by droplet extrusion under a co-axial air stream, coupled with ionotropic gelation in the presence of Ca2+. This was followed by a sintering process at various temperatures and times. The morphology of microspheres was observed under SEM, diameter measurements were performed in an optical microscope and the compression strength was evaluated using a texture analyzer. Finally, microspheres prepared using lower granulometry HAp powders and sintered at 1200 °C for 1 hour presented the best properties and were selected as the most suitable for the envisaged application.

Abstract: The biomaterial studied here is a composite associating a mineral phase of an intimate nanoscale melting of hydroxyapatite and beta tri calcium phosphate and an aqueous phase containing a synthetic polymer derived from cellulose HPMC (hydroxyl propyl methyl cellulose), marketed under name MBCP Gel (FDA approval, Biomatlante manufacturer). The present exploratory study aim was to study the safety of MBCP-gel, and to determine in the osseous healthy area the performance of MBCP gel. We expected to prove bone ingrowth into the osseous cavities created during drilling biopsy of the aseptic osteonecrosis of femoral head. The current results obtained in the first two patients with 1 year follow up demonstrate the resorption and bone ingrowth with trabecular bone architecture in the hole created into the femoral neck.

Abstract: Biodegradable in situ forming drug delivery systems that solidify or gel in the body from injectable fluids represent effective parenteral depot systems for controlled delivery of proteins. Various pharmaceutical additives were tested on their effectiveness as protein release modifiers and stabilizers. Mono-, di-, poly-saccharides, PEG2K and salting-out salts except cyclodextrins significantly decreased Tg of thermogelling polymers and their decreasing abilities were proportional to the polymer concentration and additive/polymer weight ratio up to solubility limits in aqueous media. For methyl cellulose (MC) gel, sodium carbonate, a strong salting-out salt, decreased Tg by 23 °C so that in situ gel can be formed at the body temperature. The incorporation of additives into thermogelling polymers significantly decreased the burst and retarded release kinetics. Although the pH inside gel gradually dropped down due to the polymer degradation, released model protein was confirmed to retain the original conformation.

Abstract: The primary purpose of this study was to characterize the main features of a BCP-loaded chitosan-GP composite. The two-syringe design improves the storage conditions, facilitates the sterilization procedure and provides an easy-to-use injectable biomaterial, ensuring reproducible properties with minimal manipulation. Rheological measurements confirm that the chitosan- GP/BCP composite retains the thermosensitive properties already described for chitosan-GP hydrogels. At 37°C, the system gels within 10 minutes and reaches sufficient consistency after 30 minutes to prevent the mineral granules from migration into the surrounding tissues in vivo. The compressive force needed for the injection of chitosan-GP/BCP before gelation is approximately 6.6 N, only about 6 times that required for water and much lower than the average force that the majority of adults can exert. Morphology was investigated by environmental scanning electron microscopy (ESEM), which revealed 3-D dispersion of BCP granules embedded in chitosan-GP hydrogel. This open, porous structure affords complete access for body fluids and cells to each mineral granule immediately following implantation. The design using disposable syringes equipped with 16G hypodermic needles described here allows easy in vivo delivery of a fully injectable biomaterial containing porous scaffold that naturally enhances the osteogenic activity recognized for both chitosan and BCP.

Abstract: The aim of this work was to assess the mixing, transfer and handling, properties, injectability, set time, wash-out characteristics, acceptance of hardware (i.e. stainless screws), and their delivery/transfer systems of self hardening synthetic bone cements made from calcium phosphate and calcium sulphate. Surgical procedures (i.e. cranioplasty) were performed on adult Labrador dogs using seven different bone cements from various manufacturers. Direct comparison of the defined intraoperative properties were evaluated and recorded. There is considerable variability with respect to application properties among commercially available injectable synthetic bone cements. Only one product was rated good to excellent in seven of the eight categories evaluated (6-excellent, 1-good, 1-fair) based on in-vivo tests. This study outlines the critical parameters required for successful implantation of cements that have to be understood when designing new injectable bone cements for the future.