Degradability and biocompatibility of bioglass/poly(amino acid) composites with different surface bioactivity as bone repair materials

Bioglass (BG) possesses excellent bioactivity and has been widely used in the manufacture of biomaterials. In this study, a composite with different surface bioactivity was fabricated via in situ melting polymerization by incorporating BG and poly(amino acid) (PAA) at a suitable ratio. The structure of the composite was characterized by Fourier transform infrared spectroscopy and XRD. The compressive strength of the BG/PAA composites was 139 MPa (BG:PAA = 30:70). The BG/PAA composites were degradable, and higher BG in composite showed higher weight loss after 4 weeks of incubation in simulated body fluid. In addition, the BG/PAA composite maintained adequate residual compressive strength during the degradation period. The SEM results showed the differences in surface bioactivities of the composites directly, and 30BG/PAA composite showed thicker apatite layer and higher Ca/p than 15BG/PAA. in vitro MG-63 cell culture experiments showed that the composite was noncytotoxic and thus allows cells to adhere, proliferate, and differentiate. This indicates that the composite has good biocompatibility. The implantations in the bone defects of rabbits for 4 and 12 weeks were studied. The composites had good biocompatibility and were capable of guiding new bone formation without causing any inflammation. The composite may be successfully used in the development of bone implants.     

Degradable and bioactive scaffold of calcium phosphate and calcium sulphate from self-setting cement for bone regeneration

Calcium sulphate/phosphate cement (CSPC) porous scaffolds were fabricated by introduction of calcium sulphate (CS) into calcium phosphate cement utilizing particle-leaching method. The morphology, porosity and mechanical strength as well as degradation of the CSPC scaffolds were characterized. The results reveal that the CSPC with 40 wt% CS content (40 CSPC) scaffolds with a porosity of 81% showed open macropores with the pore size of 200–500 μm. In addition, the 40 CSPC scaffolds with good degree of interconnected macropores degraded 60 wt% in Tris–HCl solution after 12 weeks. The proliferation, differentiation and morphology of MG₆₃ cells on the 40 CSPC scaffolds were determined using MTT assay, ALP activity and SEM. The results suggest that the CSPC scaffolds could stimulate cell proliferation and differentiation, indicating that CSPC scaffolds were biocompatible and had no negative effects on the cells in vitro. The CSPC scaffolds were implanted in femur bone defect of rabbits, and the in vivo biocompatibility and osteogenicity of the scaffolds were investigated. The results indicate that CSPC scaffolds exhibited good biocompatibility, degradability and osteogenesis in vivo.     

In-vitro evaluation of thermoplastic starch/ beta-tricalcium phosphate nano-biocomposite in bone tissue engineering

Thermoplastic starch (TPS), as a natural based polymer, is known to have the capability to be used in biological applications due to its biocompatibility and biodegradability. In this study, mechanical properties of TPS are enhanced by incorporating bioactive β-tricalcium phosphate (β-TCP) particles for bone tissue engineering applications. Starch-based nanocomposites containing 3, 5, and 10 wt% of β-TCP nanoparticles (TT3, TT5, TT10) were made using a co-rotating twin-screw extruder. Dynamic light scattering (DLS) and X-ray diffraction (XRD) techniques were employed to analyze the nanocomposites. Moreover, degradability, swelling degree, and biomineralization in a simulated body fluid (SBF) were studied. To investigate the dispersion of β-TCP nanoparticles in the composite and biomineralization of the nanocomposites after incubation in SBF, scanning electron microscopy (SEM) and energy dispersive X-Ray analysis (EDX) were performed. Evaluation of mechanical properties of TPS and nanocomposites demonstrated that increase in β-TCP content enhanced mechanical properties. Besides, the bioactivity of these three nanocomposite materials was proven by nucleation of hydroxyapatite on the samples’ surface after incubation in simulated body fluid (SBF). Cytotoxicity test was done as well. Results of the current study have paved the way for the application of TPS/β-TCP composite as bone tissue engineering material.     

Bone substitute of poly(amino acid)/β‐Ca2SiO4 biocomposite: Degradability and bioactivity

A poly(amino acid)/β‐Ca₂SiO₄(PAA/β‐Ca₂SiO₄) bioactive composite was prepared by in situ melting polymerization. The composition, structure, and morphology were characterized by infrared spectrometry, X‐ray diffraction, X‐ray photoelectron spectroscopy, scanning electron microscopy, and differential scanning calorimeter. The results indicated that the β‐Ca₂SiO₄ particles were uniformly distributed in the PAA matrix and some interaction was found at the interface between PAA and β‐Ca₂SiO₄. The crystallinity of PAA in the composite was found decreasing with the increase of β‐Ca₂SiO₄ content. The bioactivity of the composite was evaluated by soaking the composite in simulated body fluid (SBF) and results showed that the PAA/β‐Ca₂SiO₄ composite (PSC) could induce a dense and continuous layer of apatite after soaking for 1 week. In addition, the PSC was soaked SBF for 2 months, and the weight loss reached 8.77%, showing the composite could be degradable. Collectively, these results suggested that the incorporation of β‐Ca₂SiO₄ produced a biocomposite with enhanced bioactivity and might have potential applications as a bone tissue substitute. POLYM. COMPOS., 37:1335–1341, 2016. © 2014 Society of Plastics Engineers     

Fabrication and biocompatibility of porously bioactive scaffold of nonstoichiometric apatite and poly(ε‐caprolactone) nanocomposite

Bioactive nanocomposite of nonstoichiometric apatite (ns‐AP) and poly(ε‐caprolactone) (PCL) was synthesized and its porous scaffold was fabricated. The results show that the hydrophilicity and cell attachment ratio on the composite surface improved with the increase of ns‐AP content in PCL. The composite scaffolds with 60 wt % ns‐AP content contained open and interconnected pores ranging in size from 200 to 500 μm and exhibit a porosity of around 80%. In addition, proliferation of MG₆₃ cells on the composite scaffolds significantly increased with the increase of ns‐AP content, and the level of alkaline phosphatase (ALP) activity and nitric oxide (NO) production of the cells cultured on the composite scaffold were higher than that of PCL at 7 days, revealing that the composite scaffolds had excellent in vitro biocompatibility and bioactivity. The composite scaffolds were implanted into rabbit mandible defects, the results suggest that the introduction of ns‐AP into PCL enhanced the efficiency of new bone formation, and the ns‐AP/PCL composite exhibited in vivo good biocompatibility and osteogenesis. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The effect of tricalcium silicate incorporation on bioactivity,injectability, and mechanical properties of calcium sulfate/bioactive glass bone cement

The conventional Polymethyl methacrylate (PMMA) bone cement is not biodegradable and not bioactive to bond with the native bone and causes tissue necrosis resulting from its high exothermic polymerization. Hence, biodegradable bioactive bone cements with suitable setting time and mechanical properties should be introduced. In this study, novel bioactive bone cements containing Calcium Sulfate Hemihydrate (CSH), Bioactive Glass (BG), and Tricalcium Silicate (TSC) were developed. Firstly, CSH and BG binary system was optimized based on preliminary setting and mechanical tests. Secondly, the composite bioactive bone cements were obtained by adding different quantities of TCS to the optimized CS-BG (1.3:1 wt % ratio) system. All groups exhibited desirable handling properties, an initial setting time of lower than 15 min, injectability of greater than 85%, and controlled degradability. Moreover, they demonstrated initial compressive strength values of higher than 12 MPa, superior to trabecular bone. After 28 days of hydration, the compressive strength of the cement containing 30% TCS reached 51.04 MPa. Furthermore, the present bone cements showed favorable bioactivity and bone-bonding ability as a result of calcium carbonate and hydroxyapatite (HA) formation. Furthermore, this novel bone cement exhibited appropriate biocompatibility and mesenchymal stem cell attachment, suggesting its potential for clinical applications.     

Cytocompatibility,bioactivity and mechanical strength of calcium phosphate cement reinforced with multi-walled carbon nanotubes and bovine serum albumin

This paper reports on the in vitro cytotoxicity, bioactivity behaviour and mechanical properties of novel injectable calcium phosphate cement filled with hydroxylated multi-walled carbon nanotubes and bovine serum albumin (CPC/MWCNT-OH/BSA). To predict the in vitro bioactivity of the calcium phosphate composites, we investigated apatite formation on CPC/MWCNT-OH/BSA composites after soaking in simulated body fluid (SBF) for up to 28 days. Compressive strength tests, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and cell culture experiments with human CCD-18Co fibroblasts cell lines were performed to evaluate the effect of SBF pre-treatment on the mechanical, structural and biological properties of the CPC/MWCNT-OH/BSA composites. Although apatite formation increased significantly with SBF immersion period, the results showed that all soaked CPC/MWCNT-OH/BSA composites exhibited up to 2.5 times lower compressive strength (13–20 MPa), which were however higher than values reported for the strength of trabecular bone (2–12 MPa). Cell culture experiments showed that low concentrations (6.25 and 12.5 μg/ml) of bio-mineralised CPC/MWCNT-OH/BSA composites led to cell proliferative rather than cytotoxic effects on fibroblasts, evidenced by high cell viabilities (104–113%). The novel CPC/MWCNT-OH/BSA composites presented in this study showed favourable cytocompatible and bioactive behaviour along with high compressive strength (13–32 MPa) and are therefore considered as an attractive bone filling material.     

Fabrication and in vitro investigation of nanohydroxyapatite,chitosan, poly(L‐lactic acid) ternary biocomposite

The nanohydroxyapatite/chitosan/poly(L ‐lactic acid) (HA/CS/PLLA) ternary biocomposites were prepared by blending the hydroxyapatite/chitosan (HA/CS) nanocomposites with poly(L ‐lactic acid) (PLLA) solution. Surface modification by grafting D ‐, L ‐lactic acid onto the HA/CS nanocomposites was designed to improve the bonding with PLLA. The FTIR and ¹³C‐NMR spectrum confirmed that the oligo(lactic acid) was successfully grafted onto the HA/CS nanocomposites, and the time‐dependent phase monitoring showed that the grafted copolymers were stable. The TEM morphology of the HA/CS/PLLA ternary nanocomposites showed that nano‐HA fibers were distributed homogeneously, compacted closely and wrapped tightly by the CS and PLLA matrix. The ternary biocomposites with the HA content of 60 and 67 wt % exhibited high compressive strength of about 160 MPa and suitable hydrophilicity. The in vitro tests exhibited that the ternary biocomposites have good biodegradability and bioactivity when immersed in SBF solutions. All the results suggested that the n‐HA/CS/PLLA ternary biocomposites are appropriate to application as bone substitute in bone tissue engineering. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Wollastonite/hydroxyapatite scaffolds with improved mechanical,bioactive and biodegradable properties for bone tissue engineering

Wollastonite/hydroxyapatite composite scaffolds are proposed as bone graft. An investigation on scaffold with varying reinforcing wollastonite content fabricated by polymeric sponge replica is reported. The composition, sintering behavior, morphology, porosity and mechanical strength were characterized. All the scaffolds had a highly porous well-interconnected structure. A significant increase in mechanical strength is achieved by adding a 50% wollastonite phase. The most mechanically resistant (50/50) wollastonite/hydroxyapatite scaffolds were soaked in both simulated body fluid (SBF) and Tris–HCl solution in order to assess bioactivity and biodegradability. A carbo-hydroxyapatite layer formed on their surfaces when immersed in SBF. The biodegradability tests reveals that the composite scaffold shows a higher degradation rate compared to pure hydroxyapatite used as comparison. These results demonstrate that the incorporation of a 50% of wollastonite phase in hydroxyapatite matrix is effective in improving the strength and the bioactive and biodegradable properties of the porous scaffolds.     

In vivo biocompatibility and bioactivity of in situ synthesized hydroxyapatite/polyetheretherketone composite materials

Hydroxyapatite/polyetheretherketone (HA/PEEK) composite materials were prepared via an in situ synthesis process in order to achieve strong bonding between PEEK matrix and hydroxyapatite fillers, and ultimately to improve the mechanical properties of the composites. In the study, the biocompatibility of the synthesized HA/PEEK materials was investigated by acute toxicity test, hemolytic test, sensitization test, pyrogen test, intradermal test, and toxicity assay test on animal tissue and cells for the purpose of examining the possible adverse effects of the residue organic chemicals from the in situ synthesis process. In vivo bioactivity of both lab‐synthesized PEEK and HA/PEEK composites with various HA content was also studied. It is found that the in situ synthesized composite materials possess good biocompability without toxicity. Although the bioactivity of the material increases with HA content, the composite material with 5.6 vol % HA exhibits satisfactory bioactivity without compromising its excellent mechanical performance, which hints to a potential use as load‐bearing orthopedic material. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis of chitin calcium phosphate composite in different growth media

This paper presents some results concerning chitin calcium phosphate composites obtained in different growth media. The synthesis of chitin calcium phosphate composite was carried out by phosphorylation, calcification, and soaking in different calcium phosphate growth media. This research is focused on studying and understanding the effect of using different growth media on composite samples. Hydroxyapatite was determined in the composite samples synthesized by using both simulated body fluid (SBF) and calcium phosphorus tris (Ca‐PTris) solution. Calcium/phosphorus (Ca:P) ratio of the composite synthesized by using SBF was found higher than that of composite synthesized by using Ca‐PTris solution as calcium phosphate growth media. The Ca:P ratio of the composite (1.72) immersed in 1.5× SBF for 35 day is similar to the theoretical value of hydroxyapatite (1.67) and closer to the theoretical value of human bone (1.75). POLYM. COMPOS., 29:84–91, 2008. © 2007 Society of Plastics Engineers     

Swelling behavior of hydroxyapatite‐filled chitosan–poly(acrylic acid) polyelectrolyte complexes

A family of hydroxyapatite (HAP)‐filled chitosan (CHI)–poly(acrylic acid) (PAA) polyelectrolyte complexes was prepared for the development of a degradable biocompatible organic matrix with nascent HAP that will degrade in vivo over a period of time. The effects of complexation on the degradation profile of the composites as well as the interaction between the CHI–PAA matrix and HAP in the composite system were evaluated by studying the swelling behavior of these composites in phosphate‐buffered saline (PBS) by varying their CHI–PAA ratio and HAP content. All composite systems showed a general trend of three stages of swelling with the variation in the degree of equilibrium swelling. The percentage weight gain initially decreased in a linear way with increases in the HAP weight percentages, leading to a first equilibrium swelling, represented by the plateau; further increased to a greater extent; and finally stabilized. The CHI/PAA/HAP composites were stable in PBS up to a period of more than 45 days whereas the 50/50 CHI/PAA control sample showed a single equilibrium attained after a period of 288 h. Further exposure of the specimen to the medium led to its disintegration. It was also observed that, even though CHI and PAA were capable of binding HAP, because of the lack of efficient binding, the integrity of the CHI–HAP and PAA–HAP composites were lost within 48 h. The 50/50/80 CHI/PAA/HAP composition showed the minimum amount of swelling in the series. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4716–4722, 2006     

A Novel Method for In Situ Synthesis of Nanostructure Hydroxyapatite–nylon 66 Composites in Tissue Engineering

An interfacial polymerization method for nylon 66 was adapted to produce nanostructured composites with nanohydroxyapatite (n-HA) via in situ polymerization. Nylon 66 was synthesized in n-HA slurry to increase homogeneity and biocompatibility. Synthesis powders was characterized by XRD, TEM, TGA, and FT-IR analysis. The results showed a uniform dispersion in composites, whereas needle-like, n-HA crystals dispersed in condensed polymer matrix. The samples were immersed in SBF for bioactivity tests in different periods, and results were monitored by SEM and EDX in terms of forming an apatite layer. The mechanical properties of the n-HA/nylon66 nanocomposites are discussed in terms of n-HA loading.     

Evaluation of mechanical behavior,bioactivity, and cytotoxicity of chitosan/akermanite-TiO2 3D-printed scaffolds for bone tissue applications

This report aimed to evaluate the mechanical behavior, bioactivity, and cytotoxicity of novel chitosan/akermanite-TiO₂ (CS/AK/Ti) composite scaffolds fabricated using the 3D-printing method. The morphological and structural properties of these scaffolds were characterized by Fourier transform spectroscopy (FTIR) and scanning electron microscopy (SEM). The mechanical behavior was examined by measuring the compressive strength, while the bioactivity was estimated in the simulated body fluid (SBF), and also the cytotoxicity of the scaffolds was assessed by conducting cell culturing experiments in vitro. It was found that the mechanical properties were considerably affected by the amount of TiO_2. The scaffolds had the possessed bone-like apatite forming ability, which indicated high bioactivity. Furthermore, L929 cells spread well on the surface, proliferated, and had good viability regarding the cell behaviors. The outcomes confirmed that the morphological, biological, and mechanical properties of developed 3D-composite scaffolds nearly mimicked the features of natural bone tissue. In summary, these findings showed that the 3D-printed scaffolds with an interconnected pore structure and improved mechanical properties were a potential candidate for bone tissue applications.     

Microstructure and properties of polycaprolactone/calcium sulfate particle and whisker composites

Polycaprolactone (PCL)/calcium sulfate (CS) particle and whisker composites were prepared by coprecipitation method and studied by evaluating their microstructure, crystallization, and mechanical properties. Results show that both of the CS whisker and particle dispersed in PCL can reduce the spherulite size of PCL and improve the regularity of the spherulite. The nucleation effect of the CS whisker is stronger than that of the CS particle. Mechanical properties of PCL were obviously improved by both of the particle and whisker addition. The flexural modulus and impact strength of the whisker composites are higher than that of the particle composites, which could be explained by the interfacial debonding mechanism. On the basis of the crystallization and mechanical studies, it is found that the size of spherulites and the concentration of CS particles and whiskers have played an important role in the improvement in mechanical properties of the composite. POLYM. COMPOS. 2012. © 2012 Society of Plastics Engineers     

In vitro apatite formation of calcium phosphate composite synthesized from fish bone

Calcium phosphate-based composite (CPC) is the main biomaterial substitute used for bone repair. Properties affecting bioactivity of this composite vary depending on the types of calcium phosphate crystalline phases. Hence, in this study, bioactivity behavior of novel CPC cement by the incorporation of calcium phosphate (CP), which was obtained from fish bones, dicalcium phosphate dehydrate, and chitosan solution, was monitored in simulated body fluid (SBF). In advance, the microstructure of CP produced by heat treatment (annealing) of fish bone was evaluated at two different temperatures 600 and 900°C. The X-ray diffraction (XRD) results showed that there was no secondary phase formation aside from natural hydroxyapatite (HA) in bones annealed; and the annealing process enhanced the crystallinity of CP phase in the bone matrix particularly when annealed at 900°C. After incubation of CPC cement in SBF, bone bonding ability and producing of biomimetic HA coat on the CPC cement surface were confirmed using XRD, fourier-transform infrared spectroscopy, and scanning electron microscopy. The analysis results show that needle-like and cauliflower apatite layer with the crystallite size about 100 nm was grown on the surface of CPC cement after 28 days incubation in SBF. Regardless of above findings, we conclude that varying the annealing temperature has tremendous effect on the production of natural HA from fish bone with required properties and the ultimate morphology of obtained CPC cements after soaking is directly depended on the degree of crystallinity of the prepared natural HA.     

Melt processing and characterization of tricalcium phosphate filled polybutylene adipate-co-terephthalate/polymethyl methacrylate composites for biomedical applications

Abstract

PBAT/PMMA/MA/TCP composites were prepared by melt blending and characterized by FTIR, XRD, SEM and in vitro bioactivity studies using SBF and cell viability tests. SBF studies revealed good bioactivity nature which was observed in SEM and confirmed by EDAX. Cell viability test revealed an excellent viability of squamous cells within 2?h than the control. Soil burial tests of the composites show fast degradation within 50 days under natural conditions. The tensile and hardness properties is marginally increased than that of PBAT/PMMA blend. These biocomposites can be used for the fabrication of medical devices by melt blending and injection molding process.     

Sodium–Bioglass/Polythene Composites

We present the studies conducted on sodium–bioglass/polythene (Na–BG/PE) composites and their bioactivity in simulated body fluid (SBF). Several compositions of Na–BG/PE composites were made by hot pressing and the activity studies of the samples were carried out by immersing the composites in SBF for periods of 7, 14, and 21 days. The activity of the samples was confirmed by the cauliflower-like growth of phosphates on the surface of the samples observed in an environmental scanning electron microscope and further confirmed by energy-dispersive X-ray spectrometry (EDS). X-ray diffraction showed the presence of various types of calcium phosphate phases. Ionic movement was observed by inductively coupled plasma atomic emission spectroscopy from the sample to the SBF solution and the reverse trend was observed on the surface of the sample by EDS. Modulus of rupture of the composites increased when the polymer content was increased up to 30% by weight of polythene, beyond which the processing of composites became difficult.     

In vitro bioactivity assessment and mechanical properties of novel calcium titanate/borosilicate glass composites

Bioactive calcium titanate/borosilicate glass composites were developed. Powder mixtures of borosilicate glass and 10, 20 or 30 wt% of potassium polytitanate particles were uniaxially pressed and sintered at 850 °C for 1 h. After heat treatment the reaction between potassium polytitanate and borosilicate glass produced composites consisting of calcium titanate particles embedded in a B-rich amorphous phase. For the in vitro bioactivity assessment sintered samples were immersed in a simulated body fluid (SBF) for 21 days under physiological conditions of pH and temperature. The compressive strength of the composites was also evaluated. A homogeneous and thick apatite layer was formed on all the materials tested. Furthermore, an appropriate compressive strength was observed (68-85 MPa). These results indicate that these composites are potential materials for bone tissue replacement and regeneration.     

The effect of antimicrobial peptide HX-12C on the properties of chitosan/polyacrylic acid hydrogel

Antimicrobial peptide (AMP) hydrogel is a novel biomaterial widely used in wound healing. However, there have been limited studies investigating the effect of AMP on hydrogel properties so far. Therefore, this study aimed to examine the influence of the AMP HX-12C on the chitosan/polyacrylic acid (CS/PAA) double-network (DN) hydrogel. The results showed that the mechanical properties of CS/PAA/HX-12C hydrogel are significantly improved compared with those of CS/PAA hydrogel. The maximum tensile stress increased from 41.0 to 258.5 KPa, and the compression stress required for 80% hydrogel deformation increased from 3.7 to 6.7 MPa. Furthermore, the thermal stability of CS/PAA/HX-12C showed a noticeable enhancement when compared with CS/PAA hydrogel. In addition, the CS/PAA/HX-12C hydrogel exhibited improved porosity and swelling performance. The addition of HX-12C significantly enhanced the antibacterial activity of the hydrogel against Escherichia coli and methicillin-resistant Staphylococcus aureus. Cytotoxicity test showed that the viability of L929 cell remained above 90% after treatment with CS/PAA/HX-12C hydrogel extract, indicating the good biocompatibility. In conclusion, AMP assuredly enhances the mechanical property, swelling performance and antimicrobial activity of hydrogel. The CS/PAA/HX-12C hydrogel shows potential for use as anti-infective medical material.