Employing the cyclophosphate to accelerate the degradation of nano-hydroxyapatite/poly(amino acid) (n-HA/PAA) composite materials

Owing to the good degradability and biocompatibility of polyphosphoesters (PPEs), the aim of the current study was to investigate a novel degradable composite of nano-hydroxyapatite/poly(amino acid) (n-HA/PAA) with cyclophosphate (CPE) via in situ melting polymerization to improve the degradation of n-HA/PAA. The structure of each composite was characterized via Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The degradation properties were studied in terms of the weight loss and pH in a phosphate-buffered saline (PBS) solution, while the surface morphology was examined using a scanning electron microscope-energy dispersive spectrometer (SEM-EDS) after soaking the surface in simulated body fluid (SBF). The cell proliferation, cell adhesion, and alkaline phosphatase (ALP) activity were used for the analysis of cytocompatibility. The weight loss results showed that the n-HA/PAA composite was 9.98 wt%, weighed after soaking in the PBS solution for 12 weeks, whereas the nano-hydroxyapatite/polyphosphoester-amino acid (n-HA/PPE-AA) composite was 46.94 wt%. The pH of the composites was in a suitable range between 6.64 to 7.06 and finally stabilized at 7.39. The SEM and EDS results revealed the formation of an apatite-like layer on the surface of the n-HA/PPE-AA composites after soaking in SBF for one week. The cell counting Kit 8 (CCK-8) assay of the cell culture in the leaching liquid of the n-HA/PPE-AA composites exhibited non-cytotoxicity and high-proliferation, and the cell adhesion showed the well spreading and normal phenotype extension of the cells on the n-HA/PPE-AA composites surface. Concurrently, the co-culture results of the composites and cells confirmed that the n-HA/PPE-AA composites exhibited a higher ALP activity. In summary, the results demonstrated that the n-HA/PPE-AA composites had a controllable degradation property, good bioactivity, and cytocompatibility.     

Generation of composites for bone tissue‐engineering applications consisting of gellan gum hydrogels mineralized with calcium and magnesium phosphate phases by enzymatic means

Mineralization of hydrogels, desirable for bone regeneration applications, may be achieved enzymatically by incorporation of alkaline phosphatase (ALP). ALP‐loaded gellan gum (GG) hydrogels were mineralized by incubation in mineralization media containing calcium and/or magnesium glycerophosphate (CaGP, MgGP). Mineralization media with CaGP:MgGP concentrations 0.1:0, 0.075:0.025, 0.05:0.05, 0.025:0.075 and 0:0.1 (all values mol/dm³, denoted A, B, C, D and E, respectively) were compared. Mineral formation was confirmed by IR and Raman, SEM, ICP‐OES, XRD, TEM, SAED, TGA and increases in the the mass fraction of the hydrogel not consisting of water. Ca was incorporated into mineral to a greater extent than Mg in samples mineralized in media A–D. Mg content and amorphicity of mineral formed increased in the order A < B < C < D. Mineral formed in media A and B was calcium‐deficient hydroxyapatite (CDHA). Mineral formed in medium C was a combination of CDHA and an amorphous phase. Mineral formed in medium D was an amorphous phase. Mineral formed in medium E was a combination of crystalline and amorphous MgP. Young's moduli and storage moduli decreased in dependence of mineralization medium in the order A > B > C > D, but were significantly higher for samples mineralized in medium E. The attachment and vitality of osteoblastic MC3T3‐E1 cells were higher on samples mineralized in media B–E (containing Mg) than in those mineralized in medium A (not containing Mg). All samples underwent degradation and supported the adhesion of RAW 264.7 monocytic cells, and samples mineralized in media A and B supported osteoclast‐like cell formation. Copyright © 2014 John Wiley & Sons, Ltd.     

Tuning of the surface biological behavior of poly(L-lactide)-based composites by the incorporation of polyelectrolyte complexes for bone regeneration

Poly(L-lactide)(PLLA)-based composites have been widely used for tissue regeneration. Novel polyelectrolyte complexes (PECs) consisted of carboxymethyl starch sodium (CMS) and chitosan oligosaccharide (COS) was fabricated and evaluated. The results suggested that the CMS/COS-PECs (CC-PECs) distinguished from the original polymers alone, presenting an amorphous structure. Then, the CC-PECs/PLLA composites were prepared by varying the relative amount of CC-PECs in the PLLA-matrix, demonstrated by means of the surface morphology, hydrophilicity, water uptake, in vitro degradability and primary cell responses. The results suggested that the CC-PECs physically attached on the PLLA surface enhanced the formation of the surface seepage network, which could target modification of the surface biological behavior of the materials. The phenomena had been evidenced by the performed tests in respect to hydrophilicity, water uptake and degradation in PBS, which also may provide effective support for cell adhesion and proliferation. Further, the CC-PECs/PLLA surfaces clearly promoted the adhesion and proliferation of MC3T3-E1 cells compared with PLLA materials, indicating excellent cytocompatibility. This study suggested that the CC-PECs/PLLA-50 composite with excellent biological behavior could be a promising candidate for bone repair.     

Evaluation of the cytocompatibility hemocompatibility in vivo bone tissue regenerating capability of different PCL blends

In this study, the optimized formulations of polycaprolactone (PCL) combined with poly(lactic-co-glycolic acid) (PLGA), gelatin (GEL), and biphasic calcium phosphate (BCP) were analyzed in terms of cytocompatibility with bone-related cells, hemocompatibility, and in vivo bone-regenerating capacity to determine their potentials for bone tissue regeneration. Fiber morphology of PCL/GEL and PCL/BCP electrospun mats considerably differs from that of the PCL membrane. Based on the contact angle analyses, the addition of GEL and PLGA was shown to reduce the hydrophobicity of these membranes. The assessment of in vitro cytocompatibility using MC3T3-E1 cells indicated that all of the membranes were suitable for pre-osteoblast proliferation and adhesion, with PCL/BCP having a significantly higher reading after seven days of incubation. The results of the in vitro hemocompatibility of the different fibrous scaffolds suggest that coagulation and platelet adhesion were higher for hydrophobic membranes (PCL and PCL/PLGA), while hemolysis can be associated with fiber morphology. The potential of the membranes for bone regeneration was determined by analyzing the microCT data and tissue sections of samples implanted in 5?mm sized defects (one and two months). Although all of the membranes were suitable for pre-osteoblast proliferation, in vivo bone regeneration after two months was found to be significantly higher in PCL/BCP (p?相似文献   

含石墨烯的聚乳酸复合纳米纤维的制备及细胞相容性

利用电纺丝技术制备了聚乳酸(PLLA)-石墨烯(Gr)复合纳米纤维。通过SEM、TEM及拉曼光谱观察和分析了该复合纳米纤维的形貌及Gr在PLLA中的分散状态,通过DSC、TG、力学拉伸及接触角测试等表征方法研究了PLLA-Gr复合纳米纤维的热性能、力学性能、亲水性等物理性能,最后,通过MTT法检测一种神经胶质细胞——雪旺细胞(SCs)在该复合纳米纤维支架上的生长和增殖行为,评价其细胞相容性。结果表明：低含量的Gr能较好地分散在PLLA纳米纤维中,且随着m(Gr)∶m(PLLA)从0增加到2.0%,所得到的纤维直径呈现先减小后增加的趋势。当m(Gr)∶m(PLLA)增加到1.0%时,PLLA-Gr纳米纤维的直径达到最小,为(0.50±0.19) μm,对应的拉伸强度较未添加Gr时增加也最大达50%。PLLA-Gr纳米纤维膜的结晶度与Gr的含量和分散性有关。细胞培养1、4、7 d后的MTT检测结果表明PLLA-Gr复合纳米纤维能促进SCs的黏附和生长。PLLA-Gr复合纳米纤维具有较好的细胞相容性。     

蚕丝-聚乳酸-羟基乙酸共聚物复合编织支架的力学性能及细胞相容性

背景：与通常的合成纤维相比,蚕丝力学性能好,又具有一定的延展性,是制作组织工程韧带/肌腱的良好支架材料,但蚕丝丝素纤维降解速度缓慢,难以与组织再生速率相匹配. 目的：分析蚕丝-聚乳酸-羟基乙酸共聚物编织绳状支架的力学性能及其与骨髓间充质干细胞体外共培养的细胞相容性. 方法：通过捻拧编织蚕丝-聚乳酸-羟基乙酸共聚物细丝混合支架,并以纤维连接蛋白作表面修饰,检测支架的力学性能.将兔骨髓间充质干细胞种植在蚕丝-聚乳酸-羟基乙酸共聚物细丝混合支架上进行体外共培养,观察细胞与支架复合生长、基质形成,以及细胞与支架结合的情况. 结果与结论：蚕丝-聚乳酸-羟基乙酸共聚物混合编织支架呈乳白色,质地均匀,韧性强,为螺旋上升的绳索状,直径为2.3 mm.支架材料的最大负荷、拉伸强度、断点伸长率、弹性模量分别为（315.06±30.77） N、（75.83±7.46） MPa、（61.39±7.26）%、（213.58±23.45） MPa.扫描电镜观察显示,骨髓间充质干细胞贴附于支架表面生长,增殖良好,细胞大多呈梭形,伸出伪足匍匐于材料的表面,形态较佳,伸展良好,呈立体状生长,并分泌基质.表明蚕丝-聚乳酸-羟基乙酸共聚物编织绳状支架具有良好的机械性能及细胞相容性.     

In vitro toxicologic study of chitin short fiber reinforced polycaprolactone composite

To investigate the cytotoxicity and cytocompatibility of chitin fiber reinforced polycaprolactone composite in vitro in order to provide useful scientific basis for clinical application. Methods: Cell morphology, observation,MTF and DNA assay were used to evaluate the influence of the composite on the morphology, growth and proliferation of cultured L-929 cells. Results: The composite did not impair the morphology of cultured cells in vitro. MTF and DNA assay demonstrated that the growth and proliferation of the cultured cells were not significantly inhibited by the composite. Conclusion: The composites have fine cytocompatibility and are safe for clinical use of reconstruction of chest wall defects.     

Influence of quaternization of ammonium on antibacterial activity and cytocompatibility of thin copolymer layers on titanium

Antimicrobial coatings are able to improve the osseointegration of dental implants. Copolymers are promising materials for such applications due to their combined properties of two different monomers. To investigate the influence of different monomer mixtures, we have been synthesized copolymers of dimethyl (methacryloxyethyl) phosphonate (DMMEP) and dipicolyl aminoethyl methacrylate in different compositions and have them characterized to obtain the r-parameters. Some of the copolymers with different compositions have also been alkylated with 1-bromohexane, resulting in quaternized ammonium groups. The copolymers have been deposited onto titanium surfaces resulting in ultrathin, covalently bound layers. These layers have been characterized by water contact angle measurements and ellipsometry. The influence of quaternary ammonium groups on antibacterial properties and cytocompatibility was studied: Activity against bacteria was tested with a gram positive Staphylococcus aureus strain. Cytocompatibility was tested with a modified LDH assay after 24 and 72 h to investigate adhesion and proliferation of human fibroblast cells on modified surfaces. The copolymer with the highest content of DMMEP showed a good reduction of S. aureus and in the alkylated version a very good reduction of about 95%. On the other hand, poor cytocompatibility is observed. However, our results show that this trend cannot be generalized for this copolymer system.     

In vitro cytocompatibility evaluation of MGF-Ct24E chemically grafted and physically blended with maleic anhydride modified poly(D,L-lactic acid)

As a growth repair factor, mechano-growth factor (MGF) and its 24 amino acid peptide analogs corresponding to the unique C-terminal E-domain (MGF-Ct24E) positively regulate bone regeneration. MGF-Ct24E was introduced into the poly(D, L-lactic acid) (PDLLA) to improve bone regeneration in our previous study. MGF-Ct24E-grafted PDLLA was chemically characterized and showed potential as a biofunctional polymer. In this study, we evaluated the cytocompatibility of MGF-Ct24E chemically grafted and physically blended with maleic anhydride modified PDLLA, relative to maleic anhydride modified PDLLA (MPLA) as the control. The surface properties of these three polymer films were characterized with scanning electron microscopy and X-ray photoelectron spectroscopy. Rat calvarial osteoblasts were seeded on the three polymer films, and cell adhesion, spreading, and proliferation were assessed with an inverted microscope, laser scanning confocal microscope, and a cell counting kit-8, respectively. The alkaline phosphatase activity and extracellular calcium production were exploited to characterize the differentiation and mineralization of rat calvarial osteoblasts on various polymer films. The results revealed that compared with MPLA, MGF-Ct24E-MPLA, and MGF-Ct24E/MPLA blends promoted adhesion, spreading, proliferation, and the later differentiation and mineralization process of rat calvarial osteoblasts. In addition, the positive effect of MGF-Ct24E-MPLA on rat calvarial osteoblasts was maintained longer than the MGF-Ct24E/MPLA blends. In conclusion, MGF-Ct24E-MPLA synthesized chemically might be a promising biomaterial for bone tissue engineering.     

Water-soluble polymers bearing phosphorylcholine group and other zwitterionic groups for carrying DNA derivatives

Water-soluble polymers with equal positive and negative charges in the same monomer unit, such as the phosphorylcholine group and other zwitterionic groups, exhibit promising potential in gene delivery with appreciable transfection efficiency, compared with the traditional poly(ethylene glycol)-based polycation–gene complexes. These zwitterionic polymers with various architectural structures and properties have been synthesized by various polymerization methods, such as conventional radical polymerization, atom-transfer radical-polymerization, reversible addition-fragmentation chain-transfer polymerization, and nitroxide-mediated radical polymerization. These techniques have been used to efficiently facilitate gene therapy by fabrication of non-viral vectors with high cytocompatibility, large gene-carrying capacity, effective cell-membrane permeability, and in vivo gene-loading/releasing functionality. Zwitterionic polymer-based gene delivery vectors systems can be categorized into soluble-polymer/gene mixing, molecular self-assembly, and polymer-gene conjugation systems. This review describes the preparation and characterization of various zwitterionic polymer-based gene delivery vectors, specifically water-soluble phospholipid polymers for carrying gene derivatives.