An N-substituted polyurea coating with high affinity for heparin

A new N-substituted polyurea with tertiary amino groups in the polycarbamidic chain (NPUTA) has been synthesized. The polymer is soluble in C1-C4 alcohols, has high adhesion to polar molds, and has high H2O uptake (130-150%). The material can be coated on many biomaterials (polyurethanes, charcoal hemosorbents, cellulosic hemodialysis membranes), and high amounts of heparin can be adsorbed onto treated surfaces. NPUTA cast from 0.5-3.5% ethanol solutions can absorb large amounts of heparin from anti-coagulant solution (40-60 micrograms/cm2) and heparinized plasma. Heparin release into phosphate buffered saline (PBS) solution or plasma is minimal. The influence of NPUTA solution concentration and pre-absorbed heparin on the protein adsorption, platelet adhesion, surface induced hemolysis, and complement activation of these films has been investigated. Radiolabeled protein assays, radiolabeled platelet assays, and other methods were used. It was shown that modified surfaces for the listed materials, with heparinization, demonstrate improved in vitro blood compatibility without any changes in functional properties. For example, treatment with NPUTA/heparin does not reduce sorption of middle molecules by activated charcoal hemosorbent, while markedly and significantly decreasing platelet adhesion and complement activation. NPUTA/heparin modified, glutaraldehyde treated bovine pericardium exhibited significantly reduced calcification in a rat subcutaneous implant model. Other ex vivo circulation experiments also confirm the blood compatibility of different NPUTA treated surfaces.     

Hemocompatible cellulose dialysis membranes modified with phospholipid polymers

Hemocompatibility is one of the most important properties for hemodialysis membranes. For improvement of the hemocompatibility on a cellulose dialysis membrane, modifications with new blood-compatible phospholipid polymers were carried out. These methods included a direct grafting of the phospholipid monomer on the membrane surface, coating the membrane surface with a water-soluble graft copolymer composed of a cellulose backbone and phospholipid polymer as a branch, and covalent bonding with a reactive phospholipid polymer on the membrane surface. These modified membranes could reduce protein adsorption as well as complement activation and platelet adhesion on the surface without any adverse effects on the membrane performance.     

Synthetically modified cellulose (SMC): a cellulosic hemodialysis membrane with minimized complement activation

More dialysis treatments have been performed with cellulose based membranes than with any other material. As unmodified cellulose membranes activate the complement system, much effort has been directed toward the development of noncomplement activating cellulose membranes. One successful approach was the substitution of -OH groups in the cellobiose units of the cellulose molecule with tertiary amino groups, which resulted in a membrane called Hemophan. Synthetically modified cellulose (SMC) is a new hemodialysis membrane made by specific chemical modification whereby aromatic benzyl groups are covalently introduced into the cellulosic structure by ether bonds, creating hydrophobic domains within the overall hydrophilic cellulose surface: basic research investigations have shown that a characteristic hydrophobic-hydrophilic balance of surfaces is a prerequisite for improved hemocompatibility. Several cellulose modifications with aliphatic and aromatic groups were performed to achieve a membrane with the desired hemocompatibility profile; SMC, having hydrophobic benzyl groups, causes minimal activation of blood complement, coagulation, and cell activation systems. In vitro experiments with blood showed that C5a generation for SMC was reduced by 94% relative to Cuprophan (compared with 96% for polysulphone, a synthetic hemodialysis membrane). Activation of coagulation (formation of the thrombin-antithrombin III complex [TAT]) in a clinical study showed that SMC caused 16 ng/ml TAT generation compared with 36 ng/ml for polysulphone. SMC, a low-flux cellulosic dialysis membrane, thus combines the typically high diffusive performance characteristics of cellulosic membranes with excellent hemocompatibility, matching synthetic dialysis membranes.     

Characterization of Ceramic Composite-Membranes Prepared by ORMOSIL Coating Sol

Sol-gel methods offer many advantages over conventional slip-casting, including the ability to produce ceramic membranes. They are purer, more homogeneous, more reactive and contain a wider variety of compositions. We produced ormosil sol using sol-gel process under different molecular weight of polymer species [polyethylene glycol (PEG) ] in total system [Tetraethyl ortho silicate(TEOS)-polyethylene glycol (PEG)]. The properties of as-prepared ormosil sol such as,viscosity, gelation time were characterized. Also, the ceramic membrane was prepared by dip-coating with synthetic sol and its micro-structure was observed by scanning electron microscopy. The permeability and rejection efficiency of membrane for oil/water emulsion were evaluated as cross-flow apparatus. The ormosil sol coated Membrane is easily formed by steric effect of polymer and it improves flux efficiency because infiltration into porous support decreased. Its flux efficiency is elevated about 200(1/m2·h) compared with colloidal sol coated membrane at point of five minutes from starting test.     

A neutron reflectivity study of polymer-modified phospholipid monolayers at the solid-solution interface: polyethylene glycol-lipids on silane-modified substrates

The structure of polymer-decorated phospholipid monolayers at the solid-solution interface was investigated using neutron reflectometry. The monolayers were composed of distearoylphosphatidylethanolamine (DSPE) matrixed with varying amounts of DSPE-PEG (DSPE with polyethylene glycol covalently grafted to its headgroup). Mixed lipid monolayers were Langmuir-Blodgett deposited onto hydrophobic quartz or silicon substrates, previously hydrophobized by chemically grafting a robust monolayer of octadecyltrichlorosilane (OTS). We show that this method results in homogeneous and continuous phospholipid monolayers on the silanated substrates and determine that the grafted PEG chains extend away from the monolayers into the solvent phase as a function of their density, as expected from scaling theories. In addition, ligands were coupled to the end of the PEG chains and selective binding was demonstrated using fluorescence microscopy. Our results demonstrate that these constructs are ideal for further characterization and studies with well-defined monomolecular films.     

In vitro blood compatibility of surface-modified polyurethanes

Polyurethanes have proven durable materials for the manufacture of flexible trileaflet heart valves, during in vitro tests. The response of two polyurethanes of differing primary structure to parameters of blood compatibility has now been investigated, using an in vitro test cell. Platelet (beta-thromboglobulin) release, complement (C3a) activation, the activation of free plasma and surface-bound factor XII were studied using fresh, human blood (no anticoagulant) or citrated plasma in control and surface-modified polyurethane. Surface modifications were designed to affect material thrombogenicity and included covalent attachment of heparin, taurine, a platelet membrane glycoprotein fragment, polyethylene oxide (PEO), 3-aminopropyltriethoxysilane, and glucose or glucosamine. Unmodified control polyurethanes caused platelet release and complement activation. High molecular weight (2000 D) polyethylene oxide reduced platelet release slightly but only glucose attachment to the surface produced a significant reduction in platelet activation. All modifications reduced C3 activation compared with controls, but the greatest reduction was achieved with polyethylene oxide attachment or glycosylation. Most surface modifications were more activating of factor XII, both in plasma and on the material surfaces, than the control polyurethanes. Heparin and high molecular weight PEO produced the greatest activation of factor XII in the free plasma form, but low molecular weight PEO and glucosamine produced the greatest activation of surface-bound factor XIIa. The least activating surfaces, affecting both free plasma and surface-bound factor XIIa, were those treated with platelet membrane glycoprotein fragment and glucose. PEO surfaces performed relatively well, compared with controls and most surface modifications. The best overall surface, however, was the glucose-modified surface which was least activating considering all parameters of blood compatibility.     

A new blood compatible and permselective hollow fiber membrane for hemodialysis

The authors have prepared a blood compatible and highly permselective hemodialysis membrane composed of polyether segmented nylon. This block copolymer was synthesized by polycondensation of bis-3-aminopropyl-poly(tetramethylene oxide) (PTMO) and poly(imino-1,3-bismethyl-cyclohexyl-iminoisophtharoyl) (NyBl) prepolymer obtained by polycondensation of 1,3-bis(aminomethyl)cyclohexane (B) and isophthalic acid (I). The molecular weight (MW) calculated from the number of end-groups was 16,000-21,000. In vitro blood compatibility was evaluated in terms of platelet adhesion onto the surface. PTMO-NyBl surfaces showed excellent platelet adhesion preventing properties. The PTMO-NyBl hollow fiber membrane was obtained by a dry-wet spinning process. The membranes had higher permeability coefficients for macromolecules ranging from MW 10,000 to 20,000 than polysulfone hollow fiber membrane (PS membrane), and had acceptably low albumin permeability for use as a dialysis membrane. The ex vivo blood compatibilities of PTMO-NyBl membrane and PS membrane were investigated by extracorporeal circulation in a pig model. The PTMO-NyBl membrane gave excellent results when assessing hemodialysis leukopenia, oxidative burst, and free platelet count decrease.     

Endgroup analysis of polyethylene glycol polymers by matrix-assisted laser desorption/ionization Fourier-transform ion cyclotron resonance mass spectrometry

Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) by external injection of matrix-assisted laser desorbed and ionized (MALDI) polymers offers good possibilities for characterization of low molecular weight homopolymers (MW range up to 10 kDa). The molecular masses of the molecular weight distribution (MWD) components of underivatized and derivatized (dimethyl, dipropyl, dibutyl and diacetyl) polyethylene glycol (PEG) 1000 and 4000 were measured by MALDI-FTICR-MS. These measurements have been performed using a commercial FTICR spectrometer with a home-built external ion source. MALDI of the samples with a 2,5-dihydroxybenzoic acid matrix in a 1000:1 matrix-to-analyte molar ratio produces sodiated molecules in a sufficient yield to trap the ions in the ICR cell. The masses of the molecular weight distribution of PEG components were measured in broad-band mode with a mass accuracy of < 5 ppm in the mass range around 1000 u and within 40 ppm accuracy around 4000 u. From these measurements, the endgroup mass of the polymer was determined by correlation of the measured component mass with the degree of polymerization. The masses of the PEG endgroups have been determined within a deviation of 3-10 millimass units for the PEG1000 derivatives and 10-100 millimass units for the PEG4000 derivatives, thus confirming the identity of the distal parts of the model compounds.     

Nitric oxide prevents human platelet adhesion to fiber membranes in whole blood

During cardiopulmonary bypass or long-term extracorporeal life support, foreign surface induced platelet deposition in the oxygenator causes deterioration of gas exchange. In this study, the authors evaluated the effectiveness of nitric oxide (NO) in reducing the adhesion of platelets in whole blood to the surface of hollow fiber membranes. For this purpose, a test chamber was designed consisting of a gas exchanger with ten mitsubishi multi-layered composite hollow fibers (MHF: 257 mm OD; 203 mm ID; 70 mm length) and a polypropylene tube (16 mm OD; 100 mm length). Pure N2 (control) or nitric oxide (NO) (100 ppm, 200 ppm in N2) were delivered into the test chamber previously filled with 13 ml human whole blood. Platelet counts and platelet factor 4 (PF4), as a measure of platelet activation, were measured before and after either 1 or 2 hr of testing, and fibers were observed under scanning electron microscopic study (SEM) after each experiment. In the control and 100 ppm NO groups, platelet counts decreased and the level of PF4 increased during the 1 hr period. In the 200 ppm NO group, almost no platelet deposition could be observed on the surface of fibers under SEM. In conclusion, NO flow through hollow fiber membranes can markedly reduce platelet adhesion. Additional quantitative studies should define the optimal concentration for this effect and determine if this finding could improve oxygenator function, especially under conditions of long-term support.     

Thirst and sodium appetite after colloid treatment in rats: Role of the renin-angiotensin-aldosterone system.

Recent experiments indicated that rats usually develop sodium appetite 5 hrs after sc injection of polyethylene glycol (PEG) solution. However, sodium appetite appeared within 30–60 min if the rats had been maintained on sodium-deficient diet instead of Purina chow for 2–4 days previously. Elevated levels of aldosterone paralleled the appearance of NaCl consumption in both circumstances. In the present experiments, with 65 male albino Sprague-Dawley rats, sodium appetite was no longer potentiated by pretreatment maintenance on sodium-deficient diet when the hypersecretion of aldosterone after PEG administration was prevented by prior hypophysectomy. Conversely, sodium appetite was enhanced in PEG-treated Ss when angiotensin II (AII) was produced in unusually large amounts in the brain, owing to the systemic administration of captopril. This latter effect occurred even when drinking water was withheld and plasma sodium concentrations were markedly elevated. These and other findings raise the possibility that the normal secretion of aldosterone in rats after PEG treatment might permit physiological amounts of AII to be effective in stimulating sodium appetite. Such actions would complement the accepted physiological role of the renin-angiotensin-aldosterone system in the maintenance of blood pressure and sodium balance. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Alkylation of cellulosic membranes results in reduced complement activation

4-Vinyl pyridine was grafted to the surface of the cellulosic membrane Cuprophan, and subsequently alkylated with both C10 and C16 aliphatic chains. Complement activation of heparinized human blood, corrected for anaphylatoxin adhesion, was measured by radioimmunoassay. The surface treatments both yielded substantial reductions in C5a activity, with a lessor reduction in C3a and C4a activity. Alkylation with 10 and 16 carbon chains resulted both in enhancements of albumin adsorption and stability. These enhancements as well as the reductions in complement activation were statistically indistinguishable between the two treatments. The reduction in complement activation was influenced more by adsorption of endogenous albumin and possibly by the vinyl pyridine graft, than the removal of surface active hydroxyl groups from Cuprophan.     

An adiabatic multiple spin-echo pulse sequence: removal of systematic errors due to pulse imperfections and off-resonance effects

Poly(2-methacryloyloxyethyl phosphorylcholine) (pMPC) was grafted onto the surface of a silicon rubber (SR) membrane (pMPC-SR) by plasma induced grafted copolymerization (PIP). Argon plasma was used to activate the SR surfaces. Determination was also made of the influences of grafted copolymerization reaction time, reaction temperature, and monomer concentration on polymerization yield. The surface properties of SR were characterized by ATR-FTIR, ESCA, and SEM. In those analyses the ATR-FTIR spectra indicated that the pMPC grafted onto the SR surface at 1720 and 3300 cm(-1). The elemental composition and different carbon bindings on the surface of the SR were examined by ESCA. An increasing P1s/C1s value g was obtained in the grafted polymerization yield with a concentration of 0.05-0.5M of MPC in the isolated ethanol solution. The surface morphologies of pMPC-SR differed more than those of control and Ar plasma treated surfaces. The difference could have been caused by the homogeneous graft polymerization of pMPC onto the SR membrane. In the biological analyses, protein adsorption on pMPC-SR surfaces was reduced. The reduced level increased with an increase in the pMPC grafted amount. The epithelial cell attachment and growth onto these samples were suppressed. The blood compatibility for a series of pMPC-SR surfaces was examined by platelet adhesion. Blood platelet morphologies in contact with the high ratio of pMPC-SR surfaces were maintained, meaning that in this case the release reaction for platelets never occurred. Consequently, the high amount of pMPC-SR surface had excellent blood compatibility, further suggesting that prevention of adhesion, activation of platelets, and adsorption of blood protein could be achieved.     

Thrombogenic properties of untreated and poly(ethylene oxide)-modified polymeric matrices useful for preparing intraarterial ion-selective electrodes

In vitro platelet adhesion studies are used to compare the thrombogenic properties of various polymer matrices useful for preparing implantable ion-selective membrane electrodes. Conventional plasticized poly(vinyl chloride) and alternate polyurethane materials (Tecoflex, Pellethane) doped with proton- (tridodecylamine) and potassium-selective (valinomycin) ionophores are shown to be potentially thrombogenic. Incorporation of high molecular weight block copolymers of poly(ethylene oxide) and poly(propylene oxide) (e.g., Pluronic F108 and Tetronic 1508) within ion-selective membranes reduces platelet adhesion. A more marked decrease in platelet adhesion is, however, observed when the Tecoflex-based membranes are coated with a thin photo-cross-linked layer of poly(ethylene oxide). Such surface-modified membranes are shown to retain potentiometric ion response properties (i.e., selectivity, response times, response slopes, etc.) essentially equivalent to untreated membranes.     

Role of water in protein kinase C catalysis and its binding to membranes

The role of hydration in the catalytic activity and membrane binding of rat brain protein kinase C (PKC) was investigated by modulating the activity of water with polyethylene glycols with molecular weights of 1000-20000 and dextran with a molecular weight of 20000. These polymers create an osmotic stress due to their exclusion from hydration shells and crevices on proteins, causing dehydration. Polymers larger than 1000 caused an activation of the PKC-catalyzed phosphorylation of histone, while PEG 1000 had no significant effect. The extent of activation by PEG and dextran 20000 was larger than that of PEG 6000 or 8000 when vesicles were composed of 1:1 POPS/POPC, suggesting the presence of at least two distinct regions of exclusion on PKC: one inaccessible to PEGs larger than 1000 and the other inaccessible only to PEGs of > 10000. The extent of activation was dependent on the composition of the vesicles used. If basal activity (without PEG) was low (e.g. with low PS content in membranes), then the extent of activation was similar for all polymers larger than 1000. Binding of PKC to membranes containing 50 mol % PS was unaffected by PEG 6000 but was inhibited by PEG 20000. At a low PS content of 10%, both PEG 6000 and 20000 inhibited binding. This suggests that PKC becomes hydrated upon binding to membranes. Under conditions in which all of the enzyme is membrane-bound, both Km and Vmax for the phosphorylation of histone increased linearly with osmotic stress induced by PEG 6000. Thus, PKC becomes hydrated with 2311 +/- 476 water molecules upon binding of histone and is dehydrated by 1349 +/- 882 water molecules in going to the transition state. Km and Vmax for phosphorylation of the MARCKS peptide also increase with osmotic stress induced by PEG 6000. When protamine sulfate was used as a substrate (cofactor-independent), Vmax for the reaction was unaffected, but Km decreased with osmotic pressure (with PEG 6000), suggesting that PKC becomes dehydrated upon binding protamine. Similar results were found with a peptide substrate derived from the pseudosubstrate site of PKC epsilon. Since dextran, a polymer unrelated in structure to PEG, could cause a similar activation of PKC, the effects seen are likely due to osmotic stress and not to specific binding of PEG to PKC. Also, results obtained with PE-linked PEG were opposite to those with free PEG. PE-linked PEGs of 2000 and 5000 caused an inhibition of PKC-catalyzed phosphorylation of histone when present in membranes. If a specific interaction occurred with PEG, this would be expected to occur even with PE-PEG. The effects observed with free PEG are also independent of ionic strength. Free PEG had no effect on the bilayer to hexagonal phase transition temperature of DEPE membranes, suggesting that the effects on PKC activity are not a consequence of changes in membrane properties at the osmotic pressures used.     

Analysis of chromatin structure in vivo

Comb-like polyethylene oxide (PEO) surfaces were prepared on low-density polyethylene (PE). The comb-like PEO chain density was changed gradually along the sample lengths by corona discharge treatment with gradually increasing power and the following graft copolymerization of poly(ethylene glycol) monomethacrylate macromers (PEO-MA). The macromers with different PEO repeat unit, 1, 5, and 10, were used. The prepared comb-like PEO gradient surfaces were characterized by water contact angle, Fourier transform infrared spectroscopy in the attenuated total reflectance mode, and electron spectroscopy for chemical analysis. All these measurements indicated that the PEO chains are grafted on the PE surface with gradually increasing density of PEO. Plasma protein adsorption and platelet adhesion on the PEO gradient surfaces decreased with increasing PEO chain length and surface density. As observed by scanning electron microscopy, PEO10-MA-grafted surface with high PEO density was very effective in preventing protein adsorption and platelet adhesion and did not activate the platelets.     

Effects of dialysis membranes on the kinetics of tumor necrosis factor-alpha production by peripheral mononuclear cells in chronic hemodialysis patients

To evaluate the biocompatibility of dialysis membranes, blood samples were collected from 10 hemodialysis patients immediately before dialysis and peripheral blood mononuclear cells were isolated. The 3.0 x 10(5) cells/ml were then passed 30 times through modules made of a polyethylene glycol-grafted cellulose membrane, a polyacrylonitrile membrane, and a polysulfone membrane. Expression of messenger RNA for tumor necrosi factor-alpha (TNF-alpha) was determined. Cells were also cultured for 2 h with and without lipopolysaccharide and TNF-alpha levels in the supernatant were measured. TNF-alpha messenger RNA expression was significantly higher immediately after passage through the polyacrylonitrile membrane compared with the other membranes. Cells cultured without lipopolysaccharide, produced significantly less TNF-alpha after passage through the polysulfone membrane, while lipopolysaccharide significantly increased TNF-alpha production by cells passed through the polyacrylonitrile membrane. These results suggest that biocompatibility differs even among dialysis membranes believed to cause no complement activation.     

Protein and platelet interactions with thermally denatured fibrinogen and cross-linked fibrin coated surfaces

In this work the hypothesis that a mature, cross-linked fibrin clot, pre-formed on a biomaterial, may be relatively nonthrombogenic was investigated. A cross-linked fibrin layer was formed on polyethylene which had been precoated with thermally denatured fibrinogen. Plasma protein adsorption and platelet interactions with the cross-linked fibrin and denatured fibrinogen surfaces were investigated. The adsorption of albumin, fibrinogen, and fibronectin from plasma was measured. For all three proteins, the cross-linked fibrin surface exhibited much higher levels of adsorption than either the thermally denatured fibrinogen or the polyethylene surface. Vroman peaks were observed for fibrinogen and fibronectin on polyethylene but not on the cross-linked fibrin and thermally denatured fibrinogen materials. In dilute plasma the thermally denatured fibrinogen surface showed considerable resistance to protein adsorption. However, at plasma concentrations greater than about 5% normal, this protein resistance was apparently lost. Platelet interactions (adhesion and release of granule constituents from adherent platelets) using suspensions of washed platelets in the presence of red cells were investigated at shear rates of 50, 300, and 525 s(-1) using a cone and plate apparatus. The levels of platelet adhesion on the different surfaces were in the order: adsorbed fibrinogen > cross-linked fibrin > thermally denatured fibrinogen = polyethylene. Platelets on the cross-linked fibrin surface also showed high levels of release indicating significant platelet activation. Scanning electron microscopic observations were in agreement with the platelet adhesion and release data, showing only a few (but well-spread) adherent platelets on the cross-linked fibrin surface.     

Possible sources of right-to-left shunting in patients following a total cavopulmonary connection

Although bone wax is effective at achieving hemostasis, it is nonresorbable, causes a foreign body reaction, and inhibits osteogenesis. We report development of a polyethylene glycol/microfibrillar collagen composite (PEG/MFC) that has inherent hemostatic qualities, is biodegradable, and is compatible with bone repair. PEG/MFC composite (n = 42) was placed in 5 mm cranial defects in New Zealand white rabbits. Hemostasis and healing were compared to unfilled defects (n = 32) and defects filled with standard bone wax (n = 10). Both PEG/MFC and bone wax handled well and stopped bleeding. The polyethylene glycol component was resorbed by 8 h, and the microfibrillar collagen was resorbed over 2 months, eliciting only a minor inflammatory response during the first month. Defects filled with the PEG/MFC composite showed similar amounts of bony regeneration as did unfilled control defects. At 4 weeks, healing bone accounted for 43 +/- 13% in those treated with PEG/MFC and 47 +/- 19% defect area in untreated holes. In contrast, less than 1% of the area was bone in defects filled with bone wax (p < 0.05). PEG/MFC composite provided excellent bony hemostasis and did not inhibit bone growth.     

Role of surface glycoproteins in human platelet function

Glycoproteins present at the external surface of cells probably play specific roles in cellular function. Increasing evidence suggests that the glycoproteins span the plasma membrane with the bulk of the bound carbohydrate asymmetrically distributed on the outer surface. Micellar association of glycoproteins in membranes leads to pore formation and functional roles in transport through the membrane, while surface glycoproteins have been shown to be enzymes, to determine cell specificity and contribute to the cell surface change. The platelet plasma membrane contains 3 major glycoproteins, glycoproteins I, II and III as characterized in order of their decreasing molecular weight. Glycoprotein I appears to have the highest sialic acid content and to give rise to a platelet specific acidic macroglycopeptide on trypsin digestion. Specific glycoprotein abnormalities in the platelets of patients with Glanzmann's thrombasthenia suggest that the glycoproteins play a role in the mechanism of platelet aggregation. A much reduced content of glycoprotein I in the platelets of 2 patients with the Bernard Soulier syndrome may be associated with their defective adhesion to subendothelium and indicates a possible relationship on the platelet surface with the von Willebrand factor protein. Preliminary evidence suggests that in common with other plasma membranes the platelet membrane has a fluid structure and that the organization of the glycoproteins on the platelet surface is extremely sensitive to stimuli and susceptible to change.     

Collagen/apatite coating on 3-dimensional carbon/carbon composite

A three-dimensional carbon/carbon composite (3D C/C) was studied as potential bone-repairing material; its major mechanical properties were found to be closer to those of human bone than other common bone-repairing materials available. In vitro calcification tests revealed that as-received 3D C/C is almost bioinert in simulated body fluid (SBF) over an immersion period of 4 weeks. To improve the bioactivity of 3D C/C, surface modification was accomplished through two practical routes: (1) grafting with polyethylene glycol (PEG) and (2) phosphorylation and precalcification. After grafting with alpha, omega di(aminopropyl) polyethylene glycol 800 (NH2-PEG-NH2), a continuous layer of calcium phosphate was formed on the surface of 3D C/C in SBF after 4 weeks. Phosphorylated 3D C/C samples have the ability to induce apatite precipitation after precalcification in a saturated Ca(OH)2 solution for 1 week. To speed up the coating process, a calcification solution with collagen was developed in which a collagen/apatite coating layer can be formed on 3D C/C in 9 h in ambient conditions.