Enhanced biological and mechanical properties of well-dispersed nanophase ceramics in polymer composites: From 2D to 3D printed structures

An ideal orthopedic implant material should rapidly induce new bone formation and infiltration and completely integrate with juxtaposed bone. Such materials should also possess sufficient initial mechanical strength for load-bearing applications and should maintain mechanical integrity until new bone formation is complete and the material can fully degrade afterwards. In an effort to create such orthopedic biomaterials, in this study, nano-sized ceramics were combined with the tunable degradability and deformability properties of a select polymer (poly-lactide-co-glycolide, or PLGA). Specifically, nano-titania was chosen as a model ceramic particle (since titania is the natural oxide that forms on the widely implanted titanium) and was dispersed in a PLGA matrix using controlled sonication to imitate the nano-sized surface features and distribution of nano-ceramics in/on natural bone. The influence of surface properties (such as topography, surface area and surface roughness) on cell–material interactions was investigated. The results demonstrated that osteoblast (bone-forming cell) adhesion was the greatest when surface roughness values of the composites were closer to that of natural bone. Moreover, in vitro degradation studies demonstrated that the dispersion of nanophase titania in PLGA decreased the harmful acidic pH changes of PLGA as it degraded. From a mechanical property perspective, compared to agglomerated nano-titania in PLGA composites, well-dispersed nanophase titania in PLGA improved the tensile modulus and the strength of these composites. Lastly, in order to further mimic the hierarchical structure of bone and improve bone–material integration, a novel aerosol-based 3D printing technique was used for the first time to create nanostructured bone-like 3D ceramic/polymer composites. Osteoblast interactions with these 3D scaffolds provided evidence of further promoted bone cell infiltration into such 3D structures. In summary, this study fabricated and evaluated a promising new orthopedic nanocomposite and in doing so, elucidated a means to mimic the hierarchical macro- and nano-structure of natural bone to promote bone cell functions.     

Nanophase hydroxyapatite and poly(lactide-co-glycolide) composites promote human mesenchymal stem cell adhesion and osteogenic differentiation in vitro

Human mesenchymal stem cells (hMSCs) typically range in size from 10 to 50 μm and proteins that mediate hMSC adhesion and differentiation usually have a size of a few nanometers. Nanomaterials with a feature size smaller than 100 nm have demonstrated the unique capability of promoting osteoblast (bone forming cell) adhesion and long-term functions, leading to more effective bone tissue regeneration. For new bone deposition, MSCs have to be recruited to the injury or disease sites and then differentiate into osteoblasts. Therefore, designing novel nanomaterials that are capable of attracting MSCs and directing their differentiation is of great interest to many clinical applications. This in vitro study investigated the effects of nanophase hydroxyapatite (nano-HA), nano-HA/poly(lactide-co-glycolide) (PLGA) composites and a bone morphogenetic protein (BMP-7) derived short peptide on osteogenic differentiation of hMSCs. The short peptide was loaded by physical adsorption to nano-HA or by dispersion in nanocomposites and in PLGA to determine their effects on hMSC adhesion and differentiation. The results showed that the nano-HA/PLGA composites promoted hMSC adhesion as compared to the PLGA controls. Moreover, nano-HA/PLGA composites promoted osteogenic differentiation of hMSCs to a similar extent with or without the presence of osteogenic factors in the media. In the MSC growth media without the osteogenic factors, the nanocomposites supported greater calcium-containing bone mineral deposition by hMSC than the BMP-derived short peptide alone. The nanocomposites provided promising alternatives in controlling the adhesion and differentiation of hMSCs without osteogenic factors from the culture media, and, thus, should be further studied for clinical translation and the development of novel nanocomposite-guided stem cell therapies.     

The role of nanocrystalline titania coating on nanostructured austenitic stainless steel in enhancing osteoblasts functions for regeneration of tissue

In the context of osseointegration of metallic implants, while nanostructuring the surface favorably modulates cellular response, the disinfective attributes required during the healing process are not available. Thus, in the present study, we demonstrate that nanocrystalline titania provides cumulative benefit of enhancing osteoblasts functions to promote the efficacy of metal implants together with the disinfective attributes. To this end, the primary objective here is to examine the select functions of bone forming cells (osteoblasts) on electrocrystallized nanonodular titania-coated nanograined/ultrafine grained (NG/UFG) austenitic stainless steel. The accompanying objective is to study the disinfective/antimicrobial activity. To the best of our understanding this is the first study of nanophase titania on a non-titanium substrate. The osteoblasts functions were investigated in terms of cell attachment, proliferation, and quantitative analysis of proteins, actin and vinculin. In comparison to the bare NG/UFG substrate, the nanophase titania-coated substrate exhibited higher degree of cell attachment and proliferation which are regulated via cellular and molecular interactions with proteins, actin and vinculin. The enhanced functions of osteoblasts suggest that nanophase titania adsorbs extracellular matrix proteins, fibronectin and vitronectin from serum enhancing protein, with subsequent binding of integrins and osteoblasts precursor to titania. The antimicrobial attributes assessed in terms of degradation of methyl orange and effectiveness in killing E. coli supports the viewpoint that large surface area of titania would be instrumental in reducing the detrimental effect of biologically reactive oxygen species produced by macrophages in the vicinity of the metal bone/implant interface. In summary, the study provides some new insights concerning nanostructuring of metallic substrates with specific physical and surface properties for medical devices with significantly improved cellular response.     

Study on dispersion and electrical property of multi-walled carbon nanotubes/low-density polyethylene nanocomposites

Sonication is one of the promising approaches to disperse nanoparticles into the base material thoroughly. Furthermore, coupling treatments for MWNTs and polymer matrix also contribute to homogenous dispersion of MWNTs among polymer matrix. In this paper, MWNTs and KH-550 were dispersed with acetone via sonication method, then, the MWNTs/low density polyethylene (LDPE) composites was prepared by using melt blending process. Effects of MWNTs and LDPE coupling treatment on dispersion and electrical property of the MWNTs/LDPE nanocomposites were investigated. SEM observation on fracture surfaces of the nanocomposites explained the functions of sonication and coupling treatment on the dispersion, and electrical conductivity of the nanocomposites was measured by four-contact scheme. The results displayed that the optimum sonication temperature was 70 °C and the optimum sonication amount of MWNTs particles in 200 ml KH-550 acetone solution was 20 g. Moreover, dispersion of the nanocomposites was improved with increasing sonication power amplitude. Furthermore, dispersion and electrical conductivity of the nanocomposites with coupling treatment LDPE were better than those of the nanocomposites with uncoupling treatment LDPE. The good dispersion and electrical conductivity enhancement are based on the strong bonding and coupling reaction of MWNTs and LDPE matrix, which associated greatly with sonication and coupling treatment.     

Increased functions of osteoblasts on nanophase metals

In a recent study, researchers demonstrated that metal surfaces utilizing low-micron to nanophase topography fostered increased adhesion of osteoblasts, the cells that create the matrix of bone. In this study, Ti, Ti6Al4V, and CoCrMo alloys were investigated, and these alloys were identical to current orthopedic implant alloys except for surface topography. The objective of this in vitro research was to determine whether these same nanophase metal surfaces not only foster osteoblast adhesion but also increase osteoblast metabolic activities leading to calcium deposition. Light microscopy and Energy Dispersion Spectroscopy (EDS) were used to verify the presence of calcium and phosphorous deposition by osteoblasts cultured on the metal substrates. Results indicated that both calcium and phosphorous were deposited on several of the metal substrates. More importantly, compared to conventional metals, results provided the first evidence that more calcium and phosphorous was deposited by osteoblasts cultured on respective nanophase metals (Ti, Ti6Al4V, and CoCrMo). Nanophase CoCrMo had the most calcium and phosphorous minerals deposited by osteoblasts compared to any other metal substrate. Thus, the results of this study continue to provide evidence for the use of nanophase metals for the design of the next generation of more successful orthopedic implants.     

Preliminary Study on Aluminium-based Nanophase Composites Al_(88)Ni_(10)Y_2 and Al_(88)Ni_8Y_4

A new kind of aluminium-based alloy part amorphous/part crystalline, can be produced directlyby rapid quenching of the liquid. These materials have a novel structure of nanometer-sizedcrystals in an amorphous matrix and quite remarkable mechanical properties. The materialscan be considered to be nanophase composites. In this work Al88Ni10Y2 and Al88Ni8Y4 (atpct) nanophase composites consisting of a nanoscale dispersion of fcc-Al crystallites uniformlydispersed in an amorphous matrix, have been produced by melt-spinning. They have much highermicrohardness HV than fully amorphous alloys with the same composition. while retaining goodbending ductility The volume fraction, crystallite size and distribution of the fcc-Al phase havebeen estimated by DSC. X-ray diffraction and TEM. lt is found that the microstructure andproperties of the nanophase composites are very sensitive to the composition and the quenchingconditions. lncreasing the Y contedt and decreasing the Ni content at a given Al content givesmuch smaller dispersed nanophase aluminium crystallites. The volume fraction and crystallitesize of the fcc-Al phase increase with a decrease of wheel speed (quenching rate). The effectsof Y and Ni contents on the ease of formaticn of the nanophase composites are discussed. Theorigins of the novel mechanical properties are also considered.     

Dispersion of multi-walled carbon nanotubes and its effects on the properties of cement composites

In this study, two types of multi-walled carbon nanotubes (pristine, p-CNT and functionalized, f-CNT) were dispersed in water by sonication and then added to cement mortar. The purpose of this study was to characterize the dispersion degree of the CNTs in aqueous suspension and to investigate whether achieving dispersion in water would also result in dispersion inside mortar. Dispersion of the CNTs in water was investigated by means of UV–vis spectroscopy, using different CNT concentrations and sonication durations. Dispersion of the CNTs in cement mortar was investigated by measuring the compressive and flexural strength and fracture toughness as well as the microstructural characterizations of scanning electron microscopy and mercury intrusion porosimetry. The effects of the CNT addition on drying shrinkage and cement hydration were also investigated for cement pastes. The results of UV–vis spectroscopy showed that by increasing the sonication time to 120 min, the dispersion degree of the f-CNT suspension increased progressively, while for p-CNT, a maximum was reached with 60 min of sonication. The compressive and flexural strength and fracture toughness of mortars containing f- and p-CNTs were not significantly improved either by increasing the amount of CNT or imposing sonication in mixing water. High CNT dispersion in cement matrix was not equally obtained by utilizing highly dispersed CNT suspension. Sonication of f- and p-CNT led to a remarkable deceleration of cement hydration in the first hour of hydration and drying shrinkage of the cement composites was found to be reduced by f- and p-CNT addition.     

Preparation and bioactivity evaluation of hydroxyapatite-titania/chitosan-gelatin polymeric biocomposites

Biocomposites consisting of hydroxyapatite (HA) and natural polymers such as collagen, chitosan, chitin,and gelatin have been extensively investigated. However, studies on the combination of HA and titania with chitosan and gelatin have not been conducted yet. Novel biodegradable hydroxyapatite-titania/chitosan-gelatin polymeric composites were fabricated. In this work, our results are concerning with the preparation and characterization of HA powder and HA filler containing titania powder (10 and 30%) with a chitosan and gelatin copolymer matrix. The present research focuses on characterizing the structure of this novel class of biocomposites. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Fourier Transformed Infrared Spectroscopy (FT-IR), Scanning electron microscopy (SEM-EDAX) were employed to assess the produced composites. The mechanical properties in terms of compressive strength and hardness test were also investigated. The in vitro study in simulated body fluid (SBF) was performed to assess the bioactivity of composites. The results proved that apatite resembling natural bone are formed faster and greater in the case the composite of HA containing 10% titania into chitosan-gelatin polymeric matrix when they are soaked in a simulated body fluid (SBF) than the composite containing 30% titania. The biocomposites containing HA with 10% titania are expected to be attractive for bioapplications as bone substitutes and scaffolds for tissue engineering in future.     

Porous polymer/hydroxyapatite scaffolds: characterization and biocompatibility investigations

Poly-lactic-glycolic acid (PLGA) has been widely used as a scaffold material for bone tissue engineering applications. 3D sponge-like porous scaffolds have previously been generated through a solvent casting and salt leaching technique. In this study, polymer–ceramic composite scaffolds were created by immersing PLGA scaffolds in simulated body fluid, leading to the formation of a hydroxyapatite (HAP) coating. The presence of a HAP layer was confirmed using scanning electron microscopy, energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy in attenuated total reflection mode. HAP-coated PLGA scaffolds were tested for their biocompatibility in vitro using human osteoblast cell cultures. Biocompatibility was assessed by standard tests for cell proliferation (MTT, WST), as well as fluorescence microscopy after standard cell vitality staining procedures. It was shown that PLGA–HAP composites support osteoblast growth and vitality, paving the way for applications as bone tissue engineering scaffolds.     

Fabrication and properties of CNTs/carbon fabric hybrid multiscale composites processed via resin transfer molding technique

Carbon nanotubes (CNTs) are effective fillers/reinforcements regarding improving the properties of polymer. In the present paper, carboxylic acid functionalized CNTs were used to modify epoxy with intent to develop a nanocomposite matrix for hybrid multiscale composites combining benefits of nanoscale reinforcement with well-established fibrous composites. CNTs were dispersed in epoxy by using high energy sonication. At low contents of CNTs, hybrid multiscale composites specimens were manufactured via resin transfer molding (RTM) process. The processibility of CNTs/epoxy systems was explored with respect to their viscosity. The dispersion quality and re-agglomeration behavior of CNTs in epoxy were characterized using optical microscope. A CNTs loading of 0.025 wt% significantly improved the glass transition temperatures (Tg) of the hybrid multiscale composites. Scanning electron microscopy (SEM) was used to examine the fracture surface of the failed specimens. It is demonstrated that the addition of small amount of CNTs (0.025 wt%) to epoxy for the fabrication of multiscale carbon fabric composites via RTM route effectively improves the matrix-dominated properties of polymer based composites. Hybridization efficiency in carbon fiber reinforced composites using CNTs is found to be highly dependent on the changes in the dispersion state of CNTs in epoxy.     

Evaluation of optimal dispersion conditions for CNT reinforced epoxy composites using cyclic voltammetry measurements

The optimum dispersion time of nanoparticles is important for obtaining uniform dispersion of fillers or other additives in a matrix. In this study, the optimal dispersion time of carbon nanotube (CNT) in a matrix was investigated using cyclic voltammetry (CV), measurement for different dispersion methods and times. In addition, the mechanical properties of CNT composites manufactured using different dispersion methods were evaluated by tensile and flexural tests. The CV and mechanical test results were correlated to the dispersion condition of CNT in the composites. It was found that tip-type sonication resulted in better dispersion than bath-type sonication. Improved CNT dispersion resulted in composites with both enhanced CV measurements and improved mechanical properties. In the study reported here, improvements in dispersion were generally accompanied by higher electrical currents. This suggests that the CV measurement method is an effective tool for determining optimal dispersion times, for different CNT dispersion processes.     

Adhesion of Pseudomonas fluorescens onto nanophase materials

Nanobiotechnology is a growing area of research, primarily due to the potentially numerous applications of new synthetic nanomaterials in engineering/science. Although various definitions have been given for the word 'nanomaterials' by many different experts, the commonly accepted one refers to nanomaterials as those materials which possess grains, particles, fibres, or other constituent components that have one dimension specifically less than 100?nm. In biological applications, most of the research to date has focused on the interactions between mammalian cells and synthetic nanophase surfaces for the creation of better tissue engineering materials. Although mammalian cells have shown a definite positive response to nanophase materials, information on bacterial interactions with nanophase materials remains elusive. For this reason, this study was designed to assess the adhesion of Pseudomonas fluorescens on nanophase compared to conventional grain size alumina substrates. Results provide the first evidence of increased adhesion of Pseudomonas fluorescens on alumina with nanometre compared to conventional grain sizes. To understand more about the process, polymer (specifically, poly-lactic-co-glycolic acid or PLGA) casts were made of the conventional and nanostructured alumina surfaces. Results showed similar increased Pseudomonas fluorescens capture on PLGA casts of nanostructured compared to conventional alumina as on the alumina itself. For these reasons, a key material property shown to enhance bacterial adhesion was elucidated in this study for both polymers and ceramics: nanostructured surface features.     

The impact of fluorinated MWCNT additives on the enhanced dynamic mechanical properties of e-beam-cured epoxy

Multi-walled carbon nanotubes were embedded into e-beam-cured epoxy resin to improve the mechanical properties of epoxy resin. The surfaces of these carbon nanotubes were modified using a fluorination treatment to improve their dispersion and adhesion in epoxy resin. The dynamic mechanical properties of epoxy/carbon nanotube composites were investigated at various heating rates and frequencies. As an effect of fluorination treatment, the semi-ionic bond of C–F on the surface of multi-walled carbon nanotubes played an important role in the improved dispersion and adhesion of carbon nanotubes into the epoxy resin. The storage modulus and loss modulus of the composites increased with higher applied frequency. The activation energy of the composites was increased by the effects of a higher heating rate due to the slow heat transfer in the epoxy/carbon nanotube composites. Eventually, the dynamic mechanical properties of the investigated epoxy were significantly improved by the carbon nanotubes dispersed therein via the fluorination treatment.     

Effect of testosterone incorporation on cell proliferation and differentiation for polymer–bioceramic composites

In the current study, we characterized the polycaprolactone (PCL), poly(lactic acid-co-glycolic acid) (PLGA), and biphasic calcium phosphate (BCP) composites coated with testosterone propionate (T) using Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffraction (XRD). Osteoblastic cells were seeded with PCL/BCP, PCL/BCP/T, PLGA/PCL/BCP and PLGA/PCL/BCP/T scaffolds, and cell viability, proliferation, differentiation and adhesion were analyzed. The results of physic-chemical experiments showed no displacements or suppression of bands in the FTIR spectra of scaffolds. The XRD patterns of the scaffolds showed an amorphous profile. The osteoblastic cells viability and proliferation increased in the presence of composites with testosterone over 72?h, and were significantly greater when PLGA/PCL/BCP/T scaffold was tested against PCL/BCP/T. Furthermore alkaline phosphatase production was significantly greater in the same group. In conclusion, the PLGA/PCL/BCP scaffold with testosterone could be a promising option for bone tissue applications due to its biocompatibility and its stimulatory effect on cell proliferation.     

In situ thermal preparation of polyimide nanocomposite films containing functionalized graphene sheets

Graphene oxides (GO) were exfoliated in N,N-dimethylformamide by simple sonication treatment of the as-prepared high quality graphite oxides. By high-speed mixing of the pristine poly(amic acid) (PAA) solution with graphene oxide suspension, PAA solutions containing uniformly dispersed GO can be obtained. Polyimide (PI) nanocomposite films with different loadings of functionalized graphene sheets (FGS) can be prepared by in situ partial reduction and imidization of the as-prepared GO/PAA composites. Transmission electron microscopy observations showed that the FGS were well exfoliated and uniformly dispersed in the PI matrix. It is interesting to find that the FGS were highly aligned along the surface direction for the nanocomposite film with 2 wt % FGS. Tensile tests indicated that the mechanical properties of polyimide were significantly enhanced by the incorporation of FGS, due to the fine dispersion of high specific surface area of functionalized graphene nanosheets and the good adhesion and interlocking between the FGS and the matrix.     

A biocompatible chitosan composite containing phosphotungstic acid modified single-walled carbon nanotubes

Surface modification of carbon nanotubes is crucial for the dispersion and interfacial adhesion of carbon nanotubes in polymer composites. Here we present a novel method to construct single-walled carbon nanotube/chitosan composites using phosphotungstic acid as an anchor reagent to modify single-walled carbon nanotubes. The most direct benefit from this method is that this modification is mild but effective: the induced defects on single-walled carbon nanotubes are negligible based on Raman and transmission electron microscopy observations; and homogeneous dispersion of single-walled carbon nanotubes in chitosan matrices and strong binding between single-walled carbon nanotubes and chitosan are achieved. Moreover, according to the results of tetrazolium-based colorimetric assays in vitro, we demonstrate that the produced phosphotungstic-acid-modified single-walled carbon nanotube/chitosan composites have good biocompatibility. Thus, our study provides a feasible route to fabricate biocompatible composites containing single-walled carbon nanotubes for potential application in bone tissue engineering.     

Improved dispersion and mechanical properties of hybrid nanocomposites

Dispersion of nanoparticles and its effect on the mechanical properties were investigated by fabricating nanocomposites via conventional sonication, sol–gel, and a combination of sonication and sol–gel methods. Silica nanoparticles in epoxy produced via sol–gel was procured as Nanopox F 400 to produce silica/epoxy nanocomposite whereas the conventional sonication method was followed to produce alumina/epoxy and carbon nanofibers (CNF)/epoxy nanocomposites. Then, the conventional sonication method was employed in the presence of sol–gel nanoparticles to improve the dispersion quality of conventional dry nanoparticles as well as to increase the particle loading. In the current method, the epoxy with silica nanoparticles produced by the sol–gel method was used as the starting material for sonication. In the subsequent step, particles of the second type were added to the silica/epoxy precursor via sonication. Using this method, two different types of nanoparticles were added to produce hybrid nanocomposites with higher particle loading where alumina and CNF were used as hybridizing particles. TEM micrographs revealed an improved dispersion quality of alumina nanoparticles and CNFs in the presence of very well dispersed silica nanoparticles. The improvement in dispersion was reflected in much improved mechanical properties of the nanocomposites.     

To improve interfacial and mechanical properties of carbon fiber–modified nano-SiC–epoxy composites using dispersion and wetting control

Significant improvements in mechanical properties (particularly stiffness) result from the appropriate addition of micro-carbon fibers in the nano and heterostructures of modified nano-SiC-filled epoxy matrix composites. The optimum dispersion conditions were found to be significantly dependent upon both the amount of nano-SiC filler and the sonication time. To investigate these dispersion effects, composites were fabricated with five different nano-SiC filler concentrations and compared to the untreated composite. Changes in electrical capacitance were used as a measure of the comparative degree of dispersion in these nano-SiC–epoxy composites. FE-SEM was used to observe the interfacial changes for the different surface conditions, and the mechanical damage was evaluated by inspection of fractured surfaces. Optimal conditions of dispersion, interfacial adhesion, and aspect ratio of the modified nano-SiC fillers were found to improve the composites’ mechanical properties.     

Porous nano-hydroxyapatite/collagen scaffold containing drug-loaded ADM–PLGA microspheres for bone cancer treatment

To develop adriamycin (ADM)-encapsulated poly(lactic-co-glycolic acid) (PLGA) nanoparticles in a porous nano-hydroxyapatite/collagen scaffold (ADM–PLGA–NHAC). To provide novel strategies for future treatment of osteosarcoma, the properties of the scaffold, including its in vitro extended-release properties, the inhibition effects of ADM–PLGA–NHAC on the osteosarcoma MG63 cells, and its bone repair capacity, were investigated in vivo and in vitro. The PLGA copolymer was utilized as a drug carrier to deliver ADM–PLGA nanoparticles (ADM–PLGA–NP). Porous nano-hydroxyapatite and collagen were used to materials to produce the porous nano-hydroxyapatite/collagen scaffold (NHAC), into which the ADM–PLGA–NP was loaded. The performance of the drug-carrying scaffold was assessed using multiple techniques, including scanning electron microscopy and in vitro extended release. The antineoplastic activities of scaffold extracts on the human osteosarcoma MG63 cell line were evaluated in vitro using the cell counting kit-8 (CCK8) method and live-dead cell staining. The bone repair ability of the scaffold was assessed based on the establishment of a femoral condyle defect model in rabbits. ADM–PLGA–NHAC and NHAC were implanted into the rat muscle bag for immune response experiments. A tumor-bearing nude mice model was created, and the TUNEL and HE staining results were observed under optical microscopy to evaluate the antineoplastic activity and toxic side effects of the scaffold. The composite scaffold demonstrated extraordinary extended-release properties, and its extracts also exhibited significant inhibition of the growth of osteosarcoma MG63 cells. In the bone repair experiment, no significant difference was observed between ADM–PLGA–NHAC and NHAC by itself. In the immune response experiments, ADM–PLGA–NHAC exhibited remarkable biocompatibility. The in vivo antitumor experiment revealed that the implantation of ADM–PLGA–NHAC in the tumor resulted in a improved antineoplastic effect and fewer adverse side effects than direct intraperitoneal injection of ADM. The ADM–PLGA–NHAC developed in this study exhibited excellent extended-release drug properties, bone repairing and antineoplastic efficacy, which make it a promising osteoconductivity material with the capability to inhibit osteosarcoma.     

Graphitic carbon nanofiber (GCNF)/polymer materials. I. GCNF/epoxy monoliths using hexanediamine linker molecules

Processing methods have been optimized for the formation of graphitic carbon nanofiber (GCNF)/epoxy nanocomposites containing GCNFs highly dispersed throughout a thermoset epoxy matrix. GCNFs having a herringbone atomic structure are surface-derivatized with bifunctional hexanediamine linker molecules (GCNF-HDA) capable of covalent binding to an epoxy matrix during thermal curing and are cut to smaller dimension using high-power ultrasonication. GCNF-HDA nanofibers are dispersed in epoxy resin at 0.3 wt.% loading using variable levels of ultrasonication processing prior to thermal curing. Effects of sonication power on the quality of the GCNF-HDA/epoxy material obtained after curing have been determined from flexural property measurements, thermomechanical analysis and SEM/TEM imaging. GCNF-HDA/epoxy material of the highest quality is obtained using low-power sonication, although high-power sonication for short periods gives improved flexural properties without lowering the glass transition temperature. Good dispersion and polymer wetting of the GCNF component is evident on the nanoscale.