Effect of Collagen-Polycaprolactone Nanofibers Matrix Coating on the In Vitro Cytocompatibility and In Vivo Bone Responses of Titanium.

The objective of this study was to improve the biomechanical performance of titanium (Ti) using a biocompatible electrospun nanofiber matrix. The study is based on the hypothesis that coating a Ti surface with a nanofiber matrix (NFM) made of collagen (CG) and polycaprolactone (PCL) electrospun nanofibers could increase the mechanical fixation of Ti/bone by improving the surface and cytocompatibility properties of Ti. This study prepared Ti samples with and without CG-PCL NFM coatings. This study determined the in vitro effects of each group of Ti samples on the surface topography and cytocompatibility (osteoblast cell adhesion, proliferation, mineralization and protein adsorption) properties. This study also determined in vivo interface shear strength and bone volume fraction of each group of Ti samples with bone using a rabbit model. This study found that the CG-PCL NFM coating on Ti improved the surface roughness, osteoblast cell adhesion, proliferation, mineralization and protein adsorption properties of Ti. In vivo studies found that interface shear strength of CG-PCL NFM-coated Ti/bone samples was significantly higher compared to those values of control Ti/bone samples (p value < 0.05) due to an increase in the amount of growth of the connective tissue joining the Ti implant. Therefore, the developed CG-PCL NFM coating technique should further be investigated for its potential in clinical applications.

Antimicrobial Activity of Polycaprolactone Nanofiber Coated with Lavender and Neem Oil Nanoemulsions against Airborne Bacteria.

The development of efficient, eco-friendly antimicrobial agents for air purification and disinfection addresses public health issues connected to preventing airborne pathogens. Herein, the antimicrobial activity of a nanoemulsion (control, 5%, 10%, and 15%) containing neem and lavender oils with polycaprolactone (PCL) was investigated against airborne bacteria, including Escherichia coli, Bacillus subtilis, and Staphylococcus aureus. Various parameters such as the physicochemical properties of the nanoemulsion, pH, droplet size, the polydispersity index (PDI), the minimum inhibitory concentration (MIC), the minimum bacterial concentration (MBC), and the color measurement of the emulsion have been evaluated and optimized. Our results showed that the antimicrobial activity of PCL combined with neem and lavender oil was found to be the highest MIC and MBC against all tested bacteria. The droplet sizes for lavender oil are 21.86-115.15 nm, the droplet sizes for neem oil are 23.92-119.15 nm, and their combination is 25.97-50.22 nm. The range of pH and viscosity of nanoemulsions of various concentrations was found to be 5.8 to 6.6 pH and 0.372 to 2.101 cP. This study highlights the potential of nanotechnology in harnessing the antimicrobial properties of natural essential oils, paving the way for innovative and sustainable solutions in the fight against bacterial contamination.

Comparative Seed Proteome Profile Reveals No Alternation of Major Allergens in High-Yielding Mung Bean Cultivars.

Mung bean contains up to 32.6% protein and is one of the great sources of plant-based protein. Because many allergens also function as defense-related proteins, it is important to determine their abundance levels in the high-yielding, disease-resistant cultivars. In this study, for the first time, we compared the seed proteome of high-yielding mung bean cultivars developed by a conventional breeding approach. Using a label-free quantitative proteomic platform, we successfully identified and quantified a total of 1373 proteins. Comparative analysis between the high-yielding disease-resistant cultivar (MC5) and the other three cultivars showed that a total of 69 common proteins were significantly altered in their abundances across all cultivars. Bioinformatic analysis of these altered proteins demonstrated that PDF1 (a defensin-like protein) exhibited high sequence similarity and epitope matching with the established peanut allergens, indicating a potential mung bean allergen that showed a cultivar-specific response. Conversely, known mung bean allergen proteins such as PR-2/PR-10 (Vig r 1), Vig r 2, Vig r 4, LTP1, ß-conglycinin, and glycinin G4 showed no alternation in the MC5 compared to other cultivars. Taken together, our findings suggest that the known allergen profiles may not be impacted by the conventional plant breeding method to develop improved mung bean cultivars.

Polycaprolactone Electrospun Nanofiber Membrane with Skin Graft Containing Collagen and Bandage Containing MgO Nanoparticles for Wound Healing Applications.

The objective of this study was to create a nanofiber-based skin graft with an antimicrobial bandage that could accelerate the healing of an open wound while minimizing infection. To this end, we prepared a bi-layer construct where the top layer acts as bandage, and the bottom layer acts as a dermal equivalent graft. A collagen (CG) gel was combined without and with an electrospun polycaprolactone (PCL) membrane to prepare CG and CG-PCL dermal equivalent constructs. The antibacterial properties of PCL with and without an antibacterial agent (MgO nanoparticles) against Staphylococcus aureus (ATCC 6538) was also examined. Human dermal fibroblasts were cultured in each construct to make the dermal equivalent grafts. After culturing, keratinocytes were plated on top of the tissues to allow growth of an epidermis. Rheological and durability tests were conducted on in vitro dermal and skin equivalent cultures, and we found that PCL significantly affects CG-PCL graft biological and mechanical strength (rheology and durability). PCL presence in the dermal equivalent allowed sufficient tension generation to activate fibroblasts and myofibroblasts in the presence of transforming growth factor-beta. During culture of the skin equivalents, optical coherence tomography (OCT) showed layers corresponding to dermal and epidermal compartments in the presence or absence of PCL; this was confirmed after fixed specimens were histologically sectioned and stained. MgO added to PCL showed antibacterial activity against S. aureus. In vivo animal studies using a rat skin model showed that a polycaprolactone nanofiber bandage containing a type I collagen skin graft has potential for wound healing applications.

Evaluation of a Bioabsorbable Scaffold and Interlocked Nail System for Segmental Bone Defect.

In the current study, we designed and manufactured a scaffold and fixation system for the reconstruction of long-bone segmental defects in a rabbit tibia model. We used biocompatible and biodegradable materials, polycaprolactone (PCL) and PCL soaked with sodium alginate (PCL-Alg) to manufacture the scaffold, interlocking nail and screws using a phase separation casing method. Degradation and mechanical tests on the PCL and PCL-Alg scaffolds indicated that both were suitable for faster degradation and early weight-bearing capacity. PCL scaffold surface porosity facilitated the infiltration of alginate hydrogel through the scaffold. Cell viability results showed that the number of cells increased on Day 7 and decreased marginally by Day 14. For accurate placement of the scaffold and fixation system, a surgical jig was designed and 3D-printed using biocompatible resin in a stereolithography (SLA) 3D printer, then cured with UV light for increased strength. Our cadaver tests using New Zealand White rabbit confirmed our novel jigs' potential for accurate placement of the bone scaffold, intramedullary nail and the alignment of the fixation screws in future reconstructive surgeries on rabbit long-bone segmental defects. Additionally, the cadaver tests confirmed that our designed nails and screws were strong enough to carry the surgical insertion force. Therefore, our designed prototype has the potential for further clinical translational study using the rabbit tibia model.

Evaluation of Polycaprolactone Electrospun Nanofiber-Composites for Artificial Skin Based on Dermal Fibroblast Culture.

The study's aim was to develop a dermal equivalent scaffold that can mimic the architecture and biological performance of the human dermis. Poly ε-caprolactone (PCL) electrospun nanofiber material (ENF) was assembled with polyethylene glycol diacrylate (PEGDA), sodium alginate (SA) and type I collagen (CG1) to develop three groups of dermal equivalent scaffolds. These scaffolds were named PEGDA-PCL, SA-PCL and CG1-PCL. Scanning electron microscopy (SEM) images of cell-free scaffolds' top and cross-sectional surface were collected and analyzed to examine internal morphology, specifically the adhesiveness of PCL fibers with the different scaffolds. Human dermal fibroblasts were cultured on each of the scaffolds. Cell viability studies including cell adhesion, cell differentiation and stress fiber production were conducted on each scaffold. Furthermore, the architectural integrity of each scaffold was verified by degradation analysis for 2 weeks by soaking each scaffold in phosphate-buffered saline (PBS) solution. Finally, we conducted rheological characteristics of each scaffold. Based on our results from the above analysis, the study concluded that CG1-PCL is best suitable for the dermal equivalent model and has potential to be used as a graft for skin repair.

Incorporation of Mycobacteriophage Fulbright into Polycaprolactone Electrospun Nanofiber Wound Dressing.

The Genus Mycobacterium includes pathogens known to cause disease in mammals such as tuberculosis (Mycobacterium tuberculosis) and skin infections (M. abscessus). M. smegmatis is a model bacterium that can cause opportunistic infections in human tissues and, rarely, a respiratory disease. Due to the emergence of multidrug-resistant bacteria, phage therapy is potentially an alternative way of treating these bacterial infections. As bacteriophages are specific to their bacterial host, it ensures that the normal flora is unharmed. Fulbright is a mycobacteriophage that infects the host bacteria M. smegmatis. The main goal of this study is to incorporate Mycobacteriophage Fulbright into a polycaprolactone (PCL) nanofiber and test its antimicrobial effect against the host bacteria, M. smegmatis. Stability tests conducted over 7 days showed that the phage titer does not decrease when in contact with PCL, making it a promising vehicle for phage delivery. Antimicrobial assays showed that PCL_Fulbright effectively reduces bacterial concentration after 24 h of contact. In addition, when stored at -20 °C, the phage remains viable for up to eleven months in the fiber. Fulbright addition on the nanofibrous mats resulted in an increase in water uptake and decrease in the mechanical properties (strength and Young's modulus) of the membranes, indicating that the presence of phage Fulbright can greatly enhance the physical and mechanical properties of the PCL. Cytotoxicity assays showed that PCL_Fulbright is not cytotoxic to Balbc/3T3 mouse embryo fibroblast cell lines; thus, phage-incorporated PCL is a promising alternative to antibiotics in treating skin infections.

Use of Polycaprolactone Electrospun Nanofiber Mesh in a Face Mask.

Electrospun nanofiber mesh has previously been used as an air filtration device. However, the qualification of polycaprolactone (PCL) nanofiber mesh cloth in face masks to protect individuals against airborne particles carrying microorganisms has yet to be investigated. The long-term goal of this study is to develop methods to use PCL nanofiber mesh to provide better protection against microorganisms. To achieve this goal, we observed the morphology, water droplet absorption, thermal (differential scanning calorimetry), mechanical, and airborne particle filtering capabilities, and also the microbial activities of a PCL cloth, to evaluate whether it is suitable to act as a filter in a face mask. We have produced a polycaprolactone (PCL) nanofiber cloth after electrospinning it onto a drum for 3 and 10 min, referred to hereafter as PCL-3 and PCL-10, respectively. Our study found that the middle protection layer (control) of the Henry Schein Earloop Procedure Mask contains pores (average diameter = 5.72 ± 0.62 µm) which are 48 times larger than the diameter of a microorganism an average diameter of ~120 nanometers. However, PCL-10 nanofiber membranes show pores with an average diameter of 1.42 ± 0.34 µm. Our contact angle measurement tests found that all the samples were very hydrophobic (contact angle values varied between 120 and 150 degrees). However, both PCL cloths' contact angle values were lower compared to the control. The produced PCL cloths showed a lower water droplet absorption compared to the control. Thermal studies found that PCL is stable in extreme conditions and no plasticizing effect occurs due to the presence of a solvent. Mechanical tests showed that PCL-10 cloth had higher strength and modulus compared to the control and PCL-3 under tension loading conditions. A vacuum experiment found that the PCL-10 fiber cloth could withstand a negative pressure of 18 Psi without any signs of breakage, and the mask was able to capture airborne particles and microorganisms. The feasibility of immobilizing anti-bacterial nanoparticles with PCL during electrospinning creates the future potential of producing an anti-bacterial face mask using PCL.

Experimental Analysis of Laser Micromachining of Microchannels in Common Microfluidic Substrates.

Laser micromachining technique offers a promising alternative method for rapid production of microfluidic devices. However, the effect of process parameters on the channel geometry and quality of channels on common microfluidic substrates has not been fully understood yet. In this research, we studied the effect of laser system parameters on the microchannel characteristics of Polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), and microscope glass substrate-three most widely used materials for microchannels. We also conducted a cell adhesion experiment using normal human dermal fibroblasts on laser-machined microchannels on these substrates. A commercial CO2 laser system consisting of a 45W laser tube, circulating water loop within the laser tube and air cooling of the substrate was used for machining microchannels in PDMS, PMMA and glass. Four laser system parameters - speed, power, focal distance, and number of passes were varied to fabricate straight microchannels. The channel characteristics such as depth, width, and shape were measured using a scanning electron microscope (SEM) and a 3D profilometer. The results show that higher speed produces lower depth while higher laser power produces deeper channels regardless of the substrate materials. Unfocused laser machining produces wider but shallower channels. For the same speed and power, PDMS channels were the widest while PMMA channels were the deepest. Results also showed that the profiles of microchannels can be controlled by increasing the number of passes. With an increased number of passes, both glass and PDMS produced uniform, wider, and more circular channels; in contrast, PMMA channels were sharper at the bottom and skewed. In rapid cell adhesion experiments, PDMS and glass microchannels performed better than PMMA microchannels. This study can serve as a quick reference in material-specific laser-based microchannel fabrications.

Laser-Induced Microgrooves Improve the Mechanical Responses of Cemented Implant Systems.

The impact of a laser-induced microgroove (LIM) architecture on mechanical responses of two cemented implant systems was evaluated. One system consisted of two aluminum alloy rods bonded end-to-end by polymethylmethacrylate cement. The second system consisted of a custom-made, aluminum tibial tray (TT) cemented in an artificial canine tibia. Control specimens for each system were polished smooth at the cement interface. For LIM samples in the rod system, microgrooves were engraved (100 µm depth, 200 µm width, 500 µm spacing) on the apposing surface of one of the two rods. For TT system testing, LIM engraving (100 µm spacing) was confined to the underside and keel of the tray. Morphological analysis of processed implant surfaces revealed success in laser microgrooving procedures. For cemented rods tested under static tension, load to failure was greater for LIM samples (279.0 ± 14.9 N vs. 126.5 ± 4.5 N). Neither non-grooved nor grooved TT samples failed under cyclic compression testing (100,000 cycles at 1 Hz). Compared with control specimens, LIM TT constructs exhibited higher load to failure under static compression and higher strain at the bone interface under cyclic compression. Laser-induced microgrooving has the potential to improve the performance of cemented orthopedic implants.

Understanding the causes behind coracoid graft osteolysis in latarjet procedure (finite element analysis and comparison of three fixation methods).

BACKGROUND: Latarjet is one of the most common surgical procedure performed on patients with shoulder instability with osseous defects, some complications include coracoid bone graft osteolysis, osteoarthritis, graft detachment, and malpositioning were previously reported. Several studies investigated potential causes of graft osteolysis but still, it remains a crucial area of investigation. We aim to use finite element analysis to examine the potential correlations between three modes of fixation methods used in the Latarjet procedure (screw, wedge plate, and endobutton), and the coracoid graft osteolysis. HYPOTHESIS: Finite element analysis tested the hypothesis that there is a linear relationship between the compression stress on graft which was generated by fixation methods used in the latarjet and the coracoid graft osteolysis. MATERIAL AND METHODS: Boundary conditions and inhomogeneous material properties were carefully assigned within the material of the scapula and coracoid interface. For the screw and wedge plate fixations, an applied torque in the range of 1-1.5Nm was used to characterize the surgeon's insertion torque during the surgical operation, while a 100N compressive force was selected for the endobutton fixation. RESULTS: Relatively lesser stress magnitudes were observed with endobutton fixation method rather than screw and the wedge plate fixation. Statistical analyses revealed significant differences between the groups (p<0.05). DISCUSSION: Excessive compressive stresses within the coracoid graft regions may be responsible for osteolysis due to negative effects over biological factors such as blood flow. Our study emphasizes the importance of taking into account the fixation method while performing the Latarjet procedure. We concluded that the mode of fixation used within the Latarjet procedure has a correlation on the coracoid graft osteolysis. LEVEL OF EVIDENCE: I.

Microgroove and Collagen-poly(ε-caprolactone) Nanofiber Mesh Coating Improves the Mechanical Stability and Osseointegration of Titanium Implants.

The effect of depositing a collagen (CG)-poly-ε-caprolactone (PCL) nanofiber mesh (NFM) at the microgrooves of titanium (Ti) on the mechanical stability and osseointegration of the implant with bone was investigated using a rabbit model. Three groups of Ti samples were produced: control Ti samples where there were no microgrooves or CG-PCL NFM, groove Ti samples where microgrooves were machined on the circumference of Ti, and groove-NFM Ti samples where CG-PCL NFM was deposited on the machined microgrooves. Each group of Ti samples was implanted in the rabbit femurs for eight weeks. The mechanical stability of the Ti/bone samples were quantified by shear strength from a pullout tension test. Implant osseointegration was evaluated by a histomorphometric analysis of the percentage of bone and connective tissue contact with the implant surface. The bone density around the Ti was measured by micro-computed tomography (µCT) analysis. This study found that the shear strength of groove-NFM Ti/bone samples was significantly higher compared to control and groove Ti/bone samples (p < 0.05) and NFM coating influenced the bone density around Ti samples. In vivo histomorphometric analyses show that bone growth into the Ti surface increased by filling the microgrooves with CG-PCL NFM. The study concludes that a microgroove assisted CG-PCL NFM coating may benefit orthopedic implants.

Minimizing Stress Shielding and Cement Damage in Cemented Femoral Component of a Hip Prosthesis through Computational Design Optimization.

The average life expectancy of many people undergoing total hip replacement (THR) exceeds twenty-five years and the demand for implants that increase the load-bearing capability of the bone without affecting the short- or long-term stability of the prosthesis is high. Mechanical failure owing to cement damage and stress shielding of the bone are the main factors affecting the long-term survival of cemented hip prostheses and implant design must realistically adjust to balance between these two conflicting effects. In the following analysis we introduce a novel methodology to achieve this objective, the numerical technique combines automatic and realistic modeling of the implant and embedding medium, and finite element analysis to assess the levels of stress shielding and cement damage and, finally, global optimization, using orthogonal arrays and probabilistic restarts, were used. Applications to implants, fabricated using a homogeneous material and a functionally graded material, were presented.

Evaluation of Polyethylene Glycol Diacrylate-Polycaprolactone Scaffolds for Tissue Engineering Applications.

Polyethylene Glycol Diacrylate (PEGDA) tissue scaffolds having a thickness higher than 1 mm and without the presence of nutrient conduit networks were shown to have limited applications in tissue engineering due to the inability of cells to adhere and migrate within the scaffold. The PEGDA scaffold has been coated with polycaprolactone (PCL) electrospun nanofiber (ENF) membrane on both sides to overcome these limitations, thereby creating a functional PEGDA-PCL scaffold. This study examined the physical, mechanical, and biological properties of the PEGDA and PEGDA-PCL scaffolds to determine the effect of PCL coating on PEGDA. The physical characterization of PEGDA-PCL samples demonstrated the effectiveness of combining PCL with a PEGDA scaffold to expand its applications in tissue engineering. This study also found a significant improvement of elasticity of PEGDA due to the addition of PCL layers. This study shows that PEGDA-PCL scaffolds absorb nutrients with time and can provide an ideal environment for the survival of cells. Furthermore, cell viability tests indicate that the cell adhered, proliferated, and migrated in the PEGDA-PCL scaffold. Therefore, PCL ENF coating has a positive influence on PEGDA scaffold.

Use of Polycaprolactone Electrospun Nanofibers as a Coating for Poly(methyl methacrylate) Bone Cement.

Poly(methyl methacrylate) (PMMA) bone cement has limited biocompatibility. Polycaprolactone (PCL) electrospun nanofiber (ENF) has many applications in the biomedical field due to its excellent biocompatibility and degradability. The effect of coating PCL ENF on the surface topography, biocompatibility, and mechanical strength of PMMA bone cement is not currently known. This study is based on the hypothesis that the PCL ENF coating on PMMA will increase PMMA roughness leading to increased biocompatibility without influencing its mechanical properties. This study prepared PMMA samples without and with the PCL ENF coating, which were named the control and ENF coated samples. This study determined the effects on the surface topography and cytocompatibility (osteoblast cell adhesion, proliferation, mineralization, and protein adsorption) properties of each group of PMMA samples. This study also determined the bending properties (strength, modulus, and maximum deflection at fracture) of each group of PMMA samples from an American Society of Testing Metal (ASTM) standard three-point bend test. This study found that the ENF coating on PMMA significantly improved the surface roughness and cytocompatibility properties of PMMA (p < 0.05). This study also found that the bending properties of ENF-coated PMMA samples were not significantly different when compared to those values of the control PMMA samples (p > 0.05). Therefore, the PCL ENF coating technique should be further investigated for its potential in clinical applications.

Biomechanical Performances of Networked Polyethylene Glycol Diacrylate: Effect of Photoinitiator Concentration, Temperature, and Incubation Time.

Nutrient conduit networks can be introduced within the Polyethylene Glycol Diacrylate (PEGDA) tissue construct to enable cells to survive in the scaffold. Nutrient conduit networks can be created on PEGDA by macrochannel to nanochannel fabrication techniques. Such networks can influence the mechanical and cell activities of PEGDA scaffold. There is no study conducted to evaluate the effect of nutrient conduit networks on the maximum tensile stress and cell activities of the tissue scaffold. The study aimed to explore the influence of the network architecture on the maximum tensile stress of PEGDA scaffold and compared with the nonnetworked PEGDA scaffold. Our study found that there are 1.78 and 2.23 times decrease of maximum tensile stress due to the introduction of nutrient conduit networks to the PEGDA scaffold at 23°C and 37°C temperature conditions, respectively. This study also found statistically significant effect of network architecture, PI concentration, temperature, and wait time on the maximum failure stress of PEGDA samples (P value < 0.05). Cell viability results demonstrated that networked PEGDA hydrogels possessed increased viability compared to nonnetworked and decreased viability with increased photoinitiator concentrations. The results of this study can be used for the design of PEGDA scaffold with macrosize nutrient conduit network channels.

Peen treatment on a titanium implant: effect of roughness, osteoblast cell functions, and bonding with bone cement.

Implant failure due to poor integration of the implant with the surrounding biomaterial is a common problem in various orthopedic and orthodontic surgeries. Implant fixation mostly depends upon the implant surface topography. Micron to nanosize circular-shaped groove architecture with adequate surface roughness can enhance the mechanical interlock and osseointegration of an implant with the host tissue and solve its poor fixation problem. Such groove architecture can be created on a titanium (Ti) alloy implant by laser peening treatment. Laser peening produces deep, residual compressive stresses in the surfaces of metal parts, delivering increased fatigue life and damage tolerance. The scientific novelty of this study is the controlled deposition of circular-shaped rough spot groove using laser peening technique and understanding the effect of the treatment techniques for improving the implant surface properties. The hypothesis of this study was that implant surface grooves created by controlled laser peen treatment can improve the mechanical and biological responses of the implant with the adjoining biomaterial. The objective of this study was to measure how the controlled laser-peened groove architecture on Ti influences its osteoblast cell functions and bonding strength with bone cement. This study determined the surface roughness and morphology of the peen-treated Ti. In addition, this study compared the osteoblast cell functions (adhesion, proliferation, and differentiation) between control and peen-treated Ti samples. Finally, this study measured the fracture strength between each kind of Ti samples and bone cement under static loading. This study found that laser peen treatment on Ti significantly changed the surface architecture of the Ti, which led to enhanced osteoblast cell adhesion and differentiation on Ti implants and fracture strength of Ti-bone cement interfaces compared with values of untreated Ti samples. Therefore, the laser peen treatment method has the potential to improve the biomechanical functions of Ti implants.

Plasma nitriding of titanium alloy: Effect of roughness, hardness, biocompatibility, and bonding with bone cement.

Titanium (Ti) alloys have been widely used in orthopedics and orthodontic surgeries as implants because of their beneficial chemical, mechanical, and biological properties. Improvement of these properties of a Ti alloy, Ti-6Al-4V Eli, is possible by the use of plasma nitriding treatment on the Ti alloy. The novelty of this study is the evaluation of a DC glow discharge nitrogen plasma treatment method on the surface, mechanical and biological properties of Ti alloy. Specifically, this study measured the chemical states, roughness, hardness, and biocompatibility of plasma nitride treated Ti-6Al-4V Eli as well as determined the effect of plasma treatment on the fracture strength between the Ti alloy and bone clement. This study hypothesized that DC glow discharge nitrogen plasma treatment may alter the surface chemical and mechanical states of the Ti alloy that may influence the fracture strength of implant/cement interfaces under static load. This study found that plasma nitride treatment on Ti alloy does not have effect on the roughness and biocompatibility (P value > 0.5), but significantly effect on the hardness and fracture strength of Ti-bone cement interfaces compared to those values of untreated Ti samples (P value < 0.5). Therefore, the DC glow discharge nitrogen plasma treated Ti alloy can potentially be used for orthopedic applications.

The Effect of Nanoparticles and Alternative Monomer on the Exothermic Temperature of PMMA Bone Cement.

Poly methyl methacrylate (PMMA) cement produce exothermic reaction during its polymerization process, which damage the surrounding bone tissue during orthopedic surgery. Nanoparticles additives (magnesium oxide, hydroxyapatite, chitosan, barium sulfate and silica) and alternative monomers (glycidyl methacrylate(GMA) tri-methaxysilyl propyl methacrylate (3MPMA)), can be incorporated with the PMMA beads and methyl methacrylate (MMA) monomers, respectively, to reduce the exothermic temperature. A comparative study of the addition of these additives and monomer at different concentration on exothermic temperature of PMMA is not known and significant for designing improved PMMA cement for orthopedic applications. The goal of this study is two folds: (1) to evaluate the effect of the inclusion of the above additives with PMMA on the exothermic temperature of PMMA, (2) to evaluate the effect of the inclusion of the above alternative monomers on the exothermic temperature of PMMA. A commercial bone cement was used in this study as PMMA cement. Two wt% and six wt% of the above nanoparticle were mixed with PMMA beads. Two and six wt% of the above alterative monomers were mixed with MMA monomers. Bead and monomer ratio of 2:1 was maintained to prepare the cement samples. A 4-channel thermocouple was used to determine the temperature changes of the samples in an insulated acrylic mold during the curing period. This study found maximum curing temperature on the 2 wt% Magnesium oxide added PMMA specimen was significantly lower than other samples. Addition of 3MPMA and GMA to MMA decreased the maximum curing temperatures and curing time of specimens compared to other samples.

Fracture toughness of titanium-cement interfaces: effects of fibers and loading angles.

Ideal implant-cement or implant-bone interfaces are required for implant fixation and the filling of tissue defects created by disease. Micron- to nanosize osseointegrated features, such as surface roughness, fibers, porosity, and particles, have been fused with implants for improving the osseointegration of an implant with the host tissue in orthopedics and dentistry. The effects of fibers and loading angles on the interface fracture toughness of implant-cement specimens with and without fibers at the interface are not yet known. Such studies are important for the design of a long-lasting implant for orthopedic applications. The goal of this study was to improve the fracture toughness of an implant-cement interface by deposition of micron- to nanosize fibers on an implant surface. There were two objectives in the study: 1) to evaluate the influence of fibers on the fracture toughness of implant-cement interfaces with and without fibers at the interfaces, and 2) to evaluate the influence of loading angles on implant-cement interfaces with and without fibers at the interfaces. This study used titanium as the implant, poly(methyl methacrylate) (PMMA) as cement, and polycaprolactone (PCL) as fiber materials. An electrospinning unit was fabricated for the deposition of PCL unidirectional fibers on titanium (Ti) plates. The Evex tensile test stage was used to determine the interface fracture toughness (KC) of Ti-PMMA with and without PCL fibers at 0°, 45°, and 90° loading angles, referred to in this article as tension, mixed, and shear tests. The study did not find any significant interaction between fiber and loading angles (P>0.05), although there was a significant difference in the KC means of Ti-PMMA samples for the loading angles (P<0.05). The study also found a significant difference in the KC means of Ti-PMMA samples with and without fibers (P<0.05). The results showed that the addition of the micron- to nanosize PCL fibers on Ti improved the quality of the Ti-PMMA union. The results of the study are essential for fatigue testing and finite-element analysis of implant-cement interfaces to evaluate the performance of orthopedic and orthodontic implants.