Bio-Medical Materials and Engineering - Volume 27, issue 5

Authors: Mahomed, Aziza | Pormehr, Negin Bagheri

Article Type: Research Article

Abstract: Four specimens of Nagor silicone of different hardness (soft, medium and hard) were swollen, until they reached equilibrium (i.e. constant mass) in five liquids at 25°C, before and after accelerated aging. For the specimens swollen before accelerated aging, the greatest swelling was obtained in methyl cyclohexane, while for the specimens swollen after accelerated aging, the greatest swelling was obtained in cyclohexane. The cross-link density, υ , was also calculated from the swelling measurements for all the specimens, before and after accelerated aging, using the Flory–Rehner equation. The softer silicones, which swelled the most, had lower υ values than harder …silicones. The amount of swelling (measured in terms of ϕ ) and υ varied significantly (p < 0.05 ) in some cases, between the different silicone hardness and between different liquids. Furthermore, the cross-link density, υ , significantly (p < 0.05 ) increased after accelerated aging in most liquids. Note: ϕ is defined as the volume fraction of polymer in its equilibrium swollen state. A probability value of statistical significance of 0.05 or 5% was selected, hence if a p value of less than 0.05 was obtained, the null hypothesis was rejected (i.e. significant if p < 0.05 ). Show more

Keywords: Cross-link density, Flory–Rehner equation, Hildebrand’s solubility parameter theory, silicones, swelling of polymers in liquids

DOI: 10.3233/BME-161598

Citation: Bio-Medical Materials and Engineering, vol. 27, no. 5, pp. 437-449, 2016

Authors: Bozkurt, Selim | van Tuijl, Sjoerd | van de Vosse, Frans N. | Rutten, Marcel C.M.

Article Type: Research Article

Abstract: The aim of this study is to understand whether the phasic Continuous Flow Left Ventricular Assist Device (CF-LVAD) support would increase the arterial pulsatility. A Micromed DeBakey CF-LVAD was used to apply phasic support in an ex-vivo experimental platform. CF-LVAD was operated over a cardiac cycle by phase-shifting the pulsatile pump control with respect to the heart cycle, in 0.05 s increments in each experiment. The pump flow rate was selected as the control variable and a reference model was used to operate the CF-LVAD at a pulsatile speed. Arterial pulse pressure was the highest (9 mmHg) when the peak pump flow is …applied at the peak systole under varying speed CF-LVAD support over a cardiac cycle while it was the lowest (2 mmHg) when the peak pump flow was applied in the diastolic phase. The mean arterial pressure and mean CF-LVAD output were the same in each experiment while arterial pulse pressure and pulsatility index varied depending on the phase of reference pump flow rate signal. CF-LVAD speed should be synchronized considering the timing of peak systole over a cardiac cycle to increase the arterial pulsatility. Moreover, it is possible to decrease the arterial pulsatility under counter-pulsating CF-LVAD support. Show more

Keywords: CF-LVAD, varying speed, pulsatility, phasic CF-LVAD support

DOI: 10.3233/BME-161599

Citation: Bio-Medical Materials and Engineering, vol. 27, no. 5, pp. 451-460, 2016

Authors: Khandaker, Morshed | Riahinezhad, Shahram | Li, Yanling | Vaughan, Melville B. | Sultana, Fariha | Morris, Tracy L. | Phinney, Lucas | Hossain, Khalid

Article Type: Research Article

Abstract: 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. Show more

Keywords: Plasma nitriding, titanium, cement, interface, fracture strength, orthopedics

DOI: 10.3233/BME-161600

Citation: Bio-Medical Materials and Engineering, vol. 27, no. 5, pp. 461-474, 2016

Authors: Takeuchi, Issei | Fukuda, Kohta | Kobayashi, Shiori | Makino, Kimiko

Article Type: Research Article

Abstract: Background: Estradiol is one of the therapeutic agents for osteoporosis. We have reported transdermal permeability of estradiol-loaded nanoparticles, and permeability effect of estradiol was enhanced by using nanoparticle system and iontophoresis [Colloids and Surfaces B: Biointerfaces 97 (2012 ), 84–89]. Objective: This study was conducted in vivo to evaluate therapeutic efficacy of the estradiol-loaded PLGA nanoparticles for osteoporosis. Methods: Prior to the in vivo study, we have determined the surface charge density of the particles and found they have negatively charged polyelectrolyte layers on the surfaces. Ovariectomized female Sprague–Dawley rats were used as an …animal model of osteoporosis. They were separated into three groups by administration route of estradiol-loaded PLGA nanoparticles, passive diffusion group, iontophoresis group and control. After treatment, we have measured bone mineral density of spine using an X-ray computed tomography system. Results: Bone mineral density after iontophoresis was significantly higher than that of passive diffusion and control group. By usage of iontophoresis, the nanoparticles were permeated through follicles and migrated into capillary vessel around follicles, and the loaded drug reached effective blood concentration in plasma of rat. Conclusions: From this study, we found that the combination with charged nanoparticle system and iontophoresis is useful to osteoporosis treatment. Show more

Keywords: Estradiol, transdermal administration, iontophoresis, osteoporosis, nanoparticle, therapeutic efficacy

DOI: 10.3233/BME-161601

Citation: Bio-Medical Materials and Engineering, vol. 27, no. 5, pp. 475-483, 2016

Authors: Tang, Hao | Li, Ying | Ma, Jianwei | Zhang, Xianlin | Li, Baoe | Liu, Shimin | Dai, Fangfei | Zhang, Xiangqian

Article Type: Research Article

Abstract: A homogeneous and uniform array of nanotubes with a diameter of about 70 nm was produced on titanium (Ti) surface by anodic oxidation. The wall thickness of the nanotubes was around 20 nm, and the depth was about 200 nm. The biological properties of the anodized Ti surface were investigated by simulated body fluid (SBF) soaking test and in vitro cell culture test. The mechanical properties were evaluated by instrumented nanoindentation test and friction-wear test. The results showed that the anodized Ti surface can induce the formation of bone-like apatite after immersion in SBF for four weeks, enhance cell adhesion, proliferation and gene …expression, it also showed decreased friction coefficient, similar stiffness and Young’s modulus to those of the cortical bone. Based on these results, it can be concluded that anodic oxidation endowed the Ti surface with improved biological and mechanical properties, which was attributed to the formation of nanostructured surface. Show more

Keywords: Titanium, anodic oxidationm, mechanical properties, bioactivity, biocompatibility

DOI: 10.3233/BME-161602

Citation: Bio-Medical Materials and Engineering, vol. 27, no. 5, pp. 485-494, 2016

Authors: Zhang, Lei | Mu, Weidong | Chen, Shuangfeng | Yang, Dawei | Xu, Fei | Wu, Yaping

Article Type: Research Article

Abstract: The novel synthetic peptide P17-BMP-2 could promote cell attachment and enhance osteogenic capability. A composite, comprising nano-hydroxyapatite, collagen and poly(L-lactide) (nHAC/PLLA), was an efficient scaffold for carrier of P17-BMP-2. Our aim was to investigate whether nHAC/PLLA/P17-BMP-2 accelerates the osteogenesis as a reliable method for mandibular defect healing in this study. The repair capability was assessed by the gross observation, X-ray test and histological observation in four animal experiment groups at 2 week and 4 week after surgery: Group A (control), Group B (nHAC/PLLA treatment), Group C (nHAC/PLLA with 2 mg/g P17-BMP-2 treatment) and Group D (nHAC/PLLA with 10 mg/g P17-BMP-2 treatment). The …Lane–Sandhu X-ray scores of the four groups were compared among four groups as well. The results showed that the composites containing the highest content of P17- BMP-2 performed best. Therefore, the nHAC/PLLA with P17-BMP-2 composite can accelerate the osteogenesis for mandibular defect healing and could be an ideal biological material as a bone graft material option for clinical applications. Show more

Keywords: Mineralized collagen composite, nHAC/PLLA, P17- BMP-2, mandibular defects

DOI: 10.3233/BME-161603

Citation: Bio-Medical Materials and Engineering, vol. 27, no. 5, pp. 495-505, 2016

Authors: Masithulela, Fulufhelo

Article Type: Research Article

Abstract: Background: The recognition of RV overpressure is critical to human life, as this may signify morbidity and mortality. Right ventricle (RV) dysfunction is understood to have an impact on the performance of the left ventricle (LV), but the mechanisms remain poorly understood. It is understood that ventricular compliance has the ability to affect cardiac performance. In this study, a bi-ventricular model of the rat heart was used in preference to other, single-ventricle models. Finite element analysis (FEA) of the bi-ventricular model provides important information on the function of the healthy heart. Methods: The passive myocardium was modelled as …a nearly incompressible, hyperelastic, transversely isotropic material using finite element (FE) methods. Bi-ventricular geometries of healthy rat hearts reconstructed from magnetic resonance images were imported in Abaqus©. In simulating the normal passive filling of the rat heart, pressures of 4.8 kPa and 0.0098 kPa were applied to the inner walls of the LV and RV respectively. In addition, to simulate the overpressure of the RV, pressures of 2.4 kPa and 4.8 kPa were applied to the endocardial walls of the LV and RV respectively. As boundary conditions, the circumferential and longitudinal displacements at the base were set to zero. The radial displacements at the base were left free. Results: The results show that the average circumferential stress at the mid-wall in the overloaded model increased from 2.8 kPa to 18.2 kPa. The average longitudinal stress increased from 1.5 kPa to 9.7 kPa. Additionally, in the radial direction, the average stress increased from 0.1 kPa to 0.6 kPa in the mid-wall. The average circumferential strain was found to be 0.138 and 0.100 on the endocardium of the over pressured and healthy model respectively. The average circumferential stress at the epicardium, mid-wall and endocardium in the case of a normal heart is 10 times lower than in the overloaded heart model. Conclusion: The finite analysis method is able to provide insights into the behaviour of the over pressured model (myocardium). In the overloaded model the high stresses and strains were observed on the septal wall. The bi-ventricular model was shown to provide useful information relating to the over pressured ventricle. The possible heart dysfunction may be attributable to high stress and strain in the over pressured heart. Show more

Keywords: Myocardial stress and strain, bi-ventricular heart model, computational mechanics, biomechanics, ventricular mechanics

DOI: 10.3233/BME-161604

Citation: Bio-Medical Materials and Engineering, vol. 27, no. 5, pp. 507-525, 2016

Authors: Bousefsaf, F. | Maaoui, C. | Pruski, A.

Article Type: Research Article

Abstract: Background: Vasoconstriction and vasodilation phenomena reflect the relative changes in the vascular bed. They induce particular modifications in the pulse wave magnitude. Webcams correspond to remote sensors that can be employed to measure the pulse wave in order to compute the pulse frequency. Objective: Record and analyze pulse wave signal with a low-cost webcam to extract the amplitude information and assess the vasomotor activity of the participant. Methods: Photoplethysmographic signals obtained from a webcam are analyzed through a continuous wavelet transform. The performance of the proposed filtering technique was evaluated using approved contact probes on a …set of 12 healthy subjects after they perform a short but intense physical exercise. During the rest period, a cutaneous vasodilation is observable. Results: High degrees of correlation between the webcam and a reference sensor were obtained. Conclusions: Webcams are low-cost and non-contact devices that can be used to reliably estimate both heart rate and peripheral vasomotor activity, notably during physical exertion. Show more

Keywords: Remote photoplethysmography, vasomotor activity, webcam, continuous wavelet transform

DOI: 10.3233/BME-161606

Citation: Bio-Medical Materials and Engineering, vol. 27, no. 5, pp. 527-538, 2016

Authors: Nalbantgil, Didem | Ulkur, Feyza | Kardas, Gulfeza | Culha, Mustafa

Article Type: Research Article

Abstract: Background: Patients use mouthwashes in addition to mechanical cleaning during orthodontic treatment. The effects of mouthwashes on the archwires have not been examined yet. Objective: To compare the corrosion resistance of four different arch wires and corrosion effects of different mouthwashes to formulate a biocompatible and mechanically useful arch wire and mouthwash combination. Methods: Each group comprised of 4 wire samples of 2 cm 0.016 × 0.022 inch. 1st group: ion implanted nickel titanium (INT), 2nd group: nickel titanium, without ion implantation (NT), 3rd group: micro layered esthetic nickel titanium (ENT), 4th group: stainless steel (SS) wires. They …were immersed inside 2 ml of artificial saliva solutions (AS) for the control, or AS (9%) combined with 1 of the 3 mouthwashes (91%) for study groups, for 24 hours. These mouthwashes were essential oil (EO), chlorhexidine (CHX), sodium-fluoride (NaF). An electrochemical analyzer was used for electrochemical impedance spectroscopy measurements. Results: High corrosion resistance was obtained for ENT than the other wires. The corrosion potentials are 0.007, −0.042, 0.074 and −0.015 V (Ag/AgCl) for ENT, INT, SS and NT in the artificial salivary, respectively. In NaF containing mouthwash Rp value of ENT is significantly high in comparison to others. The impedance responses of all materials increased significantly in the presence of NaF mouthwash as well as in the CHX mouthwash. Low frequencies are seen at all materials in EO mouthwash. Diameters of loops are 22, 5.9, 5.9 and 3.7 MΩ at ENT, INT, SS and NT. Conclusions: In this study, micro layered esthetic nickel titanium wires are found biocompatible among other wires and NaF and CHX mouthwashes can be recommend for their good corrosion resistance during fixed orthodontic therapy. Show more

Keywords: Corrosion resistance, orthodontic wires, mouthwashes

DOI: 10.3233/BME-161607

Citation: Bio-Medical Materials and Engineering, vol. 27, no. 5, pp. 539-549, 2016