Displaying publications 1 - 20 of 44 in total

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  1. Low YJ, Kittur MI, Andriyana A, Ang BC, Zainal Abidin NI
    J Mech Behav Biomed Mater, 2023 Apr;140:105723.
    PMID: 36821908 DOI: 10.1016/j.jmbbm.2023.105723
    Poly(glycolide-co-caprolactone) (PGCL) has become a novice to the bioresorbable suture owing to the synergistic properties taken from the homo-polyglycolide (PGA) and polycaprolactone (PCL) such as excellent bioresorption and flexibility. In addition to under conventional monotonic loading, the understanding of mechanical responses of PGCL copolymers under complex loading conditions such as cyclic and stress relaxation is crucial for its application as a surgical suture. Consequently, the present work focuses on evaluating the mechanical responses of PGCL sutures under monotonic, cyclic, and stress relaxation loading conditions. Under monotonic loading, the stress-strain behavior of the PGCL suture was found to be non-linear with noticeable strain-rate dependence. Under cyclic loading, inelastic responses including stress-softening, hysteresis and permanent set were observed. During cyclic loading, both stress-softening and hysteresis were found to increase with the maximum strain. In multi-step stress relaxation, the PGCL sutures were observed to exhibit a strong viscoelastic response. In an attempt to describe the relationship between the stress-relaxation and strain-induced crystallization (SIC) occurring during the loading and relaxation processes, a schematic illustration of the conformational change of polymer chains in PGCL sutures was proposed in this work. Results showed that SIC was dependent on the strain level as well as the loading and relaxation durations. The inelastic phenomena observed in PGCL sutures can be thus correlated to the combined effect of stress relaxation and SIC.
    Matched MeSH terms: Absorbable Implants*
  2. Tuminoh H, Hermawan H, Ramlee MH
    J Mech Behav Biomed Mater, 2022 Nov;135:105457.
    PMID: 36116340 DOI: 10.1016/j.jmbbm.2022.105457
    In the last decade, magnesium alloys have been considered as absorbable metals for biomedical applications, while some have reached their clinical use as temporary bone implants. However, their widespread use is still limited by its strength and degradability. One way of improvement can be done by reinforcing magnesium alloys with carbon nanofibres to form composites. This work aims at developing carbon nanofibre-reinforced magnesium-zinc (Mg-Zn/CNF) composites with optimum strength and degradability while ensuring their biocompatibility. A response surface method was used to determine their optimum process parameters (composition, compaction pressure, and sintering temperature), and analyse the resulting properties (elastic modulus, hardness, weight loss, and cytocompatibility). Results showed that the optimal parameters were reached at 1.8% of CNF, 425 MPa of compaction pressure, and 500 °C of sintering temperature, whereby it gave an elastic modulus of 5 GPa, hardness of 60 Hv, and a weight loss of 51% after three days immersion in PBS. The composites exhibited a hydrophobic surface that controlled the liberation of Mg2+ and Zn2+ ions, leading to more than 70% osteoblast cells viability up to seven days of incubation. This study can also serve as a starting point for future researchers interested in finding methods to fabricate Mg-Zn/CNF composites with high mechanical characteristics, corrosion resistance, and biocompatibility.
    Matched MeSH terms: Absorbable Implants
  3. Prodan Z, Mroczek T, Sivalingam S, Bennink G, Asch FM, Cox M, et al.
    PMID: 33984478 DOI: 10.1053/j.semtcvs.2021.03.036
    Valved allografts and xenografts for reconstruction of the right ventricular outflow tract (RVOT) lack durability and do not grow. We report the first clinical use of a completely bioabsorbable valved conduit (Xeltis pulmonary valve - XPV) in children. Twelve children (six male), median age five (two to twelve) years and median weight 17 (10 to 43) kg, underwent RVOT reconstruction with the XPV. Diagnoses were: pulmonary atresia with ventricular septal defect (VSD) (n=4), tetralogy of Fallot (n=4), common arterial trunk (n=3), and transposition of the great arteries with VSD and pulmonary stenosis (n=1). All had had previous surgery, including prior RVOT conduit implantation in six. Two diameters of conduit 16mm (n=5) and 18mm (n=7) were used. At 24 months none of the patients has required surgical re-intervention, 9 of the 12 are in NYHA functional class I and three patients in NYHA class II. None of the conduits has shown evidence of progressive stenosis, dilation or aneurysm formation. Residual peak gradient of >40 mm Hg was observed in three patients, caused by kinking of the conduit at implantation in 1 and distal stenosis in the peripheral pulmonary arteries in 2 patients. Five patients developed severe pulmonary valve insufficiency (PI); the most common mechanism was prolapse of at least one of the valve leaflets. The XPV conduit is a promising innovation for RVOT reconstruction. Progressive PI requires however an improved design (geometry, thickness) of the valve leaflets.
    Matched MeSH terms: Absorbable Implants
  4. Alavi R, Akbarzadeh AH, Hermawan H
    J Mech Behav Biomed Mater, 2021 05;117:104413.
    PMID: 33640846 DOI: 10.1016/j.jmbbm.2021.104413
    In-depth analyses of post-corrosion mechanical properties and architecture of open cell iron foams with hollow struts as absorbable bone scaffolds were carried out. Variations in the architectural features of the foams after 14 days of immersion in a Hanks' solution were investigated using micro-computed tomography and scanning electron microscope images. Finite element Kelvin foam model was developed, and the numerical modeling and experimental results were compared against each other. It was observed that the iron foam samples were mostly corroded in the periphery regions. Except for quasi-elastic gradient, other mechanical properties (i.e. compressive strength, yield strength and energy absorbability) decreased monotonically with immersion time. Presence of adherent corrosion products enhanced the load-bearing capacity of the open cell iron foams at small strains. The finite element prediction for the quasi-elastic response of the 14-day corroded foam was in an agreement with the experimental results. This study highlights the importance of considering corrosion mechanism when designing absorbable scaffolds; this is indispensable to offer desirable mechanical properties in porous materials during degradation in a biological environment.
    Matched MeSH terms: Absorbable Implants*
  5. Bakhsheshi-Rad HR, Hamzah E, Ying WS, Razzaghi M, Sharif S, Ismail AF, et al.
    Materials (Basel), 2021 Apr 12;14(8).
    PMID: 33921460 DOI: 10.3390/ma14081930
    Magnesium has been recognized as a groundbreaking biodegradable biomaterial for implant applications, but its use is limited because it degrades too quickly in physiological solutions. This paper describes the research on the influence of polycaprolactone (PCL)/chitosan (CS)/zinc oxide (ZnO) composite coating (PCL/CS/ZnO) on the corrosion resistance and antibacterial activity of magnesium. The PCL/CS film presented a porous structure with thickness of about 40-50 μm, while after incorporation of ZnO into the PCL/CS, a homogenous film without pores and defects was attained. The ZnO embedded in PCL/CS enhanced corrosion resistance by preventing corrosive ions diffusion in the magnesium substrate. The corrosion, antibacterial, and cell interaction mechanism of the PCL/CS/ZnO composite coating is discussed in this study. In vitro cell culture revealed that the PCL/CS coating with low loaded ZnO significantly improved cytocompatibility, but coatings with high loaded ZnO were able to induce some cytotoxicity osteoblastic cells. It was also found that enhanced antibacterial activity of the PCL/CS/ZnO coating against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria, while less significant antibacterial activity was detected for uncoated Mg and PCL/CS coating. Based on the results, the PCL/CS coatings loaded with low ZnO content may be recommended as a candidate material for biodegradable Mg-based orthopedic implant applications.
    Matched MeSH terms: Absorbable Implants
  6. Chandrasekhar J, Sartori S, Aquino MB, Baber U, Hájek P, Atzev B, et al.
    Am J Cardiol, 2020 07 15;127:1-8.
    PMID: 32418717 DOI: 10.1016/j.amjcard.2020.04.014
    Older patients who undergo coronary interventions are at greater risk of ischemic events and less likely to tolerate prolonged dual antiplatelet therapy (DAPT) due to bleeding risk. The COMBO biodegradable polymer sirolimus-eluting stent promotes rapid endothelialization through endothelial progenitor cell capture technology which may be advantageous in elderly patients. We compared 1-year clinical outcomes and DAPT cessation events in patients >75 versus ≤75 years from the MASCOT registry. MASCOT was a prospective, multicenter cohort study of all-comers undergoing attempted COMBO stenting. The primary endpoint was 1-year target lesion failure (TLF), composite of cardiac death, myocardial infarction (MI) not clearly attributed to a nontarget vessel or clinically driven target lesion revascularization. Bleeding was adjudicated using the Bleeding Academic Research Consortium criteria. Adjusted outcomes were analyzed using Cox regression methods. The study included 18% (n = 479) patients >75 years and 72% (n = 2,135) patients ≤75 years. One-year TLF occurred in 4.6% patients >75 years versus 3.1% patients ≤75years of age, p = 0.10; adj hazard ratio 1.36, 95% confidence intervals 0.77 to 2.38, p = 0.29. There were no significant differences in cardiac death (1.7% vs 1.3%, p = 0.55), MI (2.1% vs 1.2%, p = 0.14), target lesion revascularization (1.7% vs 1.4%, p = 0.60) and definite stent thrombosis (0.8% vs 0.4%, p = 0.19). Major Bleeding Academic Research Consortium 3,5 bleeding (3.1% vs 1.5%, p = 0.01) and DAPT cessation rates (32.4% vs 23.0%, p <0.001) were significantly higher in elderly patients. In conclusion, elderly patients >75 years treated with COMBO stents had similar TLF but significantly greater incidence of bleeding than younger patients and DAPT cessation in one-third of patients over 1 year.
    Matched MeSH terms: Absorbable Implants*
  7. Wan Ahmad WA, Nakayoshi T, Mahmood Zuhdi AS, Ismail MD, Zainal Abidin I, Ino Y, et al.
    Heart Vessels, 2020 Apr;35(4):463-473.
    PMID: 31587103 DOI: 10.1007/s00380-019-01516-9
    Recent clinical trials have raised concerns about the safety and efficacy of ABSORB™ bioresorbable vascular scaffolds (BVS). The difference in the vascular healing process between SYNERGY™ bioabsorbable polymer-coated everolimus-eluting stents (BP-EES) and BVS remains unclear. The aim of the ENHANCE study was to compare vascular healing on BP-EES versus BVS by optical coherence tomography (OCT) and coronary angioscopy (CAS) at 4- and 12-month follow-ups. This is a prospective, non-randomized, single center clinical trial. Thirteen eligible patients with multivessel disease were enrolled. BP-EES and BVS were simultaneously implanted in the same patients, but in different coronary vessels. Imaging follow-up with both OCT and CAS was completed in 11 patients at 12 months. Neointimal coverage rates were similar between the two groups based on OCT measurements. The neointimal thickness of BP-EES was significantly thicker at the 12th month than at the 4th month, whereas the neointimal thickness of BVS did not change between the measurements taken at the 4th and 12th month. Existence of intra-stent thrombus was significantly higher in the BVS group, compared to the BP-EES group. On the other hand, CAS revealed that red-thrombi and yellow-plaque were more frequently observed in BVS at 4 months and up to 12-month follow-ups than in BP-EES. These findings suggested that the evidence of instability remained up to 12 months in the vascular healing with BVS, compared to that with BP-EES. Vascular healing of the stented wall was recognized at the very early phase after BP-EES implantation. However, vascular healing with BVS was still incomplete after 12 months.
    Matched MeSH terms: Absorbable Implants
  8. Yan L, Zhang M, Wang M, Guo Y, Zhang X, Xi J, et al.
    J Nanosci Nanotechnol, 2020 03 01;20(3):1504-1510.
    PMID: 31492313 DOI: 10.1166/jnn.2020.17350
    This research has been accomplished using the advanced selective laser melting (SLM) technique as well as HIP post-treatment in order to improve mechanical properties and biocompatibility of Mg- Ca-Sr alloy. Through this research it becomes clearly noticeable that the Mg-1.5Ca-xSr (x = 0.6, 2.1, 2.5) alloys with Sr exhibited better mechanical properties and corrosion potentials. This is more particular with the Mg-1.5Ca-2.5Sr alloy after HIP post-treatment allowing it to provide a desired combination of degradation and mechanical behavior for orthopedic fracture fixation during a desired treatment period. In vivo trials, there was a clear indication and exhibition that this Mg-1.5Ca-2.5Sr alloy screw can completely dissolve in miniature pig's body which leads to an acceleration in growth of bone tissues. Mg-Ca-Sr alloy proved potential candidate for use in orthopedic fixation devices through Our results concluded that Mg-Ca-Sr alloy are potential candidate for use in orthopedic fixation devices through mechanical strength and biocompatibility evaluations (in vitro or In vivo).
    Matched MeSH terms: Absorbable Implants*
  9. Krackhardt F, Kočka V, Waliszewski M, Toušek P, Janek B, Trenčan M, et al.
    Medicine (Baltimore), 2020 Feb;99(8):e19119.
    PMID: 32080086 DOI: 10.1097/MD.0000000000019119
    Stent designs with ultrathin struts may further increase the procedural success of challenging lesion subsets. The objective of this study was to assess the safety and efficacy of ultrathin strut, polymer-free sirolimus eluting stent (PF-SES) implantations in a large scale, unselected patient population.Adult patients underwent percutaneous coronary interventions (PCI) with a thin-strut PF-SES. Data from two all-comers observational studies having the same protocol (ClinicalTrials.gov Identifiers: NCT02629575 and NCT02905214) were pooled. The accumulated target lesion revascularization (TLR) rate at 9-12 months was the primary endpoint. All dual antiplatelet therapy strategies according to the applicable guidelines were permissible.In total, 7243 patients were prospectively enrolled for PCI with PF-SES in stable coronary artery disease or acute coronary syndrome (ACS). Major risk factors in the overall cohort were diabetes (37.3%), ST elevation myocardial infarction (18.1%) and non-ST myocardial infarction (24.6%). The follow-up rate was 88.6% in the overall population. The TLR rate in the overall cohort was 2.2% whereas definite/probable stent thrombosis (ST) occurred in 0.7%. In patients with in-stent restenosis lesions, the major adverse cardiac events rate was 6.4% whereas the corresponding rate for isolated left main coronary artery (LMCA) disease was highest with 6.7% followed by patients with culprit lesions in vein bypasses (VB, 7.1%). The mortality rate in patients treated in VB lesions was highest with 5.4%, followed by the isolated LMCA subgroup (3.4%) and ACS (2.6%).PCI with PF-SES in an unselected patient population, is associated with low clinical event and ST rates. Furthermore, PF-SES angioplasty in niche indications demonstrated favorable safety and efficacy outcomes with high procedural success rates.
    Matched MeSH terms: Absorbable Implants/adverse effects
  10. Campos CM, Caixeta A, Franken M, Bartorelli AL, Whitbourn RJ, Wu CJ, et al.
    Catheter Cardiovasc Interv, 2018 02 15;91(3):387-395.
    PMID: 28471086 DOI: 10.1002/ccd.27109
    OBJECTIVES: to compare the occurrence of clinical events in diabetics treated with the Absorb bioresorbable vascular scaffold (Absorb BVS; Abbott Vascular, Santa Clara, CA) versus everolimus-eluting metal stents (EES; XIENCE V; Abbott Vascular, Santa Clara, CA) BACKGROUND: There are limited data dedicated to clinical outcomes of diabetic patients treated with bioresorbable scaffolds (BRS) at 2-year horizon.

    METHODS: The present study included 812 patients in the ABSORB EXTEND study in which a total of 215 diabetic patients were treated with Absorb BVS. In addition, 882 diabetic patients treated with EES in pooled data from the SPIRIT clinical program (SPIRIT II, SPIRIT III and SPIRIT IV trials) were used for comparison by applying propensity score matching using 29 different variables. The primary endpoint was ischemia driven major adverse cardiac events (ID-MACE), including cardiac death, myocardial infarction (MI), and ischemia driven target lesion revascularization (ID-TLR).

    RESULTS: After 2 years, the ID-MACE rate was 6.5% in the Absorb BVS vs. 8.9% in the Xience group (P = 0.40). There was no difference for MACE components or definite/probable device thrombosis (HR: 1.43 [0.24,8.58]; P = 0.69). The occurrence of MACE was not different for both diabetic status (insulin- and non-insulin-requiring diabetes) in all time points up to the 2-year follow-up for the Absorb and Xience groups.

    CONCLUSION: In this largest ever patient-level pooled comparison on the treatment of diabetic patients with BRS out to two years, individuals with diabetes treated with the Absorb BVS had a similar rate of MACE as compared with diabetics treated with the Xience EES. © 2017 Wiley Periodicals, Inc.

    Matched MeSH terms: Absorbable Implants*
  11. Che Nor Zarida Che Seman, Zamzuri Zakaria
    MyJurnal
    Critical size defects (CSD) in the long bones of New Zealand White rabbits (Oryctolagus cuniculus) have been used for years as an experimental model for investigation of the effectiveness of a new bone substitute material. There are varieties of protocols available in the literature. This technical note attempts to present an alternative surgical technique of a CSD in the New Zealand white rabbit tibia. Methods: Thirty-nine New Zealand White rabbits were used in this study. A CSD of approximately 4.5 mm (width) X 9.0 mm (length) was surgically drilled at the proximal tibial metaphysis, approximately 1 cm from the knee joint. The surrounding of soft tissue was repositioned and sutured layer by layer with bioabsorbable surgical suture. Two x-rays of anteroposterior and lateral were taken before assessed under computed tomography scan at 6, 12 and 24 weeks. Results: This alternative method created CSD with less bleeding from the muscle observed. No mortality or other surgical complications observed within 6 weeks, 12 weeks and 24 weeks following surgery. Conclusion: A simple and safe method for performing CSD was demonstrated and recommended as an alternative approach for surgery on New Zealand White rabbits.
    Matched MeSH terms: Absorbable Implants
  12. Tenekecioglu E, Serruys PW, Onuma Y, Costa R, Chamié D, Sotomi Y, et al.
    JACC Cardiovasc Interv, 2017 06 12;10(11):1115-1130.
    PMID: 28527768 DOI: 10.1016/j.jcin.2017.03.015
    OBJECTIVES: The primary objective of this study was to evaluate the safety and effectiveness of the Mirage (Manli Cardiology, Singapore) bioresorbable microfiber sirolimus-eluting scaffold compared with the Absorb (Abbott Vascular, Santa Clara, California) bioresorbable vascular scaffold in the treatment of stenotic target lesions located in native coronary arteries, ranging from ≥2.25 to ≤4.0 mm in diameter. Secondary objectives were to establish the medium-term safety, effectiveness, and performance of the Mirage device.

    BACKGROUND: The current generation of bioresorbable scaffolds has several limitations, such as thick square struts with large footprints that preclude their deep embedment into the vessel wall, resulting in protrusion into the lumen with microdisturbance of flow. The Mirage sirolimus-eluting bioresorbable microfiber scaffold is designed to address these concerns.

    METHODS: In this prospective, single-blind trial, 60 patients were randomly allocated in a 1:1 ratio to treatment with a Mirage sirolimus-eluting bioresorbable microfiber scaffold or an Absorb bioresorbable vascular scaffold. The clinical endpoints were assessed at 30 days and at 6 and 12 months. In-device angiographic late loss at 12 months was quantified. Secondary optical coherence tomographic endpoints were assessed post-scaffold implantation at 6 and 12 months.

    RESULTS: Median angiographic post-procedural in-scaffold minimal luminal diameters of the Mirage and Absorb devices were 2.38 mm (interquartile range [IQR]: 2.06 to 2.62 mm) and 2.55 mm (IQR: 2.26 to 2.71 mm), respectively; the effect size (d) was -0.29. At 12 months, median angiographic in-scaffold minimal luminal diameters of the Mirage and Absorb devices were not statistically different (1.90 mm [IQR: 1.57 to 2.31 mm] vs. 2.29 mm [IQR: 1.74 to 2.51 mm], d = -0.36). At 12-month follow-up, median in-scaffold late luminal loss with the Mirage and Absorb devices was 0.37 mm (IQR: 0.08 to 0.72 mm) and 0.23 mm (IQR: 0.15 to 0.37 mm), respectively (d = 0.20). On optical coherence tomography, post-procedural diameter stenosis with the Mirage was 11.2 ± 7.1%, which increased to 27.4 ± 12.4% at 6 months and remained stable (31.8 ± 12.9%) at 1 year, whereas the post-procedural optical coherence tomographic diameter stenosis with the Absorb was 8.4 ± 6.6%, which increased to 16.6 ± 8.9% and remained stable (21.2 ± 9.9%) at 1-year follow-up (Mirage vs. Absorb: dpost-procedure = 0.41, d6 months = 1.00, d12 months = 0.92). Angiographic median in-scaffold diameter stenosis was significantly different between study groups at 12 months (28.6% [IQR: 21.0% to 40.7%] for the Mirage, 18.2% [IQR: 13.1% to 31.6%] for the Absorb, d = 0.39). Device- and patient-oriented composite endpoints were comparable between the 2 study groups.

    CONCLUSIONS: At 12 months, angiographic in-scaffold late loss was not statistically different between the Mirage and Absorb devices, although diameter stenosis on angiography and on optical coherence tomography was significantly higher with the Mirage than with the Absorb. The technique of implantation was suboptimal for both devices, and future trials should incorporate optical coherence tomographic guidance to allow optimal implantation and appropriate assessment of the new technology, considering the novel mechanical properties of the Mirage.

    Matched MeSH terms: Absorbable Implants*
  13. Bakhsheshi-Rad HR, Hamzah E, Low HT, Kasiri-Asgarani M, Farahany S, Akbari E, et al.
    Mater Sci Eng C Mater Biol Appl, 2017 Apr 01;73:215-219.
    PMID: 28183601 DOI: 10.1016/j.msec.2016.11.138
    In this work, binary Zn-0.5Al and ternary Zn-0.5Al-xMg alloys with various Mg contents were investigated as biodegradable materials for implant applications. Compared with Zn-0.5Al (single phase), Zn-0.5Al-xMg alloys consisted of the α-Zn and Mg2(Zn, Al)11 with a fine lamellar structure. The results also revealed that ternary Zn-Al-Mg alloys presented higher micro-hardness value, tensile strength and corrosion resistance compared to the binary Zn-Al alloy. In addition, the tensile strength and corrosion resistance increased with increasing the Mg content in ternary alloys. The immersion tests also indicated that the corrosion rates in the following order Zn-0.5Al-0.5Mg
    Matched MeSH terms: Absorbable Implants*
  14. Chanana BB, Chandra P, Cheng JJ, Dick R, Gwon HC, Hiremath MS, et al.
    Int J Cardiol, 2016 Nov 01;222:832-40.
    PMID: 27522385 DOI: 10.1016/j.ijcard.2016.07.273
    BACKGROUND & AIMS: Although Absorb Bioresorbable Vascular Scaffolds (A-BVS) are routinely used in the Asia-Pacific, there is little information on patient selection or deployment technique here. This document investigates the experiences of leading interventional cardiologists from the Asia-Pacific region with a focus on patient characteristics, deployment techniques and management.

    METHODS AND RESULTS: A detailed questionnaire was distributed to 28 highly-experienced interventional cardiologists ('Authors') from 13 Asia-Pacific countries. The results were discussed at a meeting on patient selection, technical consideration, deployment practices and patient management. Potential patient benefits of Absorb compared to metallic DES, the learning curve for patient selection and preparation, device deployment, and subsequent patient management approaches are presented.

    CONCLUSIONS: Current practices are derived from guidelines optimized for European patients. Differences in approach exist in the Asia-Pacific context, including limited access to imaging and frequency of occurrence of complex lesions. Nevertheless, the use of the Absorb BVS ('Absorb') in certain Asia-Pacific countries has flourished and practices here are continuing to mature.

    Matched MeSH terms: Absorbable Implants/utilization*
  15. Michael FM, Khalid M, Walvekar R, Ratnam CT, Ramarad S, Siddiqui H, et al.
    Mater Sci Eng C Mater Biol Appl, 2016 Oct 01;67:792-806.
    PMID: 27287178 DOI: 10.1016/j.msec.2016.05.037
    Bones are nanocomposites consisting of a collagenous fibre network, embedded with calcium phosphates mainly hydroxyapatite (HA) nanocrystallites. As bones are subjected to continuous loading and unloading process every day, they often tend to become prone to fatigue and breakdown. Therefore, this review addresses the use of nanocomposites particularly polymers reinforced with nanoceramics that can be used as load bearing bone implants. Further, nanocomposite preparation and dispersion modification techniques have been highlighted along with thorough discussion on the influence that various nanofillers have on the physico-mechanical properties of nanocomposites in relation to that of natural bone properties. This review updates the nanocomposites that meet the physico-mechanical properties (strength and elasticity) as well as biocompatibility requirement of a load bearing bone implant and also attempts to highlight the gaps in the reported studies to address the fatigue and creep properties of the nanocomposites.
    Matched MeSH terms: Absorbable Implants*
  16. Dambatta MS, Murni NS, Izman S, Kurniawan D, Froemming GR, Hermawan H
    Proc Inst Mech Eng H, 2015 May;229(5):335-42.
    PMID: 25991712 DOI: 10.1177/0954411915584962
    This article reports the in vitro degradation and cytotoxicity assessment of Zn-3Mg alloy developed for biodegradable bone implants. The alloy was prepared using casting, and its microstructure was composed of Mg2Zn11 intermetallic phase distributed within a Zn-rich matrix. The degradation assessment was done using potentiodynamic polarization and electrochemical impedance spectrometry. The cell viability and the function of normal human osteoblast cells were assessed using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium and alkaline phosphatase extracellular enzyme activity assays. The results showed that the degradation rate of the alloy was slower than those of pure Zn and pure Mg due to the formation of a high polarization resistance oxide film. The alloy was cytocompatible with the normal human osteoblast cells at low concentrations (<0.5 mg/mL), and its alkaline phosphatase activity was superior to pure Mg. This assessment suggests that Zn-3Mg alloy has the potential to be developed as a material for biodegradable bone implants, but the toxicity limit must be carefully observed.
    Matched MeSH terms: Absorbable Implants*
  17. Murni NS, Dambatta MS, Yeap SK, Froemming GRA, Hermawan H
    Mater Sci Eng C Mater Biol Appl, 2015 Apr;49:560-566.
    PMID: 25686984 DOI: 10.1016/j.msec.2015.01.056
    The recent proposal of using Zn-based alloys for biodegradable implants was not supported with sufficient toxicity data. This work, for the first time, presents a thorough cytotoxicity evaluation of Zn-3Mg alloy for biodegradable bone implants. Normal human osteoblast cells were exposed to the alloy's extract and three main cell-material interaction parameters: cell health, functionality and inflammatory response, were evaluated. Results showed that at the concentration of 0.75mg/ml alloy extract, cell viability was reduced by ~50% through an induction of apoptosis at day 1; however, cells were able to recover at days 3 and 7. Cytoskeletal changes were observed but without any significant DNA damage. The downregulation of alkaline phosphatase protein levels did not significantly affect the mineralization process of the cells. Significant differences of cyclooxygenase-2 and prostaglandin E2 inflammatory biomarkers were noticed, but not interleukin 1-beta, indicating that the cells underwent a healing process after exposure to the alloy. Detailed analysis on the cell-material interaction is further discussed in this paper.
    Matched MeSH terms: Absorbable Implants
  18. Sing NB, Mostavan A, Hamzah E, Mantovani D, Hermawan H
    J Biomed Mater Res B Appl Biomater, 2015 Apr;103(3):572-7.
    PMID: 24954069 DOI: 10.1002/jbm.b.33242
    This article reports a degradation study that was done on stent prototypes made of biodegradable Fe35Mn alloy in a simulated human coronary arterial condition. The stent degradation was observed for a short-term period from 0.5 to 168 h, which simulates the early period of stenting procedure. Potentiodynamic polarization and electrochemical impedance spectroscopy were used to quantify degradation rate and surface property of the stents. Results showed that signs of degradation were visible on both crimped and expanded stents after 1 h of test, mostly located on the stent's curvatures. The degradation rate of stent was higher compared to that of the original alloy, indicating the surface altering effect of stent fabrication processing to degradation. A single oxide layer was formed and detected as a porous structure with capacitive behavior. Expanded stents exhibited lower polarization resistance compared to the nonexpanded ones, indicating the cold work effect of expansion procedure to degradation.
    Matched MeSH terms: Absorbable Implants*
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