scholarly journals Study of Biodegradation of Pure Magnesium

2007 ◽  
Vol 342-343 ◽  
pp. 601-604 ◽  
Author(s):  
Yi Bin Ren ◽  
Hao Wang ◽  
Jing Jing Huang ◽  
Bing Chun Zhang ◽  
Ke Yang
Keyword(s):  
Corrosion Rate ◽  
Ph Value ◽  
Pure Magnesium ◽  
Hydrogen Release ◽  
Corrosion Properties ◽  
Production Of Hydrogen ◽  
New Type ◽  
Time Test ◽  
Hank’S Solution

Magnesium and its alloys are possible to develop new type of biodegradable medical magnesium alloys by using their active corrosion potential. The bio-corrosion properties of the high pure magnesium in the Hank’s solution were investigated in this paper, the results showed that high pure magnesium had a low corrosion rate and hydrogen release in Hank’s solution, when the pH value of solution was controlled at 7.5, the corrosion rate was under 0.2mm/year, the production of hydrogen was about 0.15ml/cm2, and if the solution wasn’t controlled on pH value, the corrosion rate was about 0.02 mm/year, production of hydrogen was about 0.1ml/cm2 . Result of in vitro Kinetic clotting time test and animal implant prep-test showed that High pure magnesium had good thromboresistant property and tissue compatibility, pure magnesium can biodegrade lowly in animal body and formed surface apatite, which proportion of Ca/P was similar with bone tissue.

scholarly journals In Vitro Corrosion of Quaternery Magnesium Alloy Foam by Addition of Zinc

2020 ◽  
Vol 2 (3) ◽  
pp. 86-92
Author(s):  
Franciska Pramuji Lestari ◽  
Sofia Marta ◽  
Aprilia Erryan ◽  
Inti Mulyati ◽  
Ika Kartika
Keyword(s):  
Corrosion Rate ◽  
Raw Materials ◽  
Galvanic Corrosion ◽  
X Ray Diffraction ◽  
Corrosion Properties ◽  
Direct Observations ◽  
Powder Metallurgy Process ◽  
Electron Dispersion ◽  
Hank’S Solution

Magnesium alloys have been intensively studied as possible resorbable material with adequate mechanical properties similar to natural bones but very poor corrosion properties. In this analysis, the addition of Zn element to quaternary Mg-Ca-Zn alloy foam was evaluated with TiH2 as a foaming agent and manufactured with high-purity raw materials the powder metallurgy process. In Hank's solution, the rate of corrosion of specimens by direct observations with Scanning Electron Microscopy ( SEM), Electron Dispersion Spectrometry (EDS), static immersion studies, potentiodynamic evaluations, and X-Ray Diffraction (XRD). The specimens post-immersion characteristics and the corresponding Hank's solutions were examined at 2, 4, 6, 24, 48, and 72 hours of immersion. The findings show that the microstructure of alloy morphology, such as pores, pitting corrosion, needle shapes, and galvanic corrosion has the main corrosion products Mg(OH)2 and Ca10(PO4)6(OH)2. The addition of less than 6 percent wt Zn will minimize the corrosion rate but increase with 10 percent wt Zn. From this study, Mg-Zn-Ca alloy at 6 percent wt Zn has the lowest corrosion rate with slow pH changes in the process.

In Vitro Corrosion and Biocompatibility of Coated MgCa1.0 Magnesium Alloys

2011 ◽  
Vol 690 ◽  
pp. 409-412
Author(s):  
Paul Rosemann ◽  
Susanne Bender ◽  
Andreas Heyn ◽  
Jürgen Schmidt
Keyword(s):  
Magnesium Alloy ◽  
Corrosion Rate ◽  
Ph Value ◽  
Corrosion Behaviour ◽  
Dip Coating ◽  
Chemical Oxidation ◽  
Essential Elements ◽  
Noise Measurements

As bio-absorbable implant material the magnesium alloy Mg-1Ca is able to degrade in-vivo. The mechanical properties of this alloy are similar to those of human bone; both Mg and Ca are essential elements in human body. The main problem is the high corrosion rate of this alloy. Two coating systems based on plasma-chemical oxidation and an organic dip coating are applied onto MgCa1.0 magnesium alloy in order to slow down the corrosion rate. The corrosion behaviour of the coated alloys was investigated with electrochemical noise measurements. The influence of hydrogen evolution and increasing pH-value on the cytotoxicity was examined. The results of these investigations suggest that a combination of both coating systems leads to promising degradation properties.

scholarly journals The Effect of pH on the Corrosion Rate of 316L Stainless Steel, Nitinol, and Titanium-6%Aluminium-4%Vanadium in Hank’s Solution

2021 ◽  
Vol 18 (1) ◽  
pp. 1
Author(s):  
Nik Rozlin Nik Masdek ◽  
Nor’Aini Wahab ◽  
Natasha Ahmad Nawawi ◽  
Aznul Tajudin
Keyword(s):  
Stainless Steel ◽  
Corrosion Rate ◽  
Potentiodynamic Polarization ◽  
316L Stainless Steel ◽  
Ph Value ◽  
Corrosion Behaviour ◽  
Research Work ◽  
Biological Condition ◽  
Effect Of Ph ◽  
Hank’S Solution

Nowadays, the application of 316L Stainless Steel, Nitinol and Ti-6Al-4V alloys as biomaterials have become popular due to their implant performance and durability. In this research work, the effect of pH on the corrosion rate of 316L Stainless Steel, Nitinol and Ti-6Al-4V alloys have been investigated. An electrochemical method was applied in order to investigate the corrosion behaviour of these biomaterials under simulated biological condition. The potentiodynamic polarization were performed in a Hank’s solution at pH value 7.4 (neutral) and 5.2 (acidic). SEM, XRD, microhardness and surface roughness were also carried out to characterise the corroded surface. The potentiodynamic polarization results showed that both Ti-6Al-4V and 316L stainless steel had high corrosion rate at pH 5.2 (acidic) as compared to pH 7.4 (neutral). The corrosion rate for Ti-6Al-4V alloys at pH 7.4 was 22.80×10-3 mmpy before it increased to 23.65×10-3 mmpy at pH 5.2. Similar behaviour was observed for 316L stainless steel where at pH 7.4 and increase the corrosion rate increasing from 2.387×10-3 mmpy at pH 7.4 to 5.325×10-3 mmpy at pH 5.2. However different corrosion behaviour was observed for Nitinol as the corrosion rate decreasing from 17.65×10-3 mmpy to 16.04×10-3 mmpy at pH 7.4 and 5.2, respectively. Hence, the decrease of pH value was found to not cause any significant effect on the corrosion resistance of Nitinol as compared to 316L SS and Ti-6Al-4V alloys.

Microstructural and Corrosion Behavior of Biodegradable Magnesium Alloys for Biomedical Implant

2015 ◽  
Vol 819 ◽  
pp. 331-336
Author(s):  
H.Y. Tok ◽  
Esah Hamzah ◽  
Hamid Reza Bakhsheshi-Rad
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Microstructural Analysis ◽  
Corrosion Current ◽  
Immersion Test ◽  
Ternary Alloys ◽  
Corrosion Properties ◽  
X Ray ◽  
Electrochemical Tests ◽  
Production Of Hydrogen

Magnesium and its alloys have great potential as biodegradable metallic implant materials with good mechanical properties. However, the poor corrosion rate and the production of hydrogen during degradation hindered its application. Binary alloy, Mg-3Ca and ternary alloy, Mg-3Ca-3Zn alloy were studied to investigate their bio-corrosion properties. Microstructure evolution and surfaces of corroded alloys were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The bio-corrosion behavior of the Mg alloys was investigated using immersion and electrochemical tests in Kokubo solution. Microstructural analysis showed that binary Mg-3Ca alloy consisted of α-Mg and Mg2Ca phases and ternary Mg-3Ca-3Zn alloy consisted of α-Mg, Ca2Mg6Zn3 and Mg2Ca phases. These phases had significant effect on the corrosion resistant of the alloy. Electrochemical test showed an improvement in ternary alloys where the corrosion current density reduced from 0.497 mA/cm2 in Mg-3Ca to 0.312 mA/cm2 in Mg-3Ca-3Zn alloy. Ternary Mg-3Ca-3Zn showed significant lower corrosion rate (1.1 mg/cm2/day) compared to binary Mg-3Ca (5.8 mg/cm2/day) alloy after 14 days immersion test.

Rhenium-188 Labeled Hydroxyapatite and Rhenium-188 Sulfur Colloid

1997 ◽  
Vol 36 (02) ◽  
pp. 71-75 ◽  
Author(s):  
S. Glatz ◽  
S. N. Reske ◽  
K. G. Grillenberger
Keyword(s):  
Synovial Fluid ◽  
Ph Value ◽  
Surgical Removal ◽  
Radiation Synovectomy ◽  
Sulfur Colloid ◽  
Target Organs ◽  
Aseptic Conditions ◽  
In Vitro Stability ◽  
Potential Use

Summary Aim: One therapeutic approach to rheumatoid arthritis and other inflammatory arthropathies besides surgical removal of inflamed synovium is radiation synovectomy using beta-emitting radionuclides to destroy the affected synovial tissue. Up to now the major problem associated with the use of labeled particles or colloids has been considerable leakage of radionuclides from the injected joint coupled with high radiation doses to liver and other non target organs. In this study we compared 188Re labeled hydroxyapatite particles and 188Re rhenium sulfur colloid for their potential use in radiation synovectomy. Methods: To this end we varied the labeling conditions (concentrations, pH-value, heating procedure) and analyzed the labeling yield, radiochemical purity, and in vitro stability of the resulting radiopharmaceutical. Results: After optimizing labeling conditions we achieved a labeling yield of more than 80% for 188Re hydroxyapatite and more than 90% for the rhenium sulfur colloid. Both of the radiopharmaceuticals can be prepared under aseptic conditions using an autoclav for heating without loss of activity. In vitro stability studies using various challenge solutions (water, normal saline, diluted synovial fluid) showed that 188Re labeled hydroxyapatite particles lost about 80% of their activity within 5 d in synovial fluid. Rhenium sulfur colloid on the other hand proved to be very stable with a remaining activity of more than 93% after 5 d in diluted synovial fluid. Conclusion: These in vitro results suggest that 188Re labeled rhenium sulfur colloid expects to be more suitable for therapeutic use in radiation synovectomy than the labeled hydroxyapatite particles.

The Flowing Clotting Time (Thrombus Formation Time) a Sensitive Test of Hypercoagulability

1969 ◽  
Vol 21 (03) ◽  
pp. 516-523
Author(s):  
H Engelberg ◽  
L. P Engelberg
Keyword(s):  
Thrombus Formation ◽  
Formation Time ◽  
Sensitive Test ◽  
Clotting Time ◽  
Reliable Test ◽  
Time Test ◽  
Plasma Heparin

SummaryThe addition of small amounts of extrinsic thromboplastin or of thrombin to blood in vitro accelerated coagulation more frequently and to a greater extent when determined by the flowing time test than when measured by the silicone clotting time, or by the blood or plasma heparin tolerance tests. Similar results were obtained when intrinsic thromboplastin formation was stimulated by contact with glass. However there was little or no acceleration of the flowing clotting time of plasma obtained from aliquots of the thromboplastin-containing blood. These results indicate that the flowing clotting time (thrombus formation time) of whole blcod is a more reliable test of hypercoagulability than previously described blood or plasma clotting time tests.

In vitro Lipolysis as a Tool for the Establishment of IVIVC for Lipid-Based Drug Delivery Systems

2019 ◽  
Vol 16 (8) ◽  
pp. 688-697
Author(s):  
Ravinder Verma ◽  
Deepak Kaushik
Keyword(s):  
Drug Delivery ◽  
Ph Value ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Rapid Screening ◽  
Resonance Spectroscopy ◽  
Fed State ◽  
In Vitro Lipolysis ◽  
Ph Stat

: In vitro lipolysis has emerged as a powerful tool in the development of in vitro in vivo correlation for Lipid-based Drug Delivery System (LbDDS). In vitro lipolysis possesses the ability to mimic the assimilation of LbDDS in the human biological system. The digestion medium for in vitro lipolysis commonly contains an aqueous buffer media, bile salts, phospholipids and sodium chloride. The concentrations of these compounds are defined by the physiological conditions prevailing in the fasted or fed state. The pH of the medium is monitored by a pH-sensitive electrode connected to a computercontrolled pH-stat device capable of maintaining a predefined pH value via titration with sodium hydroxide. Copenhagen, Monash and Jerusalem are used as different models for in vitro lipolysis studies. The most common approach used in evaluating the kinetics of lipolysis of emulsion-based encapsulation systems is the pH-stat titration technique. This is widely used in both the nutritional and the pharmacological research fields as a rapid screening tool. Analytical tools for the assessment of in vitro lipolysis include HPLC, GC, HPTLC, SEM, Cryo TEM, Electron paramagnetic resonance spectroscopy, Raman spectroscopy and Nanoparticle Tracking Analysis (NTA) for the characterization of the lipids and colloidal phases after digestion of lipids. Various researches have been carried out for the establishment of IVIVC by using in vitro lipolysis models. The current publication also presents an updated review of various researches in the field of in vitro lipolysis.

Improving Topical Skin Delivery of Monocrotaline Via Liposome Gel-based Nanosystems

2019 ◽  
Vol 16 (10) ◽  
pp. 940-950 ◽  
Author(s):  
Jiandong Yu ◽  
Zhi Chen ◽  
Yan-zhi Yin ◽  
Chaoyuan Tang ◽  
Enying Hu ◽  
...  
Keyword(s):  
Gradient Method ◽  
Encapsulation Efficiency ◽  
Ph Value ◽  
Topical Administration ◽  
Ph Gradient ◽  
Stability Factor ◽  
Buffer Solution ◽  
Skin Delivery ◽  
Skin Retention

Background: In this study, a liposomal gel based on a pH-gradient method was used to increase the skin-layer retention of monocrotaline (MCT) for topical administration. Methods: Using the Box-Behnken design, different formulations were designed to form liposome suspensions with optimal encapsulation efficiency (EE%) and stability factor (KE). In order to keep MCT in liposomes and accumulate in skin slowly and selectively, MCT liposome suspensions were engineered into gels. Results: A pH-gradient method was used to prepare liposome suspensions. The optimal formulation of liposome suspensions (encapsulation efficiency: 83.10 ± 0.21%) was as follows: MCT 12 mg, soybean phosphatidyl choline (sbPC) 200 mg, cholesterol (CH) 41 mg, vitamin E (VE) 5 mg, and citric acid buffer solution (CBS) 4.0 10 mL (pH 7.0). The final formulation of liposomal gels consisted of 32 mL liposome suspensions, 4.76 mL deionized water, 0.40 g Carbopol-940, 1.6 g glycerol, 0.04 g methylparaben, and a suitable amount of triethanolamine for pH value adjustment. The results of in vitro drug release showed that MCT in liposomal gels could be released in 12 h constantly in physiological saline as a Ritger-Peppas model. Compared with plain MCT in gel form, liposomal MCT in gel had higher skin retention in vitro. Conclusion: In this study, liposomal gels were formed for greater skin retention of MCT. It is potentially beneficial for reducing toxicities of MCT by topical administration with liposomal gel.

scholarly journals Photocuring Hyaluronic Acid/Silk Fibroin Hydrogel Containing Curcumin Loaded CHITOSAN Nanoparticles for the Treatment of MG-63 Cells and ME3T3-E1 Cells

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2302
Author(s):  
Qingwen Yu ◽  
Zhiyuan Meng ◽  
Yichao Liu ◽  
Zehao Li ◽  
Xing Sun ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Bone Regeneration ◽  
Water Uptake ◽  
Silk Fibroin ◽  
Bone Repair ◽  
Ph Value ◽  
Chitosan Nanoparticles ◽  
Vitro Assay ◽  
Long Term Treatment

After an osteosarcoma excision, recurrence and bone defects are significant challenges for clinicians. In this study, the curcumin (Cur) loaded chitosan (CS) nanoparticles (CCNP) encapsulated silk fibroin (SF)/hyaluronic acid esterified by methacrylate (HAMA) (CCNPs-SF/HAMA) hydrogel for the osteosarcoma therapy and bone regeneration was developed by photocuring and ethanol treatment. The micro or nanofibers networks were observed in the CCNPs-SF/HAMA hydrogel. The FTIR results demonstrated that alcohol vapor treatment caused an increase in β-sheets of SF, resulting in the high compression stress and Young’s modulus of CCNPs-SF/HAMA hydrogel. According to the water uptake analysis, SF caused a slight decrease in water uptake of CCNPs-SF/HAMA hydrogel while CCNPs could enhance the water uptake of it. The swelling kinetic results showed that both the CCNPs and the SF increased the swelling ratio of CCNPs-SF/HAMA hydrogel. The accumulative release profile of CCNPs-SF/HAMA hydrogel showed that the release of Cur from CCNPs-SF/HAMA hydrogel was accelerated when pH value was decreased from 7.4 to 5.5. Besides, compared with CCNPs, the CCNPs-SF/HAMA hydrogel had a more sustainable drug release, which was beneficial for the long-term treatment of osteosarcoma. In vitro assay results indicated that CCNPs-SF/HAMA hydrogel with equivalent Cur concentration of 150 μg/mL possessed both the effect of anti-cancer and promoting the proliferation of osteoblasts. These results suggest that CCNPs-SF/HAMA hydrogel with superior physical properties and the bifunctional osteosarcoma therapy and bone repair may be an excellent candidate for local cancer therapy and bone regeneration.

scholarly journals Assessment of Galvanostatic Anodic Polarization to Accelerate the Corrosion of the Bioresorbable Magnesium Alloy WE43

2021 ◽  
Vol 11 (5) ◽  
pp. 2128
Author(s):  
Nils Wegner ◽  
Frank Walther
Keyword(s):  
Magnesium Alloy ◽  
Corrosion Rate ◽  
Dissolution Rate ◽  
Anodic Polarization ◽  
Technical Application ◽  
Efficient Manner ◽  
Corrosion Morphology ◽  
Application Range ◽  
Alloy We43

In the field of surgery, bioresorbable magnesium is considered a promising candidate. Its low corrosion resistance, which is disadvantageous for technical application, is advantageous for surgery since the implant fully degrades in the presence of the water-based body fluids, and after a defined time the regenerating bone takes over its function again. Therefore, knowledge of the corrosion behavior over several months is essential. For this reason, an in vitro short-time testing method is developed to accelerate the corrosion progress by galvanostatic anodic polarization without influencing the macroscopic corrosion morphology. The initial corrosion rate of the magnesium alloy WE43 is calculated by detection of the hydrogen volume produced in an immersion test. In a corresponding experimental setup, a galvanostatic anodic polarization is applied with a three-electrode system. The application range for the polarization is determined based on the corrosion current density from potentiodynamic polarization. To correlate the initial corrosion rate, and accelerated dissolution rate, the corrosion morphologies of both test strategies are characterized by microscopy images, as well as energy dispersive X-ray spectroscopy and Fourier-transform infrared spectroscopy. The results demonstrate that the dissolution rate can be increased in the order of decades with the limitation of a changed corrosion morphology with increasing polarization. With this approach, it is possible to characterize and exclude new unsuitable magnesium alloys in a time-efficient manner before they are used in subsequent preclinical studies.

Sign in / Sign up

Export Citation Format

Share Document