scholarly journals Microstructural Precipitation Evolution and In Vitro Degradation Behavior of a Novel Chill-Cast Zn-Based Absorbable Alloy for Medical Applications

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 586
Author(s):  
Ana Laura Ramirez–Ledesma ◽  
Paola Roncagliolo–Barrera ◽  
Carlo Paternoster ◽  
Riccardo Casati ◽  
Hugo Lopez ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Alloy System ◽  
X Ray Diffraction ◽  
In Vitro Degradation ◽  
Transmission Microscopy ◽  
Optical Scanning ◽  
Degradation Rates ◽  
Scanning Transmission ◽  
Chill Cast

In recent years, increasing interest has been placed in the development of Zn alloys for absorbable biomedical applications. It has been demonstrated that these alloys are potential candidates for endovascular applications. In the present work, a novel Zn-12.5Ag-1Mg alloy was investigated as a potential biomedical absorbable material. As a reference, the exhibited biocompatible properties are compared with those of pure Zn and a Zn-1Mg alloy. All the alloys investigated in this work were cast in a water-cooled Cu-mold (chill casting). Subsequently, the alloys were solution-treated and then extruded. The microstructural evolution at each stage of the alloy processing was resolved by analytical means including optical, scanning, transmission microscopy, and X-ray diffraction. By these means, the various phases belonging to this alloy system were disclosed. In addition, determinations of both corrosion and mechanical properties were carried out in the proposed Zn-12.5Ag-1Mg alloy. In particular, an excellent combination of strength and ductility was found, which is attributed to grain refinement as well as the precipitation of a uniform distribution of refined phases (i.e., AgZn solid solution, ε-AgZn3, and Ag0.15MgZn1.85 intermetallics). All the precipitated intermetallics were embedded in a η-Zn matrix. As for the corrosion degradation in the physiological NaCl solution in the as-extruded condition, the experimental outcome indicates that the Zn-12.5Ag-1Mg alloy exhibits degradation rates far superior to currently reported ones for Zn-based alloys intended for absorbable biomedical applications.

scholarly journals Effects of Water Cooling on the Microstructure of Electron Beam Additive-Manufactured Ti-6Al-4V

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1742
Author(s):  
Alexey Panin ◽  
Sergey Martynov ◽  
Marina Kazachenok ◽  
Lyudmila Kazantseva ◽  
Alexander Bakulin ◽  
...  
Keyword(s):  
Water Cooling ◽  
X Ray Diffraction ◽  
Transmission Microscopy ◽  
Optical Scanning ◽  
Compressive Stresses ◽  
Building Process ◽  
Scanning Transmission ◽  
Columnar Grains ◽  
Cooling Effects ◽  
Martensite Structure

The inferior mechanical properties of EBAM Ti-6Al-4V samples are due to the coarse columnar grains containing coarse lamellar structures. One can expect that water cooling of the build platform will increase the cooling rate of the molten pool during the build-up process, causing microstructure refinement. In the present work, the substrate cooling effects on the microstructure and phase composition of EBAM Ti-6Al-4V samples are studied using optical, scanning electron, and scanning transmission microscopy, as well as X-ray diffraction analysis. It is shown that the microstructure of the EBAM Ti-6Al-4V samples built on the substrate without water cooling consists predominantly of columnar prior β grains with lateral sizes ranging up to 2000 µm, while cooling of the build platform causes the appearance of equiaxed prior β grains measuring 1000 µm. Moreover, the refinement of the martensite structure and the precipitation of α″ martensite platelets within a laths occur in the EBAM Ti-6Al-4V samples built on the water-cooled build platform. An explanation of the mechanisms underlying the α′→α + β and α′→α + α″ + β transformations during the building process is provided based upon ab initio calculations. The fragmentation of the a laths under the residual compressive stresses is discussed.

scholarly journals Preparation of lotus nanofibers-alginate porous membranes for biomedical applications

BioResources ◽  
2020 ◽  
Vol 15 (3) ◽  
pp. 6471-6487
Author(s):  
Jinfeng Zhang ◽  
Guangting Han ◽  
Yuanming Zhang ◽  
Ying Gong ◽  
Wei Jiang
Keyword(s):  
Tissue Engineering ◽  
Biomedical Applications ◽  
Porous Scaffold ◽  
Carboxymethyl Chitosan ◽  
Porous Membranes ◽  
In Vitro Degradation ◽  
Ph Values ◽  
Degradation Rates ◽  
Scaffold Materials

Tissue and organ failure or loss is a major problem for human health, and the construction of tissue engineering porous scaffold materials is a core step in the repair of damaged tissue and organs. Fibers from the lotus (Nelumbo nucifera) plant can be a source of superfine fibers. Such fibers have excellent biocompatibility, and they are easy to convert into nanofibers that could be applied for tissue engineering. Lotus fibers were carboxyl-modified with the TEMPO/NaClO/NaBr system, and lotus nanofibers were prepared. The effect of oxidation conditions on their morphologies and degrees of oxidation were investigated. The diameters of the lotus nanofibers were about 15 nm. Additionally, the degrees of oxidation of lotus nanofibers increased with an increase of oxidation time. Moreover, the oxidized sodium alginate membranes crosslinked with carboxymethyl chitosan degraded quickly, with the degradation rates increased by 82.1% or 100.0% during a 14-day period. By increasing the dosage of carboxymethyl chitosan, the pH values tend to rise. In comparison, the degradation rates of the lotus nanofibers/alginate porous membranes crosslinked with carboxymethyl chitosan exhibited better performance in terms of microstructure, porosity, water absorption, mechanical properties (0.36 MPa /7.7%), and in vitro degradation (59.2%).

IN VITRO DEGRADATION OF MIMOSINE BY MICROORGANISMS FROM THE ESOPHAGEAL SAC OF VOLES (Microtus arvalis)

1986 ◽  
Vol 66 (2) ◽  
pp. 547-551 ◽  
Author(s):  
H. KUDO ◽  
K.-J. CHENG ◽  
W. MAJAK ◽  
J. W. HALL ◽  
T. ARAI ◽  
...  
Keyword(s):  
Pyridine Ring ◽  
Microbial Growth ◽  
Early Stage ◽  
Microtus Arvalis ◽  
In Vitro Degradation ◽  
Ruminal Microorganisms ◽  
Highly Active ◽  
Alfalfa Hay ◽  
Degradation Rates

The microbiota in the esophageal sac of voles fed either cubed alfalfa hay or concentrate pellets were assayed to determine their capacity to anaerobically degrade mimosine in vitro. Differences (P < 0.01) were found between the two diets during the growth phase. The sac contents of voles fed concentrate pellets degraded mimosine and 3-hydroxy-4-(1H)-pyridone (DHP) rapidly, but inocula from voles fed cubed alfalfa hay only hydrolyzed mimosine to DHP. Degradation of the pyridine ring occurred at the early stage of incubation, concurrently with microbial growth. Thereafter, degradation rates appear to have been almost negligible and very similar for both diets. These results agree with previous data obtained with ruminal microorganisms, where highly active inocula were also associated with animals on concentrate diets. Key words: Detoxification, hydrolysis, esophageal sac, mimosine, 3-hydroxy-4- (1H)-pyridone, voles

scholarly journals Development of Nontoxic Biodegradable Polyurethanes Based on Polyhydroxyalkanoate and L-lysine Diisocyanate with Improved Mechanical Properties as New Elastomers Scaffolds

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1927 ◽  
Author(s):  
Cai Wang ◽  
Jiapeng Xie ◽  
Xuan Xiao ◽  
Shaojun Chen ◽  
Yiping Wang
Keyword(s):  
Tissue Regeneration ◽  
Biomedical Applications ◽  
Poly Ethylene Glycol ◽  
In Vitro Degradation ◽  
Elongation At Break ◽  
Molar Ratios ◽  
Soft Tissue Regeneration ◽  
Biodegradable Polyurethane ◽  
Poly Ethylene

A nontoxic and biodegradable polyurethane was prepared, characterized, and evaluated for biomedical applications. Stretchable, biodegradable, and biocompatible polyurethanes (LPH) based on L-lysine diisocyanate (LDI) with poly(ethylene glycol) (PEG) and polyhydroxyalkanoates(PHA) of different molar ratios were synthesized. The chemical and physical characteristics of the LPH films are tunable, enabling the design of mechanically performance, hydrophilic, and biodegradable behavior. The LPH films have a Young’s modulus, tensile strength, and elongation at break in the range of 3.07–25.61 MPa, 1.01–9.49 MPa, and 102–998%, respectively. The LPH films demonstrate different responses to a change of temperature from 4 to 37 °C, with the swelling ratio for the same sample at equilibrium varying from 184% to 151%. In vitro degradation tests show the same LPH film has completely different degradation morphologies in pH of 3, 7.4, and 11 phosphate buffered solution (PBS). In vitro cell tests show feasibility that some of the LPH films are suitable for culturing rat bone marrow stem cells (rBMSCs), for future soft-tissue regeneration. The results demonstrate the feasibility of the LPH scaffolds for many biomedical applications.

scholarly journals Morphology andIn VitroBehavior of Electrospun Fibrous Poly(D,L-lactic acid) for Biomedical Applications

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Toshihiro Inami ◽  
Yasuhiro Tanimoto ◽  
Masayuki Ueda ◽  
Yo Shibata ◽  
Satoshi Hirayama ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Biomedical Applications ◽  
Polymer Concentration ◽  
The Body ◽  
Solution Flow Rate ◽  
Apatite Formation ◽  
X Ray Diffraction ◽  
Solution Flow

This work describes the fabrication, optimization, and characterization of electrospun fibrous poly(D,L-lactic acid) (PDLLA) for biomedical applications. The influences of the polymer concentration of the electrospinning solution (5, 10, or 15 wt%) and the solution flow rate (0.1, 0.5, 1.0, or 2.0 mL/h) on the morphology of the obtained fibrous PDLLA were evaluated. Thein vitrobiocompatibility of two types of PDLLA, ester terminated PDLLA (PDLLA-R) and carboxyl terminated PDLLA (PDLLA-COOH), was evaluated by monitoring apatite formation on samples immersed in Hanks’ balanced salt (HBS) solution. 15 wt% polymer solution was the most beneficial for preparing a fibrous PDLLA structure. Meanwhile, no differences in morphology were observed for PDLLA prepared at various flow rates. Apatite precipitate is formed on both types of PDLLA only 1 day after immersion in HBS solution. After 7 days of immersion, PDLLA-COOH showed greater apatite formation ability compared with that of PDLLA-R, as measured by thin-film X-ray diffraction. The results indicated that the carboxyl group is effective for apatite precipitation in the body environment.

MPACVD Nanocrystalline Diamond for Biomedical Applications

2007 ◽  
Vol 280-283 ◽  
pp. 1595-1598 ◽  
Author(s):  
Chuan Lin Zheng ◽  
Rong Qi ◽  
Wu Bao Yang
Keyword(s):  
Biomedical Applications ◽  
Microwave Plasma ◽  
Optical Glass ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Processing Parameters ◽  
Nanocrystalline Diamond ◽  
X Ray Diffraction ◽  
Nanocrystalline Diamond Films

In the present paper, nanocrystalline diamond films (NDFs) were fabricated on optical glass using microwave plasma assisted chemical vapor deposition (MPACVD). The suitable processing parameters are as followings: methane concentration 3% in argon, total deposition pressure 13.3 kPa, substrate temperature 500 °C. The diamond films were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. In vitro osteoblast cell cultures and platelet adhesion tests were applied to evaluate the biocompatibility of the nanocrystalline diamond films (NDFs). All results indicate that the diamond films exhibit better tissue compatibility and hemocompatibility which are very suitable for biomedical applications.

scholarly journals Biosynthesis of spinel nickel ferrite nanowhiskers and their biomedical applications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hajar Q. Alijani ◽  
Siavash Iravani ◽  
Shahram Pourseyedi ◽  
Masoud Torkzadeh-Mahani ◽  
Mahmood Barani ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Nickel Ferrite ◽  
Biomedical Applications ◽  
Leishmania Major ◽  
X Ray Diffraction ◽  
Green Method ◽  
X Ray ◽  
Transmission Electron ◽  
Low Toxicity

AbstractGreener methods for the synthesis of various nanostructures with well-organized characteristics and biomedical applicability have demonstrated several advantages, including simplicity, low toxicity, cost-effectiveness, and eco-friendliness. Spinel nickel ferrite (NiFe2O4) nanowhiskers with rod-like structures were synthesized using a simple and green method; these nanostructures were evaluated by X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, and X-ray energy diffraction spectroscopy. Additionally, the prepared nanowhiskers could significantly reduce the survival of Leishmania major promastigotes, at a concentration of 500 μg/mL; the survival of promastigotes was reduced to ≃ 26%. According to the results obtained from MTT test (in vitro), it can be proposed that further studies should be conducted to evaluate anti-leishmaniasis activity of these types of nanowhiskers in animal models.

scholarly journals In Vitro Corrosion Behavior of Biodegradable Iron Foams with Polymeric Coating

Materials ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 184 ◽  
Author(s):  
Radka Gorejová ◽  
Renáta Oriňaková ◽  
Zuzana Orságová Králová ◽  
Matej Baláž ◽  
Miriam Kupková ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Polymeric Coating ◽  
Attractive Alternative ◽  
In Vitro Degradation ◽  
Corrosion Rates ◽  
Degradation Rates ◽  
Ft Ir ◽  
Resorbable Implants

Research in the field of biodegradable metallic scaffolds has advanced during the last decades. Resorbable implants based on iron have become an attractive alternative to the temporary devices made of inert metals. Overcoming an insufficient corrosion rate of pure iron, though, still remains a problem. In our work, we have prepared iron foams and coated them with three different concentrations of polyethyleneimine (PEI) to increase their corrosion rates. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX), Fourier-transform infrared spectroscopy (FT-IR), and Raman spectroscopy were used for characterization of the polymer coating. The corrosion behavior of the powder-metallurgically prepared samples was evaluated electrochemically using an anodic polarization method. A 12 weeks long in vitro degradation study in Hanks’ solution at 37 °C was also performed. Surface morphology, corrosion behavior, and degradation rates of the open-cell foams were studied and discussed. The use of PEI coating led to an increase in the corrosion rates of the cellular material. The sample with the highest concentration of PEI film showed the most rapid corrosion in the environment of simulated body fluids.

Physicochemical and In Vitro Degradation Behaviors of Fibrous Membranes with Different Polycaprolactone and Gelatin Proportions

2020 ◽  
Vol 20 (12) ◽  
pp. 7376-7384
Author(s):  
Chen Yuan ◽  
Xin Ren ◽  
Huilin Ye ◽  
Shue Jin ◽  
Yi Zuo ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Biomedical Applications ◽  
Composite Membranes ◽  
Mechanical Tests ◽  
In Vitro Degradation ◽  
Electrospun Membranes ◽  
Degradation Behaviors ◽  
Fibrous Membranes ◽  
Degradation Properties

Mechanical and degradation properties are crucial factors of guided tissue/bone regeneration (GTR/GBR) membranes. In this work, a series of fibrous membranes with different ratios of polycaprolactone (PCL) and gelatin (Gel) were prepared (PCL:Gel = 1:9 (P1G9), 3:7 (P3G7), 5:5 (P5G5), 7:3 (P7G3), and 9:1 (P9G1)) by electrospinning, and their physicochemical properties and In Vitro degradation behaviors were systematically investigated. Mechanical tests showed that tensile strength was enhanced with the presence of Gel, and the tensile strength of the P9G1 membrane reached nearly three times that of the pure PCL membrane. The degradation rate of the composite membranes could be adjusted by controlling the ratio of PCL and Gel; the higher the Gel content was, the faster the degradation of the PCL/Gel membrane. The higher PCL content favored maintaining the fibrous structure of the electrospun membranes. These findings will be beneficial for designing PCL/Gel composite materials for biomedical applications.

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