Biodegradation of Poly(3-Hydroxybutyrate) and Poly(3-Hydroxybutyrate-Co-3-Hydroxy-4-Methylvalerate) Films by Porcine Pancreatic Lipase

In the current work, the degradation of poly (3-hydroxybutyrate) (PHB) and poly (3-hydroxybutyrate-co-3-hydroxy-4-methylvalerate) (PHB4MV) films was studied in vitro by pancreatic lipase. The changes in film properties were traced by several analytical methods: the change of weight, molecular weight, and Young’s modulus (by nanoindentation) were measured. During the six months of polymer films degradation the weight of samples decreased slightly, while a great increase in Young's modulus due to the relatively fast degradation of the amorphous areas was observed, as well as molecular weight of polymers decreased significantly. Weight loss of PHB4MV is faster than degradation rate of PHB, but the molecular weight of PHB 1700 decrease rapidly than PHB4MV; the Young’s modulus of polymers remained relatively unchanged.

Download Full-text

Degradation of 3D-Printed Porous Polylactic Acid Scaffolds Under Mechanical Stimulus

Frontiers in Bioengineering and Biotechnology ◽

10.3389/fbioe.2021.691834 ◽

2021 ◽

Vol 9 ◽

Author(s):

Heming Chen ◽

Quan Shi ◽

Hengtao Shui ◽

Peng Wang ◽

Qiang Chen ◽

...

Keyword(s):

Molecular Weight ◽

Numerical Model ◽

Young’S Modulus ◽

Polylactic Acid ◽

Young's Modulus ◽

Average Molecular Weight ◽

Mechanical Stimulus ◽

Number Average Molecular Weight ◽

3D Printed

Polylactic acid (PLA) is a biodegradable polymer commonly used as a scaffold material to repair tissue defects, and its degradation is associated with mechanical stimulus. In this study, the effect of mechanical stimulus on the degradation of 3D-printed PLA scaffolds was investigated by in vitro experiments and an author-developed numerical model. Forty-five samples with porosity 64.8% were printed to carry out the degradation experiment within 90 days. Statistical analyses of the mass, volume fraction, Young’s modulus, and number average molecular weight were made, and the in vitro experiments were further used to verify the proposed numerical model of the scaffold degradation. The results indicated that the mechanical stimulus accelerated the degradation of the PLA scaffold, and the higher mechanical stimulus led to a faster degradation of the scaffolds at the late stage of the degradation process. In addition, the Young’s modulus and the normalized number average molecular weight of the PLA scaffolds between the experiments and the numerical simulations were comparable, especially for the number average molecular weight. The present study could be helpful in the design of the biodegradable PLA scaffolds.

Download Full-text

The Changes in Surface Morphology and Mechanical Properties of Poly(3-Hydroxybutyrate) and its Copolymer Films during In Vitro Degradation

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.258.354 ◽

2016 ◽

Vol 258 ◽

pp. 354-357 ◽

Cited By ~ 2

Author(s):

Vsevolod Zhuikov ◽

Anton Bonartsev ◽

Dmitry Bagrov ◽

Alexey Rusakov ◽

Alexey Useinov ◽

...

Keyword(s):

Young’S Modulus ◽

Lamellar Structure ◽

Young's Modulus ◽

Film Surface ◽

Film Properties ◽

Surface Appearance ◽

Force Microscopy ◽

Copolymer Films ◽

Atomic Force

In the current work, we studied the degradation of PHB films in vitro by pancreatic lipase and in phosphate buffer saline (PBS). We traced the changes in film properties by several analytical methods: the change of weight, surface roughness and morphology (by atomic-force microscopy) and Young’s modulus (by nanoindentation) were measured.PHB is a semicrystalline polymer and thus the films have lamellar structure. During biodegradation, three types of changes were observed on the film surface: appearance of new lamellae, disappearance of lamellae and disintegration of lamellae into shorter fragments. During the six months of polymer films degradation the weight of samples decreased; and an increase in Young's modulus due to the relatively fast degradation of the amorphous areas was observed by nanoindentation.

Download Full-text

AFM-based Analysis of Wharton’s Jelly Mesenchymal Stem Cells

International Journal of Molecular Sciences ◽

10.3390/ijms20184351 ◽

2019 ◽

Vol 20 (18) ◽

pp. 4351

Author(s):

Renata Szydlak ◽

Marcin Majka ◽

Małgorzata Lekka ◽

Marta Kot ◽

Piotr Laidler

Keyword(s):

Stem Cells ◽

Mesenchymal Stem Cells ◽

Young’S Modulus ◽

Young's Modulus ◽

Wharton’S Jelly ◽

In Vitro Cultivation ◽

Multipotent Stem Cells ◽

Wharton's Jelly ◽

Migration Potential

Wharton’s jelly mesenchymal stem cells (WJ-MSCs) are multipotent stem cells that can be used in regenerative medicine. However, to reach the high therapeutic efficacy of WJ-MSCs, it is necessary to obtain a large amount of MSCs, which requires their extensive in vitro culturing. Numerous studies have shown that in vitro expansion of MSCs can lead to changes in cell behavior; cells lose their ability to proliferate, differentiate and migrate. One of the important measures of cells’ migration potential is their elasticity, determined by atomic force microscopy (AFM) and quantified by Young’s modulus. This work describes the elasticity of WJ-MSCs during in vitro cultivation. To identify the properties that enable transmigration, the deformability of WJ-MSCs that were able to migrate across the endothelial monolayer or Matrigel was analyzed by AFM. We showed that WJ-MSCs displayed differences in deformability during in vitro cultivation. This phenomenon seems to be strongly correlated with the organization of F-actin and reflects the changes characteristic for stem cell maturation. Furthermore, the results confirm the relationship between the deformability of WJ-MSCs and their migration potential and suggest the use of Young’s modulus as one of the measures of competency of MSCs with respect to their possible use in therapy.

Download Full-text

Novel Biocompatible Zr-Based Alloy with Low Young’s Modulus and Magnetic Susceptibility for Biomedical Implants

Materials ◽

10.3390/ma13225130 ◽

2020 ◽

Vol 13 (22) ◽

pp. 5130

Author(s):

Renhao Xue ◽

Dong Wang ◽

Dawei Yang ◽

Ligang Zhang ◽

Xiaoning Xu ◽

...

Keyword(s):

Magnetic Susceptibility ◽

Young’S Modulus ◽

Blood Compatibility ◽

Young's Modulus ◽

Emission Spectrometry ◽

Biomedical Implants ◽

Ion Release ◽

Mg63 Cells ◽

Ti Addition

The microstructure, mechanical properties, magnetic susceptibility, electrochemical corrosion performance, in vitro cell compatibility and blood consistency of Zr-16Nb-xTi (x = 0, 4, 8, 12 and 16 wt.%) materials were investigated as potential materials for biomedical implants. X-ray diffraction (XRD) and Transmission electron microscopy (TEM) analyses revealed the secondary phase martensite α’ formed during the quenching process. The phase composition contained metastable β and martensite α’, resulting from Ti addition. These phase constitutions were the main causes of a low Young’s modulus and magnetic susceptibility. The in vitro cytocompatibility analysis illustrated that the MG63 cells maintained high activity (from 91% to 97%) after culturing in Zr-16Nb-xTi extraction media for 12 days due to the high internal biocompatibility of Zr, Nb and Ti elements, as well as the optimal corrosion resistance of Zr-16Nb-xTi. On the basis of Inductively coupled plasma optical emission spectrometry (ICP-OES) ion release studies, the concentration of Zr, Nb and Ti was noted to reach the equipment detective limit of 0.001 mg/L, which was much lower than pure Ti. With respect to the corrosion behavior in Hank’s solution, Zr-16Nb-16Ti displayed superior properties, possessing the lowest corrosion current density and widest passivation region, attributed to the addition of Ti. The blood compatibility test illustrated that the Zr-16Nb-xTi materials were nonhemolytic, and the platelets maintained a spherical shape, with no aggregation or activation on Zr-16Nb-xTi. Overall, Ti addition has obvious effects on the developed Zr-16Nb-xTi alloys, and Zr-16Nb-4Ti exhibited low magnetic susceptibility, low modulus, good biocompatibility and proper corrosion properties, demonstrating the potential of use as implant biomaterials.

Download Full-text

Mechanical Properties and Microarchitecture of Nanoporous Hydroxyapatite Bioceramic Nanoparticle Coatings on Ti and TiN

MRS Proceedings ◽

10.1557/proc-975-0975-dd06-15 ◽

2006 ◽

Vol 975 ◽

Author(s):

Andrei Stanishevsky ◽

Shafiul Chowdhury ◽

Nathaniel Greenstein ◽

Helene Yockell-Lelievre ◽

Jari Koskinen

Keyword(s):

Mechanical Properties ◽

Young’S Modulus ◽

Young's Modulus ◽

Biological Response ◽

Dip Coating ◽

Nano Crystalline ◽

Ceramic Manufacturing ◽

Nanoparticle Coatings

ABSTRACTThe hydroxyapatite (HA) based bioceramic materials are usually prepared at high sintering temperatures to attain suitable mechanical properties. The sintering process usually results in a material which is compositionally and morphologically different from nonstoichiometric nano-crystalline HA phase of hard tissue. At the same time, HA particulates used as precursors in ceramic manufacturing are often very similar to the natural HA nanocrystals. It has been shown that synthetic nanoparticle HA (nanoHA) based materials improve the biological response in vitro and in vivo, but the information on mechanical properties of these materials is scarce.In this work we studied the HA nanoparticle (10 – 80 nm mean size) coatings with 30 – 70% porosity prepared by a dip-coating technique on Ti and TiN substrates. It has been found that the mechanical properties of HA nanoparticle coatings are strongly influenced by the initial size, morphology, and surface treatment of nanoparticles. The nanoindentation Young's modulus and hardness of as–deposited nanoHA coatings were in the range of 2.5 – 6.9 GPa and 80 – 230 MPa, respectively. The coatings were stable after annealing up to at least 600 °C, reaching the Young's modulus up to 23 GPa and hardness up to 540 MPa, as well as in simulated body fluids.

Download Full-text

Degradation study of polyester fiber in swimming pool water

Textile Research Journal ◽

10.1177/0040517520934507 ◽

2020 ◽

Vol 91 (1-2) ◽

pp. 51-61

Author(s):

Caroline Apoloni Cionek ◽

Catia Nunes ◽

Adonilson Freitas ◽

Natalia Homem ◽

Edvani Muniz ◽

...

Keyword(s):

Weight Loss ◽

Young’S Modulus ◽

Melting Temperature ◽

Young's Modulus ◽

Onset Temperature ◽

Swimming Pool ◽

Experimental Methodology ◽

Stress Tests ◽

Pool Water ◽

Swimming Pool Water

The disinfection of swimming pool water is vital to maintain water quality. The chemicals used in this practice can damage the fabrics of bathing suits and shorten the shelf life of the textile substrate. The degradation of polyester, a polymer that is widely used in bathing suits for swimming pools, was investigated. For this, a 23 factorial design was employed for the experimental methodology. The effect of several variables was analyzed in a simulated swimming pool batch, such as textile-exposure time, concentration of the used disinfection product, and batch temperature. The response variables were enthalpy of fusion ΔHm, melting temperature and crystallinity (obtained by differential scanning calorimetry), percentage of weight loss, temperature of maximum rate of weight loss, onset temperature and endset temperature (measured through thermogravimetric analysis), and Young's modulus values (measured in strain-stress tests in the row and column directions). The factors of temperature, time, and the concentration of disinfectant were significant for melting temperature, crystallinity, onset temperature, and Young's modulus for columns. The analyses of variance were obtained using software Design-Expert DX7. Attenuated total reflectance-Fourier transform infrared spectroscopy analysis showed changes in band intensities at 695 cm−1, which were attributed to ester groups, as well as a decrease of the carbonyl band at 1712 cm−1, which was attributed to the hydrolysis of the material. Analysis through scanning electronic microscopy images showed the appearance of stretch marks in the constituent filaments of the tested textiles, which suggests a surface degradation occurred.

Download Full-text

Comparative investigations of in vitro and in vivo bioactivity of titanium vs. Ti–24Nb–4Zr–8Sn alloy before and after sandblasting and acid etching

RSC Advances ◽

10.1039/d0ra00280a ◽

2020 ◽

Vol 10 (40) ◽

pp. 23582-23591

Author(s):

Xin Liu ◽

Yumei Niu ◽

Weili Xie ◽

Daqing Wei ◽

Qing Du

Keyword(s):

Young’S Modulus ◽

Young's Modulus ◽

Stress Shielding ◽

Acid Etching ◽

Implant Material ◽

Before And After ◽

New Type

To avoid the failure of clinical surgery due to “stress shielding” and the loosening of an implant, a new type of alloy, Ti–24Nb–4Zr–8Sn (TNZS), with a low Young's modulus acted as a new implant material in this work.

Download Full-text

Role of pH on stability and mechanical properties of gelatin films

Journal of Bioactive and Compatible Polymers ◽

10.1177/0883911511431484 ◽

2012 ◽

Vol 27 (1) ◽

pp. 67-77 ◽

Cited By ~ 41

Author(s):

Michela Gioffrè ◽

Paola Torricelli ◽

Silvia Panzavolta ◽

Katia Rubini ◽

Adriana Bigi

Keyword(s):

Mechanical Properties ◽

Young’S Modulus ◽

Triple Helix ◽

Young's Modulus ◽

In Vitro Tests ◽

Diffraction Reflection ◽

X Ray Diffraction ◽

Solution Ph ◽

Gelatin Films

The effect of the film-forming solution pH on the triple-helix content, thermal stability, and mechanical properties of gelatin films was investigated. The films were prepared from solutions at different pHs of type A pigskin gelatin, and their mechanical characteristics were determined. At pHs higher than 9 and lower than 5, Young’s modulus, E, and the stress at break, σb, of the films decreased significantly. Cross-linking with genipin reduced deformation at break, ϵb, and increased Young’s modulus. The intensity of the 1.1-nm X-ray diffraction reflection and the denaturation enthalpy decreased at these pHs, indicating that the triple helix reduced. Preliminary in vitro tests on the cross-linked samples indicated good cell proliferation and viability.

Download Full-text

Recent Studies on the Application of Enzymes in the Synthesis of Polyesters

MRS Proceedings ◽

10.1557/proc-218-31 ◽

1990 ◽

Vol 218 ◽

Author(s):

Cary J. Morrow ◽

Eugenia M. Brazwell ◽

Dianela Filos ◽

Juanita Mercure ◽

Rosemary Romero ◽

...

Keyword(s):

Molecular Weight ◽

Ambient Temperature ◽

Organic Solvents ◽

Pancreatic Lipase ◽

Bound Water ◽

Optically Active ◽

Porcine Pancreatic Lipase ◽

Dibenzyl Ether ◽

High Boiling Solvent ◽

Hydrolysis Of

AbstractEnzyme-catalyzed preparation of polymers offers several potentially valuable advantages over the usual polymerization procedures. This paper summarizes our successful use of lipase-catalyzed polycondensations to prepare both a series of achiral [AA-BB]x polyesters from bis(2,2,2- trichloroethyl) alkanedioates and diols and of an optically active, epoxy-substituted polyester having a stereochemical purity estimated to be greater than 96%, from racemic bis(2,2,2-trichloroethyl) trans-3,4-epoxyhexanedioate and 1,4-butanediol. All of the reactions were carried out at ambient temperature in anhydrous, low to intermediate polarity, organic solvents such as ether, THF, 2-ethoxyethyl ether, dibenzyl ether, o-dichlorobenzene, or methylene choride, using porcine pancreatic lipase (PPL) as the catalyst. The molecular weight achieved by the polycondensation is limited by accumulation of the trihaloethanol that forms as the reaction progresses, probably because it frees enzyme-bound water permitting hydrolysis of the polymer to occur. This problem has been alleviated by using a high boiling solvent and removing the alcohol by placing the re'action mixture under vacuum.

Download Full-text