scholarly journals Crystallization and degradation behaviour of multiblock copolyester blends in Langmuir monolayers

2021 ◽  
Author(s):  
Victor Izraylit ◽  
Yue Liu ◽  
Natalia A. Tarazona ◽  
Rainhard Machatschek ◽  
Andreas Lendlein
Keyword(s):  
Structural Changes ◽  
Soft Tissues ◽  
Soft Segment ◽  
Unmet Need ◽  
Hydrolytic Degradation ◽  
Langmuir Monolayers ◽  
Degradation Behaviour ◽  
Network Nodes ◽  
Fixation Devices ◽  
Hydrolysis Of

AbstractSupporting the wound healing of soft tissues requires fixation devices becoming more elastic while degrading. To address this unmet need, we designed a blend of degradable multiblock copolymers, which is cross-linked by PLA stereocomplexation combining two soft segments differing substantially in their hydrolytic degradation rate. The degradation path and concomitant structural changes are predicted by Langmuir monolayer technique. The fast hydrolysis of one soft segment leads to a decrease of the total polymer mass at constant physical cross-linking density. The corresponding increase of the average spacing between the network nodes suggests the targeted increase of the blend’s flexibility. Graphic abstract

scholarly journals Imaging of Joint and Soft Tissue Involvement in Systemic Lupus Erythematosus

2021 ◽  
Vol 23 (9) ◽  
Author(s):  
Andrea Di Matteo ◽  
Gianluca Smerilli ◽  
Edoardo Cipolletta ◽  
Fausto Salaffi ◽  
Rossella De Angelis ◽  
...  
Keyword(s):  
Systemic Lupus Erythematosus ◽  
Soft Tissue ◽  
Lupus Erythematosus ◽  
Structural Damage ◽  
Structural Changes ◽  
Soft Tissues ◽  
Imaging Techniques ◽  
Joint Involvement ◽  
Systemic Lupus ◽  
Muscle Involvement

Abstract Purpose of Review To highlight the potential uses and applications of imaging in the assessment of the most common and relevant musculoskeletal (MSK) manifestations in systemic lupus erythematosus (SLE). Recent Findings Ultrasound (US) and magnetic resonance imaging (MRI) are accurate and sensitive in the assessment of inflammation and structural damage at the joint and soft tissue structures in patients with SLE. The US is particularly helpful for the detection of joint and/or tendon inflammation in patients with arthralgia but without clinical synovitis, and for the early identification of bone erosions. MRI plays a key role in the early diagnosis of osteonecrosis and in the assessment of muscle involvement (i.e., myositis and myopathy). Conventional radiography (CR) remains the traditional gold standard for the evaluation of structural damage in patients with joint involvement, and for the study of bone pathology. The diagnostic value of CR is affected by the poor sensitivity in demonstrating early structural changes at joint and soft tissue level. Computed tomography allows a detailed evaluation of bone damage. However, the inability to distinguish different soft tissues and the need for ionizing radiation limit its use to selected clinical circumstances. Nuclear imaging techniques are valuable resources in patients with suspected bone infection (i.e., osteomyelitis), especially when MRI is contraindicated. Finally, dual energy X-ray absorptiometry represents the imaging mainstay for the assessment and monitoring of bone status in patients with or at-risk of osteoporosis. Summary Imaging provides relevant and valuable information in the assessment of MSK involvement in SLE.

Actuators Based on Oligo[(ε-caprolactone)-co-glycolide] with Accelerated Hydrolytic Degradation

MRS Advances ◽  
2019 ◽  
Vol 5 (12-13) ◽  
pp. 655-666
Author(s):  
Maria Balk ◽  
Marc Behl ◽  
Andreas Lendlein
Keyword(s):  
Shape Memory ◽  
Shape Memory Polymer ◽  
Hydrolytic Degradation ◽  
Life Time ◽  
Melting Transition ◽  
Multifunctional Materials ◽  
Degradation Behaviour ◽  
Molecular Weights ◽  
Function Relationship ◽  
Macroscopic Shape

ABSTRACTPolyester-based shape-memory polymer actuators are multifunctional materials providing reversible macroscopic shape shifts as well as hydrolytic degradability. Here, the function-function interdependencies (between shape shifts and degradation behaviour) will determine actuation performance and its life time.In this work, glycolide units were incorporated in poly(ε-caprolactone) based actuator materials in order to achieve an accelerated hydrolytic degradation and to explore the function-function relationship. Three different oligo[(ε-caprolactone)-co-glycolide] copolymers (OCGs) with similar molecular weights (10.5 ± 0.5 kg∙mol−1) including a glycolide content of 8, 16, and 26 mol% (ratio 1:1:1 wt%) terminated with methacrylated moieties were crosslinked. The obtained actuators provided a broad melting transition in the range from 27 to 44 °C. The hydrolytic degradation of programmed OCG actuators (200% of elongation) resulted in a reduction of sample mass to 51 wt% within 21 days at pH = 7.4 and 40 °C. Degradation results in a decrease of Tm associated to the actuating units and increasing Tm associated to the skeleton forming units. The actuation capability decreased almost linear as function of time. After 11 days of hydrolytic degradation the shape-memory functionality was lost. Accordingly, a fast degradation behaviour as required, e.g., for actuator materials intended as implant material can be realized.

scholarly journals Preparation and Properties of Nanocellulose from Miscanthus x giganteus

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Valerii A. Barbash ◽  
Olha V. Yashchenko ◽  
Olesia A. Vasylieva
Keyword(s):  
Structural Changes ◽  
Thermochemical Treatment ◽  
Crystallinity Index ◽  
Alkaline Treatment ◽  
X Ray Diffraction ◽  
Miscanthus X Giganteus ◽  
X Ray ◽  
Second Stage ◽  
20 Nm ◽  
Hydrolysis Of

Miscanthus x giganteus stalks were used to make organosolvent pulp and nanocellulose. The organosolvent miscanthus pulp (OMP) was obtained through thermal treatment in the mixture of glacial acetic acid and hydrogen peroxide at the first stage and the alkaline treatment at the second stage. Hydrolysis of the never-dried OМP was carried out by a solution of sulfuric acid with concentrations of 43% and 50% and followed by ultrasound treatment. Structural changes and the crystallinity index of OMP and nanocellulose were studied by SEM and FTIR methods. X-ray diffraction analysis confirmed an increase in the crystallinity of OMP and nanocellulose as a result of thermochemical treatment. We show that nanocellulose has a density of up to 1.6 g/cm3, transparency up to 82%, and a crystallinity index of 76.5%. The AFM method showed that the particles of nanocellulose have a diameter in the range from 10 to 20 nm. A thermogravimetric analysis confirmed that nanocellulose films have a denser structure and lower mass loss in the temperature range of 320–440°C compared to OMP. The obtained nanocellulose films have high tensile strength up to 195 MPa. The nanocellulose obtained from OMP exhibits the improved properties for the preparation of new nanocomposite materials.

Raman and Surface Enhanced Raman Spectroscopy of Titanium Carboxylates

1992 ◽  
Vol 271 ◽  
Author(s):  
Beatrice A. Van Vlierberge-Torgerson ◽  
Dilum Dunuwila ◽  
Kris A. Berglund
Keyword(s):  
Raman Spectroscopy ◽  
Structural Changes ◽  
Titanium Isopropoxide ◽  
Surface Enhanced Raman Spectroscopy ◽  
Organic Films ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Metal Organic ◽  
The Relationship ◽  
Hydrolysis Of

ABSTRACTPorous stable metal-organic films can be processed under mild conditions by the hydrolysis of carboxylic acid and titanium isopropoxide mixtures. It is of importance to establish the structure of such materials. Raman spectroscopy is a useful technique in determining structural changes in titanium isopropoxide carboxylate solutions, but weak scattering does not allow for study of thin films unless surface enhancement is used. In an attempt to elucidate the relationship between coating solutions and the final structure of a cast film, we discuss Raman spectra of precursor solutions in a variety of conditions.

Enhanced hydrolysis of hydrothermally and autohydrolytically treated sugarcane bagasse and understanding the structural changes leading to improved saccharification

2020 ◽  
Vol 139 ◽  
pp. 105639 ◽  
Author(s):  
Kamalpreet Kaur Brar ◽  
Melissa C. Espirito Santo ◽  
Vanessa O.A. Pellegrini ◽  
Eduardo R. deAzevedo ◽  
Francisco E.C. Guimaraes ◽  
...  
Keyword(s):  
Sugarcane Bagasse ◽  
Structural Changes ◽  
Hydrolysis Of

Relation between Surface Area and Surface Potential Change during (co)Polyesters Degradation as Langmuir Monolayer

MRS Advances ◽  
2019 ◽  
Vol 5 (12-13) ◽  
pp. 667-677
Author(s):  
Natalia A. Tarazona ◽  
Rainhard Machatschek ◽  
Andreas Lendlein
Keyword(s):  
Surface Area ◽  
Surface Potential ◽  
Degradation Products ◽  
Degradation Mechanism ◽  
Langmuir Monolayers ◽  
Langmuir Monolayer ◽  
Potential Change ◽  
Alkaline Conditions ◽  
Hydrolysis Of ◽  
Random Scission

ABSTRACTPolyhydroxyalkanoates (PHAs) are degradable (co)polyesters synthesized by microorganisms with a variety of side-chains and co-monomer ratios. PHAs can be efficiently hydrolyzed under alkaline conditions and by PHA depolymerase enzymes, altering their physicochemical properties. Using 2D Langmuir monolayers as model system to study the degradation behavior of macromolecules, we aim to describe the the interdependency between the degradation of two PHAs and the surface potential, which influences material-proteins interaction and cell response. We hypothesize that the mechanism of hydrolysis of the labile ester bonds in (co)polyesters defines the evolution of the surface potential, owing to the rate of accumulation of charged insoluble degradation products. The alkaline hydrolysis and the enzymatically catalyzed hydrolysis of PHAs were previously defined as chain-end scission and random-scission mechanisms, respectively. In this study, these two distinct scenarios are used to validate our model. The surface potential change during the chain-end scission of poly(3-R-hydroxybutyrate) (PHB) under alkaline conditions was compared to that of the enzymatically catalyzed hydrolysis (random-scission) of poly[(3-R-hydroxyoctanoate)-co-(3-R-hydroxyhexanoate)] (PHOHHx), using the Langmuir monolayer technique. In the random-scission mechanism the dissolution of degradation products, measured as a decrease in the area per molecule, was preceded by a substantial change of the surface potential, provoked by the negative charge of the broken ester bonds accumulated in the air-water interface. In contrast, when chains degraded via the chain-ends, the surface potential changed in line with the dissolution of the material, presenting a kinetic dependent on the surface area of the monolayers. These results provide a basis for understanding PHAs degradation mechanism. Future research on (co)polymers with different main-chain lengths might extend the elucidation of the surface potential development of (co)polyesters as Langmuir monolayer.

scholarly journals Molecular Modeling and Experimental Investigation of Hydrolytically Degradable Polymeric Biomaterials

2010 ◽  
Vol 76 ◽  
pp. 16-24 ◽  
Author(s):  
Dieter Hofmann ◽  
Maria Entrialgo ◽  
Jürgen Reiche ◽  
Karl Kratz ◽  
Andreas Lendlein
Keyword(s):  
Molecular Modeling ◽  
Biodegradable Polymers ◽  
Diffusion Processes ◽  
Hydrolytic Degradation ◽  
Langmuir Monolayers ◽  
Bulk Water ◽  
Experimental Investigations ◽  
Volume Distribution ◽  
Chemical Studies ◽  
Polar Functional Groups

Biodegradable polymers are applied in temporary implants, such as surgical sutures and controlled drug delivery systems. They are also of relevance in biomaterial-based Regenerative Therapies, where they provide a temporary substitute of the extra-cellular matrix. A major limitation of established degradable implant materials is the fact, that their degradation behavior can not be reliably predicted applying existing experimental methodologies. Therefore a knowledge-based approach is clearly needed to overcome this problem and to enable the tailored design of biodegradable polymers. Here we describe two methods, which can be applied in this approach: molecular modeling combining atomistic bulk and interface models with quantum chemical studies and experimental investigations of macromolecule degradation in Langmuir monolayers. The polymers utilized to exemplarily illustrate the concepts are aliphatic (co)polyesters [e.g. poly(-caprolactone) (PCL), polyglycolide (PGA), poly(rac-lactide) (PDLLA), poly[(rac-lactide)-co-glycolide] (PLGA)] and copoly(ether)esteruretanes as multiblock copolymers. The molecular modeling approach permits to efficiently investigate the influence of micro-structural properties like free volume distribution, cohesive energy density and concentration of polar functional groups on the bulk water uptake as one constituent part of hydrolytic degradation. The Langmuir monolayer investigations on polymer degradation on the other hand yield the dynamics of bond splitting during degradation within hours separately from time consuming diffusion processes, which may take months in bulk samples.

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