scholarly journals Poly(-caprolactone)/graphene oxide composite systems: A comparative study on hydrolytic degradation at extreme pH values

2020 ◽  
Vol 10 (6) ◽  
pp. 892-902
Author(s):  
Alberto J. Campillo-Fernández ◽  
Pablo González-Reed ◽  
Ana Vidaurre ◽  
Isabel Castilla-Cortázar
Keyword(s):  
Graphene Oxide ◽  
Degradation Kinetics ◽  
Morphological Changes ◽  
Hydrolytic Degradation ◽  
Degradation Behavior ◽  
Composite Systems ◽  
Ph Values ◽  
Speed Up ◽  
Poly Caprolactone ◽  
Degradation Time

Polycaprolactone/Graphene oxide (PCL/GO) composites are shown to be promising substrates for tissue engineering as their degradation behavior is a key aspect in this type of application. The present paper studies the effect of different GO contents (0.1, 0.2 and 0.5 wt%) of PCL/GO composites on accelerated hydrolytic degradation at extreme pH values. Degradation kinetics at pH 13 is strongly affected by GO content, and speed up at higher percentages. The composite with 0.5 wt% of GO was completely degraded in 72 hours, while degradation at pH 1 presents a different profile and seems to have an induction period that lasts more than 1500 hours. Morphological changes, molecular weight distribution, weight loss, degree of swelling and calorimetric properties were investigated as a function of degradation time. According to the results obtained, the addition of small percentages of GO significantly influences the degradation behavior of the composites acting as degradation modulators.

Computer-Aided 4D Modeling of Hydrolytic Degradation in Micropatterned Bioresorbable Membranes

2013 ◽  
Vol 7 (2) ◽  
Author(s):  
Ibrahim T. Ozbolat ◽  
Michelle Marchany ◽  
Joseph A. Gardella ◽  
Bahattin Koc
Keyword(s):  
Degradation Kinetics ◽  
Morphological Changes ◽  
Dynamic Geometry ◽  
Hydrolytic Degradation ◽  
Controlled Drug Release ◽  
Polymeric Membranes ◽  
Surface Erosion ◽  
Computer Aided ◽  
Kinetics Of

Real-time degradation studies of bioresorbable polymers can take weeks, months, and even years to conduct. For this reason, developing and validating mathematical models that describe and predict degradation can provide a means to accelerate the development of materials and devices for controlled drug release. This study aims to develop and experimentally validate a computer-aided model that simulates the hydrolytic degradation kinetics of bioresorbable polymeric micropatterned membranes for tissue engineering applications. Specifically, the model applies to circumstances that are conducive for the polymer to undergo surface erosion. The developed model provides a simulation tool enabling the prediction and visualization of the dynamic geometry of the degrading membrane. In order to validate the model, micropatterned polymeric membranes were hydrolytically degraded in vitro and the morphological changes were analyzed using optical microscopy. The model is then extended to predict spatiotemporal degradation kinetics of variational micropatterned architectures.

Degradation Kinetics Study of Anastrozole in Different Conditions by Reverse-Phase High-Performance Liquid Chromatography and Confirmation of its Major Degradation Product by Ultra-Performance Liquid Chromatography with Tandem Mass Spectrometry

2019 ◽  
Vol 15 (3) ◽  
pp. 217-223 ◽  
Author(s):  
Linjia Sun ◽  
Xiaoyang Sun ◽  
Yu Chen ◽  
Binjie Wang ◽  
Xiaohui Chen
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Degradation Kinetics ◽  
Ultra Performance Liquid Chromatography ◽  
Degradation Behavior ◽  
Chromatography Method ◽  
Ph Values ◽  
Different Temperatures ◽  
Liquid Chromatography Method

Background: Drug stability is essential in the process of drug production, storage, appliance, and so on. Some drugs’ degradation products may even have a toxic side effect, which can result in safety risks and economic losses. Therefore, it is very imperative to develop a suitable stability indicating an analytical method for anastrozole which could be used for stability testing, routine and in-process quality control analysis or other further studies. Methods: A reverse-phase high-performance liquid chromatography method was developed and validated for the degradation kinetics study of anastrozole, a selective non-steroid third-generation aromatase inhibitor, which would provide a basis for further studies on anastrozole. The degradation product was confirmed by ultra-performance liquid chromatography with tandem mass spectrometry. Results: Results showed that the degradation behavior of anastrozole followed first-order kinetics in different temperatures, pH values and oxidation conditions. It was suggested that the degradation behavior of anastrozole was pH-dependent and it’s more stable at lower pH values. Conclusion: A high performance liquid chromatography method was established and used to determine the residual concentration of anastrozole in this study. It was found that the degradation behavior of anastrozole followed first-order kinetics at different temperatures, pH values and oxidation conditions. According to the results, the degradation of anastrozole was found to be pH-dependent and it is more unstable in alkaline conditions. The information of degradation kinetics will be useful for understanding the chemical stability of anastrozole and provide a reference for the further preparation research and clinical therapy of anastrozole.

scholarly journals Degradation and Recycling of Films Based on Biodegradable Polymers: A Short Review

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 651 ◽  
Author(s):  
Roberto Scaffaro ◽  
Andrea Maio ◽  
Fiorenza Sutera ◽  
Emmanuel Gulino ◽  
Marco Morreale
Keyword(s):  
Biodegradable Polymers ◽  
Environmental Performance ◽  
Hydrolytic Degradation ◽  
Thermal Stabilization ◽  
Short Review ◽  
Polymeric Films ◽  
Poly Lactic Acid ◽  
Degradation Behavior ◽  
Degradation Behaviour ◽  
Poly Caprolactone

The environmental performance of biodegradable materials has attracted attention from the academic and the industrial research over the recent years. Currently, degradation behavior and possible recyclability features, as well as actual recycling paths of such systems, are crucial to give them both durability and eco-sustainability. This paper presents a review of the degradation behaviour of biodegradable polymers and related composites, with particular concern for multi-layer films. The processing of biodegradable polymeric films and the manufacturing and properties of multilayer films based on biodegradable polymers will be discussed. The results and data collected show that: poly-lactic acid (PLA), poly-butylene adipate-co-terephthalate (PBAT) and poly-caprolactone (PCL) are the most used biodegradable polymers, but are prone to hydrolytic degradation during processing; environmental degradation is favored by enzymes, and can take place within weeks, while in water it can take from months to years; thermal degradation during recycling basically follows a hydrolytic path, due to moisture and high temperatures (β-scissions and transesterification) which may compromise processing and recycling; ultraviolet (UV) and thermal stabilization can be adequately performed using suitable stabilizers.

Graphene oxide induced hydrolytic degradation behavior changes of poly(l-lactide) in different mediums

2016 ◽  
Vol 56 ◽  
pp. 220-228 ◽  
Author(s):  
Jin Duan ◽  
Yi-ning Xie ◽  
Jing-hui Yang ◽  
Ting Huang ◽  
Nan Zhang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Hydrolytic Degradation ◽  
Behavior Changes ◽  
Degradation Behavior

scholarly journals Difference in polypropylene fragmentation mechanism between marine and terrestrial regions

2021 ◽  
Vol 3 (9) ◽  
Author(s):  
Hisayuki Nakatani ◽  
Takuya Muraoka ◽  
Yuina Ohshima ◽  
Suguru Motokucho
Keyword(s):  
Environmental Stress ◽  
Advanced Oxidation Process ◽  
List Type ◽  
Patch Structure ◽  
Stress Cracking ◽  
Fragmentation Mechanisms ◽  
Environmental Stress Cracking ◽  
Speed Up ◽  
Degradation Time ◽  
Delamination Behavior

AbstractTwo kinds of marine polypropylene (M1-PP and M2-PP) and one land PP (L-PP) samples were collected from two beaches and land in Japan, respectively, to study the fragmentation mechanisms. Delamination was observed on both M1-PP and M2-PP surfaces. Moreover, there was no delamination but an abrasion patch structure on the surface of L-PP. The delamination was studied using an advanced oxidation process-degraded PP as the marine PP model. The number and shape of cracks varied with an increase in degradation time. The fluctuations in the values and ratios of the carbonyl index as well as the weight change ratio were due to repeated oxidation and delamination. We found that the delamination behavior depends on the oxidation state. Poly(oxyethylene)8 octylphenyl ether (POE8) surfactant treatment caused the delamination to speed up, which is a typical characteristic of polyolefin environmental stress cracking (ESC). These results reveal that delamination is based on ESC.Article Highlights Two kinds of marine and one land polypropylene (PP) samples were collected from two beaches and land, respectively, to study the fragmentation mechanisms. Delamination was observed on both of marine PP surfaces. Moreover, there was no delamination but an abrasion patch structure on the land PP surface. We found that the delamination was based on environmental stress cracking mechanism by employing a marine PP model.

scholarly journals Effects of innate immune receptor stimulation on extracellular α-synuclein uptake and degradation by brain resident cells

2021 ◽  
Author(s):  
Changyoun Kim ◽  
Somin Kwon ◽  
Michiyo Iba ◽  
Brian Spencer ◽  
Edward Rockenstein ◽  
...  
Keyword(s):  
Degradation Kinetics ◽  
Morphological Changes ◽  
Direct Interaction ◽  
Innate Immune ◽  
Pathological Feature ◽  
Tlr2 Expression ◽  
Immune Receptors ◽  
Age Related ◽  
Stimulation Of

AbstractSynucleinopathies are age-related neurological disorders characterized by the progressive deposition of α-synuclein (α-syn) aggregates and include Parkinson’s disease (PD) and dementia with Lewy bodies (DLB). Although cell-to-cell α-syn transmission is thought to play a key role in the spread of α-syn pathology, the detailed mechanism is still unknown. Neuroinflammation is another key pathological feature of synucleinopathies. Previous studies have identified several immune receptors that mediate neuroinflammation in synucleinopathies, such as Toll-like receptor 2 (TLR2). However, the species of α-syn aggregates varies from study to study, and how different α-syn aggregate species interact with innate immune receptors has yet to be addressed. Therefore, we investigated whether innate immune receptors can facilitate the uptake of different species of α-syn aggregates. Here, we examined whether stimulation of TLRs could modulate the cellular uptake and degradation of α-syn fibrils despite a lack of direct interaction. We observed that stimulation of TLR2 in vitro accelerated α-syn fibril uptake in neurons and glia while delaying the degradation of α-syn in neurons and astrocytes. Internalized α-syn was rapidly degraded in microglia regardless of whether TLR2 was stimulated. However, cellular α-syn uptake and degradation kinetics were not altered by TLR4 stimulation. In addition, upregulation of TLR2 expression in a synucleinopathy mouse model increased the density of Lewy-body-like inclusions and induced morphological changes in microglia. Together, these results suggest that cell type-specific modulation of TLR2 may be a multifaceted and promising therapeutic strategy for synucleinopathies; inhibition of neuronal and astroglial TLR2 decreases pathogenic α-syn transmission, but activation of microglial TLR2 enhances microglial extracellular α-syn clearance.

Bioresorbable electrospun nanofibrous scaffolds loaded with bioactive molecules

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Chiara Gualandi ◽  
Piotr Wilczek ◽  
Maria Letizia Focarete ◽  
Gianandrea Pasquinelli ◽  
Michal Kawalec ◽  
...  
Keyword(s):  
Mononuclear Cells ◽  
Degradation Kinetics ◽  
Hydrolytic Degradation ◽  
Mesenchymal Cells ◽  
Bioactive Molecules ◽  
Differential Interference Contrast Microscopy ◽  
Electrospinning Technique ◽  
Ki 67 ◽  
Nanofibrous Scaffolds

AbstractElectrospinning technology is used to fabricate sub-micrometric fiber mats made of a random equimolar poly(lactide-co-glycolide) copolymer (PLGA), whose in vitro hydrolytic degradation kinetics is investigated over a period of 49 days in phosphate buffer at 37 °C. The PLGA mats show a decrease of molecular weight (by GPC) from the very beginning of the experiment, whereas a macroscopic weight loss from the samples is appreciated (by gravimetry) only after 20 days of buffer exposure. The molar mass distribution curves remain monomodal during the degradation experiment suggesting that no acid auto-catalyzed hydrolysis, commonly observed in bulk specimens, occurs in sub-micrometric PLGA fibers. PLGA scaffolds containing Endothelial Growth Factor Supplement (ECGS) were also fabricated by electrospinning, from ECGS-containing polymer solutions. Mesenchymal cells derived from human bone marrow mononuclear cells were cultured in the presence of such ECGS-loaded PLGA scaffolds. Flow cytometry and Differential Interference Contrast microscopy were used to characterize the cell cultures over a 7 day period. The results of AnexinV/PI staining and of intranuclear Ki-67 protein expression show, together with concomitant cell morphology modifications, that growth factors released from the scaffolds support the survival, proliferation and growth of the mesenchymal cells. This result demonstrates that ECGS maintains its bioactivity upon release from the electrospun fibers and shows the versatility of the electrospinning technique.

Structural and morphological changes in Poly(caprolactone)/poly(vinyl chloride) blends caused by UV irradiation

2007 ◽  
Vol 43 (3) ◽  
pp. 1063-1069 ◽  
Author(s):  
Sandra Mara Martins-Franchetti ◽  
Adriana Campos ◽  
Terry A. Egerton ◽  
Jim R. White
Keyword(s):  
Vinyl Chloride ◽  
Uv Irradiation ◽  
Morphological Changes ◽  
Poly Vinyl Chloride ◽  
Poly Caprolactone

PLA membranes loaded with dba analogs. Controlled release study during hydrolitic degradation

2020 ◽  
Vol 4 (1) ◽  
pp. 8-20
Author(s):  
GA. Alcántara Blanco ◽  
N. Urdaneta ◽  
MA. Sabino
Keyword(s):  
Hydrolytic Degradation ◽  
Controlled Drug Release ◽  
Release Profile ◽  
Poly Lactic Acid ◽  
Solvent Casting ◽  
Ph Conditions ◽  
Uv Visible ◽  
Loss Of Mass ◽  
Fluorescent Compounds ◽  
Degradation Time

In this research two dibenzylideneacetone (DBA) analogs compounds: (1E,4E)-1-(4-(dimethylamino)phenyl)-5-(4-methoxyphenyl)penta-1,4-dien-3-one (DBA-1) and (1E,4E)-1-(4-methoxyphenyl)-5-(4-nitrophenyl)penta-1,4-dien-3-one (DBA-2) were encapsulated in poly(lactic acid) (PLA) membranes. These DBA analogs can have several applications such as in the development of controlled drug release systems and tissue engineering.  The membranes were elaborated by solvent casting. It was found that these fluorescent compounds have a small percentage of hemolysis in human blood red cells at concentrations between 200-500 µg/mL. Therefore, they can be considered not-toxic at these concentrations. The hydrolytic degradation of PLA membranes loaded with the DBA analogs was studied at a temperature of 37 °C under solutions at acid, neutral, and basic pH conditions for a maximum time of six weeks. The hydrolysis was monitored by measuring the loss of mass of the membranes, changes in pH environments, variations in the molecular weight of PLA matrix, and changes in surface morphology observed through Scanning the Electron Microscopy (SEM) technique. Applying UV-visible spectrophotometry, the amount released from the DBA analogs in the PLA membranes was determined during the degradation time, and finally, the release profile was obtained. It was observed employing SEM that the membranes presented a major degradation under basic pH conditions, with a higher percentage of release in an acid medium for both analogues of DBA studied

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