scholarly journals Comparative Structure-Property Characterization of Poly(3-Hydroxybutyrate-Co-3-Hydroxyvalerate)s Films under Hydrolytic and Enzymatic Degradation: Finding a Transition Point in 3-Hydroxyvalerate Content

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 728 ◽  
Author(s):  
Vsevolod A. Zhuikov ◽  
Yuliya V. Zhuikova ◽  
Tatiana K. Makhina ◽  
Vera L. Myshkina ◽  
Alexey Rusakov ◽  
...  
Keyword(s):  
Molecular Mass ◽  
Enzymatic Degradation ◽  
Food Packaging ◽  
Hydrolytic Degradation ◽  
Analytical Techniques ◽  
Degree Of Crystallinity ◽  
Structure Property ◽  
Crystallinity Degree ◽  
Average Value

The hydrolytic and enzymatic degradation of polymer films of poly(3-hydroxybutyrate) (PHB) of different molecular mass and its copolymers with 3-hydroxyvalerate (PHBV) of different 3-hydroxyvalerate (3-HV) content and molecular mass, 3-hydroxy-4-methylvalerate (PHB4MV), and polyethylene glycol (PHBV-PEG) produced by the Azotobacter chroococcum 7B by controlled biosynthesis technique were studied under in vitro model conditions. The changes in the physicochemical properties of the polymers during their in vitro degradation in the pancreatic lipase solution and in phosphate-buffered saline for a long time (183 days) were investigated using different analytical techniques. A mathematical model was used to analyze the kinetics of hydrolytic degradation of poly(3-hydroxyaklannoate)s by not autocatalytic and autocatalytic hydrolysis mechanisms. It was also shown that the degree of crystallinity of some polymers changes differently during degradation in vitro. The total mass of the films decreased slightly up to 8–9% (for the high-molecular weight PHBV with the 3-HV content 17.6% and 9%), in contrast to the copolymer molecular mass, the decrease of which reached 80%. The contact angle for all copolymers after the enzymatic degradation decreased by an average value of 23% compared to 17% after the hydrolytic degradation. Young’s modulus increased up to 2-fold. It was shown that the effect of autocatalysis was observed during enzymatic degradation, while autocatalysis was not available during hydrolytic degradation. During hydrolytic and enzymatic degradation in vitro, it was found that PHBV, containing 5.7–5.9 mol.% 3-HV and having about 50% crystallinity degree, presents critical content, beyond which the structural and mechanical properties of the copolymer have essentially changed. The obtained results could be applicable to biomedical polymer systems and food packaging materials.

scholarly journals Microbial and Enzymatic Degradation of Synthetic Plastics

2020 ◽  
Vol 11 ◽  
Author(s):  
Nisha Mohanan ◽  
Zahra Montazer ◽  
Parveen K. Sharma ◽  
David B. Levin
Keyword(s):  
Microbial Degradation ◽  
Enzymatic Degradation ◽  
Polymer Surface ◽  
Amorphous Region ◽  
Degree Of Crystallinity ◽  
Crystalline Region ◽  
Molecular Weights ◽  
Chemical Structures ◽  
Lower Temperature

Synthetic plastics are pivotal in our current lifestyle and therefore, its accumulation is a major concern for environment and human health. Petroleum-derived (petro-)polymers such as polyethylene (PE), polyethylene terephthalate (PET), polyurethane (PU), polystyrene (PS), polypropylene (PP), and polyvinyl chloride (PVC) are extremely recalcitrant to natural biodegradation pathways. Some microorganisms with the ability to degrade petro-polymers under in vitro conditions have been isolated and characterized. In some cases, the enzymes expressed by these microbes have been cloned and sequenced. The rate of polymer biodegradation depends on several factors including chemical structures, molecular weights, and degrees of crystallinity. Polymers are large molecules having both regular crystals (crystalline region) and irregular groups (amorphous region), where the latter provides polymers with flexibility. Highly crystalline polymers like polyethylene (95%), are rigid with a low capacity to resist impacts. PET-based plastics possess a high degree of crystallinity (30–50%), which is one of the principal reasons for their low rate of microbial degradation, which is projected to take more than 50 years for complete degraded in the natural environment, and hundreds of years if discarded into the oceans, due to their lower temperature and oxygen availability. The enzymatic degradation occurs in two stages: adsorption of enzymes on the polymer surface, followed by hydro-peroxidation/hydrolysis of the bonds. The sources of plastic-degrading enzymes can be found in microorganisms from various environments as well as digestive intestine of some invertebrates. Microbial and enzymatic degradation of waste petro-plastics is a promising strategy for depolymerization of waste petro-plastics into polymer monomers for recycling, or to covert waste plastics into higher value bioproducts, such as biodegradable polymers via mineralization. The objective of this review is to outline the advances made in the microbial degradation of synthetic plastics and, overview the enzymes involved in biodegradation.

scholarly journals Study of the Influence of PCL on the In Vitro Degradation of Extruded PLA Monofilaments and Melt-Spun Filaments

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 171
Author(s):  
Vivien Barral ◽  
Sophie Dropsit ◽  
Aurélie Cayla ◽  
Christine Campagne ◽  
Éric Devaux
Keyword(s):  
Melt Spinning ◽  
Large Range ◽  
Hydrolytic Degradation ◽  
In Vitro Degradation ◽  
Crystallinity Degree ◽  
Mechanical And Physical Properties ◽  
Spinning Process ◽  
Bioresorbable Implants ◽  
The Impact

This work presents the effect of a melt-spinning process on the degradation behavior of bioresorbable and immiscible poly(d,l-lactide) (PLA) and polycaprolactone (PCL) polymer blends. A large range of these blends, from PLA90PCL10 (90 wt% PLA and 10 wt% PCL) to PLA60PCL40 in increments of 10%, was processed via extrusion (diameter monofilament: ∅ ≈ 1 mm) and melt spinning (80 filaments: 50 to 70 µm each) to evaluate the impact of the PCL ratio and then melt spinning on the hydrolytic degradation of PLA, which allowed for highlighting the potential of a textile-based scaffold in bioresorbable implants. The morphologies of the structures were investigated via extracting PCL with acetic acid and scanning electron microscopy observations. Then, they were immersed in a Dulbecco’s Modified Eagle Medium (DMEM) media at 50 °C for 35 days and their properties were tested in order to evaluate the relation between the morphology and the evolution of the crystallinity degree and the mechanical and physical properties. As expected, the incorporation of PCL into the PLA matrix slowed down the hydrolytic degradation. It was shown that the degradation became heterogeneous with a small ratio of PCL. Finally, melt spinning had an impact on the morphology, and consequently, on the other properties over time.

scholarly journals In Vitro Degradation of Plasticized PLA Electrospun Fiber Mats: Morphological, Thermal and Crystalline Evolution

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2975
Author(s):  
Adrián Leonés ◽  
Laura Peponi ◽  
Marcela Lieblich ◽  
Rosario Benavente ◽  
Stefano Fiori
Keyword(s):  
Lactic Acid ◽  
Electrospun Fiber ◽  
Hydrolytic Degradation ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
In Vitro Test ◽  
Fiber Mats ◽  
Whole Process ◽  
Vitro Test

In the present work, fiber mats of poly(lactic acid), PLA, plasticized by different amounts of oligomer lactic acid, OLA, were obtained by electrospinning in order to investigate their long term hydrolytic degradation. This was performed in a simulated body fluid for up to 352 days, until the complete degradation of the samples is reached. The evolution of the plasticized electrospun mats was followed in terms of morphological, thermal, chemical and crystalline changes. Mass variation and water uptake of PLA-based electrospun mats, together with pH stability of the immersion media, were also studied during the in vitro test. The results showed that the addition of OLA increases the hydrolytic degradation rate of PLA electrospun fiber mats. Moreover, by adding different amounts of OLA, the time of degradation of the electrospun fiber mats can be modulated over the course of a year. Effectively, by increasing the amount of OLA, the diameter of the electrospun fibers decreases more rapidly during degradation. On the other hand, the degree of crystallinity and the dimension of the α crystals of the electrospun fiber mats are highly affected not only by the presence but also by the amount of OLA during the whole process.

scholarly journals The Growth of 3T3 Fibroblasts on PHB, PLA and PHB/PLA Blend Films at Different Stages of Their Biodegradation In Vitro

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 108
Author(s):  
Vsevolod A. Zhuikov ◽  
Elizaveta A. Akoulina ◽  
Dariana V. Chesnokova ◽  
You Wenhao ◽  
Tatiana K. Makhina ◽  
...  
Keyword(s):  
Polymer Films ◽  
Enzymatic Degradation ◽  
Dynamic Change ◽  
Hydrolytic Degradation ◽  
Degradation Process ◽  
Past Century ◽  
Scanning Calorimetry ◽  
Blend Films ◽  
3T3 Fibroblasts

Over the past century there was a significant development and extensive application of biodegradable and biocompatible polymers for their biomedical applications. This research investigates the dynamic change in properties of biodegradable polymers: poly(3-hydroxybutyrate (PHB), poly-l-lactide (PLA), and their 50:50 blend (PHB/PLA)) during their hydrolytic non-enzymatic (in phosphate buffered saline (PBS), at pH = 7.4, 37 °C) and enzymatic degradation (in PBS supplemented with 0.25 mg/mL pancreatic lipase). 3T3 fibroblast proliferation on the polymer films experiencing different degradation durations was also studied. Enzymatic degradation significantly accelerated the degradation rate of polymers compared to non-enzymatic hydrolytic degradation, whereas the seeding of 3T3 cells on the polymer films accelerated only the PLA molecular weight loss. Surprisingly, the immiscible nature of PHB/PLA blend (showed by differential scanning calorimetry) led to a slower and more uniform enzymatic degradation in comparison with pure polymers, PHB and PLA, which displayed a two-stage degradation process. PHB/PLA blend also displayed relatively stable cell viability on films upon exposure to degradation of different durations, which was associated with the uneven distribution of cells on polymer films. Thus, the obtained data are of great benefit for designing biodegradable scaffolds based on polymer blends for tissue engineering.

scholarly journals Effect of Crystallinity on the Properties of Polycaprolactone Nanoparticles Containing the Dual FLAP/mPEGS-1 Inhibitor BRP-187

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2557
Author(s):  
Antje Vollrath ◽  
Christian Kretzer ◽  
Bärbel Beringer-Siemers ◽  
Blerina Shkodra ◽  
Justyna A. Czaplewska ◽  
...  
Keyword(s):  
Enzymatic Degradation ◽  
Drug Loading ◽  
Degree Of Crystallinity ◽  
Copolymer Composition ◽  
Vis Spectroscopy ◽  
Bulk Polymers ◽  
Formulation Parameters ◽  
Human Polymorphonuclear Leukocytes ◽  
In Vitro Performance

Seven polycaprolactones (PCL) with constant hydrophobicity but a varying degree of crystallinity prepared from the constitutional isomers ε-caprolactone (εCL) and δ-caprolactone (δCL) were utilized to formulate nanoparticles. The aim was to investigate the effect of the crystallinity of the bulk polymers on the enzymatic degradation of the particles. Furthermore, their efficiency to encapsulate the hydrophobic anti-inflammatory drug BRP-187 and the final in vitro performance of the resulting NPs were evaluated. Initially, high-throughput nanoprecipitation was employed for the εCL and δCL homopolymers to screen and establish important formulation parameters (organic solvent, polymer and surfactant concentration). Next, BRP-187-loaded PCL nanoparticles were prepared by batch nanoprecipitation and characterized using dynamic light scattering, scanning electron microscopy and UV-Vis spectroscopy to determine and to compare particle size, polydispersity, zeta potential, drug loading as well as the apparent enzymatic degradation as a function of the copolymer composition. Ultimately, NPs were examined for their potency in vitro in human polymorphonuclear leukocytes to inhibit the BRP-187 target 5-lipoxygenase-activating protein (FLAP). It was evident by Tukey’s multi-comparison test that the degree of crystallinity of copolymers directly influenced their apparent enzymatic degradation and consequently their efficiency to inhibit the drug target.

PENERAPAN STRATEGI CONTEXTUAL TEACHING AND LEARNING (CTL)UNTUK MENINGKATKAN HASIL BELAJAR IPS SISWA KELAS VSD NEGERI 010 SILIKUAN HULU KECAMATAN UKUI

2016 ◽  
Vol 5 (2) ◽  
pp. 320
Author(s):  
Siwi Enggar Makarti
Keyword(s):  
Learning Outcomes ◽  
Primary Schools ◽  
Teaching And Learning ◽  
Descriptive Analysis ◽  
Analytical Techniques ◽  
Research Subjects ◽  
Student Activities ◽  
Student Activity ◽  
Average Value ◽  
Contextual Teaching

The background of this study is the low learning outcomes IPS. It is characterized by the acquisition of the average value of social studies students at 59.10 with the percentage of students learning completeness amounted to 50.00% from 20 students. This research is a classroom action research (PTK) which aims to improve student learning outcomes through the implementation of strategies IPS Contextual Teaching and Learning (CTL). This study was conducted in 010 primary schools Silikuan Ukui Hulu subdistrict, with research subjects fifth grade students with a number of 20 students. This study was conducted by two cycles. The data used in this study are the activities of teachers, student activities, and learning outcomes are collected using the observation technique teacher and student activities and written tests, while the analytical techniques used in this research is descriptive analysis. The study states that the acquisition of the activities of teachers and students and learning outcomes in each cycle has increased. This is supported by: (1) the percentage of activity the teachers in the first cycle of the first meeting by 45%, in the first cycle of meetings II percentage teacher activity by 52%, the percentage of teacher activity in the second cycle of the first meeting by 65%, the percentage of teacher activity in the second cycle meeting II by 75%; (2) the percentage of student activity in the first cycle of the first meeting by 49%, in the first cycle of meetings II percentage of student activity by 60%, the percentage of the activity of students in the second cycle the first meeting by 63%, the percentage of student activity on the second cycle of meeting II by 79% ; (3) learning outcomes in basic score of 59,10.Dan which reached KKM 65 only 10 students or (50%). The first cycle of the average value obtained by the students reached 63.6. Students who achieve KKM there are 13 students or 65 (65%). Cycle II average value obtained students achieve value above 67 means the KKM. Students who reached the last 16 students or (80%).

Investigation of the effect of loratadine and calcium ions on oxidoreductase activity of catalase enzyme

2020 ◽  
Vol 16 ◽  
Author(s):  
Edhem Hasković ◽  
Safija Herenda ◽  
Zehra Halilović ◽  
Snežana Unčanin ◽  
Denis Hasković ◽  
...  
Keyword(s):  
Calcium Ions ◽  
Enzyme Reaction ◽  
Analytical Techniques ◽  
Competitive Inhibitor ◽  
Cellular Functions ◽  
Oxidoreductase Activity ◽  
H1 Antihistamines ◽  
Activity Of Enzymes ◽  
The Given

Background: The Spectrophotometric method is one of the most suitable analytical techniques for testing the activity of enzymes under the influence of various factors. Methods: The effect of H1-antihistamines of loratadine and calcium ions on enzyme catalase under in vitro conditions was investigated in this paper. Results and Discussion: It has been shown that loratadine isa partial inhibitor of catalase, but this effect is diminished in the presence of calcium ions. Calcium as well as other cations are important for many biological and cellular functions. The kidneys play a central role in the homeostasis of these ions. The activity of the catalase enzyme under the given conditions, the type of inhibition,and the kinetic parameters of the enzyme reaction were determined. Conclusion: We concluded that loratadine is a partially competitive inhibitor.

scholarly journals Migration of Silver and Copper Nanoparticles from Food Coating

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 380
Author(s):  
Hamed Ahari ◽  
Leila Khoshboui Lahijani
Keyword(s):  
Copper Nanoparticles ◽  
Inductively Coupled Plasma ◽  
Food Packaging ◽  
Human Life ◽  
Analytical Techniques ◽  
Optical Emission ◽  
Atomic Emission ◽  
The Body ◽  
Toxic Effects ◽  
Inductively Coupled

Packaging containing nanoparticles (NPs) can increase the shelf life of products, but the presence of NPs may hazards human life. In this regard, there are reports regarding the side effect and cytotoxicity of nanoparticles. The main aim of this research was to study the migration of silver and copper nanoparticles from the packaging to the food matrix as well as the assessment techniques. The diffusion and migration of nanoparticles can be analyzed by analytical techniques including atomic absorption, inductively coupled plasma mass spectrometry, inductively coupled plasma atomic emission, and inductively coupled plasma optical emission spectroscopy, as well as X-ray diffraction, spectroscopy, migration, and titration. Inductively coupled plasma-based techniques demonstrated the best results. Reports indicated that studies on the migration of Ag/Cu nanoparticles do not agree with each other, but almost all studies agree that the migration of these nanoparticles is higher in acidic environments. There are widespread ambiguities about the mechanism of nanoparticle toxicity, so understanding these nanoparticles and their toxic effects are essential. Nanomaterials that enter the body in a variety of ways can be distributed throughout the body and damage human cells by altering mitochondrial function, producing reactive oxygen, and increasing membrane permeability, leading to toxic effects and chronic disease. Therefore, more research needs to be done on the development of food packaging coatings with consideration given to the main parameters affecting nanoparticles migration.

scholarly journals Simple Equations Pertaining to the Particle Number and Surface Area of Metallic, Polymeric, Lipidic and Vesicular Nanocarriers

2021 ◽  
Vol 89 (2) ◽  
pp. 15
Author(s):  
M. R. Mozafari ◽  
E. Mazaheri ◽  
K. Dormiani
Keyword(s):  
Drug Delivery ◽  
Surface Area ◽  
Particle Number ◽  
Analytical Techniques ◽  
Metallic Particles ◽  
Nutraceutical Compounds ◽  
Mathematical Formulas ◽  
Simple Equations

Introduction: Bioactive encapsulation and drug delivery systems have already found their way to the market as efficient therapeutics to combat infections, viral diseases and different types of cancer. The fields of food fortification, nutraceutical supplementation and cosmeceuticals have also been getting the benefit of encapsulation technologies. Aim: Successful formulation of such therapeutic and nutraceutical compounds requires thorough analysis and assessment of certain characteristics including particle number and surface area without the need to employ sophisticated analytical techniques. Solution: Here we present simple mathematical formulas and equations used in the research and development of drug delivery and controlled release systems employed for bioactive encapsulation and targeting the sites of infection and cancer in vitro and in vivo. Systems covered in this entry include lipidic vesicles, polymeric capsules, metallic particles as well as surfactant- and tocopherol-based micro- and nanocarriers.

scholarly journals ZO-3, a Novel Member of the MAGUK Protein Family Found at the Tight Junction, Interacts with ZO-1 and Occludin

1998 ◽  
Vol 141 (1) ◽  
pp. 199-208 ◽  
Author(s):  
Julie Haskins ◽  
Lijie Gu ◽  
Erika S. Wittchen ◽  
Jennifer Hibbard ◽  
Bruce R. Stevenson
Keyword(s):  
Amino Acid ◽  
Tight Junction ◽  
Molecular Mass ◽  
Mdck Cells ◽  
Cdna Libraries ◽  
Pdz Domains ◽  
Large Tumor ◽  
Junction Protein ◽  
Discs Large

A 130-kD protein that coimmunoprecipitates with the tight junction protein ZO-1 was bulk purified from Madin-Darby canine kidney (MDCK) cells and subjected to partial endopeptidase digestion and amino acid sequencing. A resulting 19–amino acid sequence provided the basis for screening canine cDNA libraries. Five overlapping clones contained a single open reading frame of 2,694 bp coding for a protein of 898 amino acids with a predicted molecular mass of 98,414 daltons. Sequence analysis showed that this protein contains three PSD-95/SAP90, discs-large, ZO-1 (PDZ) domains, a src homology (SH3) domain, and a region similar to guanylate kinase, making it homologous to ZO-1, ZO-2, the discs large tumor suppressor gene product of Drosophila, and other members of the MAGUK family of proteins. Like ZO-1 and ZO-2, the novel protein contains a COOH-terminal acidic domain and a basic region between the first and second PDZ domains. Unlike ZO-1 and ZO-2, this protein displays a proline-rich region between PDZ2 and PDZ3 and apparently contains no alternatively spliced domain. MDCK cells stably transfected with an epitope-tagged construct expressed the exogenous polypeptide at an apparent molecular mass of ∼130 kD. Moreover, this protein colocalized with ZO-1 at tight junctions by immunofluorescence and immunoelectron microscopy. In vitro affinity analyses demonstrated that recombinant 130-kD protein directly interacts with ZO-1 and the cytoplasmic domain of occludin, but not with ZO-2. We propose that this protein be named ZO-3.

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