Low Molecular Weight Degradation Products Research Articles

Abiotic degradation and accelerated ageing of microplastics from biodegradable and recycled materials in artificial seawater

Microplastics (MPs) are considered one of the most widespread pollutants in all ecosystems worldwide. In the environment, MPs can undergo hydrolysis and/or oxidation, resulting in the release of low-molecular weight degradation products, along with additives, and adsorbed organic pollutants. In this study, the morphological, chemical, and thermal changes of microplastics obtained from two biodegradable plastics, polylactic acid and Mater-Bi®, and a recycled plastic, recycled-polyethylene terephthalate, were examined after accelerated ageing under photo-oxidative conditions in synthetic seawater in a Solarbox system, and after thermal treatment in the dark. Thermal properties were studied by thermogravimetric analysis, differential scanning calorimetry, and evolved gas analysis-mass spectrometry. Compositions and changes of chemical components of the polymers were evaluated by attenuated total reflection-Fourier transform infrared spectroscopy and pyrolysis-gas chromatography–mass spectrometry. The leachable fractions and degradation products released in synthetic seawater by degraded MPs were characterized by gas chromatography–mass spectrometry. This study allowed us to identify hydrolysis as the main degradation pathway of the polymers under analysis, and to characterize not only the oligomers and degradation products released in the water as a consequence of degradation, but also additives used in plastic item formulations. This study improves our understanding of these polymers' behavior under accelerated ageing conditions.

Extensive HPLC-tandem mass spectrometry characterization of soluble degradation products of biodegradable nanoplastics under environmentally relevant temperature and irradiation conditions

The low molecular weight degradation products of nanosize biodegradable plastics were identified by mass spectrometry. The only detected products for PLA, PCL and PET were found to a rise from hydrolysis.

Biochemical disorders in the thyroid gland in rats with hyperhomocysteinemia

Background: In recent years, significant progress has been made in elucidating the mechanisms of development of complications associated with hyperhomocysteinemia (HC), but little is known about the disorders in the thyroid gland. This study aimed to determine the levels of low-molecularweight degradation products and peptides in the thyroid gland of rats with HC. In addition, markers of inflammation and the proteolytic state were also assessed. Methods: HC was induced by intragastric administration of DL-homocysteine thiolactone (100 mg.kg-1 of body weight) to albino non-linear male rats. The levels of low-molecular-weight substances (LMWS) of various nature were detected at wavelengths of 254 and 280 nm. The levels of MMP-2 and cytokine profiles were detected by enzyme-linked immunosorbent assay. The protein composition and the presence of active enzymes were assessed by SDS-polyacrylamide gel electrophoresis and zymography, respectively. Results: Obtained results can indicate the enhancement of catabolic reactions, confirmed by the accumulation of LMWS in the blood and thyroid gland of the rats with HC. The state of inflammation, evidenced by the significantly increased pro-inflammatory cytokines, was also revealed. HC was accompanied by the activation of proteolysis, expressed by an increase in overall proteolytic activity, the level of MMP-2, and changes in protein profile. Proteins accumulated with a molecular weight of less than 30 kDa simultaneously with the decrease in the level of high-molecular-weight proteins.

Thermochemical liquefaction of wheat straw in sub- and supercritical tetralin

The present work investigates the thermochemical conversion of wheat straw biomass in a suband supercritical tetralin medium. The experiment was carried out in a batch reactor at 285, 330, 380, 420 and 460 °C for 10 minutes. The process of straw liquefaction in subcritical tetralin was characterised by relatively high efficiency. At 420 °C, the biomass conversion rate amounted to 98.2% a.d.m. The maximum yield of liquid products during liquefaction (81.6% a.d.m.) was obtained at 380 °C. The liquid products were fractionated by successive extraction with hexane, water and ethanol. According to GC-MS data, the liquefaction products soluble in hexane comprised a mixture of low-molecular weight degradation products of straw components and tetralin derivatives, including methyl esters of fatty acids, aromatic compounds, alkanes and minor alcohols and ketones. When the process temperature increased, the content of esters diminished, followed by an increment in the proportion of aromatic compounds up to 50% rel. No esters and phenolic compounds were present in the liquefaction products soluble in hexane obtained at 460 °C. Dehydrogenation, alkylation and isomerisation of tetralin with the formation of naphthalene, 1,4-dihydronaphthalene and alkyl derivatives of tetralin, naphthalene and indane occurred under the given conditions. The conducted comparative analysis of infrared spectra for straw and solid products of liquefaction suggested that, at temperatures of up to 330 °C, the process of polysaccharide fragmentation is more pronounced in the straw biomass, while, at higher temperatures, the process of lignin fragmentation prevails. As a result, the IR-spectrum of the solid product obtained at 380 °C revealed weakly pronounced absorption bands of alkylaromatic structural fragments. At the same time, only the absorption bands of mineral components in straw ash and adsorbed water were observed in the IR-spectrum of the solid product obtained at 420 °C.

Safety assessment of subtilisin QK in rats

BackgroundSubtilisin QK is a serine protease in the subtilisin family, and is fermented by Bacillus subtilis QK02. The fibrinolytic activity of subtilisin QK was measured by detecting low molecular weight degradation products using a spectrophotometric method developed by Japan Bio Science Laboratory Co., Ltd. Subtilisin QK powder can maintain its fibrinolytic activity for more than 24 months when it is stored at room temperature and protected from light. Our previous results showed that subtlisin QK directly degraded cross-linked fibrins in the fibrin plate assay and effectively inhibited thrombosis in the mouse thrombus model. The aim of this study was to determine the acute toxicity, potential subchronic toxicity, and safety pharmacology of subtilisin QK in Sprague–Dawley (SD) rats.MethodsIn the acute toxicity study, a single oral dose of 100,000 FU/kg was administered to 10 female and 10 male SD rats. In the 28-day subchronic toxicity, 60 female and 60 male SD rats were randomly assigned to four experimental groups (daily oral dose of 0, 2500, 7500 and 25,000 FU/kg). In the safety pharmacology study, 20 female and 20 male SD rats were randomly assigned to four experimental groups (single oral dose of 0, 500, 1500 and 5000 FU/kg).ResultsNo death occurred and no adverse effects were observed in the acute toxicity study at a dose of 100,000 FU/kg. In the 28-day subchronic toxicity study, several hematological and blood biochemical parameters showed increases or decreases; however, due to the lack of a dose–response relationship, these differences were considered unrelated to treatment. In the safety pharmacology study, no adverse effects were observed on the central nervous of SD rats post-administration up to a dose of 5000 FU/kg subtilisin QK.ConclusionThe results showed that oral consumption of subtilisin QK is of low toxicological concern. No adverse effects were observed at doses of 2500, 7500, and 25,000 FU/kg in the 28-day subchronic toxicity, and the no-observed-adverse-effect level (NOAEL) of subtilisin QK was 25,000 FU/kg.

Controllable Degradation of Poly (trimethylene carbonate) via Self-blending with Different Molecular Weights

Blend films of Poly (trimethylene carbonate) (PTMC) homopolymers with different molecular weights were prepared. The in vitro enzymatic degradation tests were carried out in lipase solutions to investigate the effect of self-blending on the degradation performance of PTMC. It was observed that the mass loss decreased as the proportion of low molecular weight PTMC in the blend film increased. And the sample's mass loss with the mass ratio of PTMC334/PTMC57=1/16 reached almost 30% after seven weeks, which corresponded to the minimum degradation rate constant k value of 5.219. It is also indicated by the changes in weight as well as the macroscopic and microscopic morphology. Furthermore, during the degradation cycle, the thickness of the film also became thinner with the mass loss, confirming the surface erosion degradation mechanism of the PTMC blend films. The conclusion that PTMC does not produce acidic degradation products has also been confirmed. Finally, decreases in glass transition temperature (Tg) and thermal stability were found along with the film degraded, attributing to the accumulation of low molecular weight degradation products on the surface. In brief, the long-acting application of PTMC in biomedical fields could be satisfied by precisely tailoring the degradation properties via its self-blending with different molecular weights.

The in‐vitro biocompatibility of ureido‐pyrimidinone compounds and polymer degradation products

AbstractSupramolecular biomaterials based on ureido‐pyrimidinone (UPy) moieties are versatile polymer materials as their function can be tailored to the application. These UPy‐materials can be designed into polymer coatings, self‐healing polymers, hydrogels and elastomers. The biocompatibility of UPy‐based materials and their degradation products is a long‐term success requirement for many regenerative medicine and biomedical applications. Earlier research has shown that UPy‐based materials and polymers display no immediate toxic effects, but in‐depth in‐vitro studies on potential UPy‐polymer degradation products have not been executed. Owing to their resemblance to naturally occurring purines and pyrimidines, UPy‐compounds and their degradation products could potentially initiate an immune response or be mutagenic. Accordingly, 11 selected UPy‐compounds were synthesized, and their effect on cell viability, wound healing, and their immunogenicity and potential mutagenic potential, were studied. We showed that low molecular weight degradation products of UPy‐based biomaterials do not affect cell viability, nor do these interfere with several aspects of endothelial function including proliferation, angiogenic sprouting and cellular migration even in levels exceeding plausibly attainable concentrations. Furthermore, the compounds are neither immunogenic nor mutagenic, showing that UPy‐biomaterials exhibit good biocompatibility in vitro, and could in principle be used in humans.

Immunological effects of Chondrus armatus carrageenans and their low molecular weight degradation products.

Ability of high molecular weight (HMW) κ- and λ-carrageenans of the red marine algae Chondrus armatus and their low molecular weight degradation products (LMWDPs) (0.7-20 and 10-170 kDa respectively) to influence functional properties (motility and phagocytosis) of murine peritoneal macrophages was assessed in this study as an in vitro and a weeklong feeding experiment. We demonstrated that, with an exception of one, all carrageenan samples at 100 μg/ml increased cellular motility and dose-dependently decreased phagocytic activity; LMWDPs of λ-carrageenan suppressed motility and had no effect on phagocytosis. Oral administration of all the carrageenan samples at 100 μg/kg/day for 7 days to mice had no effect on their clinical appearance, body weight, weight of their liver, spleen or thymus or development of noticeable changes to their inner organs. All samples induced a shift of the cell composition of the peritoneal cavity towards macrophages. Consumption of LMWDPs of κ-carrageenan resulted in development of leukopenia, however, no changes to relative WBC count were introduced by either of the samples. All samples decreased murine peritoneal macrophages phagocytic activity, with λ-samples possessing higher efficacy than their κ-counterparts; all LMWDPs stimulated peritoneal macrophages motility, with κ-samples possessing higher efficacy than their λ-counterparts In conclusion, we have shown that κ- and λ-carrageenans of the C. armatus and their LMWDPs suppress phagocytotic activity of peritoneal macrophages under both in vitro and in vivo conditions. This allows them to be viewed as pharmacologically active substances andpropagates the need for their further investigation as such.

Microwave-assisted solvent extraction and double-shot analytical pyrolysis for the quali-quantitation of plasticizers and microplastics in beach sand samples

Pollution from microplastics (MPs) needs to be evaluated by deploying reliable analytical techniques that provide qualitative and quantitative data on the extent of contamination in the various environmental matrices. Solvent extraction of MPs followed by pyrolysis-gas chromatography-mass spectrometry (Py-GC–MS) provides data that not only regard the soluble plastics, but also the organic additives contained in MPs and the low-molecular weight degradation products of insoluble plastics. In this study, the potential of microwave-assisted solvent extraction and double-shot Py-GC–MS was investigated in order to obtain quali-quantitative information on polystyrene and on phthalate plasticizers in environmental samples. The method was validated and provided recoveries higher than 96 %, and detection limits lower than 1 ng and 1 μg for phthalates and polystyrene, respectively. We used the method to analyze samples of sand collected from a shoreline in Tuscany (central Italy) and thereby determine the content of phthalates and polystyrene at different depths and distances from the coastline. Qualitative data were also obtained regarding the presence of oxidation products derived from polyethylene and polypropylene. The different contents of plasticizers, plastics, and degradation products in the investigated samples are discussed in relation to how environmental agents affect the leaching and degradation processes of the polymers.

Identification of low molecular weight degradation products from chitin and chitosan by electrospray ionization time-of-flight mass spectrometry

The beneficial effects provided by chitosan oligosaccharides (COS) make them of interest in medical research. The monomers that constitute COS confer distinct properties, so controlling COS composition during their production is significant. In this work, we degraded chitin and chitosan polymers and identified low molecular weight products such as COS that formed, using electrospray ionization time-of-flight mass spectrometry. Our results show that hydrochloric acid, hydrogen peroxide, and nitrous acid generate distinct products from chitin and chitosan. Hydrochloric acid degrades chitin and chitosan to produce glucosamine (GlcN) monomers and oligomers. Hydrogen peroxide degrades chitosan to produce GlcN and N-acetyl-d-glucosamine (GlcNAc) monomers and oligomers, and nitrous acid degrades chitosan to produce 2,5-anhydro- d-mannose. Our studies show that COS composition is dictated by both the degradation protocol and the starting polymer. Additionally, our results enable selection of degradation protocols based on their ability to degrade chitin and chitosan and facilitate the production of COS with desired compositions.

In vitro antitumor and immunotropic activity of carrageenans from red algae Chondrus armatus and their low-molecular weight degradation products.

Antitumor and immunotropic effects of κ-, λ-carrageenan from red marine algae Chondrus armatus and their low-molecular weight (LMW) degradation products were explored. Effects on human esophageal cancer cell lines KYSE30 and FLO1 viability and ability to induce production of pro- and anti-inflammatory cytokines by human monocytes was assessed. All polysaccharides demonstrated antimetabolic and cytostatic activity towards cancer lines, with high-molecular weight carrageenans possessing higher antimetabolic and lower cytostatic activity than their LMW degradation products. All carrageenans induced monocytes to produce pro-inflammatory cytokines IL1β, IL6, IL18, and TNFα. However, secretion of anti-inflammatory cytokine IL10 was induced only by LMW λ-carrageenan, which exhibited the highest cytokine production inducing efficacy overall. We demonstrate that LMW carrageenan degradation products not only retain biological activity of their precursors, but also increase their efficacy in type-dependent manner, allowing for their future development for pharmacological practice.

Applications of Raman spectroscopy in art and archaeology

Applications of Raman spectroscopy in art and archaeology

Stanovení aktivity proteolytických enzymů během výroby sladu

Proteolytic enzymes (proteases) are widely represented in living organisms where they catalyze the hydrolysis of peptide bonds in proteins and peptides. In malting barley, they are found in small quantities, and their activation takes place only in the process of controlled germination – malt production. In germinating barley, proteases hydrolyze storage proteins to high molecular and low molecular weight degradation products while simultaneously synthesizing other proteins. The final grain modification affects significantly quality of the produced malts and subsequently also technology and characters of the produced beer.

Linseed oil as a model system for surface enhanced Raman spectroscopy detection of degradation products in artworks

AbstractEarly evidence of materials decay can provide diagnostic insights to conservators and scientists enhancing the overall knowledge on art materials. Limited knowledge is available on the long‐term behavior of synthetic and natural polymers used in art. This research poses the foundations for studies on organic materials suffering from autoxidation processes, using nondestructive surface enhanced Raman spectroscopy (SERS) for the detection of commonly present low molecular weight degradation products. Such products are here considered molecular markers for diagnostic investigations, and SERS allows detection limits never reached before. 3D aluminum (Al)‐coated SERS substrates are optimized for in situ sampling of artifacts, testing different reference materials, sampling strategies, and instrumental conditions. Linseed oil is an organic material widely used in art, which degradation mechanisms are well‐known. Considering that many polymeric compounds follow similar degradation pathways, linseed oil seemed an excellent model material for a wider research on SERS for polymers degradation in artworks.

Products of Metabolism and Processing of Lactic Acid Bacteria as Functional Ingredients

Lactic acid bacteria (LAB) and bifidobacteria (BB) are unique substances that have a lot of biological and physiological effects. Structural components of LAB and BB – peptidoglycans, compounds of the muramylpeptide series, teichoic acids – have powerful immunological properties. Metabolites of LAB and BB – organic acids, hydrogen peroxide, bacteriocins, etc. – provide antagonistic activity, have an indirect impact on the immune system, reducing the antigenic load caused by pathogenic microorganisms. The expediency of peptidoglycans degradation of LAB and BB cell walls is substantiated. Low molecular weight products of the degradation can easily be absorbed and enter into biochemical processes, accelerating the expected functional-physiological effect. To obtain low-molecular products of peptidoglycans degradation, a combination of LAB and BB was used. The combination of LAB and BB is the sum of the test cultures of Lactobacillus acidophilus, Lactobacillus delbrueckii subsp. Bulgaricus, Bifidobacterium bifidum, Lactococcus cremoris, Streptococcus termophilus. Destruction of peptidoglycans of bacterial cell walls was carried out using a combination of disintegrating factors. The efficiency of destruction was determined by the accumulation of low molecular weight peptides (with molecular weight up to 1500 Da), amino acids and soluble protein in the disintegrate. It has been established that the highest accumulation of low molecular weight degradation products occurs when using autolysis followed by enzymatic hydrolysis during 180 min with the ratio of the enzyme : substrate 1 : 100. At the same time ≈ 53% of protein substances pass from insoluble to soluble state. The molecular weight of the obtained products is determined by the gel chromatography method. The qualitative and quantitative content of organic acids, amino acids and vitamins of group В in the hydrolysis products composition was investigated. It was shown that the obtained product possesses high biological effect in the experiment on animals.

Degradable, Dendritic Polyols on a Branched Polyphosphazene Backbone.

Herein, we present the design, synthesis, and characterization of fully degradable, hybrid, star-branched dendritic polyols. First multiarmed polyphosphazenes were prepared as a star-branched scaffold which upon functionalization produced globular branched hydroxyl-functionalized polymers with over 1700 peripheral functional end groups. These polyols with unique branched architectures could be prepared with controlled molecular weights and relatively narrow dispersities. Furthermore, the polymers are shown to undergo hydrolytic degradation to low molecular weight degradation products, the rate of which could be controlled through postpolymerization functionalization of the phosphazene backbone.

Degradation and kinetic modeling of polyvinyl alcohol in aqueous solutions by a H2O2/Mn(II) system

This paper is about the degradation of polyvinyl alcohol (PVA) in aqueous solutions using a H2O2/Mn(II) system. Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC) were applied to analyze the degradation products of PVA, and the results revealed that the backbone chain of PVA could be effectively broken and oxidized. Several unsaturated degradation products, including carboxylic acids, ketones, aldehydes, olefins, and alkynes were also detected and identified by gas chromatography-mass spectrometry (GC-MS), which indicated that higher treatment temperatures would considerably promote the generation of lower molecular weight degradation products. According to the work presented in this paper, the degradation efficiency of PVA increased from 55 % at 60 oC to 99 % at 90 oC after treatment when the initial PVA concentration was 5 %, at pH=3 with a H2O2 and Mn(II) dose of 100 ml/l and 0.6 mol/l, respectively. In addition, kinetic modeling indicated that the experimental results were best fitted by the Page-modified model with an activation energy of 48.78 kJ/mol.

Restructuration kinetics of amphiphilic intraocular lenses during aging

Photooxidation and hydrolysis are the two primary aging factors of intraocular lenses. Opacifications, dislocations, glistening and yellowing of the implanted acrylic lenses, which are due to chain scissions and depolymerization, are the consequences of aging from the clinical perspective. The purpose of this study was to examine the consequence of the aging of intraocular lenses on chemical and surface properties. Acrylic lenses made of poly acrylic-co-polystyrene polymer were artificially aged by photooxidation and hydrolysis from 2 to 20 years. Degradation products were observed by Reverse-phase High-Performance Liquid Chromatography RP-HPLC and thermogravimetric analysis (TGA). The surface, which was analyzed by atomic force microscopy (AFM) and fibronectin adhesion kinetics, was chosen as an indicator of intraocular biocompatibility. Low-molecular-weight degradation products (LMWP) result from chain scission under both hydrolysis and photooxidation. The osmotic effects of water enable degradation products to migrate through the polymer. A portion of the degradation products exudate in the surrounding center, whereas a portion link with lateral chains of the polymer. At the same time, the surface roughness evolves to externalize the most hydrophilic chains. As a result, the fibronectin adhesion level decrease with time, which indicates the existence of a biocompatible kinetic for implanted intraocular lenses.

Thermal-oxidation mechanism of dioctyl adipate base oil

Abstract The ester base oil of dioctyl adipate (DOA) was oxidized in an oven at 200 °C for 30 h, and variations in the physicochemical and tribological properties were studied. To investigate the thermal-oxidation mechanism, the thermal-oxidation products were analyzed by gas chromatography–mass spectrometry (GC−MS), and the thermal-oxidation process was simulated using visual reactive force field molecular dynamics (ReaxFF MD). The results indicated that the total acid number (TAN) increased significantly because of the presence of 14% carboxylic acids and low molecular weight monoesters. The tribological properties were improved by the formation of the strongly polar carboxylic acids. Additionally, the increase in kinematic viscosity was limited due to the formation of high molecular weight polymerization products and low molecular weight degradation products. Thermal-oxidative degradation and polymerization mechanisms were proposed by combining ReaxFF MD simulations and GC−MS results.

Biodegradable HEMA-based hydrogels with enhanced mechanical properties.

Hydrogels are widely used in the biomedical field. Their main purposes are either to deliver biological active agents or to temporarily fill a defect until they degrade and are followed by new host tissue formation. However, for this latter application, biodegradable hydrogels are usually not capable to sustain any significant load. The development of biodegradable hydrogels presenting load-bearing capabilities would open new possibilities to utilize this class of material in the biomedical field. In this work, an original formulation of biodegradable photo-crosslinked hydrogels based on hydroxyethyl methacrylate (HEMA) is presented. The hydrogels consist of short-length poly(2-hydroxyethyl methacrylate) (PHEMA) chains in a star shape structure, obtained by introducing a tetra-functional chain transfer agent in the backbone of the hydrogels. They are cross-linked with a biodegradable N,O-dimethacryloyl hydroxylamine (DMHA) molecule sensitive to hydrolytic cleavage. We characterized the degradation properties of these hydrogels submitted to mechanical loadings. We showed that the developed hydrogels undergo long-term degradation and specially meet the two essential requirements of a biodegradable hydrogel suitable for load bearing applications: enhanced mechanical properties and low molecular weight degradation products. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1161-1169, 2016.