Effects of petroleum-based and biopolymer-based nanoplastics on aquatic organisms: A case study with mechanically degraded pristine polymers.

Mismanaged plastic litter submitted to environmental conditions may breakdown into smaller fragments, eventually reaching nano-scale particles (nanoplastics, NPLs). In this study, pristine beads of four different types of polymers, three oil-based (polypropylene, PP; polystyrene, PS; and low-density polyethylene, LDPE) and one bio-based (polylactic acid, PLA) were mechanically broken down to obtain more environmentally realistic NPLs and its toxicity to two freshwater secondary consumers was assessed. Thus, effects on the cnidarian Hydra viridissima (mortality, morphology, regeneration ability, and feeding behavior) and the fish Danio rerio (mortality, morphological alterations, and swimming behavior) were tested at NPLs concentrations in the 0.001 to 100 mg/L range. Mortality and several morphological alterations were observed on hydras exposed to 10 and 100 mg/L PP and 100 mg/L LDPE, whilst regeneration capacity was overall accelerated. The locomotory activity of D. rerio larvae was affected by NPLs (decreased swimming time, distance or turning frequency) at environmentally realistic concentrations (as low as 0.001 mg/L). Overall, petroleum- and bio-based NPLs elicited pernicious effects on tested model organisms, especially PP, LDPE and PLA. Data allowed the estimation of NPLs effective concentrations and showed that biopolymers may also induce relevant toxic effects.

Maysin plays a protective role against α-Synuclein oligomers cytotoxicity by triggering autophagy activation.

Parkinson's disease (PD) is a widespread neurodegenerative disorder characterized by the progressive loss of neurons. The accumulation of aggregated forms of the α-Synuclein (Syn) protein is the main cause of neurotoxicity in PD by disrupting cellular homeostasis until neuronal death. Scientific research is constantly looking for natural products as preventive agents against the progression of several neurodisorders due their safety and non-toxic nature. Neuroprotective phytochemicals include Maysin (Mys), the most abundant C-glycosilflavone in corn silk. In this work, the Mys protective role against damage by Syn amyloid aggregates - oligomers and fibrils - was investigated in SH-SY5Y human neuroblastoma cells obtaining novel and interesting information concerning the Mys molecular mechanism of action. Mys showed effectiveness in preventing the typical toxic events induced by Syn amyloid aggregates, i.e. oxidative stress and imbalance of intracellular calcium homeostasis. Mys exhibited a cytoprotective role, especially against Syn oligomers injury, activating an autophagic degradative process, thus playing a key role on several features of amyloid neurotoxicity. Therefore, Mys could be proposed for the first time to the scientific community as an interesting novel natural compound that might allow to develop alternative strategies to prevent the damage of Syn oligomers involved in Parkinson's disease.

In-vitro degradation and toxicological assessment of pulsed electric fields crosslinked zein-chitosan-poly(vinyl alcohol) biopolymeric films.

We investigated the in vitro degradation and cytotoxic effects of edible films developed from pulsed electric fields (PEF) treated zein-chitosan-poly(vinyl alcohol) dispersions at specific energy 60-70, 385-400, and 620-650 kJ/kg. The degradation was evaluated using both simulated gastro-intestinal electrolyte solutions (SGES) and enzyme hydrolysis. The results of ortho-phthaldialdehyde (OPA) test indicated that the chemical breakdown of the films in SGES and enzyme increased with degradation time, but the product's features were unmodified. The Fourier Transform Infrared spectroscopy (FTIR) data showed enhancement of zein and chitosan transformation from ordered helices to ß-sheet conformation. Relative cell survival rates of Hepa-1c1c7 cells investigated using 3-[4,5- dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) showed that the survival remained higher than 70% in both the supernatant and the residue of the SGES degraded samples and the supernatant from enzyme hydrolysis, which suggested that there was no significant toxicity of the films in the tested system. Although the residue from pancreatic digestion (240 min) (i.e. undigested films and a cocktail of digestion enzymes) expressed cytotoxicity activity, there was limited evidence of direct toxicity of the films. The findings of the study demonstrate the potential for PEF modified zein-chitosan-poly(vinyl alcohol) films as value-added biomaterials for the application in edible food packaging.

Subacute feeding toxicity of low-sodium sausages manufactured with sodium substitutes and biopolymer-encapsulated saltwort (Salicornia herbacea) in a mouse model.

BACKGROUND: Low-sodium sausages were manufactured using sodium substitution and biopolymer encapsulation. A diet comprising 10% treatment sausages (six treatment groups: C (100% NaCl), T1 (55% sodium substitute + 45% saltwort salt), T2 (55% sodium substitute + 45% saltwort salt with chitosan), T3 (55% sodium substitute + 45% saltwort salt with cellulose), T4 (55% sodium substitute + 45% saltwort salt with dextrin), and T5 (55% sodium substitute + 45% saltwort salt with pectin)) was added to a 90% commercial mouse diet for 4 weeks. RESULTS: Subacute toxicity, hematology, liver function, and organ weight tests in low-sodium sausage groups showed results similar to those of the control group, and all toxicity test levels were within normal ranges. CONCLUSIONS: All low-sodium sausage types tested are suggested to be safe in terms of subacute toxicity. Moreover, low-sodium sausages can be manufactured by biopolymer encapsulation of saltwort using pectin, chitosan, cellulose, and dextrin without toxicity. © 2019 Society of Chemical Industry.

Probing the Origin of the Toxicity of Oligomeric Aggregates of α-Synuclein with Antibodies.

The aggregation of α-synuclein, a protein involved in neurotransmitter release at presynaptic terminals, is associated with a range of highly debilitating neurodegenerative conditions, most notably Parkinson's disease. Intraneuronal inclusion bodies, primarily composed of α-synuclein fibrils, are the major histopathological hallmarks of these disorders, although small oligomeric assemblies are believed to play a crucial role in neuronal impairment. We have probed the mechanism of neurotoxicity of α-synuclein oligomers isolated in vitro using antibodies targeting the N-terminal region of the protein and found that the presence of the antibody resulted in a substantial reduction of the damage induced by the aggregates when incubated with primary cortical neurons and neuroblastoma cells. We observed a similar behavior in vivo using a strain of C. elegans overexpressing α-synuclein, where the aggregation process itself is also partially inhibited as a result of incubation with the antibodies. The similar effects of the antibodies in reducing the toxicity of the aggregated species formed in vitro and in vivo provide evidence for a common origin of cellular impairment induced by α-synuclein aggregates.

Extracellular biopolymers produced by Dictyosphaerium family - Chemical and immunomodulative properties.

Many microalgal species produce a wide range of highly-value products which are interesting for biotechnological applications. Cultivation of microalgal species Dictyosphaerium pulchellum and Dictyosphaerium tetrachotomum, strains Ruzicka and Fott resulted yields of 0.2, 0.7 and 1.8 g/L of extracellular biopolymers (EPSs), respectively. All biopolymers were shown to be anionic proteoglycans. The sugar composition analyses of all EPSs showed high contents of hexoses and the presence of partially methylated monosaccharide residues, i.e. hexoses, and deoxy hexoses. The dominant sugar component of all EPSs was found to be galactose. Extracellular microalgal biopolymers were subjected to immunobiological and immunotoxicological evaluation using murine melanoma cancer cells B16, murine fibroblast cell line NIH-3T3, murine macrophages cell line RAW 264.7 and skin construct EpiDerm™ (EPI-200). The EPSs exerted the antiproliferative effectivity; treatment of EPS induced proinflammatory cytokines TNF-α, IL-6, IL-12, IL-1ß and IL-17, also engaged in anti-cancer immunity. Immunotoxicological studies revealed their non-toxic character and safe application on EpiDerm™.

Sustainable Production of Fine Chemicals and Materials Using Nontoxic Renewable Sources.

Due to declining hydrocarbon resources and strengthening environmental regulations, significant attention is directed toward sustainable and nontoxic supplies for the development of green technologies in a variety of industries. This account provides an overview on the sources and recent applications of such materials surveying the most common nontoxic and renewable resources that can be obtained from biological sources. Developing a broad array of technologies based on these materials would establish a truly sustainable green chemical industry. The study thematically discusses various compound groups, eg, carbohydrates, proteins, and triglycerides (oils). Since often the monomers or building blocks of these biopolymers are of significant importance and produced in large amounts, the applications of these compounds are also reviewed.

Characterization and toxicity of a phosphate-binding exobiopolymer produced by Acinetobacter haemolyticus MG606.

A novel, phosphate-binding exobiopolymer (EBP) produced by Acinetobacter haemolyticus MG606 was characterized and its biocompatibility evaluated in RAW 264.7 cells and in mice. EBP was identified as a 50 kDa heteropolysaccharide composed of pentose and hexose sugars. EBP exhibited cytotoxicity, stimulation of free radical production and loss of mitochondrial and lysosomal integrity in RAW 264.7 cells at 500 µg/mL concentration while lower concentrations exhibited no significant (p > 0.05) effect on these parameters. EBP exhibited dose-dependent mortality, body weight reduction, hypothermia and clinical signs of toxicity in mice following intraperitoneal administration. The LD50 of EBP was determined to be 92.31 mg/kg. Overall, the results of our study suggest that composition of EBP produced by A. haemolyticus MG606 is distinct from EBP produced by other Acinetobacter spp. The high biocompatibility supports application of EBP as a safe biosorbent for phosphate remediation.

Safety Assessment of Microbial Polysaccharide Gums as Used in Cosmetics.

The Cosmetic Ingredient Review Expert Panel assessed the safety of 34 microbial polysaccharide gums for use in cosmetics, finding that these ingredients are safe in cosmetic formulations in the present practices of use and concentration. The microbial polysaccharide gums named in this report have a variety of reported functions in cosmetics, including emulsion stabilizer, film former, binder, viscosity-increasing agent, and skin-conditioning agent. The Panel reviewed available animal and clinical data in making its determination of safety.

Geotextile composition, application and ecotoxicology-A review.

Geosynthetics is the umbrella term for thin, flexible material sheets applied in civil and environmental engineering, of which geotextiles form the largest group. Most geotextiles consist of a polymer from the polyolefin, polyester or polyamide family, and additives to improve their stability. The polymer may degrade into microplastic particles over time and under various conditions and can cause adverse effects, as species may ingest these particles or encounter adverse effects due to the interference of the particles with e.g. their photosynthesis system in the case of algae. Leaching of additives may occur from the intact material, as they are often not covalently bound to the polymer backbone, but is greatly enhanced when micro-sized plastic particles have been formed. A total of 42 polymer additives were identified, of which 26 had ecotoxicity information available in terms of a REACH persistence, toxicity and bioaccumulation (PBT) assessment. Of these, 15 were classified as (very) persistent and 2 as toxic. A survey to assess potential toxicity of the remaining 16 substances revealed that no ecotoxicity studies had been performed on 13 of these compounds. For 3 compounds, other toxicity data was found, as well as of several chemical groups known to be used as additives in geotextiles. The current knowledge is thus lacking in two domains: on the one hand, ecotoxicity data is scarce as many substances have not yet been the subject of ecotoxicological studies. On the other hand, in situ toxic effects might be missed by the current approach of single compound toxicity testing. Moreover, environmental occurrence data of the additives are extremely scarce.

Extracellular Polymeric Substances of Aphanizomenon flos-aquae (EPS-A) Induced Apoptosis in Astrocytes of Zebrafish.

In this study, extracellular polymeric substances of Aphanizomenon flos-aquae (EPS-A) were investigated in order to explore their effect on astrocytes of zebrafish and potential risk for environment. Astrocytes were treated with varying concentrations of EPS-A, the results showed that EPS-A inhibited astrocytes growth in a dose-and time-dependent manner. With the concentrations of EPS-A increasing, the adherent ability of astrocytes decreased and the number of astrocytes floating in the culture medium increased. When treated with 2.35 µg/mL EPS-A, EPS-A induced cell cycle arrest and made the collapse of mitochondrial membrane potential and then led to astrocytes apoptosis. The results suggested that EPS-A could pose a threat to zebrafish and represent risk for environment, so regularly monitoring the presence of EPS-A was very important in nutrient-rich freshwaters when A. flos-aquae blooms broke out.

Antimicrobial efficacy and in vivo toxicity studies of a quaternized biopolymeric flocculant.

This study evaluated the antibacterial spectrum and safety of a chemically modified biopolymeric flocculant (TMB) against waterborne pathogens. The biopolymer previously characterized as polysaccharide with flocculating activity is produced extracellularly by the bacterium Klebsiella terrigena. The amino sugars on the polymer were chemically modified by quaternization, which resulted in N,N,N trimethyl biopolymer (TMB). Quaternization was effective in imparting biocidal activity to TMB against five selected waterborne pathogens, namely, Aeromonas hydrophila, Yersinia enterocolitica, Salmonella typhimurium, Listeria monocytogenes and Escherichia coli O157:H7. 99.999% inactivation was achieved with S. typhimurium at a dose of 60 µg ml(-1) of TMB within 60 min at the ambient temperature, followed by other pathogens. Haemotological, histopathological and general examinations indicated no adverse effects in Swiss albino mice fed with the quaternized biopolymer (120 mg kg(-1) body weight(-1) day(-1)) over a period of 30 days. These results suggested that TMB was tolerated well without any signs of toxicity and may have potential application as a safe, antimicrobial bioflocculant for both removing and inactivating waterborne pathogens.

Synthesis, colloidal properties and cytotoxicity of biopolymer nanoparticles.

To characterize the physicochemical and biological stability of nanodevices suitable for biomedical applications, polylactic acid (PLA) nanoparticles (NPs) of 112 ± 6 nm and polyhydroxy butyrate (PHB) of 15 ± 5 nm size were prepared by standardizing the suitable method for each. Morphology of NPs was studied by scanning and transmission electron microscopy and temperature stability by thermogravimetric analysis. Their stability in biological fluids (simulated gastrointestinal and saliva) and tolerance against 0.5 mM NaCl were analyzed. PHB NPs remained stable in all fluids, while after 24 h treatment, the PLA NPs showed the beginning of disintegration with intestinal fluid mimic. In addition to the preparation of polyethylene glycol (PEG) surface-coated NPs, PLA-PEG-PLA triblock copolymer (MW ∼ 7,366 Da) was also chemically synthesized and characterized. Cytotoxicity of all forms of nanoparticles was tested by MTT assay and by annexin pi staining.

How epigallocatechin gallate can inhibit α-synuclein oligomer toxicity in vitro.

Oligomeric species of various proteins are linked to the pathogenesis of different neurodegenerative disorders. Consequently, there is intense focus on the discovery of novel inhibitors, e.g. small molecules and antibodies, to inhibit the formation and block the toxicity of oligomers. In Parkinson disease, the protein α-synuclein (αSN) forms cytotoxic oligomers. The flavonoid epigallocatechin gallate (EGCG) has previously been shown to redirect the aggregation of αSN monomers and remodel αSN amyloid fibrils into disordered oligomers. Here, we dissect EGCG's mechanism of action. EGCG inhibits the ability of preformed oligomers to permeabilize vesicles and induce cytotoxicity in a rat brain cell line. However, EGCG does not affect oligomer size distribution or secondary structure. Rather, EGCG immobilizes the C-terminal region and moderately reduces the degree of binding of oligomers to membranes. We interpret our data to mean that the oligomer acts by destabilizing the membrane rather than by direct pore formation. This suggests that reduction (but not complete abolition) of the membrane affinity of the oligomer is sufficient to prevent cytotoxicity.

Development of a biopolymer nanoparticle-based method of oral toxicity testing in aquatic invertebrates.

Aquatic toxicity testing generally focuses on the water absorption/dermal route of exposure to potential toxic chemicals, while much less work has been done on the oral route of exposure. This is due in part to the difficulties of applying traditional oral toxicity testing to aquatic environments, including the tendency for test chemicals to dissolve into water. The use of biopolymer nanoparticles to encapsulate test chemicals onto food to prevent dissolution is one solution presented herein. The biopolymers zein and chitosan were explored for their previously known nanoparticle-forming abilities. Nanoparticles containing the test chemical rhodamine B were formed, applied as films to coat food, and then fed to the test organism, the freshwater amphipod Hyalella azteca. In feeding trials both zein and chitosan nanoparticles showed a significantly lower release rate of rhodamine B into water than food dyed with rhodamine B without biopolymer nanoparticles. Zein nanoparticles also showed better retention ability than chitosan nanoparticles. Both kinds of nanoparticles showed no significant effect on the survival, growth, or feeding behavior of H. azteca. Thus these biopolymers may be an effective system to encapsulate and deliver chemicals to aquatic invertebrates without interfering with common toxicity assessment endpoints like survival and growth.

Protective effect of leptin and ghrelin against toxicity induced by amyloid-ß oligomers in a hypothalamic cell line.

In addition to cognitive decline, Alzheimer's disease (AD) patients also exhibit an unexplained weight loss that correlates with disease progression. In young and middle-aged AD patients, large amounts of amyloid-ß (Aß) deposits were observed in the hypothalamus, a brain region involved in the control of feeding and body weight through the action of peripheral metabolic peptides, which have recently been shown to have neuroprotective effects. Moreover, levels of peripheral metabolic peptides, such as leptin and ghrelin, are changed in AD patients. The present study aimed to investigate the role of Aß peptide in the survival of hypothalamic cells and to explore the receptor-mediated protective effect of leptin and ghrelin against Aß-induced toxicity in these cells. Using the mHypoE-N42 cell line, we demonstrated for the first time that oligomeric Aß is toxic to hypothalamic cells, leading to cell death. It was also demonstrated that leptin and ghrelin protect these cells against AßO-induced cell death through the activation of the leptin and ghrelin receptors, respectively. Furthermore, ghrelin and leptin prevented superoxide production, calcium rise and mitochondrial dysfunction triggered by AßO. Taken together, these results suggest that peripheral metabolic peptides, in particular leptin and ghrelin, might be considered as preventive strategies for ameliorating hypothalamic alterations in AD.

Therapeutic approaches against common structural features of toxic oligomers shared by multiple amyloidogenic proteins.

Impaired proteostasis is one of the main features of all amyloid diseases, which are associated with the formation of insoluble aggregates from amyloidogenic proteins. The aggregation process can be caused by overproduction or poor clearance of these proteins. However, numerous reports suggest that amyloid oligomers are the most toxic species, rather than insoluble fibrillar material, in Alzheimer's, Parkinson's, and Prion diseases, among others. Although the exact protein that aggregates varies between amyloid disorders, they all share common structural features that can be used as therapeutic targets. In this review, we focus on therapeutic approaches against shared features of toxic oligomeric structures and future directions.

Combining two technologies: multifunctional polymers and self-nanoemulsifying drug delivery system (SNEDDS) for oral insulin administration.

The aim of the study is to develop a self-nanoemulsifying drug delivery system (SNEDDS) based on thiolated chitosan for oral insulin administration. The preparations were characterized by particle size, entrapment efficiency, stability and drug release. Serum insulin concentrations were determined after oral administration of all formulations. Insulin SNEDDS formulation was served as control. The optimized SNEDDS consists of 65% (w/w) miglyol 840, 25% (w/w) cremophor EL, 10% (w/w) co-solvents (a mixture of DMSO and glycerol). The formulations in the presence or absence of insulin (5mg/mL) were spherical with the size range between 80 and 160 nm. Entrapment efficiency of insulin increased significantly when the thiolated chitosan was employed (95.14±2.96%), in comparison to the insulin SNEDDS (80.38±1.22%). After 30 min, the in vitro release profile of insulin from the nanoemulsions was markedly increased compared to the control. In vivo results showed that insulin/thiolated chitosan SNEDDS displayed a significant increase in serum insulin (p-value=0.02) compared to oral insulin solution. A new strategy to combine SNEDDS and thiolated chitosan described in the study would therefore be a promising and innovative approach to improve oral bioavailability of insulin.

Autophagy master regulator TFEB induces clearance of toxic SERPINA1/α-1-antitrypsin polymers.

Deficiency of SERPINA1/AAT [serpin peptidase inhibitor, clade A (α-1 antiproteinase, antitrypsin), member 1/α 1-antitrypsin] results in polymerization and aggregation of mutant SERPINA1 molecules in the endoplasmic reticulum of hepatocytes, triggering liver injury. SERPINA1 deficiency is the most common genetic cause of hepatic disease in children and is frequently responsible for chronic liver disease in adults. Liver transplantation is currently the only available treatment for the severe form of the disease. We found that liver-directed gene transfer of transcription factor EB (TFEB), a master regulator of autophagy and lysosomal biogenesis, results in marked reduction of toxic mutant SERPINA1 polymer, apoptosis and fibrosis in the liver of a mouse model of SERPINA1 deficiency. TFEB-mediated correction of hepatic disease is dependent upon increased degradation of SERPINA1 polymer in autolysosomes and decreased expression of SERPINA1 monomer. In conclusion, TFEB gene transfer is a novel strategy for treatment of liver disease in SERPINA1 deficiency. Moreover, this study suggests that TFEB-mediated cellular clearance may have broad applications for therapy of human disorders due to intracellular accumulation of toxic proteins.

Macroporous structures based on biodegradable polymers--candidates for biomedical application.

New hybrid cryogels comprising natural polymers (free atelocollagen or atelocollagen mixed with a hyaluronic acid derivative) and a synthetic polyester--poly(ε-caprolactone)--were successfully developed by a cryogenic treatment and a subsequent freeze-drying step. Systematic studies on the effect of preparation conditions (reaction mixture composition, total concentration of the feed dispersion, and freezing regime) on cryogelation efficiency were conducted. The degree of cross-linking and the morphology of the obtained materials were analyzed using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and (environmental) scanning electron microscopy (ESEM/SEM) techniques. Considering their possible biomedical application, the developed macroporous hydrogels were also investigated in terms of swelling behavior and hemo/biocompatibility. The produced hydrogels had an uniform interconnected open porous structure with a porosity of up to 95% and pores size in the range of 83-260 µm. All obtained cryogels were elastic, mechanically stable, with a superfast swelling kinetics. In vitro hemocompatibility assay gave hemolysis ratios (HRs) lower than 0.5%, which is below the permissible limit of 5%. The in vivo tolerance tests performed by implantation of cryogel specimens into Wistar rats proved their biocompatibility.