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There is mounting evidence that plastic and microplastic contamination of soils can affect physico-chemical processes and soil fauna, as has been excellently summarised in many recently published meta-analyses and systematic reviews elsewhere. It has become clear that impacts are highly context dependent on, e.g. polymer type, shape, dose and the soil itself. Most published studies are based on experimental approaches using (semi-)controlled laboratory conditions. They typically focus on one or several representative animal species and their behaviour and/or physiological response — for example, earthworms, but rarely on whole communities of animals. Nevertheless, soil animals are rarely found in isolation and form part of intricate foodwebs. Soil faunal biodiversity is complex, and species diversity and interactions within the soil are very challenging to unravel, which may explain why there is still a dearth of information on this. Research needs to focus on soil animals from a holistic viewpoint, moving away from studies on animals in isolation and consider different trophic levels including their interactions. Furthermore, as evidence obtained from laboratory studies is complemented by relatively few studies done in field conditions, more research is needed to fully understand the mechanisms by which plastic pollution affects soil animals under realistic field conditions. However, field-based studies are typically more challenging logistically, requiring relatively large research teams, ideally of an interdisciplinary nature to maintain long-term field experiments. Lastly, with more alternative, (bio)degradable and/or compostable plastics being developed and used, their effects on soil animals will need to be further researched.

Plastic is exceedingly abundant in soils, but little is known about its ecological consequences for soil microbiome functioning. Here we report the impacts of polyethylene and biodegradable Ecovio and BI-OPL plastic films buried in alpine soils for 5 months on the genetic potential of the soil microbiome using shotgun metagenomics. The microbiome was more affected by Ecovio and BI-OPL than by polyethylene. Fungi, α- and β-Proteobacteria dominated on the biodegradable films. Ecovio and BI-OPL showed signs of degradation after the incubation, whereas polyethylene did not. Genes involved in cellular processes and signaling (intracellular trafficking, secretion, vesicular transport), as well as metabolism (carbohydrate, lipid and secondary metabolism), were enriched in the plastisphere. Several α/β-hydrolase gene families (cutinase_like, polyesterase-lipase-cutinase, carboxylesterase), which encode enzymes essential to plastic degradation, and carbohydrate-active genes involved in lignin and murein degradation increased on Ecovio and BI-OPL films. Enriched nitrogen fixation and organic N degradation and synthesis genes and decreased nitrification genes on Ecovio altered the biogeochemical cycling, leading to higher ammonium concentrations and depletion of nitrite and nitrate in the soil. Our results indicate that plastics affect the alpine soil microbiome and its functions and suggest that the plastisphere has an untapped microbial potential for plastic biodegradation., Journal of Hazardous Materials, 441, ISSN:0304-3894, ISSN:1873-3336

Chitin-based nanoparticles are polysaccharide materials that can be produced from a waste stream of the seafood industry: crustacean shells. These nanoparticles have received exponentially growing attention, especially in the field of medicine and agriculture owing to their renewable origin, biodegradability, facile modification, and functionality adjustment. Due to their exceptional mechanical strength and high surface area, chitin-based nanoparticles are ideal candidates for reinforcing biodegradable plastics to ultimately replace traditional plastics. This review discusses the preparation methods for chitin-based nanoparticles and their applications. Special focus is on biodegradable plastics for food packaging making use of the features that can be created by the chitin-based nanoparticles.

In this study, the optimisation of a process for producing medium-chain-length polyhydroxyalkanoate (mcl-PHA) by Pseudomonas putida KT2440 when fed with a polyethene (PE)-derived fatty acid mixture was investigated. The PE was pyrolysed to produce a hydrocarbon wax that was subsequently oxidised to produce a mixture of fatty acids, purified, and used as a PHA substrate for the growth and selection of microorganisms. Based on the shaken flask screening, a production strain, i.e., Pseudomonas putida KT2440, was selected for conducting bioreactor studies. Feeding PE-derived fatty acids in a 20-L setup resulted in high mcl-PHA yields (83.0 g L−1 CDW with 65% PHA in 25 h). Furthermore, life-cycle assessment (LCA) was conducted to determine the environmental advantages of the proposed process and its impacts compared to those of other technologies for treating PE-derived waste streams. We conclude that processing waste PE into PHA, rather than incineration, produces biodegradable material while also reducing the additional emissions that arise from traditional PE waste treatment processes, such as incineration to gain energy.

Biodegradable plastics are contributing to a circular economy as enabler for organic waste recycling to close the nutrient loop. A polymer is designated as biodegradable if microbial oxidation and hydrolysis processes result in the complete transformation of polymer carbon into biomass and CO2. Still, there are concerns that the loss of structural integrity during biodegradation might produce persistent microplastic fragments. Biodegradable plastics are often blends whose components could show different abilities to degrade, e.g. due to inhomogeneity in the chemical structure, crystallinity and the microbial colonization. Specifically, the blend of polylactide (PLA, susceptible to hydrolysis) with aliphatic-aromatic ester copolymers (e.g. PBAT, suceptible to enzymatic cleavage) is relevant for food packaging, which can be collected and composted. The various product shapes can also lead to a change in fragmentation and degradation behaviour. To gain a mechanistic understanding of copolymer blend biodegradation we studied an aromatic-aliphatic copolymer blend in different shapes (cryomilled particles, films and polymer-coated paper cups) under industrial composting conditions, and compared them against the non-blended polymer matrix. During biodegradation (ISO 14855), CO2 evolution was monitored. Using a non-destructive and efficient extraction protocol, the particle number and size distribution, and the state of copolymer degradation were assessed via fluorescence microscopy and chemically selective Raman microscopy. Staining selectivity was additionally cross-checked by an independent incubation of pre-labeled films and fragments. Biodegradation of the polymer blend led first to fragmentation, but the previously formed fragments further degraded to complete biomineralization. The interim number of fragments per composted polymer ranked highest for film shape, lower for fragment shape, and two orders of magnitude lower for film-coated paper cups. Intermittently, up to 0.0012% of the mass of polymer was in fragments below 25 µm, but less than 10⁽-10) at 90% CO2. Fragment counts dissipated with 2.5 days halftime for the realistic film shape. Also see: https://micro2022.sciencesconf.org/426019/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

With the increasingly serious pollution of plastics, biodegradable plastics (BDPs) have attracted attention as a new material that can replace conventional plastics in certain applications. The global production of BDPs also gradually increases in recent years. However, unfortunately, with the application of BDPs, some potential problems are gradually exposed. The biodegradability of BDPs needs suitable conditions, which is difficult for the natural environment to reach the necessary conditions. If the degradation conditions are not met, BDPs and conventional plastics are basically the same in terms of the longevity. The biodegradable microplastics (BMPs) can also be formed by BDPs entering the environment. Up to now, the research on the degradation and application of BDPs is relatively common. The environmental and ecological effects of the BMPs, the adsorption and release of toxic substances, and the role of BMPs as vectors of microorganisms, epiphytes, and plants still need to be studied. This paper focuses on the formation mechanism and the environmental behavior of BMPs. The role of BMPs as multiple stronger vectors of microorganisms and pollutants compared to conventional microplastics is also discussed. Systematic research on environmental pollution and ecotoxicology of BMPs should be carried out as soon as possible.

Finding alternatives to diminish plastic pollution has become one of the main challenges of modern life. A few alternatives have gained potential for a shift toward a more circular and sustainable relationship with plastics. Biodegradable polymers derived from bio- and fossil-based sources have emerged as one feasible alternative to overcome inconveniences associated with the use and disposal of non-biodegradable polymers. The biodegradation process depends on the environment’s factors, microorganisms and associated enzymes, and the polymer properties, resulting in a plethora of parameters that create a complex process whereby biodegradation times and rates can vary immensely. This review aims to provide a background and a comprehensive, systematic, and critical overview of this complex process with a special focus on the mesophilic range. Activity toward depolymerization by extracellular enzymes, biofilm effect on the dynamic of the degradation process, CO2 evolution evaluating the extent of biodegradation, and metabolic pathways are discussed. Remarks and perspectives for potential future research are provided with a focus on the current knowledge gaps if the goal is to minimize the persistence of plastics across environments. Innovative approaches such as the addition of specific compounds to trigger depolymerization under particular conditions, biostimulation, bioaugmentation, and the addition of natural and/or modified enzymes are state-of-the-art methods that need faster development. Furthermore, methods must be connected to standards and techniques that fully track the biodegradation process. More transdisciplinary research within areas of polymer chemistry/processing and microbiology/biochemistry is needed.

Microplastics (MPs) have been widely distributed on Earth and have drawn global concern for freshwater and marine ecosystems. Biodegradable plastics have risen in popularity to replace nonbiodegradable plastics all over the world. The effects of biodegradable plastics on denitrifying and anammox bacteria in freshwater sediment remain largely unknown. In this study, water column reactors containing polylactic acid (PLA) or polybutylene adipate-co-terephthalate (PBAT) MPs in sediment were established to simulate lake ecosystems and analyze the effects of biodegradable MPs on sedimentary nitrogen transformation microorganisms. The total organic carbon (TOC) concentrations in the PLA and PBAT groups were slightly higher than those in the control group, which might be related to the slow degradation of these two plastics. Denitrifying and anammox bacterial diversities decreased after adding MPs to sediments for 30 days, and the dominant OTUs of these two bacteria were differentiated from the control. The abundance levels of nirS denitrifying and anammox bacteria on the PLA MP surface were significantly higher than those in the other groups (P 0.05), but they were lower in the PBAT groups than in the other groups. As an excellent electron donor for the denitrification process, lactic acid release from PLA degradation resulted in the enrichment of denitrifying and anammox bacteria on the MP surfaces. However, PBAT led to various responses of bacteria in an anaerobic environment. In addition, the redundancy analysis results indicated that total phosphorus, TOC and nitrate were strongly negatively correlated with the abundance levels of denitrifying and anammox bacteria. Our findings provided insight into the effects of MPs, especially the biodegradable ones, on sedimentary nitrogen-transformation bacteria.

Biodegradable plastic mulch film (BDM) is an environmentally friendly alternative to conventional polyethylene mulch, and has been growingly used in agriculture. However, practical degradation performance of BDM, especially the widely used type of blended polylactic acid (PLA)/polybutylene adipate (PBAT) in different ratios, and microbial alteration in soil environments, remain largely unrevealed. In this study, four types of BDM blended with 40-80% PLA and 20-60% PBAT were comparatively investigated through microcosm soil incubation experiments for 105 days, and combined with conditions of different soil moisture or pH. Microbiome within film-surrounding soil were assayed using 16 S rRNA high-throughput sequencing. Results showed a trend of increasing degradation efficiency with the increase of PLA proportion, and 70% PLA and 30% PBAT group presented the highest weight loss rate, i.e., 60.16 ± 5.86%. In addition, degradation and aging of PLA/PBAT varied among different soil moisture and pH values. A moderate moisture, i.e., 60% and a neutral pH7.0 caused significantly high degradation efficiency compared to other moisture or pH conditions. Moreover, bacterial abundance and community structure in the surrounding soil were related to soil moisture and pH. PLA/PBAT incubation treatment induced a remarkable increase in abundance of degradation-related species Pseudomonas and Sphingomonas. Bacterial richness and diversity in soil correspondingly respond to ratio-different PLA/PBAT's degradation under moisture/pH-different conditions through a redundancy analysis. Altogether, these findings indicate that practical degradation of PLA/PBAT film is closely related to soil environments and bacterial community. It is significant for the application of biodegradable plastics in agriculture on the perspective of soil sustainability.

Crop safety Biodegradable mulches (BDM) are increasingly valued and used for substituting non-biodegradable plastic mulches polluting agricultural soils. They are tilled into soil, where they fragment and release compounds throughout their bio- degradation. The consequences of BDM use on the plant-soil environment have been partially studied with pristine and with artificially-weathered BDM fragments. However, to guarantee safety use of BDM, studies on the BDM debris ef- fects are required. For this, to determine potential effects of the field-weathering BDM on plants, a mesocosm experi- ment was performed by sowing seeds from two major plant species commonly cultivated with BDM, tomato (Lycopersicon esculentum) and lettuce (Lactuca sativa), in plant pots containing pristine and field-weathered pieces from seven different BDM formulations, one paper mulch, a polyethylene (PE) mulch, and no-mulch control pots. Germination of both plant species was unaffected by any of the mulch treatments; however, PHB (polyhydroxybutyrate)-based BDM fragments severely inhibited tomato and lettuce plant growth, 90 and 95 %, respec- tively. Moreover, all pristine and field-weathered BDM significantly delayed lettuce plant development. Tomato plant growth progressed better, but growth retardation was also evidenced with most field-weathered BDM treatments. Overall, field-weathered fragments caused stronger effects on plants than the pristine unused ones. No effects were found for PE mulch, either pristine or field-weathered. The obtained results highlight that BDM debris may alter plant development depending on their nature and on their weathering, rather than on their physical presence, and ev- idence the need to conduct further experiments on the impact of field-weathered BDM on the plant-soil environment. Financial support from the University of Lleida Grant Program and from the Spanish Ministry of Science and Innovation, RTA2015-00047-C05-05 project, is gratefully acknowledged.

Bioplastics (biodegradable plastics) potentially offer an encouraging alternative to conventional (petroleum-based) plastics. In practice, bioplastics inevitably generate a large number of bio-microplastics (bio-MPs, diameter5 mm) during the degradation progress. However, the impact of bio-MPs on plant and soil health within agroecosystems remains incomplete. Here, a field study was conducted to investigate the effect of two shapes (fiber and powder) of pure polylactic acid (PLA) bio-MPs on oat (Avena sativa L.) and soybean (Glycinemax (L.) Merr.) growth and soil health. Our results showed that PLA application at a representative soil loading rate of 0.2% (w/w) had no significant effect on soil enzyme activities, soil physicochemical properties (soil water content, pH, etc.), root characteristics, plant biomass, and crop yield. Thus, we conclude that soil quality, plant health, and ecosystem multifunctionality were not affected by PLA over one growing season (5 months) in the presence of either bio-MP shape (fiber and powder) for either crop species (oat and soybean). Overall, PLA based bio-MPs may not pose a significant threat to agroecosystem functions in the short term (days to months) in the field, thus may provide a viable environmentally benign solution to replace traditional non-biodegradable plastics in agroecosystems.

We present an approach to fabricate biological matrix composites made entirely from cultured plant cells. We utilize the cell’s innate ability to synthesize nanofibrillar cell walls, which serve as the composite’s fundamental building blocks. Following a controlled compression/dehydration process, the cells arrange into lamellar structures with hierarchical features. We demonstrate that the native cell wall nanofibrils tether adjacent cells together through fibrillar interlocking and intermolecular hydrogen bonding. These interactions facilitate intercellular adhesion and eliminate the need for other binders. Our fabrication process utilizes the entire plant cell, grown in an in vitro culture; requires no harsh chemical treatments or waste-generating extraction or selection processes; and leads to bulk biocomposites that can be produced in situ and biodegrade in soil. The final mechanical properties are comparable to commodity plastics and can be further modulated by introducing filler particles.

Background This work evaluated the performances of protein-based bioplastics obtained from black soldier fly (Hermetia illucens) prepupae. Protein films were synthesized by film casting, using both the whole proteins and their soluble fraction at pH = 10. The effects of glycerol as a plasticizer and of citric acid as a mild crosslinker on film properties were also evaluated. Results Films obtained using the soluble protein fraction were the strongest, as well as the most homogeneous and transparent ones. Protein mild crosslinking improved film tensile properties, especially in films obtained with the whole protein fraction. Non-crosslinked samples had a high affinity with water while crosslinking almost eliminated the ability of films to absorb water. All protein-based films proved to be effective barriers to red light (transmittance less than 2%). Conclusions Bioplastics derived from black soldier fly prepupae may find applications in the agricultural sector (biodegradable pots, mulching films, utensils) and deserve to be tested for food and non-food packaging. © 2021 Society of Chemical Industry.

As plastic consumption has increased, environmental problems associated with the accumulation of plastic wastes have started to emerge. These include the non-degradability of plastic and its disintegration into sub-micron particles. Although some biodegradable plastic products have been developed to relieve the landfill and leakage burden, a significant portion of discarded plastics are inevitably still incinerated. The concern here is that incinerating plastics may result in the emission of toxic volatile organic compounds (VOCs). Moreover, lack of policy and the limited market share contributes to the indiscriminate discarding of biodegradable plastics, whereby it is mixed and subsequently incinerated with non-degradable plastics. The aim of this study was therefore to qualitatively and quantitatively analyze the VOCs emitted from both non-degradable and biodegradable plastics during combustion employing gas chromatography mass spectrometry. Here, non-degradable poly(vinyl chloride) and poly(ethylene terephthalate) emitted 10-115 and 6-22 ppmv of VOCs, respectively. These emission levels were more than 100 times higher than the VOC concentrations of 0.1-0.5 and 0.1-1.8 ppmv obtained for biodegradable polyhydroxyalkanoate and polylactic acid, respectively. Notably, due to the presence of a repeating butylene group in both non-degradable and biodegradable plastics, 1,3-butadiene accounted for the highest concentration among the VOCs identified, with concentrations of 6-116 ppmv and 0.5-558 ppmv obtained, respectively. During the evaluation of gas barrier films employed for food packaging purposes, non-degradable aluminum-coated multilayered films emitted 9-515 ppmv of VOCs, compared to the 2-41 ppmv VOCs emitted by biodegradable nanocellulose/nanochitin-coated films. Despite the significantly lower levels of VOCs emitted during the incineration of biodegradable plastics, this does not represent suitable waste treatment solution because VOCs are still emitted during incomplete combustion. This study aims to encourage further research into diverse combustion conditions for plastics and stimulate discussions on the fate of discarded plastics.

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUG Attribution-NonCommercial-NoDerivatives 4.0 International Due to environmental persistence, lack of a proper land-based waste management, and global circulation, marine ecosystems are especially threatened by plastics. The search for alternatives to conventional oil-based polymers gave rise to novel materials commercialized under different “green” labels based on compostability. However, current international standards are not effective in predicting actual biodegradability of plastic objects in natural scenarios, and degradation of these novel bioplastics in marine conditions is unwarranted. We present a simple and rapid standard protocol based on their biological oxygen demand, intended to support policy-makers and plastic industry in the search for truly marine-biodegradable plastics. Improvements include: development of an environmentally relevant nutrient formulation following Redfield ratio (106C:16 N:1P); use of a natural inoculum representative of marine habitats (sediment pore water); standardization of the test material by grinding to particles below 250 μm to shorten the incubation period, and selection of a truly biodegradable biopolymer (PHB), used as positive control. This protocol was successfully applied to show that commercial compostable plastics are not biodegradable in marine environments. Agencia Estatal de Investigación | Ref. PCI2020-112110 Ministerio de Universidades | Ref. FPU19/02280

Conventional plastics are being slowly replaced by biodegradable ones to prevent plastic pollution. However, in the natural environment, the biodegradation of plastics is usually slow or incomplete due to unfavorable conditions and leads to faster micro-bioplastic formation. Many analytical methods were developed to determine microplastics, but micro-bioplastics are still overlooked. This work presents a simple method for determining poly-3-hydroxybutyrate and polylactic acid micro-bioplastics in soil based on the thermogravimetry–mass spectrometry analysis of low molecular gases evolved during pyrolysis. For the method development, model soils containing different soil organic carbon contents were spiked with micro-bioplastics. Specific gaseous pyrolysis products of the analytes were identified, while the ratio of their amounts appeared to be constant above the level of detection of the suggested method. The constant ratio was explained as a lower soil influence on the evolution of the gaseous product, and it was suggested as an additional identification parameter. The advantages of the presented method are no sample pretreatment, presumably no need for an internal standard, low temperature needed for the transfer of gaseous products and the possibility of using its principles with other, cheaper detectors. The method can find application in the verification of biodegradation tests and in the monitoring of soils after the application of biodegradable products.

Four types of biodegradable plastics were evaluated for their biodegradability in seawater collected at Ajigaura coast, Japan, in the presence or absence of marine sand. One of the plastics, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), showed a degree of biodegradation in a seawater sample, and the addition of marine sand markedly accelerated its biodegradation. The addition of marine sand did not affect the bacterial composition of the biofilm that formed on PHBH, and the family Rhodobacteraceae, which was predicted to contribute to the degradation of PHBH, was dominant in biofilm communities regardless of the addition of marine sand. Marine sand may serve as a bacterial source, resulting in the accelerated degradation of PHBH.

[eng] Rapid population growth is leading to many environmental problems, among which a large waste generation should be highlighted. More than 40% of these wastes correspond to organic wastes that are mainly treated by composting, anaerobic digestion, incineration, or even landfilled. Hence, it is important to implement new treatment strategies within the circular economy concept transforming organic waste treatment plants into biorefineries. In this way, acidogenic fermentation emerges as a key technology to valorise these substrates producing high value- added products such as volatile fatty acids (VFAs), that could be further transformed into bioplastics (i.e., polyhydroxyalkanoates or PHA). Consequently, acidogenic fermentation and co-fermentation of waste activated sludge (WAS) and food waste (FW) were studied to achieve a VFA-rich effluent for its subsequent conversion into PHA. The pH effect on the acidogenic fermentation of FW was studied in batch mode (pH range from 4 to 11) and in semi-continuous fermenters working under acidic (6) and alkaline pH (9.5-10). Batch tests revealed that pH between 6-9 could lead to a higher VFA production, with a higher acetic acid content when pH increased within this range. In the semi-continuous fermenters, a maximum VFAs yield of 503.1 mgCOD/gVS was obtained when working at pH 6 with acetic, butyric and caproic acids as majoritarian VFAs, while at pH 10, a lower yield (315.1 mgCOD/gVS) was obtained with acetic as the main acid. WAS and FW co-fermentation was explored (50%, 70% and 90% WAS on VS basis), demonstrating the benefits, since a higher fermentation yield was obtained in WAS/FW co-fermentation assays compared to WAS or FW mono-fermentation. In all mixtures tested, the buffer capacity of WAS was enough to maintain the pH above inhibitory levels without reagents addition. Moreover, when the proportion of FW in the WAS/FW was raised, more butyric and less propionic acid was produced achieving a maximum fermentation yield of 480 mgCOD/gVS when the mixture was 50%FW+50%WAS. Since the effect of each FW fraction has been barely studied, discontinuous assays using diverse FW fractions were also performed. The principal components analysis (PCA) revealed the relation between each fraction and each fermentation profile. Furthermore, these assays were essential to understanding the importance of balancing the protein-to-carbon ratio to achieve a maximum VFA yield of about 500 mgCOD/gVS. WAS and FW co-fermentation was studied under long-term conditions in semi-continuous fermenters at several organic loading rates (OLR). This study demonstrated the importance of microorganisms’ immigration with the feed substrates and their adaptation in semi-continuous processes. The stages carried out at OLR 9 and 11 gVS/(L·d) obtained lower VFAs yields probably due to the methanogenic activity favoured at the neutral pH. However, when higher OLR were applied (14 and 18 gVS/(L·d)), the pH started to decrease with a concomitant increase on the VFA yield until achieving a maximum of 475 mgCOD/gVS, with butyric as the main acid. Moreover, this study demonstrates that not only the FW properties and its proportion affect the obtained VFA yield and distribution on co-fermentation, but also the WAS characteristics are important, especially when the pH is low, and the buffering capacity could avoid a sudden drop in the pH. Finally, the start-up and operation of a sequencing batch reactor (SBR) to select PHA-storing microorganisms was performed using a VFA-rich feeding with an OLR of 2.0 and 2.8 gCOD/(L·d). The biomass selection was carried out with a double growth limitation strategy (feast/famine and uncoupled carbon and nitrogen feeding). The successful selection of PHA-storing biomass was confirmed in batch accumulations assays where VFA pulse feeding strategy was used obtaining a PHA content between 44 and 46% (on SS basis) with polyhydroxybutyrate (PHB) as the main component., [spa] El gran crecimiento poblacional está comportando una gran generación de residuos que necesitan ser tratados de la mejor manera posible. Por ello, la Unión Europea propone implementar nuevas estrategias de tratamiento de residuos dentro del concepto de economía circular mediante la transformación de las plantas de residuos en biorrefinerías, donde los residuos son concebidos como productos. En este sentido, el proceso de fermentación acidogénica emerge como una tecnología clave para valorizar los sustratos orgánicos en forma de productos de alto valor añadido como son los ácidos grasos volátiles (AGVs) que pueden ser usados para la producción de bioplásticos (polihidroxialcanoatos o PHA). Los residuos alimentarios y los fangos activos de las depuradoras son los residuos orgánicos más generados en las zonas urbanas. Actualmente son tratados por separado, pero debería contemplarse su tratamiento conjunto ya que resultaría beneficioso debido a las sinergias que se formarían. Por este motivo, la presente tesis se basa en el estudio de la fermentación acidogénica de estos residuos por separado, así como su tratamiento conjunto (co-fermentación) con el fin de generar un efluente rico de AGVs para su posterior conversión en PHA. Para ello, se llevaron a cabo estudios en discontinuo y en semi-continuo para comprobar el efecto del pH en la fermentación de los residuos alimentarios viendo que tiene un papel crucial. Seguidamente, se estudió la co-fermentación de fangos activados con los residuos alimentarios en diferentes proporciones. Este estudio demostró que la capacidad tampón del fango era suficiente para sostener el pH por encima de los niveles inhibitorios. Asimismo, se mostraron sinergias al co-fermentar estos residuos con producciones mayores que mono-fermentando, viendo que la proporción de cada residuo afectaba a la producción y perfil de los AGVs. Además, también se estudió la relación entre cada fracción de los residuos alimentarios y el perfil de producción de ácidos. También se comparó el efecto de trabajar en discontinuo y semi-continuo viendo que tenía importantes efectos debido a la inmigración y adaptación de los microorganismos. Finalmente, se estudió la viabilidad de producir PHA usando un efluente sintético rico en AGVs obteniendo unos buenos porcentajes de acumulación del biopolímero.

Non-biodegradable microplastics have become a global problem. We propose a new enzyme-embedded biodegradable plastic that can be self-biodegraded anytime and anywhere. Proteinase K from Tritirachium album was embedded in poly(l-lactic acid) (PLLA). The PLLA solution-cast film with embedded proteinase K showed weight loss of 78% after 96 h incubation. In addition, PLLA extruded films embedding immobilized proteinase K encapsulated in polyacrylamide were produced at 200 °C and embedded-enzyme degradation was monitored. Immobilized proteinase K embedded in the extruded film maintained its degradation activity and degraded the PLLA film from inside to make small holes and cavities, suggesting that immobilization is a powerful technique to prepare thermoforms with embedded enzymes. The rate of embedded-enzyme degradation was accelerated by dividing the film into smaller pieces, which can be regarded as a model experiment for biodegradation of microplastics. Various biodegradable plastics with specific embedded enzymes will contribute to solve global environmental problems.

Benign strictures of the bile duct may be difficult to treat endoscopically due to altered bowel anatomy. Furthermore, recurrence of stenosis and symptoms remains high. The aim of the Spanish Prospective Registry BiELLA study was to investigate the safety and efficacy of absorbable stents in the treatment of benign biliary strictures and their outcomes on the medium and long-term follow-up. A prospective, multicenter, observational, non-randomized study (the BiELLA study) was conducted from January 2014 to September 2018. One hundred fifty-nine patients with benign biliary strictures, mostly postsurgical, were enrolled for implantation of absorbable biliary stents in the 11 participating Spanish tertiary hospitals. The average patient follow-up was 45.4 ± 15.9 months (range, 12–60 months). The follow-up data included symptoms, biochemical parameters, and ultrasound images at 1, 6, and 12 months and then yearly for up to 60 months. The immediate technical and clinical success rates were 100%. In all patients, stent placement resulted in improvement of clinical symptoms and biochemical parameters. The primary mean patency for stent was 86.7, 79.6, and 78.9% at 12, 36, and 60 months, respectively (95% CI). Biliary restenosis and occlusion occurred in 40 (26.6%) patients. Of the 40 patients, 18 (12%) patients were treated with a second stent and 22 (14.6%) patients had operative repair of the recurrent strictures. There were no major complications associated with stent implantation. Implantation of an absorbable polydioxanone biliary stent is safe and effective for treatment of benign biliary strictures refractory to balloon dilatation or other biliary intervention. • Percutaneous implantation of biodegradable prostheses for the treatment of benign postsurgical biliary strictures is a safe and effective procedure. • More than 75% of the patients presented patency of the stented biliary tree at 5 years follow-up. • Absorbable stents improved clinical symptoms and signs (jaundice, itching, fever), and laboratory parameters in a few days after stent placement.

Made available in DSpace on 2020-12-10T19:56:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-04-08 National Institutes of Health (NIH, National Institute of Dental and Craniofacial Research/NIDCR) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) A photocrosslinkable gelatin methacryloyl (GelMA) hydrogel has been widely examined in regenerative engineering because of its good cell-tissue affinity and degradability in the presence of matrix metalloproteinases. A halloysite aluminosilicate nanotube (HNT) is a known reservoir for the loading and sustained delivery of therapeutics. Here, we formulate injectable chlorhexidine (CHX)-loaded nanotube-modified GelMA hydrogel that is cytocompatible and biodegradable and provides sustained release of CHX for infection ablation while displaying good biocompatibility. The effects of HNTs and CHX on hydrogel degradability and mechanical properties, as well as on the kinetics of CHX release, and on the antimicrobial efficacy against oral pathogens were systematically assessed. Cytocompatibility in stem cells from human exfoliated deciduous teeth and inflammatory response in vivo using a subcutaneous rat model were determined. Our hydrogel system, that is, (CHX)-loaded nanotube-modified GelMA showed minimum localized inflammatory responses, supporting its ability for drug delivery applications. Moreover, we showed that the incorporation of CHX-loaded nanotubes reduces the mechanical properties, increases the swelling ratio, and diminishes the degradation rate of the hydrogels. Importantly, the presence of CHX-loaded nanotubes inhibits bacterial growth with minimal cell toxicity. Our findings provide a new strategy to modify GelMA hydrogel with chlorhexidine-loaded nanotubes for clinical use as an injectable drug delivery strategy for dental infection ablation. Univ Michigan, Sch Dent, Dept Cariol Restorat Sci & Endodont, Ann Arbor, MI 48109 USA Univ Fed Pelotas, Sch Dent, Dept Restorat Dent, BR-96010610 Pelotas, RS, Brazil Sao Paulo State Univ, Sch Dent, Dept Dent Mat & Prosthodont, BR-01049010 Araraquara, SP, Brazil Univ Michigan, Coll Pharm, Dept Pharmaceut Sci, Ann Arbor, MI 48109 USA Univ Michigan, Biointerfaces Inst, Ann Arbor, MI 48109 USA Univ Michigan, Sch Dent, Dept Biol & Mat Sci & Prosthodont, Ann Arbor, MI 48109 USA Sao Paulo State Univ, Sch Dent, Dept Dent Mat & Prosthodont, BR-01049010 Araraquara, SP, Brazil National Institutes of Health (NIH, National Institute of Dental and Craniofacial Research/NIDCR): K08DE023552 National Institutes of Health (NIH, National Institute of Dental and Craniofacial Research/NIDCR): R01DE026578

Lignin (LIG) is a renewable biopolymer with well-known antimicrobial and antioxidant properties. In the present work LIG was combined with poly(butylene succinate) (PBS), a biocompatible/biodegradable polymer, to obtain composites with antimicrobial and antioxidant properties. Hot melt extrusion was used to prepare composites containing up to 15% (w/w) of LIG. Water contact angle measurements suggested that the incorporation of LIG did not alter the wettability of the material. The material density increased slightly when LIG was incorporated (, Highlights • Lignin/Poly(butylene succinate) composites were prepared using hot melt extrusion. • The composites containing up to 15% of lignin. • The presence of lignin in the composite did not alter significantly their mechanical properties. • Lignin-containing composites showed antioxidant activity. • Lignin-containing composites showed resistance to Staphylococcus aureus adherence.

Tooth defect and tooth loss are common clinical diseases in stomatology. Compared with the traditional oral restoration treatment, tooth regeneration has unique advantages and is currently the focus of oral biomedical research. It is known that dozens of cytokines/growth factors and other bioactive factors are expressed in a spatial-temporal pattern during tooth development. On the other hand, the technology for spatial-temporal control of drug release has been intensively studied and well developed recently, making control release of these bioactive factors mimicking spatial-temporal pattern more feasible than ever for the purpose of tooth regeneration. This article reviews the research progress on the tooth development and discusses the future of tooth regeneration in the context of spatial-temporal release of developmental factors.

The microplastic that pollutes the ocean is a serious problem around the world. The bioplastic consisting of biopolymers which is degraded in nature, is one of the strategies to solve this problem. Although the bioplastics consisting of protein, polysaccharide, polylactic acid, etc., have been reported, which consist of DNA, one of the most important materials in the genetic process, have not been reported to the best of our knowledge. In addition, a large amount of DNA-containing materials, such as salmon milts, is discarded as industrial waste around the world. Therefore, we demonstrated the preparation of a bioplastic consisting of salmon milt DNA. The DNA plastic was prepared by the immersion of a DNA pellet in a formaldehyde (HCHO) solution and heating. As a result, the water-stable DNA plastics were obtained at the HCHO concentration of 20% or more. Particularly, the DNA plastic with a 25% HCHO treatment showed water-insoluble, thermally stable, and highly mechanical properties. These are due to the formation of a three-dimensional network via the crosslinking reaction between the DNA chains. In addition, since DNA in plastic possesses the double-stranded structure, these plastics effectively accumulated the DNA intercalator, such as ethidium bromide. Furthermore, the DNA plastics indicated a biodegradable property in a nuclease-containing aqueous solution and the biodegradable stability was able to be controlled by the HCHO concentration. Therefore, salmon milt DNA has shown the potential to be a biodegradable plastic.

The influence of the inoculum-substrate ratio (ISR) on the mesophilic and thermophilic biochemical methane potential test of two biodegradable plastics was evaluated. Poly(lactic acid) (PLA) and polyhydroxybutyrate (PHB) were selected for this study, the first for being recalcitrant to mesophilic anaerobic digestion (AD) and the second, by contrast, for being readily biodegradable. Several ISRs, calculated on the basis of volatile solids (VS), were tested: 1, 2, 2.85, 4, and 10 g(VS of inoculum).g(VS of substrate)

Among global efforts facing plastic pollution, their gradual replacement with alternative materials has gained strength during the last decade. We identified five stakeholders and their respective key participation in the chain of bio-based, biodegradable and compostable plastics (BBCP), which have contributed to several flaws on governance of these materials. The widespread unfamiliarity of the consumers about biodegradability concepts has been leading to misguided purchase decisions and disposal practices, along with possible littering behavior. Simultaneously, the adoption of greenwashing practices by stores and manufacturers contribute to disseminating misguided decisions on plastic consumption. Such issues are further aggravated by the lack of certification standards concerning the impact of littering, including the assessment of persistency and toxicity, also covering those made with biodegradable plastics.". Moreover, even though such alternative polymers were originally conceived as a strategy to minimize plastics pollution, the almost inexistence of specific regulatory frameworks in different political scales may convert them in a relevant part of the problem. Therefore, the governance systems and management strategies need to incorporate BBCP as potentially hazardous waste as they do for conventional plastics.

Many ways are being developed in the realm of agriculture to increase crop yield while inflicting minimal damage to the soil and environment. One among them is the application of agricultural, biodegradable mulch (BDM) films. Organic substances or synthetic materials are used for making mulches. Also, bio-based polymers derived from bacteria, microorganisms, or fossil fuels are used to make BDM films. BDM films are used in crop production because of their high agronomical advantages which lead to sustainable agriculture. These films are placed on the soil's surface, around the plants. Mulches help in conserving the moisture, control the temperature of the soil, control the growth of the weed, and help in the utilization of soil nutrients thus, overall enhancing the crop yield. The usage of plastic mulch in agriculture has expanded substantially all around the world, over the past ten years, this is because polyethylene films are cheaper, easily produced, highly flexible, and durable. However, the improper disposal of used plastic films has resulted in soil pollution and environmental contamination. Traditional mulches are replaced by BDM, which is a more environmentally friendly alternative. After being used, degradable mulch films could be tilled into the soil and are expected to disintegrate over time. This review focuses on the BDMs, their history, plastic mulches, how BDMs became an alternative source for plastic mulches, their composition, and also addresses their significance. In addition, we discuss the environmental impact of films, including how it alters the climate, soil, temperature, and weed management.

Amphiphilic copolymers with pendant functional groups in polyester segments are widely used in nanomedicine. These enriched functionalities are designed to form covalent conjugates with payloads or provide additional stabilization effects for encapsulated drugs. A general method is successfully developed for the efficient preparation of functional biodegradable PEG-polyester copolymers via click chemistry. Firstly, in the presence of mPEG as initiator, Sn(Oct)2-catalyzed ring-opening polymerization of the α-alkynyl functionalized lactone with D,L-lactide or ε-caprolactone afforded linear mPEG-polyesters bearing multiple pendant alkynyl groups. Kinetic studies indicated the formation of random copolymers. Through copper-catalyzed azide-alkyne cycloaddition reaction, various small azido molecules with different functionalities to polyester segments are efficiently grafted. The molecular weights, polydispersities and grafting efficiencies of azido molecules of these copolymers were investigated by NMR and GPC. Secondly, it is demonstrated that the resulting amphiphilic functional copolymers with low CMC values could self-assemble to form nanoparticles in aqueous media. In addition, the in vitro degradation study and cytotoxicity assays indicated the excellent biodegradability and low cytotoxicity of these copolymers. This work provides a general approach toward the preparation of functional PEG-polyester copolymers in a quite efficient way, which may further facilitate the application of functional PEG-polyesters as drug delivery materials.

There have been many studies on the development biodegradable films using starch isolated from various food sources as a substitute for synthetic plastic packaging films. In this study, starch was extracted from ginkgo (Ginkgo biloba) nuts, which were mainly discarded and considered an environment hazard. The prepared starch (GBS) was then used for the preparation of antioxidant films by incorporating various amounts of cinnamon (Cinnamomum zeylanicum) essential oil (CZEO), which provides antioxidant activity. The prepared GBS films with CZEO were characterized by measuring physical, optical, and thermal properties, along with antioxidant activity (ABTS, DPPH, and FRAP) measurements. With the increasing amount of CZEO, the flexibility and antioxidant activities of the GBS films increased proportionally, whereas the tensile strength of the films decreased. The added CZEO also increased the water vapor permeability of the GBS films, and the microstructure of the GBS films was homogeneous overall. Therefore, the obtained results indicate that the developed GBS films containing CZEO are applicable as antioxidant food packaging.

We aimed to prepare a bioactive and biodegradable bilayer mesh formed by fibroblast growth factor (FGF) loaded gelatin film layer, and poly ε-caprolactone (PCL) film layer, and to investigate its treatment efficacy on esophageal anastomosis. It is envisaged that the bioactive mesh in in vivo model would improve tissue regeneration in rats. The full thickness semicircular defects of 0.5x0.5 cm2 were created in anterior walls of abdominal esophagus. The control group had abdominal esophagus isolated with distal esophageal blunt dissection, and sham group had primer anastomosis. In the test groups, the defects were covered with bilayer polymeric meshes containing FGF (5µg/2 cm²), or not. All rats were sacrificed for histopathology investigation after 7 or 28 days of operation. The groups are coded as FGF(-)-7th d, FGF(+)-7th d, and FGF(+)-28th d, based on their content and operation day. Highest burst pressures were obtained for FGF(+)-7th d, and FGF(+)-28th d groups (p

Nowadays, microplastics represent emergent pollutants in terrestrial ecosystems that exert impacts on soil properties, affecting key soil ecological functions. In agroecosystems, plastic mulching is one of the main sources of plastic residues in soils. The present research aimed to evaluate the effects of two types of plastic sheets (un-biodegradable and biodegradable) on soil abiotic (pH, water content, concentrations of organic and total carbon, and total nitrogen) and biotic (respiration, and activities of hydrolase, dehydrogenase, β-glucosidase and urease) properties, and on phytotoxicity (germination index of Sorghum saccharatum L. and Lepidium sativum L.). Results revealed that soil properties were mostly affected by exposure time to plastics rather than the kind (un-biodegradable and biodegradable) of plastics. After six months since mesocosm setting up, the presence of un-biodegradable plastic sheets significantly decreased soil pH, respiration and dehydrogenase activity and increased total and organic carbon concentrations, and toxicity highlighted by S. saccharatum L. Instead, the presence of biodegradable plastic sheets significantly decreased dehydrogenase activity and increased organic carbon concentrations. An overall temporal improvement of the investigated properties in soils covered by biodegradable plastic sheets occurred.

Plastic mulch is frequently used to increase crop yield, resulting in large quantities of residues accumulating in soil due to low recovery rates. However, the effects of microplastic residues from traditional and biodegradable plastic films on soil nitrogen (N) transformation and bioavailability are not well understood. Here, the main objectives were to examine the effects of micro-sized residues (diameter5 mm) of polyethylene (PE) and biodegradable plastic mulch films (PLA) on the soil N in two contrasting soils (clay soil and sandy loam soil) in different temperatures (15 °C vs. 25 °C). Results showed that the microplastic presence showed a little effect on soil N transformation and bioavailability at 15 °C, but both microplastics significantly decreased NO

9 pages, 7 figures, supplementary data https://doi.org/10.1016/j.scitotenv.2022.155264, Plastic in the ocean releases organic compounds that are able to enter the marine dissolved organic carbon pool and be utilized by heterotrophic bacteria. However, no information is known about which groups of bacteria are able to grow and degrade plastic leachates. Here we characterized a marine bacterial community from the NW Mediterranean Sea growing on plastic leachates and quantified its total activity. We used two petro-based plastics, low density polyethylene (LDPE) and polystyrene, and one biodegradable plastic, polylactic acid (PLA), to generate leachates under irradiated (UV–Vis) and non-irradiated conditions. Then we incubated them with a natural bacterial inoculum and determined the single-cell activity and associated taxonomy of the bacterial groups, using a combination of Catalyzed Reporter Deposition-Fluorescence In Situ Hybridization (CARDFISH) and BioOrthogonal Non-Canonical Amino acid Tagging (BONCAT). The community growing in the leachates was mainly composed of Alteromonas (Gammaproteobacteria), followed by Roseobacter (Alphaproteobacteria) and unclassified Gammaproteobacteria. Overall, marine bacteria in the irradiated treatments showed higher total activity compared to the non-irradiated ones, with the community growing on LDPE's leachates presenting the highest values. The biodegradable PLA leachates presented lower activity than those from petro-based plastics but similar bacterial composition, suggesting that it is possible that PLA could last in the ocean as much as petro-based plastics do. The results from this study show the impact of marine plastic debris in the marine microbial community and the marine carbon cycle, This work and C.R.-C. involvement was supported by ComFuturo Program from Fundación General CSIC and a Retos Investigación-2019 project (PID2019-109889RJ-I00) from the Spanish Ministry of Science and Innovation and the Agencia Estatal de Investigación. C.R.-C. also thanks ISDIN for financial support. M.S. was supported by MIAU (RTI2018-101025-B-I00) from the Spanish Ministry of Science and Innovation. S.B. was funded by the Erasmus+ Program. This work acknowledges the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

Biodegradation of microplastics (MPs) in contaminated biowastes has received big scientific attention during the past few years. The aim here is to study the impacts of livestock manure biochar (LMBC) on the biodegradation of polyhydroxyalkanoate microplastics (PHA-MPs) during composting, which have not yet been verified. LMBC (10% wt/wt) and PHA-MPs (0.5% wt/wt) were added to a mixture of pristine cow manure and sawdust for composting, whereas a mixture without LMBC served as the control (CK). The maximum degradation rate of PHA-MPs (22–31%) was observed in the thermophilic composting stage in both mixtures. LMBC addition significantly (P < 0.05) promoted PHA-MPs degradation and increased the carbon loss and oxygen loading of PHA-MPs compared to CK. Adding LMBC accelerated the cleavage of C–H bonds and oxidation of PHA-MPs, and increased the O–H, C[dbnd]O and C–O functional groups on MPs. Also, LMBC addition increased the relative abundance of dominant microorganisms (Firmicutes, Proteobacteria, Deinococcus-Thermus, Bacteroidetes, Ascomycota and Basidiomycota) and promoted the enrichment of MP-degrading microbial biomarkers (e.g., Bacillus, Thermobacillus, Luteimonas, Chryseolinea, Aspergillus and Mycothermus). LMBC addition further increased the complexity and connectivity between dominant microbial biomarkers and PHA-MPs degradation characteristics, strengthened their positive relationship, thereby accelerated PHA-MPs biodegradation, and mitigated the potential environmental and human health risk. These findings provide a reference point for reducing PHA-MPs in compost and safe recycling of MPs contaminated organic wastes. However, these results should be validated with other composting matrices and conditions. Refereed/Peer-reviewed

Orientador: Ana Rita Morales Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química Resumo: Este trabalho apresenta um estudo inédito de nanocargas híbridas na matriz do bipolímero poli(adipato-co-tereftalato de butileno) ¿ (PBAT), visando melhorar as propriedades de permeabilidade ao O2, vapor d¿água e barreira a radiação ultravioleta do PBAT para utilização em embalagens de alimentos. O principal objetivo deste trabalho foi avaliar o efeito da combinação de nanoargilas de diferentes morfologias, montmorilonita (MMT) e sepiolita (SEP), e nano-dióxido de titânio (nano-TiO2). A primeira etapa constituiu na seleção e caracterização das nanopartículas utilizadas. As amostras foram processadas em misturador Drais e prensa, e os filmes produzidos em extrusora balão. Foram avaliadas as propriedades de permeabilidade ao O2 e vapor d¿água, porcentagem de transmissão de luz (T%) na região ultravioleta e visível, e ensaios de resistência à tração. A permeabilidade ao O2 e vapor d¿água apresentaram redução de 47 % e 49 %, respectivamente comparada ao PBAT puro. Para estas propriedades apenas a MMT apresentou influência estatisticamente significativa, reduzindo a permeabilidade com o aumento da concentração de MMT. Apenas o nano-TiO2 apresentou influência estatisticamente significativa na T%, o aumento da concentração de nano-TiO2 diminuiu a transmissão de luz do PBAT de 50,3 % para até 4,7 % na região UV e de 75,7 % para até 47,8 % na região de luz visível. Já para os ensaios de resistência à tração, apenas o módulo de Young apresentou aumento estatisticamente significativo com a adição das nanocargas. Este comportamento pode estar associado a uma boa dispersão das cargas na matriz conferindo um efeito de reforço ao material. A dispersão destas nanocargas nos filmes foi avaliada por MET, MEV, reometria e DRX. Verificou-se uma boa dispersão com a combinação das três nanocargas, sugerindo assim um efeito sinergístico entre estas. Nestas amostras, observou-se também que a argila MMT apresentou estruturas esfoliadas e intercaladas, corroborando os resultados obtidos em permeabilidade. Utilizou-se DSC e DRX para verificar que as nanocargas não conferiram alteração significativa no grau de cristalinidade, concluindo-se que apenas a dispersão/esfoliação da argila MMT contribuiu para redução da permeabilidade do PBAT. Pela análise TGA verificou-se que a adição das nanocargas diminuiu sutilmente a estabilidade térmica dos nanocompósitos, porém sem comprometer sua temperatura de processamento. Finalmente, foram realizadas análises de mineralização e monitoramento da desintegração do PBAT e nanocompósitos. A adição das nanocargas conferiu uma taxa de mineralização mais lenta dos nanocompósitos comparada ao PBAT puro, conforme observado também pela análise visual e MEV. Contudo, ao final do período total de monitoramento (6 meses) foi possível observar indícios de degradação para todas as amostras. Os resultados de FTIR indicaram, tanto para o PBAT puro quanto para os nanocompósitos, uma maior taxa de degradação no primeiro mês de monitoramento, o que pode ser atribuído à redução das unidades alifáticas (BA) e relativo aumento das unidades BT ao longo do tempo de degradação, corroborando os resultados de DSC Abstract: This work presents an inedited study of hybrid nanofillers in the poly(butylene adipate-co-terephthalate) ¿ (PBAT) bipolymer matrix, aiming to improve the O2 and water vapor permeability, and ultraviolet radiation barrier of PBAT for food packaging application. The main objective of this work was to evaluate the effect of the nanoclays combination of different morphologies, montmorillonite (MMT) and sepiolite (SEP), and titanium nano-dioxide (nano-TiO2). The first step was the selection and characterization of the nanoparticles used. The samples were processed in a Drais mixer and press, and the films were produced by extrusion blowing. The properties of O2 and water vapor permeability, transmittance of ultraviolet and visible light (T%) and mechanical properties were evaluated. The O2 and water vapor permeability presented reduction of 47% and 49%, respectively, compared to neat PBAT. For these properties, only MMT showed a statistically significant influence, reducing the permeability with increasing of MMT concentration. Only nano-TiO2 showed a statistically significant influence on T%, the increase of nano-TiO2 concentration decreased the light transmission of PBAT from 50.3% to 4.7% in the UV region and from 75.7% to 47.8% in the visible light region, without compromising the translucency of the material. For the tensile strength tests, only the Young's modulus presented a statistically significant increase with the addition of nanofillers. This behavior may be associated with a good dispersion of the fillers in the matrix giving a reinforcing effect to the material. The dispersion of these nanofillers in the films was evaluated by TEM, SEM, rheometry and XRD. Good dispersion was observed with the combination of the three nanofillers, thus suggesting a synergistic effect between them. In these samples, it was also observed that the MMT clay showed exfoliated and intercalated structures, corroborating the results obtained in permeability tests. DSC and XRD permitted to verify that the nanofillers did not confer significant change in the crystallinity degree, concluding that only the dispersion/exfoliation of the MMT clay contributed to the reduction of the PBAT permeability. By the TGA analysis, it was verified that the addition of the nanofillers slightly decreased the thermal stability of the nanocomposites, but without compromising its processing temperature. Finally, mineralization and disintegration monitoring of PBAT and nanocomposites were carried out. The addition of nanofillers reduced mineralization rate compared to neat PBAT, which is coherent with visual analysis and SEM. However, at the end of the total monitoring period (6 months) it was possible to observe evidence of degradation for all samples. FTIR results indicated, for neat PBAT and its nanocomposites, a higher degradation rate in the first month monitoring that might be attributted to the reduction of aliphatic units (BA) and relative increasing of aromatic units (BT) over time, corroborating DSC analysis Doutorado Engenharia Química Doutora em Engenharia Química CAPES 33003017034P8

Intensive exploitation, poor recycling, low repeatable use, and unusual resistance of plastics to environmental and microbiological action result in accumulation of huge waste amounts in terrestrial and marine environments, causing enormous hazard for human and animal life. In the last decades, much scientific interest has been focused on plastic biodegradation. Due to the com-paratively short evolutionary period of their appearance in nature, sufficiently effective enzymes for their biodegradation are not available. Plastics are designed for use in conditions typical for human activity, and their physicochemical properties roughly change at extreme environmental parameters like low temperatures, salt, or low or high pH that are typical for the life of extremophilic microorganisms and the activity of their enzymes. This review represents a first attempt to summa-rize the extraordinarily limited information on biodegradation of conventional synthetic plastics by thermophilic, alkaliphilic, halophilic, and psychrophilic bacteria in natural environments and laboratory conditions. Most of the available data was reported in the last several years and concerns moderate extremophiles. Two main questions are highlighted in it: which extremophilic bacteria and their enzymes are reported to be involved in the degradation of different synthetic plastics, and what could be the impact of extremophiles in future technologies for resolving of pollution prob-lems. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Inherently conducting polymers (ICPs) are a specific category of synthetic polymers with distinctive electro-optic properties, which involve conjugated chains with alternating single and double bonds. Polyaniline (PANI), as one of the most well-known ICPs, has outstanding potential applications in biomedicine because of its high electrical conductivity and biocompatibility caused by its hydrophilic nature, low-toxicity, good environmental stability, and nanostructured morphology. Some of the limitations in the use of PANI, such as its low processability and degradability, can be overcome by the preparation of its blends and nanocomposites with various (bio)polymers and nanomaterials, respectively. This review describes the state-of-the-art of biological activities and applications of conductive PANI-based nanocomposites in the biomedical fields, such as antimicrobial therapy, drug delivery, biosensors, nerve regeneration, and tissue engineering. The latest progresses in the biomedical applications of PANI-based nanocomposites are reviewed to provide a background for future research.

Poly(glycerol adipate) (PGA) is a biodegradable, biocompatible, polymer with a great deal of potential in the field of drug delivery. Active drug molecules can be conjugated to the polymer backbone or encapsulated in self-assembled nanoparticles for targeted and systemic delivery. Here, a range of techniques have been used to characterise the enzymatic degradation of PGA extensively for the first time and to provide an indication of the way the polymer will behave and release drug payloads in vivo. Dynamic Light Scattering was used to monitor change in nanoparticle size, indicative of degradation. The release of a fluorescent dye, coupled to PGA, upon incubation with enzymes was measured over a 96 h period as a model of drug release from polymer drug conjugates. The changes to the chemical structure and molecular weight of PGA following enzyme exposure were characterised using FTIR, NMR and GPC. These techniques provided evidence of the biodegradability of PGA, its susceptibility to degradation by a range of enzymes commonly found in the human body and the polymer’s potential as a drug delivery platform.

Electrospinning is a fabrication technique to generate three dimensional scaffolds with a fiber structure that imitates extracellular matrix for tissue engineering constructs. The versatile characteristics of the electrospinning process yields designer scaffolds made of biodegradable polymers or natural proteins with controllable fiber diameters, biodegradation, and mechanical properties. A limitation of conventional electrospun scaffolds is the dense fiber packing with low porosity that leads to poor cell infiltration. Electrospraying sacrificial polyethylene oxide (PEO) microparticles in combination with electrospun scaffolds are a method to increase porosity. We report the effectiveness of electrospraying PEO microparticles to increase porosity of the most commonly used biodegradable polymers: polyglycolic acid (PGA), poly (lactic-co-glycolic) acid (PLGA), and polycaprolactone (PCL). The biodegradable polymer electrospun scaffolds with the sacrificial PEO microparticles were found to have improved cell proliferation and infiltration with human fibroblasts compared to conventional electrospun scaffolds. The mechanical properties of the more robust PGA and PLGA had minor changes, but the more elastic PCL was observed to be weaker and less stiff after the removal of the PEO microparticles. Therefore, this study found PEO microparticles can increase porosity and cell infiltration with stable mechanical properties for a wide variety of biodegradable polymers in electrospun scaffolds.

Transdermal administration via skin appendages enables both localized and systemic drug delivery, as well as minimizes incidental toxicity. However, the design of an appropriate effective method for the clinical use remains challenging. Here, we introduce calcium carbonate-based carriers for the transdermal transportation of bioactive substances. The proposing system represents easily manufacturable biodegradable particles with a large surface area enabling a high payload ability. Topical application of submicron porous СaCO3 particles in rats followed by the therapeutic ultrasound treatment results in their deep penetration through the skin along with the plentiful filling of the hair follicles. Exploiting the loading capacity of porous particles, we demonstrate efficient transportation of a fluorescent marker along the entire depth of the hair follicle down the bulb region. In vivo monitoring of the carrier degradation reveals the active dissolution/recrystallization of CaCO3 particles resulting in their total resorption within 12 days. The proposed particulate system serves an intrafollicular depot for drug storage and prolonged in situ release over this period. The urinary excretion profile proves the systemic absorption of the fluorescent marker. Hence, the elaborated transdermal delivery system outlooks promising for medical applications. The drug delivery to different target regions of the hair follicle may contribute to regenerative medicine, immunomodulation and treatment of various skin disorders. In the meantime, the systemic uptake of transported drug opens an avenue for perspective delivery routes beyond the scope of dermatology.

This study investigates the mechanical properties and in vitro cytotoxicity of two-dimensional (2D) graphene oxide nanoribbons and nanoplatelets (GONRs and GONPs) reinforced porous polymeric nanocomposites. Highly porous poly(propylene fumarate) (PPF) nanocomposites were prepared by dispersing 0.2 wt % single- and multiwalled SONRs (SWGONRs and MWGONRs) and GONPs. The mechanical properties of scaffolds were characterized using compression testing and in vitro cytocompatibility was assessed using QuantiFlour assay for cellularity and PrestoBlue assay for cell viability. Immunofluorescence was used to assess collagen-I expression and deposition in the extracellular matrix. Porous PPF scaffolds were used as a baseline control and porous single and multiwalled carbon nanotubes (SWCNTs and MWCNTs) reinforced nanocomposites were used as positive controls. Results show that incorporation of 2D graphene nanomaterials leads to an increase in the mechanical properties of porous PPF nanocomposites with following the trend: MWGONRs > GONPs > SWGONRs > MWCNTs > SWCNTs > PPF control. MWGONRs showed the best enhancement of compressive mechanical properties with increases of up to 26% in compressive modulus (i.e., Young's modulus), ~60% in yield strength, and ~24% in the ultimate compressive strength. Addition of 2D nanomaterials did not alter the cytocompatibility of porous PPF nanocomposites. Furthermore, PPF nanocomposites reinforced with SWGONRs, MWGONRs, and GONPs show an improvement in the adsorption of collagen-I compared to PPF baseline control. The results of this study show that 2D graphene nanomaterial reinforced porous PPF nanocomposites possess superior mechanical properties, cytocompatibility, and increased protein adsorption. The favorable cytocompatibility results opens avenues for in vivo safety and efficacy studies for bone tissue engineering applications. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1143-1153, 2019.

The strength, flexibility and light weight of traditional oil-derived plastics make them ideal materials for a large number of applications, including packaging, medical devices, building, transportation, etc. However, the majority of produced plastics are single-use plastics, which, coupled with a throw-away culture, leads to the accumulation of plastic waste and pollution, as well as the loss of a valuable resource. In this review we discuss the advances and possibilities in the biotransformation and biodegradation of oil-based plastics. We review bio-based and biodegradable polymers and highlight the importance of end-of-life management of biodegradables. Finally, we discuss the role of a circular economy in reducing plastic waste pollution.

Polyhydroxyalkanoates (PHA) are polyesters of various hydroxyl alkanoates that are synthesized by many gram-positive and gramnegative bacteria from about 75 different genera. PHA genes database is a repository of genes and its genomic information related to PHA.It contains data on the genomic characterization of intermediates of PHA. These include CAB genes, responsible for biodegradable plastic synthesis. The genomic database provides data on PHA genes from archaeal, bacterial and eukaryotic genomes.

The yeast Pseudozyma antarctica secretes a concentrated biodegradable plastic (BP)-degrading enzyme when cultivated with xylose. Treatment with the culture filtrate reduced the puncture strength of commercial BP mulch films. After burying the film in soil, the residual amount of solid film was reduced significantly, and none was recovered after 5 weeks. The dynamics of soil fungal communities were analyzed weekly after burying the film using 18S rDNA polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) profiling of soil DNA. In the soil containing enzyme-treated film, the native community essentially recovered within 24 weeks. In comparison, the untreated solid film remained in the soil for 12 weeks and the response of the soil-fungal community was relatively slow; it had not recovered within 24 weeks.

In recent years, under the pressure of resource shortage and white pollution, the development and utilization of biodegradable wood-plastic composites (WPC) has become one of the hot spots for scholars’ research. Here, corn straw fiber (CSF) was chosen to reinforce a poly(lactic acid) (PLA) matrix with a mass ratio of 3:7, and the CSF/PLA composites were obtained by melt mixing. The results showed that the mechanical properties of the corn straw fiber core (CSFC) and corn straw fiber skin (CSFS) loaded PLA composites were stronger than those of the CSFS/PLA composites when the particle size of CSF was low. The tensile strength and bending strength of CSFS/CSFC/PLA are 54.08 MPa and 87.24 MPa, respectively, and the elongation at break is 4.60%. After soaking for 8 hours, the water absorption of CSF/PLA composite reached saturation. When the particle size of CSF is above 80 mesh, the saturated water absorption of the material is kept below 7%, and CSF/PLA composite has good hydrophobicity, which is mainly related to the interfacial compatibility between PLA and CSF. By observing the microstructure of the cross section of the CSF/PLA composite, the research found that the smaller the particle size of CSF, the smoother the cross section of the composite and the more unified the dispersion of CSF in PLA. Therefore, exploring the composites formed by different components of CSF and PLA can not only expand the application range of PLA, but also enhance the application value of CSF in the field of composites.

Plastic products are widely used around the world, but waste plastic is not reasonably managed and causes serious plastic pollution. Biodegradable plastics (BPs) provide an alternative to conventional plastics, but not all BPs can be completely degraded under natural conditions. Instead, they may break down into microplastics (MPs) faster than conventional plastics, posing an additional threat to soil environment. In this paper, the definition, applications, and degradation behaviors of BPs, including biodegradable microplastics (BMPs), are reviewed, and we comprehensively summarized the eco-toxicological effects of BMPs in soil ecosystems, in terms of physical and chemical properties of soil, soil nutrient cycling, soil bacterial and fungal communities, soil flora and fauna. The compound effects of BMPs and other pollutants were also addressed. The results revealed that BMPs made different or more severely effects compared to conventional MPs. Overall, this review aims to address gaps in knowledge, shed light on the ecological effects of BPs and BMPs in soil. BPs are not a perfect substitute to solve plastic pollution, and further exploration should focus on their generation, environmental behavior, ecological impact and whether BMPs cause more harm than conventional MPs.

On the market of plastics there are more and more plastics described as biodegradable, oxobiodegradable, which are to be completely safe for the environment, have to decompose much faster than conventional plastics, in natural conditions, e.g. composting process. The information provided by the makers of such materials raises many doubts and controversies related to the real decomposition of the material and its environmental safety. The aim of this study was to present the most important information on biodegradable and oxobiodegradable plastics, used as packaging for goods, food and waste bags, determining the possibility of decomposition of these materials and identifying problems that arise at various stages of their life cycle. The collected information confirms the necessity to modify the regulations and standards for biodegradable and oxobiodegradable plastics, in order to eliminate from the market products that may determine a serious threat to the environment and animal health and life. The main problem is the decomposition of plastics under different environmental conditions, which are different than those found during laboratory tests.

The objective of this work was to develop a chitosan/agar-agar bioplastic film incorporated with bacteriocin that presents active potential when used as food packaging. The formulation of the film solution was determined from an experimental design, through the optimization using the desirability function. After establishing the concentrations of the biopolymers and the plasticizer, the purified bacteriocin extract of Lactobacillus sakei was added, which acts as an antibacterial agent. The films were characterized through physical, chemical, mechanical, barrier, and microbiological analyses. The mechanical properties and water vapor permeability were not altered by the addition of the extract. The swelling property decreased with the addition of the extract and the solubility increased, however, the film remained intact when in contact with the food, thus allowing an efficient barrier. Visible light protection was improved by increased opacity and antibacterial capacity was effective. When used as Minas Frescal cream cheese packaging, it contributed to the increase of microbiological stability, showing a reduction of 2.62 log UFC/g, contributing a gradual release of the active compound into the food during the storage time. The film had an active capacity that could be used as a barrier to the food, allowing it to be safely packaged.

In the wake of plastic pollution increasing around the world, biodegradable plastics are one of the fastest-growing segments within the global plastics market. The biodegradation of these plastics depends on diverse factors including, but not limited to, the physicochemical structure of the materials, environmental conditions, and the microbial populations involved in the biodegradation. Although laboratory-based biodegradation tests simulate natural processes, they cannot precisely mimic the natural biodegradation of biodegradable plastics due to the disparity of several factors. In addition, the biodegradation levels claimed and/or reported by individuals and studies in different environments vary to a great extent. Biodegradable plastics are considered a sustainable alternative to non-biodegradable conventional plastics and are being promoted as an eco-friendlier choice for consumers. However, biodegradable plastics might not be as biodegradable as commonly believed, particularly in natural environments. This mini-review aims to bridge the following three gaps in biodegradable plastics by elucidating the common misconceptions and truths about biodegradation: i) the gaps among reported biodegradation level of biodegradable plastics; ii) the gaps between the biodegradation conditions in the controlled laboratory system and in the natural environment; and iii) the gaps between public perception and the actual environmental fate of biodegradable products. These gaps are critically reviewed with feasible solutions. This work will ease the assessment of biodegradable plastics and provide sound communication on corresponding claims–a prerequisite for successful market performance.