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  • Open access
  • 75 Reads
PHB Produced by Bacteria Present in the Argan Field Soil: A New Perspective for the Synthesis of the Bio-Based Polymer

Bio-based plastics, i.e. non-synthetic polymers produced starting from renewable resources, are gaining special attention as a feasible solution to the environmental issues caused by the concerns due to the impact of waste plastics. Such materials, furthermore, can also represent an alternative to petroleum-derived polymers, due to the scarcity of this raw material in the close future. In the polyhydroxyalkanoates (PHA) family, polyhydroxybutyrate (PHB) has been the first to be synthesized and characterized. PHB soon gained a great attention from industrial and academic researchers since it can be synthesized from a wide variety of available carbon sources, such as agro-industrial and domestic wastes. The aim of this original research has been the identification of the presence of PHB synthetizing bacteria in some soils in Morocco region and the production of the bio-based PHB. In particular, the soils of the argan fields in Taroudant were considered. Taroudant is a southwestern region of Morocco where the argan oil tree Aragania spinosa is an endemic and preserved species. Starting from rizhospheric soil samples of an argan crop area, we isolated heat-resistant bacteria and obtained pure cultures of it. These bacteria present intracellular endospores stained by Schaeffer-Fulton methods. The presence of intracellular endospores is a very important starting point to verify the effective production of PHB as compartmentalised material. Further analyses are currently ongoing to try to extract and characterize PHB granules.

  • Open access
  • 56 Reads
[4+4] anthracene photodimerization for controlled folding of single chain polymer nanoparticles

Single chain nanoparticles (SCNPs) have promising applications in a variety of fields, most notably catalysis. Current interest lies in achieving custom control over the resulting structure and size of the nanoparticles as well as ability of additional functionalization. The potential applications vary widely from catalysis applications to nanocarriers. Such intricate applications require a high level of control over the synthesised nanoparticles, which is one of the challenges in this field and is targeted by development of a range of experimental and modelling methods.

Reversible photochemical reactions possess a much-looked-for benefit of allowing substantial control over the reaction in space and time, [1] thus holding strong potential for folding of polymer chains into single chain nanoparticles. Therefore, herein, a kinetic model for small molecule photochemical reaction is developed for reversible anthracene dimerization in solution. [2,3] Determination of wavelength dependent kinetic parameters for anthracene dimerization and its reverse reaction together with calculation of competitive absorption from 260 to 330 nm permits intricate control over the extent of the photochemical reaction through time, intensity and wavelength of irradiation. [3] Furthermore, the small-molecule model is currently being extended for the application in the single-chain polymer folding by using polymer chains synthesised with anthracene units incorporated.

  • Open access
  • 89 Reads
Extended Food Shelf-Life via Gamma Irradiation Modified Kraft Paper

Cellulose, the main constituent of paper-based food packages, is a favorable substrate for fungal growth. Gamma irradiation is a well-established low-cost treatment used for decontamination of paper objects. The dose rate plays an important role in the efficacy of the radiation treatment, but further chemical treatment is also important for imparting specific properties for food packaging applications. The aim of this study is to evaluate the influence of γ-radiation dose and bioactive compounds grafting on appearance, structure and properties of two cellulosic substrates: unbleached and bleached Kraft cellulose paper. In this sense, Kraft paper has been activated using gamma irradiation treatment and grafted with two bioactive compounds, namely clove oil and rosehip seed oil. The experimental results showed that: (a) no significant changes of the irradiated samples took place, which prove a good durability; (b) the morphological and structural changes took place after modification with bioactive compounds, imprinting antimicrobial and antioxidant properties to modified substrates; (c) the modified materials extended the shelf-life of tested aliments, indicating that the new obtained materials are suitable for food packaging applications.

  • Open access
  • 51 Reads
Fabrication and Characterization of Air-jet-Spun Nanofibers and Thin Films from Corn Zein Protein for the Delivery of Therapeutic Molecules

Corn zein protein is a cheap, widely available biopolymer that is easily extracted from corn and processed into useful forms. In this study, zein was dissolved along with several model drugs or sodium citrate, which was then cast into thin films or air-spun into nanofibers. The molecular weight, solubility and charge of the selected model drugs are different, and the weight percentage of citrate also varies (1-30%). The integrity of the loaded biomaterials were characterized through FTIR, SEM, DSC, and TGA analysis. Due to the high surface-area-to-volume ratio of nanofibers, FTIR analysis showed that the therapeutics interacted strongly with the protein structure of zein nanofibers, transforming their structure from a random coil network to a more ordered alpha helical structure. Zein films did not show this obvious shift. This structural change reflects the results of the drug release study, where nanofibers showed a slower, sustained release of therapeutics compared to their film counterparts. Statistical analysis by T-Test proved a significant difference in release from fibers vs. release from films (P<0.01 for low wt%). The structural integration of zein with its therapeutics also improves the thermal properties of the biomaterial, where fibers did not degrade until temperatures reached 160°C, but films degrade earlier at 130°C. Finally, the biocompatibility of zein was confirmed by culturing HEK293 cells on different zein films and fibers for 72 hours. An MTT assay confirmed good biocompatibility and an improved density of fibers and films compared to a blank control. These promising results demonstrate that corn zein has a large potential in the field of drug delivery and biomaterials.

  • Open access
  • 57 Reads
Green degradable (co)polyacrylics: a kinetic Monte Carlo study

One of the major challenges for todays society is the management and handling of plastic/polymer waste. Two main solutions have been put forward towards solving this issue: (i) recycling of the currently existing bulk polymers either through mechanical, thermal or chemical treatments or (ii) the development of degradable substitutes with the same or even better properties as the conventional bulk polymers. A bottleneck in both cases is understanding the degradation of polymer materials on a molecular level, as polymer chains tend to break first at certain functional groups or structural defects of which the location and prevalence is highly important. In this work we present a unified matrix-based elementary step driven kinetic Monte Carlo (kMC) strategy modeling both for the polymerization and degradation of conventional and (bio)degradable polymer materials. This model is able to track the location and quantity of these structural defects or functional groups throughout both polymerisation and degradation. The ultimate focus is on the radical copolymerization of MMA with 2-methylene-1,3-dioxepane (MDO) and the subsequent hydrolysis of the resulting poly(MMA-MDO) toward biodegradable and functional oligomers. [1,2] We highlight the relevance of product heterogeneity resulting from batch operation and its influence on the (bio)degradation of the copolymers.

[1] D. Gigmes, P.H.M. Van Steenberge, D. Diri, D.R. D’hooge, Y. Guillaneuf, C. Lefay ‘Macromol. Rapid Commun. 2018, 39, 1800193

[2] K. De Smit, Y.W. Marien, K.M. Van Geem, P.H.M. Van Steenberge, D.R. D’hooge React. Chem. Eng. 2020. in press

  • Open access
  • 71 Reads
Electrospun Silk-Cellulose Composite Nanomaterials using Ionic Liquid Regenerated Films

Electrospinning is a widely used technique to draw recalcitrant biopolymer solutions into micro to nanoscale materials in a simple and economical way. The first focus of this research involved using ionic liquids as a non-volatile solvent for natural insoluble biopolymers such as silk and cellulose (or cellulose derivatives). Compared to traditional organic solvents, ionic liquids can dissolve the biopolymers without altering the molecular weight of the biopolymer. The second focus of this research explored the dissolution of IL-regenerated composites into organic solvents and directly electrospun to produce composite nanomaterials. Various ratios of silk-cellulose bio-composite films regenerated from ionic liquids were used as the raw materials and sequentially dissolved/dispersed into Formic Acid-CaCl2 solution in order to initiate electrospinning of silk-cellulose nanomaterials. In this study, 1-ethyl-3-methylimidizolium acetate (EMIMAc) ionic liquid was used and the regenerated films were coagulated in baths of EtOH or water. Because of the variability of ionic liquids, the nanomaterials produced using this technique have unique and tunable properties such as large surface area to volume ratios and low structural defects. FTIR and SEM results suggest that the structure and morphology of the final nanosized samples becomes more globular when the biopolymer composition ratio has increased cellulose content. TGA results demonstrated that the electrospun materials have better thermal stability than the original films. This two-step electrospinning method, using ionic liquid as a non-volatile solvent to first dissolve and mix raw natural materials, may lead to extensive research into its biomedical and pharmaceutical applications in the future.