Biobased and Natural Polymers

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Biomacromolecules, Biobased and Biodegradable Polymers".

Deadline for manuscript submissions: closed (31 August 2022) | Viewed by 28221

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Bionanotools Laboratory, Center for Research in Biological Chemistry and Molecular Materials (CiQUS), Universidade de Santiago de Compostela, Campus Vida, 15782 Santiago de Compostela, Spain
Interests: biotechnology; biomaterials; proteins
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Special Issue Information

Dear Colleagues,

Although we have been developing synthetic polymers for more than a century, we must not forget that nature is the ultimate source of polymeric materials such as polysaccharides, proteins, or polyesters. Through natural selection over time, the structure of natural polymers has been refined to the point of achieving properties which are difficult to replicate for synthetic polymers. Natural polymers have conserved characteristics, in term of composition and molecular weight; moreover, they are liable to chemical modifications or engineering to produce thousands of applications. The materials made of biopolymers have impressive properties, such as silk or pollen grains, whose composition and structure make them hard to emulate for current technology. From bulk materials to nanotechnology, biobased polymers are widely employed due to their improved biocompatibility and biodegradability, being of great interest for biomedicine and pharmaceutical sciences, as well as to produce ecofriendly packages or plastics.

This Special Issue on “Biobased and Natural Polymers” is dedicated to articles and reviews addressing synthesis, purification, characterization, and applications of polymers of natural origin, biobased materials, and tailor-made biopolymers. Innovative approaches on biomedical, pharmaceutical, material sciences, as well as the description or application of new and classical biopolymers are welcome of this Special Issue.

Dr. Jose Manuel Ageitos
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • biopolymer
  • biomaterial
  • biomedical polymer
  • bioplastic
  • polysaccharide
  • protein
  • polyester

Published Papers (10 papers)

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Research

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13 pages, 2339 KiB  
Article
Crabs Marine Waste—A Valuable Source of Chitosan: Tuning Chitosan Properties by Chitin Extraction Optimization
by Cristiana Luminița Gîjiu, Raluca Isopescu, Daniel Dinculescu, Maria Memecică, Manuela-Rossemary Apetroaei, Mirela Anton, Verginica Schröder and Ileana Rău
Polymers 2022, 14(21), 4492; https://doi.org/10.3390/polym14214492 - 24 Oct 2022
Cited by 10 | Viewed by 1967
Abstract
Chitin extraction from crab shells was studied experimentally and optimized aiming to obtain chitosan with predefined deacetylation degree and molecular mass. To find out the optimum operating conditions that ensure the obtaining of a chitosan with highest deacetylation degree and specific molecular mass [...] Read more.
Chitin extraction from crab shells was studied experimentally and optimized aiming to obtain chitosan with predefined deacetylation degree and molecular mass. To find out the optimum operating conditions that ensure the obtaining of a chitosan with highest deacetylation degree and specific molecular mass four parameters were varied: the concentration of NaOH and the temperature for deproteinization step, respectively HCl concentration and the number of acidic treatments for the demineralization stage. The experiment was carried on following Taguchi orthogonal array L9, and the best combination of factors was found using the desirability function approach. The optimization results showed that 5% NaOH concentration and low temperatures lead to a chitosan with high deacetylation degree. High molecular mass chitosan is obtained when a single step acidic treatment is used, while a chitosan with low molar mass is obtained for multiple acid contacts and higher HCl concentration. Full article
(This article belongs to the Special Issue Biobased and Natural Polymers)
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11 pages, 1640 KiB  
Article
Initiated Chemical Vapor Deposition (iCVD) of Bio-Based Poly(tulipalin A) Coatings: Structure and Material Properties
by Valeria Graur, Adrivit Mukherjee, Khaled O. Sebakhy and Ranjita K. Bose
Polymers 2022, 14(19), 3993; https://doi.org/10.3390/polym14193993 - 23 Sep 2022
Cited by 6 | Viewed by 2010
Abstract
A solvent-free route of initiated chemical vapor deposition (iCVD) was used to synthesize a bio-renewable poly(α-Methylene-γ-butyrolactone) (PMBL) polymer. α-MBL, also known as tulipalin A, is a bio-based monomer that can be a sustainable alternative to produce polymer coatings with interesting material properties. The [...] Read more.
A solvent-free route of initiated chemical vapor deposition (iCVD) was used to synthesize a bio-renewable poly(α-Methylene-γ-butyrolactone) (PMBL) polymer. α-MBL, also known as tulipalin A, is a bio-based monomer that can be a sustainable alternative to produce polymer coatings with interesting material properties. The produced polymers were deposited as thin films on three different types of substrates—polycarbonate (PC) sheets, microscopic glass, and silicon wafers—and characterized via an array of characterization techniques, including Fourier-transform infrared (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR), ultraviolet visible spectroscopy (UV–vis), differential scanning calorimetry (DSC), size-exclusion chromatography (SEC), and thermogravimetric analysis (TGA). Optically transparent thin films and coatings of PMBL were found to have high thermal stability up to 310 °C. The resulting PMBL films also displayed good optical characteristics, and a high glass transition temperature (Tg~164 °C), higher than the Tg of its structurally resembling fossil-based linear analogue-poly(methyl methacrylate). The effect of monomer partial pressure to monomer saturation vapor pressure (Pm/Psat) on the deposition rate was investigated in this study. Both the deposition rate and molar masses increased linearly with Pm/Psat following the normal iCVD mechanism and kinetics that have been reported in literature. Full article
(This article belongs to the Special Issue Biobased and Natural Polymers)
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21 pages, 3022 KiB  
Article
Potential Applications of an Exopolysaccharide Produced by Bacillus xiamenensis RT6 Isolated from an Acidic Environment
by Elisa Huang-Lin, Enrique Sánchez-León, Ricardo Amils and Concepcion Abrusci
Polymers 2022, 14(18), 3918; https://doi.org/10.3390/polym14183918 - 19 Sep 2022
Cited by 7 | Viewed by 2004
Abstract
The Bacillus xiamenensis RT6 strain was isolated and identified by morphological, biochemical and molecular tests from an extreme acidic environment, Rio Tinto (Huelva). Optimisation tests for exopolysaccharide (EPS) production in different culture media determined that the best medium was a minimal medium with [...] Read more.
The Bacillus xiamenensis RT6 strain was isolated and identified by morphological, biochemical and molecular tests from an extreme acidic environment, Rio Tinto (Huelva). Optimisation tests for exopolysaccharide (EPS) production in different culture media determined that the best medium was a minimal medium with glucose as the only carbon source. The exopolymer (EPSt) produced by the strain was isolated and characterised using different techniques (GC-MS, HPLC/MSMS, ATR-FTIR, TGA, DSC). The molecular weight of EPSt was estimated. The results showed that the average molecular weight of EPSt was approximately 2.71 × 104 Da and was made up of a heteropolysaccharide composed of glucose (60%), mannose (20%) and galactose (20%). The EPSt showed antioxidant capabilities that significantly improved cell viability. Metal chelation determined that EPSt could reduce the concentration of transition metals such as iron at the highest concentrations tested. Finally, the emulsification study showed that EPSt was able to emulsify different natural polysaccharide oils, reaching up to an 80% efficiency (olive and sesame oil), and was a good candidate for the substitution of the most polluting emulsifiers. The EPSt was found to be suitable for pharmaceutical and industrial applications. Full article
(This article belongs to the Special Issue Biobased and Natural Polymers)
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17 pages, 4450 KiB  
Article
Grape Canes (Vitis vinifera L.) Applications on Packaging and Particleboard Industry: New Bioadhesive Based on Grape Extracts and Citric Acid
by Jorge Santos, João Pereira, Danilo Escobar-Avello, Irene Ferreira, Carlos Vieira, Fernão D. Magalhães, Jorge Manuel Martins and Luísa H. Carvalho
Polymers 2022, 14(6), 1137; https://doi.org/10.3390/polym14061137 - 12 Mar 2022
Cited by 14 | Viewed by 3017
Abstract
The main by-product generated in the wine industry are the grape canes, derived from the pruning process. In order to increase the valorisation possibilities of this highly polyphenolic lignocellulosic material, this work focuses on its applicability in the materials industry. As a first [...] Read more.
The main by-product generated in the wine industry are the grape canes, derived from the pruning process. In order to increase the valorisation possibilities of this highly polyphenolic lignocellulosic material, this work focuses on its applicability in the materials industry. As a first step, we demonstrate the viability of using grape cane particles as raw material for particleboard production, combined with a melamine formaldehyde urea (MFU) binder. In addition, looking for the application of these particleboards in the food packaging industry, particleboards based on grape canes were also produced using a new bioadhesive, obtained from the grape cane extract and citric acid. The self-condensation reaction of the grape cane extracts, and the curing reaction with citric acid, were studied by FTIR-ATR and ABES showing the feasibility of this new bioadhesive formulation. Looking for a zero-waste process, the effect of the type of raw material (fresh grape cane, solid by-product of the extraction) and of the extract used on the properties of particleboard were also studied. Citric acid was demonstrated to be a good crosslinking agent for grape cane extract. This work shows that it is possible to produce a new lignocellulosic product based only on grape cane particles using a binder based on grape cane extracts and citric acid. The implemented methodology allowed producing particleboards with applicability in the food-packaging industry, minimizing the waste generated in the process. Full article
(This article belongs to the Special Issue Biobased and Natural Polymers)
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20 pages, 1166 KiB  
Article
A Systematic Study of the Antioxidant Capacity of Humic Substances against Peroxyl Radicals: Relation to Structure
by Olga I. Klein, Natalia A. Kulikova, Andrey I. Konstantinov, Maria V. Zykova and Irina V. Perminova
Polymers 2021, 13(19), 3262; https://doi.org/10.3390/polym13193262 - 25 Sep 2021
Cited by 13 | Viewed by 2696
Abstract
Humic substances (HS) are natural supramolecular systems of high- and low-molecular-weight compounds with distinct immunomodulatory and protective properties. The key beneficial biological activity of HS is their antioxidant activity. However, systematic studies of the antioxidant activity of HS against biologically relevant peroxyl radicals [...] Read more.
Humic substances (HS) are natural supramolecular systems of high- and low-molecular-weight compounds with distinct immunomodulatory and protective properties. The key beneficial biological activity of HS is their antioxidant activity. However, systematic studies of the antioxidant activity of HS against biologically relevant peroxyl radicals are still scarce. The main objective of this work was to estimate the antioxidant capacity (AOC) of a broad set of HS widely differing in structure using an oxygen radical absorption capacity (ORAC) assay. For this purpose, 25 samples of soil, peat, coal, and aquatic HS and humic-like substances were characterized using elemental analysis and quantitative 13C solution-state NMR. The Folin–Ciocalteu method was used to quantify total phenol (TP) content in HS. The determined AOC values varied in the range of 0.31–2.56 μmol Trolox eqv. mg−1, which is close to the values for ascorbic acid and vitamin E. Forward stepwise regression was used to reveal the four main factors contributing to the AOC value of HS: atomic C/N ratio, content of O-substituted methine and methoxyl groups, and TP. The results obtained clearly demonstrate the dependence of the AOC of HS on both phenolic and non-phenolic moieties in their structure, including carbohydrate fragments. Full article
(This article belongs to the Special Issue Biobased and Natural Polymers)
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17 pages, 2682 KiB  
Article
Synthesis of New Chitosan from an Endemic Chilean Crayfish Exoskeleton (Parastacus Pugnax): Physicochemical and Biological Properties
by César Burgos-Díaz, Mauricio Opazo-Navarrete, José Luis Palacios, Tamara Barahona, Yohanna Mosi-Roa, Fresia Anguita-Barrales and Mariela Bustamante
Polymers 2021, 13(14), 2304; https://doi.org/10.3390/polym13142304 - 14 Jul 2021
Cited by 11 | Viewed by 3055
Abstract
Chitin is one of the most abundant natural polysaccharides in the world and it is mainly used to produce chitosan by a deacetylation process. In the present study, the extraction of chitin and chitosan from the Parastacus pugnax (P. pugnax) crayfish [...] Read more.
Chitin is one of the most abundant natural polysaccharides in the world and it is mainly used to produce chitosan by a deacetylation process. In the present study, the extraction of chitin and chitosan from the Parastacus pugnax (P. pugnax) crayfish exoskeleton was studied for the first time. Thus, the P. pugnax crayfish exoskeleton was converted to chitosan following the steps of depigmentation, deproteinization, and deacetylation. The produced chitosan (Chitosan-CGNA) was characterized in terms of the protein content, solubility, degree of deacetylation, viscosity, molecular weight, FTIR, SEM, XRD, antimicrobial, and antioxidant activity. The results showed that the obtained chitosan had a high degree of deacetylation (91.55%) and a medium molecular weight (589.43 kDa). The antibacterial activity of the chitosan was tested against bacterial strains relevant for the food industry and the lowest minimum inhibitory concentration (MIC) values were evidenced with Salmonella tiphymurium (S. typhimurium), Staphylococcus aureus (S. aureus), Enterococcus faecalis (E. faecalis) and Listeria. Monocytogenes (L. monocytogenes). Moreover, the Chitosan-CGNA showed an effect on DPPH radical scavenging activity, and its antioxidant activity was dependent on concentration and deacetylation degree. These results suggest that P. pugnax exoskeleton could be an excellent natural source for the production of chitosan with potential applications in the health system, and to prevent infections associated with pathogens strains. Full article
(This article belongs to the Special Issue Biobased and Natural Polymers)
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18 pages, 6583 KiB  
Article
Purification of Hollow Sporopollenin Microcapsules from Sunflower and Chamomile Pollen Grains
by Jose Manuel Ageitos, Sandra Robla, Lorena Valverde-Fraga, Marcos Garcia-Fuentes and Noemi Csaba
Polymers 2021, 13(13), 2094; https://doi.org/10.3390/polym13132094 - 25 Jun 2021
Cited by 14 | Viewed by 3232
Abstract
Pollen grains are natural microcapsules comprised of the biopolymer sporopollenin. The uniformity and special tridimensional architecture of these sporopollenin structures confer them attractive properties such as high resistance and improved bioadhesion. However, natural pollen can be a source of allergens, hindering its biomedical [...] Read more.
Pollen grains are natural microcapsules comprised of the biopolymer sporopollenin. The uniformity and special tridimensional architecture of these sporopollenin structures confer them attractive properties such as high resistance and improved bioadhesion. However, natural pollen can be a source of allergens, hindering its biomedical applicability. Several methods have been developed to remove internal components and allergenic compounds, usually involving long and laborious processes, which often cannot be extended to other pollen types. In this work, we propose an abridged protocol to produce stable and pristine hollow pollen microcapsules, together with a complete physicochemical and morphological characterization of the intermediate and final products. The optimized procedure has been validated for different pollen samples, also producing sporopollenin microcapsules from Matricaria species for the first time. Pollen microcapsules obtained through this protocol presented low protein content (4.4%), preserved ornamented morphology with a nanoporous surface, and low product density (0.14 g/cm3). These features make them interesting candidates from a pharmaceutical perspective due to the versatility of this biomaterial as a drug delivery platform. Full article
(This article belongs to the Special Issue Biobased and Natural Polymers)
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13 pages, 271 KiB  
Article
In Vivo Characterization and Application of the PHA Synthase from Azotobacter vinelandii for the Biosynthesis of Polyhydroxyalkanoate Containing 4-Hydroxybutyrate
by Pei-Shze Mok, Jo-Ann Chuah, Nazalan Najimudin, Pauline-Woan-Ying Liew, Bor-Chyan Jong and Kumar Sudesh
Polymers 2021, 13(10), 1576; https://doi.org/10.3390/polym13101576 - 14 May 2021
Cited by 2 | Viewed by 2181
Abstract
Polyhydroxyalkanoate (PHA) is a biodegradable thermoplastic naturally synthesized by many microorganisms, and the PHA synthase (PhaC) is known to be the key enzyme involved in determining the material properties and monomer composition of the produced PHA. The ability to exploit widely distributed, commonly [...] Read more.
Polyhydroxyalkanoate (PHA) is a biodegradable thermoplastic naturally synthesized by many microorganisms, and the PHA synthase (PhaC) is known to be the key enzyme involved in determining the material properties and monomer composition of the produced PHA. The ability to exploit widely distributed, commonly found soil microorganisms such as Azotobacter vinelandii to synthesize PHA containing the lipase-degradable 4-hydroxybutyrate (4HB) monomer will allow for convenient production of biocompatible and flexible PHA. Comparisons between the A. vinelandii wild type and mutant strains, with and without a surface layer (S-layer), respectively, in terms of gene or amino acid sequences, synthase activity, granule morphology, and PHA productivity, revealed that the S-layer is the sole factor affecting PHA biosynthesis by A. vinelandii. Based on PHA biosynthesis using different carbon sources, the PhaC of A. vinelandii showed specificity for short-chain-length PHA monomers, making it a member of the Class I PHA synthases. In addition, it was proven that the PhaC of A. vinelandii has the inherent ability to polymerize 4-hydroxybutyrate (4HB) and the mediated accumulation of PHA with 4HB fractions ranging from 10 mol% to as high as 22 mol%. The synthesis of biocompatible PHA containing tailorable amounts of 4HB with an expanded range of elasticity and lipase-degradability will enable a wider range of applications in the biomedical field. Full article
(This article belongs to the Special Issue Biobased and Natural Polymers)
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11 pages, 5013 KiB  
Article
Antioxidant Potential of Physicochemically Characterized Gracilaria blodgettii Sulfated Polysaccharides
by Bilal Muhammad Khan, Li-Xin Zheng, Wajid Khan, Aftab Ali Shah, Yang Liu and Kit-Leong Cheong
Polymers 2021, 13(3), 442; https://doi.org/10.3390/polym13030442 - 30 Jan 2021
Cited by 12 | Viewed by 2369
Abstract
Marine rhodophyte polysaccharides have a wide range of described biological properties with nontoxic characteristics, and show great potential in prebiotics and the functional foods industries. However, there is a virtual lack of Gracilaria blodgettii polysaccharides (GBP) profiling and their bioactivities. This study was [...] Read more.
Marine rhodophyte polysaccharides have a wide range of described biological properties with nontoxic characteristics, and show great potential in prebiotics and the functional foods industries. However, there is a virtual lack of Gracilaria blodgettii polysaccharides (GBP) profiling and their bioactivities. This study was designed while keeping in view the lack of physical and chemical characterization of GBP. This polysaccharide was also not previously tested for any bioactivities. A linear random coil conformation was observed for GBP, which was found to be a polysaccharide. A significant sulfate (w/w, 9.16%) and 3,6-anhydrogalactose (AHG, w/w, 17.97%) content was found in GBP. The significant difference in its setting (27.33 °C) and melting (64.33 °C) points makes it resistant to increasing heat. This, in turn, points to its utility in industrial scale processing and in enhancing the shelf-life of products under high temperatures. A radical scavenging activity of 19.80%, 25.42% and 8.80% was noted for GBP (3 mg/mL) in 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2’-azino-bis (ABTS) and hydroxyl radical (HO) scavenging assays, respectively. Therefore, the findings suggest that Gracilaria blodgettii polysaccharides display a good antioxidant potential and may have potential applications in the functional food industry. Full article
(This article belongs to the Special Issue Biobased and Natural Polymers)
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Review

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23 pages, 2182 KiB  
Review
Collagen Alignment via Electro-Compaction for Biofabrication Applications: A Review
by Benjamin P. Carr, Zhi Chen, Johnson H. Y. Chung and Gordon G. Wallace
Polymers 2022, 14(20), 4270; https://doi.org/10.3390/polym14204270 - 12 Oct 2022
Cited by 7 | Viewed by 3609
Abstract
As the most prevalent structural protein in the extracellular matrix, collagen has been extensively investigated for biofabrication-based applications. However, its utilisation has been impeded due to a lack of sufficient mechanical toughness and the inability of the scaffold to mimic complex natural tissues. [...] Read more.
As the most prevalent structural protein in the extracellular matrix, collagen has been extensively investigated for biofabrication-based applications. However, its utilisation has been impeded due to a lack of sufficient mechanical toughness and the inability of the scaffold to mimic complex natural tissues. The anisotropic alignment of collagen fibres has been proven to be an effective method to enhance its overall mechanical properties and produce biomimetic scaffolds. This review introduces the complicated scenario of collagen structure, fibril arrangement, type, function, and in addition, distribution within the body for the enhancement of collagen-based scaffolds. We describe and compare existing approaches for the alignment of collagen with a sharper focus on electro-compaction. Additionally, various effective processes to further enhance electro-compacted collagen, such as crosslinking, the addition of filler materials, and post-alignment fabrication techniques, are discussed. Finally, current challenges and future directions for the electro-compaction of collagen are presented, providing guidance for the further development of collagenous scaffolds for bioengineering and nanotechnology. Full article
(This article belongs to the Special Issue Biobased and Natural Polymers)
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