Biodegradable Polymers for Medical Applications

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Processing and Engineering".

Deadline for manuscript submissions: closed (25 November 2020) | Viewed by 22818

Special Issue Editors


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Guest Editor
Department of Mining-Metallurgy Engineering and Materials Science, POLYMAT, University of the Basque Country (UPV/EHU), School of Engineering, Alameda de Urquijo s/n, 48013 Bilbao, Spain
Interests: polymeric biomaterials; biodegradable polymers; polylactides; bioactive polymer hybrids; tissue engineeringstructure-property relationships of biodegradable polymers for medical applications
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Guest Editor
The University of the Basque Country (UPV/EHU) and Basque Center for Macromolecular Design and Engineering POLYMAT, 480130 Bilbao, Spain
Interests: polymer/polymer complexes; polymer blends; specific interactions; structural analysis of crystalline polymers by FTIR; molecular modeling
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Campus Bizkaia, Universidad del Pais Vasco - Euskal Herriko Unibertsitatea, Bilbao, Spain
Interests: bioresorbable polymers; polymer capsules; 3-dimensional scaffolds; oxidative stress; tissue engineering

Special Issue Information

Dear Colleagues,

Contrarily to their nondegradable counterparts, biodegradable polymers undergo a degradation process under physiological conditions, making them perfect candidates for several biomedical applications. As implants, the use of biodegradable polymers avoids the need for a second surgery to remove the implant at the end of its functional life. Further, in load-bearing applications, biodegradable implants allow a progressive transfer of the mechanical load to the newly formed tissue as they slowly degrade. In the field of tissue engineering, the combination of stem cells with biodegradable scaffolds currently represents a promising therapeutic approach to assure the survival, differentiation, and functional integration of the transplanted cells. Thus, the scaffolds not only provide a substrate for cells to attach and proliferate but also, if adequately designed, modulate stem cell differentiation. Biodegradable polymers, in the form of films, nano-/microparticles, polymer capsules, etc. have also been employed as drug delivery devices in the biomedical field. By controlling several parameters such as the physical and chemical interactions between the drug and the polymer and the degradation rate of the polymer, a controlled delivery of the drug at the desired rate and duration can be achieved, thus maintaining the drug level in the body within the therapeutic window.  

For all these purposes, either synthetic (e.g., polylactide, polycaprolactone, polyglycolide) or natural polymers (e.g., collagen, elastin, hyaluronic acid) have been successfully employed. Thanks to the advances in polymer synthesis, the intrinsic properties of the biodegradable polymers (e.g., mechanical properties, degradation rate, hydrophobicity/hydrophilicity) can be finely controlled to meet the requirement of the specific biomedical application. These properties can be further tuned by blending, copolymerizing, and/or compounding with nano-/microparticles that can provide advanced functionalities. Last but not least, biodegradable polymers showing nano-/microstructured surfaces can be manufactured by advanced fabrication techniques, including 3D printing, electrowriting, electrospinning, self-assembly, etc. These complex topographies can mimic the extracellular matrix where cells reside, improving, accordingly, the interaction between the polymeric substrate and cells in terms of adhesion, proliferation, and differentiation.

In this current Special Issue of Polymers, we invite contributions covering the most relevant aspects of biodegradable polymers for biomedical applications. Both original or review articles addressing the synthesis of novel biodegradable polymers for biomedical applications, the fabrication of biomimetic polymeric scaffolds via advanced fabrication techniques, and the study of their interaction with cells, the development of micro-/nanoentities for drug delivery purposes and in vivo tests of biodegradable polymers and nanocomposites are welcome.

Prof. Jose-Ramon Sarasua
Dr. Aitor Larrañaga
Dr. Emiliano Meaurio
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

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

  • Biodegradable polymers
  • Tissue engineering
  • Drug delivery devices
  • Three-dimensional scaffolds
  • Nanotopography
  • Cell differentiation
  • Nanocomposites

Published Papers (5 papers)

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Research

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14 pages, 8565 KiB  
Article
Novel Hydrogels of Chitosan and Poly(vinyl alcohol) Reinforced with Inorganic Particles of Bioactive Glass
by O. Sánchez-Aguinagalde, Ainhoa Lejardi, Emilio Meaurio, Rebeca Hernández, Carmen Mijangos and Jose-Ramon Sarasua
Polymers 2021, 13(5), 691; https://doi.org/10.3390/polym13050691 - 25 Feb 2021
Cited by 17 | Viewed by 2739
Abstract
Chitosan (CS) and poly(vinyl alcohol) (PVA) hydrogels, a polymeric system that shows a broad potential in biomedical applications, were developed. Despite the advantages they present, their mechanical properties are insufficient to support the loads that appear on the body. Thus, it was proposed [...] Read more.
Chitosan (CS) and poly(vinyl alcohol) (PVA) hydrogels, a polymeric system that shows a broad potential in biomedical applications, were developed. Despite the advantages they present, their mechanical properties are insufficient to support the loads that appear on the body. Thus, it was proposed to reinforce these gels with inorganic glass particles (BG) in order to improve mechanical properties and bioactivity and to see how this reinforcement affects levofloxacin drug release kinetics. Scanning electron microscopy (SEM), X-ray diffraction (XRD), swelling tests, rheology and drug release studies characterized the resulting hydrogels. The experimental results verified the bioactivity of these gels, showed an improvement of the mechanical properties and proved that the added bioactive glass does affect the release kinetics. Full article
(This article belongs to the Special Issue Biodegradable Polymers for Medical Applications)
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18 pages, 2624 KiB  
Article
Dynamic Mechanical Control of Alginate-Fibronectin Hydrogels with Dual Crosslinking: Covalent and Ionic
by Sara Trujillo, Melanie Seow, Aline Lueckgen, Manuel Salmeron-Sanchez and Amaia Cipitria
Polymers 2021, 13(3), 433; https://doi.org/10.3390/polym13030433 - 29 Jan 2021
Cited by 14 | Viewed by 4618
Abstract
Alginate is a polysaccharide used extensively in biomedical applications due to its biocompatibility and suitability for hydrogel fabrication using mild reaction chemistries. Though alginate has commonly been crosslinked using divalent cations, covalent crosslinking chemistries have also been developed. Hydrogels with tuneable mechanical properties [...] Read more.
Alginate is a polysaccharide used extensively in biomedical applications due to its biocompatibility and suitability for hydrogel fabrication using mild reaction chemistries. Though alginate has commonly been crosslinked using divalent cations, covalent crosslinking chemistries have also been developed. Hydrogels with tuneable mechanical properties are required for many biomedical applications to mimic the stiffness of different tissues. Here, we present a strategy to engineer alginate hydrogels with tuneable mechanical properties by covalent crosslinking of a norbornene-modified alginate using ultraviolet (UV)-initiated thiol-ene chemistry. We also demonstrate that the system can be functionalised with cues such as full-length fibronectin and protease-degradable sequences. Finally, we take advantage of alginate’s ability to be crosslinked covalently and ionically to design dual crosslinked constructs enabling dynamic control of mechanical properties, with gels that undergo cycles of stiffening–softening by adding and quenching calcium cations. Overall, we present a versatile hydrogel with tuneable and dynamic mechanical properties, and incorporate cell-interactive features such as cell-mediated protease-induced degradability and full-length proteins, which may find applications in a variety of biomedical contexts. Full article
(This article belongs to the Special Issue Biodegradable Polymers for Medical Applications)
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20 pages, 4440 KiB  
Article
Natural Cellulose Fibers for Surgical Suture Applications
by María Paula Romero Guambo, Lilian Spencer, Nelson Santiago Vispo, Karla Vizuete, Alexis Debut, Daniel C. Whitehead, Ralph Santos-Oliveira and Frank Alexis
Polymers 2020, 12(12), 3042; https://doi.org/10.3390/polym12123042 - 18 Dec 2020
Cited by 16 | Viewed by 5593
Abstract
Suture biomaterials are critical in wound repair by providing support to the healing of different tissues including vascular surgery, hemostasis, and plastic surgery. Important properties of a suture material include physical properties, handling characteristics, and biological response for successful performance. However, bacteria can [...] Read more.
Suture biomaterials are critical in wound repair by providing support to the healing of different tissues including vascular surgery, hemostasis, and plastic surgery. Important properties of a suture material include physical properties, handling characteristics, and biological response for successful performance. However, bacteria can bind to sutures and become a source of infection. For this reason, there is a need for new biomaterials for suture with antifouling properties. Here we report two types of cellulose fibers from coconut (Cocos nucifera) and sisal (Agave sisalana), which were purified with a chemical method, characterized, and tested in vitro and in vivo. According to SEM images, the cellulose fiber from coconut has a porous surface, and sisal has a uniform structure without internal spaces. It was found that the cellulose fiber from sisal has mechanical properties closer to silk fiber biomaterial using Ultimate Tensile Strength. When evaluating the cellulose fibers biodegradability, the cellulose from coconut showed a rapid weight loss compared to sisal. The antifouling test was negative, which demonstrated that neither possesses intrinsic microbicidal activity. Yet, a weak biofilm was formed on sisal cellulose fibers suggesting it possesses antifouling properties compared to cellulose from coconut. In vivo experiments using healthy mice demonstrated that the scarring and mechanical connection was like silk for both cellulose fibers. Overall, our results showed the potential use of cellulose fibers from vegetal for surgical sutures due to excellent mechanical properties, rapid degradation, and no bacterial adhesion. Full article
(This article belongs to the Special Issue Biodegradable Polymers for Medical Applications)
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18 pages, 6147 KiB  
Article
Microstructural Changes during Degradation of Biobased Poly(4-hydroxybutyrate) Sutures
by Ina Keridou, Lourdes Franco, Luis J. del Valle, Juan C. Martínez, Lutz Funk, Pau Turon and Jordi Puiggalí
Polymers 2020, 12(9), 2024; https://doi.org/10.3390/polym12092024 - 4 Sep 2020
Cited by 3 | Viewed by 2471
Abstract
Fibers of poly(4-hydroxybutyrate) (P4HB) have been submitted to both hydrolytic and enzymatic degradation media in order to generate samples with different types and degrees of chain breakage. Random chain hydrolysis is clearly enhanced by varying temperatures from 37 to 55 °C and is [...] Read more.
Fibers of poly(4-hydroxybutyrate) (P4HB) have been submitted to both hydrolytic and enzymatic degradation media in order to generate samples with different types and degrees of chain breakage. Random chain hydrolysis is clearly enhanced by varying temperatures from 37 to 55 °C and is slightly dependent on the pH of the medium. Enzymatic attack is a surface erosion process with significant solubilization as a consequence of a preferent stepwise degradation. Small angle X-ray diffraction studies revealed a peculiar supramolecular structure with two different types of lamellar stacks. These were caused by the distinct shear stresses that the core and the shell of the fiber suffered during the severe annealing process. External lamellae were characterized by surfaces tilted 45° with respect to the stretching direction and a higher thickness, while the inner lamellae were more imperfect and had their surfaces perpendicularly oriented to the fiber axis. In all cases, WAXD data indicated that the chain molecular axis was aligned with the fiber axis and molecules were arranged according to a single orthorhombic structure. A gradual change of the microstructure was observed as a function of the progress of hydrolysis while changes were not evident under an enzymatic attack. Hydrolysis mainly affected the inner lamellar stacks as revealed by the direct SAXS patterns and the analysis of correlation functions. Both lamellar crystalline and amorphous thicknesses slightly increased as well as the electronic contrast between amorphous and crystalline regions. Thermal treatments of samples exposed to the hydrolytic media revealed microstructural changes caused by degradation, with the inner lamellae being those that melted faster. Full article
(This article belongs to the Special Issue Biodegradable Polymers for Medical Applications)
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Review

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47 pages, 5334 KiB  
Review
Biomedical Applications of Bacteria-Derived Polymers
by Jonathan David Hinchliffe, Alakananda Parassini Madappura, Syed Mohammad Daniel Syed Mohamed and Ipsita Roy
Polymers 2021, 13(7), 1081; https://doi.org/10.3390/polym13071081 - 29 Mar 2021
Cited by 24 | Viewed by 6295
Abstract
Plastics have found widespread use in the fields of cosmetic, engineering, and medical sciences due to their wide-ranging mechanical and physical properties, as well as suitability in biomedical applications. However, in the light of the environmental cost of further upscaling current methods of [...] Read more.
Plastics have found widespread use in the fields of cosmetic, engineering, and medical sciences due to their wide-ranging mechanical and physical properties, as well as suitability in biomedical applications. However, in the light of the environmental cost of further upscaling current methods of synthesizing many plastics, work has recently focused on the manufacture of these polymers using biological methods (often bacterial fermentation), which brings with them the advantages of both low temperature synthesis and a reduced reliance on potentially toxic and non-eco-friendly compounds. This can be seen as a boon in the biomaterials industry, where there is a need for highly bespoke, biocompatible, processable polymers with unique biological properties, for the regeneration and replacement of a large number of tissue types, following disease. However, barriers still remain to the mass-production of some of these polymers, necessitating new research. This review attempts a critical analysis of the contemporary literature concerning the use of a number of bacteria-derived polymers in the context of biomedical applications, including the biosynthetic pathways and organisms involved, as well as the challenges surrounding their mass production. This review will also consider the unique properties of these bacteria-derived polymers, contributing to bioactivity, including antibacterial properties, oxygen permittivity, and properties pertaining to cell adhesion, proliferation, and differentiation. Finally, the review will select notable examples in literature to indicate future directions, should the aforementioned barriers be addressed, as well as improvements to current bacterial fermentation methods that could help to address these barriers. Full article
(This article belongs to the Special Issue Biodegradable Polymers for Medical Applications)
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