Nanostructured Polymer Composites for Biomedical Applications

Sarat Kumar Swain, Mohammad Jawaid

• Publisher: Elsevier
• Year: 2019
• Print ISBN: 9780128167717
• eBook ISBN: 9780128168929
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Nanostructured Polymer Composites for Biomedical Applications addresses the challenges researchers face regarding the creation of nanostructured polymer composites that not only have superior performance and mechanical properties, but also have acceptable biological function. This book discusses current efforts to meet this challenge by discussing the multidisciplinary nature of nanostructured polymer composite biomaterials from various fields, including materials science, polymer science, biomedical engineering and biomedicine. This compilation of existing knowledge will lead to the generation of new terminology and definitions across individual disciplines. As such, this book will help researchers and engineers develop new products and devices for use in effective medical treatment. - Summarizes the most recent strategies to develop nanostructured polymer composite biomaterials for biomedicine - Outlines the major preparation and characterization techniques for a range of polymer nanocomposites used in biomedicine - Explores the design of new types of nanostructured polymer composites for applications in drug delivery, tissue engineering, gene therapy and bone replacement

Chapter 1

Biomedical Applications of Nanostructured Polymeric Materials

Magdalena Stevanović, Institute of Technical Sciences of the Serbian Academy of Sciences and Arts, Belgrade, Serbia

Abstract

Nanostructured polymeric materials have been extensively used in different areas of biomedicine. They are polymeric materials in nanometer scale or composites containing polymeric nanomaterials. In particular, improvements in polymer-correlated nanomaterials have brought about a groundbreaking change to the fields of biomedicine and innovative biomaterials. The materials which belong to this group of nanostructured polymeric materials are a wide variety of nanoparticles, nanocapsules, nanogels, nanofibers, nanocomposites, micelles, dendrimers, and polymersomes. They can be used in controlled and targeted drug delivery, bioimaging, tissue engineering, and regenerative medicine. This chapter addresses issues regarding nanostructured polymeric materials, their production methods, characterizations, and biomedical applications.

Keywords

Polymers; nanostructures; nanocarriers; biomaterials; biomedical applications

1.1 Introduction

Polymeric materials in the nanometer scale, as well as their composites, are of great importance in the field of biomedicine. Development in this area has led to significant progress in terms of improvement in the field of already existing biomaterials as well as the synthesis of a new one with tailor-made properties and functionalities. Such materials include nanoparticles, nanocapsules, nanofibers, nanogels, nanocomposites, micelles, polymersomes, and dendrimers. These nanostructured polymeric materials have been widely exploited for different biomedical purposes, for instance, in controlled and targeted delivery of medicaments, bioimaging, regenerative medicine, gene therapy, etc. The advantages of special features of nanostructures increase the efficiency and accuracy of medical diagnosis, treatment, and observation at the level of individual molecules or molecular structures. Different active substances can be delivered by polymer particles. For these purposes and the preparation of such particles at the nanoscale, natural (chitosan, alginate, albumin, etc.) as well as synthetic polymers [polylactides (PLA), polyglycolides, poly(lactide-co-glycolides), poly(ε-caprolactone) (PCL), and also tyrosine-derived polymers] can be used. However, natural polymers often lack consistency from batch to batch, which often makes them difficult for use in preparing biomaterials with reproducible properties and other desirable characteristics [1,2]. Conversely, synthetic polymers can be synthesized with high enough purity as well as reproducibility. One of the important basic requirements in drug delivery of medicaments is a spherical form of the polymer micro- and nanoparticles as well as for them to be narrow. The morphology of the particles has a crucial role in processes which occur between particles and cells. For intravenous administration of particles, the most important parameters are encapsulation efficiency and loading amount, the charge of the particles, and the dynamics of the release. Degradation is also a very important factor which influences the release of the active substance from polymer particles. Therefore it is crucial and necessary to examine the degradation process of such systems. It is also important to develop a process for the production of nanoparticles that will be environmentally friendly. This is, without doubt, a challenge and involves nontoxic materials and especially solvents, materials which are biodegradable, processes that require less energy, etc. All this presents challenges in the field of research of different nanostructured polymeric materials for biomedical applications. In this chapter different types of nanostructured polymeric materials, their production methods, characterizations, and applications are described. This chapter highlights innovative nanosystems and their applications in different biomedical fields and will also be a contribution to the development of commercial-scale production and further applications of nanostructured polymeric materials.

1.2 Nanostructured Polymeric Materials

Various materials, including nanoparticles, nanocapsules, nanofibers, nanogels, nanocomposites, micelles, polymersomes, and dendrimers, are all used for different applications in biomedicine.

1.2.1 Nanoparticles

Nanoparticles have been explored for more than a decade for numerous applications [1,2]. This approach offers several advantages compared to other systems for delivery of medicaments. Nanocarriers are used for (1) delivering immobilized active substances; (2) increasing the stability of drugs by chemical or physical means; (3) enhancing the solubility of drugs; (4) delivering a higher amount of medicaments to specific areas; and (5) conducting specific, targeted, treatments based on the ligands attached to the cells [1]. The most commonly used nanoparticles for such purposes are polymeric nanoparticles. Among polymers of natural origin, the most commonly used for preparing nanoparticles is chitosan. Chitosan is most often examined in the preparation of formulations for medical applications through the skin, that is, topical delivery. Chitosan is a water-soluble polysaccharide extracted from chitin. It may serve as a bioadhesive. Also, it can bind to mucoproteins that are negatively charged while chitosan is positively charged. This is important since it leads to prolonging of the circulation time of drugs based on chitosan and thus enhances their bioavailability [3]. From the literature, the most common methods for synthesis of nanoparticles from chitosan are ionic cross-linking, or covalent cross-linking [4], precipitation [5], polymerization [6], or self-assembly procedures [7]. Based on the techniques applied for the preparation of particles, their sizes vary from several nanometers to several hundred nanometers. Complexes of chitosan and drug are usually obtained through interactions among positively charged (cationic) chitosan and negatively charged (anionic) drugs [8,9]. By tailoring the degradation, it is possible to influence and control the drug-delivery release from chitosan-based nanoparticles. In this respect, such a system can enable the release of the drug over a period of several days to several months [10]. Alginate is also representative of natural polymers. It also belongs to the group of polysaccharides. Recently, Ibrahim et al. reported on the preparation of alginate nanoparticles with an immobilized drug, brimonidine [11]. This system has shown improvement in vivo regarding intraocular pressure when compared to commercially available brimonidine-tartrate eye drops [11]. In another study, the use of nanoparticles for immobilization of antimicrobial substances has been examined. For this purpose have been used chitosan and alginate. The system showed superior in vitro antimicrobial activity in comparison with benzoyl-peroxide [12]. The next representative of natural polymers is albumin. Albumin nanoparticles are nontoxic, biocompatible, and biodegradable carriers of different active substances [13,14]. These nanoparticles are often used for producing systems in controlled drug delivery [15,16]. They have gained significant attention in this field due to their high binding capacity. Recently, Das et al. illustrated that albumin nanoparticles containing aspirin achieved the release of aspirin in vitro for 72 h and have potential as a topical system for diabetic retinopathy [15]. In a study by Lomis et al., a method for obtaining human serum albumin nanoparticles with encapsulated anticancer drug paclitaxel was described. The synthesis was done by the emulsion evaporation method and high-pressure homogenizer. In vitro assessment of drug release and a cytotoxicity study were both done with breast cancer cells. After applying different concentrations of paclitaxel, dose-dependent toxicity on cells was demonstrated [16]. In a study by Lu et al., albendazole was loaded into particles, a conjugate of bovine serum albumin and polycaprolactone. The size of these nanoparticles was about 100 nm and they were prepared for the treatment of pancreatic carcinoma cells [17]. PCL is representative of synthetic polymers. It is extensively used for the production of nanocarriers. It is a biocompatible, biodegradable polymer which possesses suitable rheological characteristics, such as a low glass transition temperature [18]. Due to its semicrystalline nature, the degradation of PCL is slower than in other polyesters [degradation rates: poly(glycolic acid)>poly(lactide-co-glycolide)>poly(L-lactic acid)>PCL] [18]. As a consequence, PCL is often modified to adjust its biodegradability to meet the specifications of the targeted biomedical application [19,20]. PCL spherical micro- and nanoparticles have been synthesized by a physicochemical solvent–nonsolvent technique and by employing different types of polyelectrolytes as stabilizers in synthesis at room and elevated temperatures. The particles with polyglutamic acid had spherical shapes, with smooth surfaces and size less than 1 μm [21]. Poly(lactic-co-glycolic acid) (PLGA) is also a biodegradable polymer widely used in medical devices and pharmaceutical formulations. It has many advantages, such as exceptional properties which make PLGA easy for operating. It is also easy to manipulate and tailor the degradation and biocompatibility of this polymer for specific applications. PLGA is an FDA-approved polymer for different purposes. It is a copolymer which may have different ratios of monomers in the chain and molecular weights. In PLGA nanoparticles it is possible to immobilize/encapsulate different active substances as well as to modify the surface of such particles to be site-specific in the body [22]. Depending on the chosen materials, techniques for the synthesis of polymeric micro- and nanoparticles generally can be classified into several groups. These include polymerization of monomers, dispersion of preformed polymers, and coacervation [23]. PLGA can be produced as nanoparticles using different methods, such as emulsification-evaporation method [24–26], emulsification-solvent diffusion method [27,28], nanoprecipitation [29,30], and spray-dr...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Dedication
• List of Contributors
• About the Editor's
• Preface
• Chapter 1. Biomedical Applications of Nanostructured Polymeric Materials
• Chapter 2. Recent Advances in Nanostructured Polymer Composites for Biomedical Applications
• Chapter 3. Micromechanical Characterization of Poly(Lactic Acid)/Halloysite Bionanocomposite Membrane
• Chapter 4. Mechanical and Biodegradation Properties of Nanostructured Polymer Composites Under Degradation Behavior
• Chapter 5. Electrospun Matrices from Natural Polymers for Skin Regeneration
• Chapter 6. Nanostructure–Polymer Composites for Soft-Tissue Engineering
• Chapter 7. Carbohydrate-Based Nanohydrogels for Drug-Delivery Applications
• Chapter 8. Recently Emerging Trends in Bone Replacement Polymer Nanocomposites
• Chapter 9. Nanostructured Polymer Composites for Bio-Applications
• Chapter 10. Nanostructured Biopolymers for Application as Drug-Delivery Vehicles
• Chapter 11. Applications of Nanostructured Polymer Composites for Gene Delivery
• Chapter 12. Nanostructured Polymer Biocomposites: Pharmaceutical Applications
• Chapter 13. Use of Nanostructured Polymer in the Delivery of Drugs for Cancer Therapy
• Chapter 14. Nanostructured Polymer Composites for Dental Fillings
• Chapter 15. Chitosan-Based Nanobiocomposites for Wound-Healing Applications
• Chapter 16. Biomedical Applications of Polymer/Layered Double Hydroxide Bionanocomposites
• Chapter 17. Nanotechnology in Cancer Treatment as a Trojan Horse: From the Bench to Preclinical Studies
• Chapter 18. Layered Double Hydroxide-Decorated Hydrogel for Biomedical Applications
• Chapter 19. Polymeric Composites for Joint Replacement
• Chapter 20. Processing and Biomedical Applications of Polymer/Organo-modified Clay Bionanocomposites
• Chapter 21. Antimicrobial Activities of Graphene–Polymer Nanocomposites
• Chapter 22. Graphene Oxide for Drug Delivery and Cancer Therapy
• Chapter 23. Recent Advances in Nanostructured Polymer Composites for Biomedical Applications
• Index