Electrospun Nanofibers: Materials,Synthesis Parameters,and Their Role in Sensing Applications

Since the last decade, electrospinning is garnering more attention in the scientific research community, industries, applications like sensing (glucose, H₂O₂, dopamine, ascorbic acid, uric acid, neurotransmitter, etc.), biomedical applications (wound dressing, wound healing, skin, nerve, bone tissue engineering, and drug delivery systems), water treatment, energy harvesting, and storage applications. This review paper provides a brief overview of the electrospinning method, history of the electrospinning, factors affecting the electrospun nanofibers, and their morphology with different materials and composites (metals, metal oxides, 2D material, polymers and copolymers, carbon-based materials, etc.) used in the electrospinning technique with optical spinning parameters. Moreover, this paper deliberates the application of electrospun nanofibers and fibrous mats for sensing (electrochemical, optical, fluorescence, colorimetric, mechanical, photoelectric, mass sensitive change, resistive, ultrasensitive, etc.) in most illustrative representations. In the end, the challenges, opportunities of the electrospun nanofibers, and new direction for future progress are also discussed.     

Electrospinning of Polymers,Their Modeling and Applications

Although there are several methods for obtaining sub-micro or nanofibers, electrospinning is perhaps the most versatile process. Nanotechnology has been widely accepted as dealing with the science and technology where at least one dimension is of roughly 1 to 100 nm. Electrospinning has been recognized as a feasible technique for the fabrication of polymeric nanofiber yarns. Various materials including polymers, composites, ceramics and metals have been electrospun into nanofibers. The nanofibers thus produced exhibit novel and significantly improved physical, chemical and biological properties due to their nanolevel size. In this article, the electrospinning process, along with its modeling equations and applications have been discussed. Some typical case studies regarding electrospinning under various categories have also been discussed.     

Nanocomposites of Polymeric Biomaterials Containing Carbonate Groups: An Overview

The modification of biomaterials using nanoadditives can lead to the development of novel materials for a wide variety of biomedical applications such as drug administration systems, tissue engineering, bioresistance coatings, and biomedical instruments. Moreover, a further improvement of mechanical and thermal properties of aforementioned biomaterials while maintaining their dimensional stability is a goal of major scientific researches. Aliphatic polycarbonates (APCs) containing carbonate groups such as poly(trimethylene carbonate), poly(propylene carbonate), poly(ethylene carbonate), poly(dimethyl trimethylene carbonate), etc., have become much more interesting compared to other biodegradable materials due to their unique physical and chemical properties. This review presents the effect of applying different kinds of nanoparticles (NPs) on the mechanical, thermal, and viscoelastic properties as well as dimensional stability and biocompatibility of APCs. The dispersion process of nanofillers within polymer matrices has been divided into two groups, solution and melt mixing techniques. Moreover, synthesis procedures of APC loaded NPs for drug delivery systems and electrospinning of nanofiber mats have also been reviewed. In order to clarify the effect of NPs on the overall characteristics of the APC biomaterials, the detailed mechanism of improving process have been extensively discussed.     

Extracellular matrix regenerated: tissue engineering via electrospun biomimetic nanofibers

While electrospinning had seen intermittent use in the textile industry from the early twentieth century, it took the explosion of the field of tissue engineering, and its pursuit of biomimetic extracellular matrix (ECM) structures, to create an electrospinning renaissance. Over the past decade, a growing number of researchers in the tissue engineering community have embraced electrospinning as a polymer processing technique that effectively and routinely produces non‐woven structures of nanoscale fibers (sizes of 80 nm to 1.5 µm). These nanofibers are of physiological significance as they closely resemble the structure and size scale of the native ECM (fiber diameters of 50 to 500 nm). Attempts to replicate the many roles of native ECM have led to the electrospinning of a wide array of polymers, both synthetic (poly(glycolic acid), poly(lactic acid), polydioxanone, polycaprolactone, etc.) and natural (collagen, fibrinogen, elastin, etc.) in origin, for a multitude of different tissue applications. With various compositions, fiber dimensions and fiber orientations, the biological, chemical and mechanical properties of the electrospun materials can be tailored. In this review we highlight the role of electrospinning in the engineering of different tissues and applications (skin/wound healing, cartilage, bone, vascular tissue, urological tissues, nerve, and ligament), and discuss its potential role in future work. Copyright © 2007 Society of Chemical Industry     

Review on Nanocellulose Polymer Nanocomposites

Recently, nanocellulosic materials have been received significant research interest as potential nanofiller for the reinforcements in the polymer matrices due to its renewable in nature, readily availability, biocompatibility, inexpensive, excellent physical properties, tailorable surface properties, etc. In this review, author attempted to provide an overview of various methods for nanocellulose reinforced polymer nanocomposites fabrications, properties of nanocellulose-based nanocomposites, and their applications. The review has been emphasized for the reinforcement of nanocellulose in various polymer matrices viz. hydrophilic, hydrophobic matrices. Nanocellulose reinforced polymer nanocomposites have huge potential in diverse applications which ranges from biomedical, packaging, electronic to environmental, water treatment fields etc.     

Electrospun polymeric nanofibers for dental applications

Electrospinning is an economical, efficient, and versatile process for the preparation of continuous nanofibers with desired patterns, tailored fiber diameters, and orientations. Since its invention, electrospinning has been utilized to prepare nanofibers from several natural polymers and synthetic polymers for use as scaffolds in tissue engineering, regeneration, and biomedical applications. Furthermore, complex scaffolds were prepared by electrospinning complex polymer solutions formulated by blending natural and synthetic organic polymers with bioceramics and other inorganic molecules. Lately, coaxial electrospinning has emerged as a promising technology in the preparation of drug-loaded biodegradable core-shell structured micro/nanofibers for sustained drug delivery applications. This paper will discuss the basic mechanism of electrospinning, parameters governing the electrospinning process, various materials investigated for use in the electrospinning process, and its recent advances.     

Novel 3D electrospun polyamide scaffolds prepared by 3D printed collectors and their interaction with chondrocytes

Electrospinning is significantly one of the simple and versatile methods for producing micro- and nanofibrous scaffolds. Its assembly can be modified in different ways to combine material properties with different morphological structures for biomedical applications. In this process, collector design plays an important role to determine the nanofiber orientation in electrospun nanoweb. In this work, 3D patterned scaffolds were produced by electrospinning of polyamide-66 solution on different 3D collectors that have been obtained. The aim of this work is to investigate the attachment of the chondrocyte cells on the prepared electrospun scaffolds that have different types of nanofiber orientations that could be used in tissue engineering applications.     

Ionomer‐based polyurethanes: a comparative study of properties and applications

Polyurethanes cover a large range of materials exhibiting various physical and mechanical properties making them useful in different applications such as elastomers or biomaterials, for instance. The introduction of ionic groups in the polyurethane backbone opens the way to new applications where the ionic groups can act as physical crosslinkers that greatly modify the final mechanical and thermal properties of the materials. Furthermore, the hydrophilicity of the chains can be enhanced by the presence of the ionic species, and so the materials can be processed as conventional dispersions even in a polar solvent such as water. As a consequence the applications are numerous; the main commercial outlets are focused on coatings and textiles industries where they can be used as waterproof coatings or substitutes for leather. But these materials can also be used in high‐tech industries for shape memory materials, biomedical devices and biocompatible materials. This review summarizes the latest developments of this class of promising materials and provides the reader with the potentialities of these polymers in various areas.     

Electrospinning of nanofibers

Nanotechnology is the study and development of materials at nano levels. It is one of the rapidly growing scientific disciplines due to its enormous potential in creating novel materials that have advanced applications. This technology has tremendously impacted many different science and engineering disciplines, such as electronics, materials science, and polymer engineering. Nanofibers, due to their high surface area and porosity, find applications as filter medium, adsorption layers in protective clothing, etc. Electrospinning has been found to be a viable technique to produce nanofibers. An in‐depth review of research activities on the development of nanofibers, fundamental understanding of the electrospinning process, and properties of nanostructured fibrous materials and their applications is provided in this article. A detailed account on the type of fibers that have been electrospun and their characteristics is also elaborated. It is hoped that the overview article will serve as a good reference tool for nanoscience researchers in fibers, textiles, and polymer fields. Furthermore, this article will help with the planning of future research activities and better understanding of nanofiber characteristics and their applications. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 557–569, 2005     

Electrospun polymer nanofibers: The booming cutting edge technology

Electrospinning has been recognized as a simple and efficient technique for the fabrication of ultrathin fibers from a variety of materials including polymers, composite and ceramics. Significant progress has been made throughout the past years in electrospinning and the resulting fibrous structures have been exploited in a wide range of potential applications. This article reviews the state-of-art of electrospinning to prepare fibrous electrode materials and polymer electrolytes based on electrospun membranes in the view of their physical and electrochemical properties for the application in lithium batteries. The review covers the electrospinning process, the governing parameters and their influence on fiber or membrane morphology. After a brief discussion of some potential applications associated with the remarkable features of electrospun membranes, we highlight the exploitation of this cutting edge technology in lithium batteries. Finally the article is concluded with some personal perspectives on the future directions in the fascinating field of energy storage.     

Polyamides Derived from Terpenes: Advances in Their Synthesis,Characterization and Applications

Polyamides are very important polymers, with applications from commodities up to high-performance materials for, for example, fibers or for the biomedical sector. Nowadays, still most of them are synthesized from fossil resources. With regards to sustainability and bioeconomy, and especially regarding the new structures and properties that can thus be achieved, the preparation of polyamides (PAs) from natural precursors is getting more and more important. For this, especially the utilization of terpenes, a large and important group of natural products with different functions in nature (regulators, defense signals, etc.), is important, which is described herein. Similar approaches are interesting from a scientific point of view regarding, for example, structure-function-relations, but also with regards to different applications as, for example, high-performance or biomedical materials. Practical applications: Terpene-based polyamides can find many applications, from commodities up to high-performance fibers and special materials in (bio)medicine, for example, drug delivery, tissue engineering, etc.     

Biological and mechanical enhancement of zirconium dioxide for medical applications

Extensive research in global biomedical industry has been driven rapidly due to problems faced in bone implants such as loosening of implants in knee and hip prosthesis as well as short service life of orthopaedic implants. Advances in biomedical engineering have resulted in formation of various materials utilized for orthopaedic transplants and artificial implants. Among the various available materials zirconium dioxide is observed as potential material for biomedical application due to its superior biocompatibility, good compression resistance (2000 MPa), good viability of cell culture, good opacity, and radiopacifying capacity showcasing it's diverse applications in bone and tissue regeneration, orthopaedic implants as well as bone resorption. Bone tissue regenerative modifications is accompanied with coating of zirconium dioxide on metal alloys or 316 L SS substrate, composite formation with silica carbide or organic acids (usnic acid), surface propargylation achieved using chemical treatment of propargyl bromide, electrochemical treatment of zirconium dioxide to evaluate corrosion resistance, etc. Zirconium dioxide is also recorded for exhibiting enhanced mechanical properties as well as biocompatibility in hip arthroplasty as well as bone implants; it also serves application in bone cement to provide adhesion between the biomedical implants. The review paper majorly focuses on effective utilization of zirconium dioxide with various additive materials and functionalization techniques used for enhancement of properties, enabling the application of material in orthopaedic implants as well as bone tissue applications. The mechanical and biological performance analysis of various orthopaedic implants containing zirconium dioxide has been elaborately discussed along with possible measures implemented to enlarge the life of biomedical implant.     

Nanofiber technology: current status and emerging developments

Nanofibers have emerged as exciting one-dimensional nanomaterials for a broad spectrum of research and commercial applications owing to their unique physicochemical properties and characteristics. As a class of nanomaterials with cross-sectional diameters ranging from tens to hundreds of nanometers, nanofibers possess extremely high specific surface area and surface area-to-volume ratio. They are capable of forming networks of highly porous mesh with remarkable interconnectivity between their pores, making them an attractive choice for a host of advanced applications. In fact, the significant impact of nanofiber technology can be traced from the wide range of fundamental materials that can be used for the synthesis of nanofibers. These include natural polymers, synthetic polymers, carbon-based materials, semiconducting materials, and composite materials. Correspondingly, the emerging proof-of-concept applications of nanofibers spanning several important areas have been rapidly reported. This Review explores the current status and up-and-coming development of nanofiber technology, with an emphasis on its syntheses and applications. First, we highlight the current and emerging strategies used in synthesizing nanofibers. We briefly introduce the various established nanofiber synthesis techniques, especially the electrospinning method. We then focus on the emerging nanofiber synthesis strategies, such as solution blow spinning, centrifugal jet spinning, and electrohydrodynamic direct writing. Next, we discuss the emerging applications of nanofiber technology in various fields, specifically in three important areas of energy generation and storage, water treatment and environmental remediation, and healthcare and biomedical engineering. Despite all these advancements, there are still challenges to be addressed and overcome for nanofiber technology to move towards maturation. Nevertheless, we envision that with further progress in the development of nanofiber synthesis strategies and identification of “killer” applications of nanofibers, nanofiber technology will mature and move beyond its current state towards commercial realization and applications.     

A review on the processing–morphology–property relationship in biodegradable polymer composites containing carbon nanotubes and nanofibers

Carbon nanofillers containing biodegradable polymer composites have become an emerging frontier in materials science and engineering because of their potential as environmentally friendly materials in multiple applications, from load-bearing to advanced packaging to biomedical applications. Herein, we present the effect of processing parameters on the final morphology and the resulting properties of the biodegradable polymer composites containing carbon nanotubes (CNTs) or carbon nanofibers (CNFs). Various strategies can be employed to develop such composites; however, the type of morphology, which results during processing, significantly affects the final properties of the obtained composites. Therefore, various processing strategies such as melt-blending, additive manufacturing, and electrospinning are critically reviewed, together with the potential applications in load-bearing, tissue engineering, electromagnetic shielding, gas sensing, and packaging. Finally, we discuss the existing challenges and future directions in designing CNTs/CNFs containing biodegradable polymer composites with desired properties.     

Structural and mechanical properties of new block copolymers designed for biomedical use

Copolymers containing blocks of conventional polymers and polyamidoamine blocks have been prepared in order to couple good mechanical properties with the ability to form stable complexes with heparin which will induce non-thrombogenic characteristics to the polymer. The tensile properties of these new non-thrombogenic materials (polyamidoamine/polystyrene block copolymers with different polystyrene contents) have been studied and compared with structural data obtained by X-ray diffraction technique. The results show that two distinct phases are present in the copolymers. These materials have potential for applications in biomedical fields.     

Designing Molecular Building Blocks for Functional Polymersomes

In recent years various polymeric vesicles have been reported that show promising results for drug delivery applications, nanomotors and/or nanoreactors. These polymeric vesicles can be assembled from many different materials and various coupling reactions have been applied for functionalization of the vesicles. However, the designs reported are still rather simple, as it is challenging to mimic biological complex systems. In this review we focus on the properties of widely used hydrophobic polymers to better understand polymersome properties for various applications. Examples are shown of how researchers have used and modulated block‐copolymers and their properties to their advantage. Furthermore, an overview of possible end group functionalizations of nanoparticles is reported, giving insight in recent developments of smart nanoparticles for biomedical applications.     

Polymeric nanofibers containing solid nanoparticles prepared by electrospinning and their applications

Generally, polymer solution or sol–gel is used to produce electrospun nanofibers via the electrospinning technique. In the utilized sol–gel, the metallic precursor should be soluble in a proper solvent since it has to hydrolyze and polycondensate in the final solution; this strategy straitens the applications of the electrospinning process and limits the category of the electrospinnable materials. In this study, we are discussing electrospinning of a colloidal solution process as an alternative strategy. We have utilized many solid nanopowders and different polymers as well. All the examined colloids have been successfully electrospun. According to the SEM and FE SEM analyses for the obtained nanofiber mats, the polymeric nanofibers could imprison the small nanoparticles; however, the big size ones were observed attaching the nanofiber mats. Successfully, the proposed strategy could be exploited to prepare polymeric nanofibers incorporating metal nanoparticles which might have interesting properties compared with the pristine. For instance, PCL/Ti nanofiber mats exhibited good bioactivity compared with pristine PCL. The proposed strategy can be considered as an innovated methodology to prepare a new class of the electrospun nanofiber mats which cannot be obtained by the conventional electrospinning technique.     

Recent developments in plant oil based functional materials

The increasing interest of academic and industrial sectors in the use of bio‐based materials mirrors the overwhelming need for replacing, as much as possible, petroleum derived chemicals, reducing the negative environmental impact derived from their usage. Vegetable oils fulfill this goal extremely well, because of their worldwide availability, large volume production at comparatively low prices and versatility of the modifications and reactions in which they can participate to produce a large variety of different monomers and polymer precursors. Further reactions of these chemicals can lead to very different types of final materials with varied applications. It is because of this remarkable versatility that many review articles have appeared during the last few years; many of them have dealt with the various routes for vegetable oil modification and options for polymer synthesis, whilst others were dedicated to the analysis of the properties of the derived materials, generally focusing on structural properties. In this review, we focus on the capabilities of vegetable oils to be modified and/or reacted to obtain materials with functional properties suitable for use in coatings, conductive or insulating materials, biomedical, shape memory, self‐healing and thermoreversible materials as well as other special functional applications. © 2015 Society of Chemical Industry     

Biodegradable synthetic polymers: Preparation, functionalization and biomedical application

Biodegradable polymers have been widely used and have greatly promoted the development of biomedical fields because of their biocompatibility and biodegradability. The development of biotechnology and medical technology has set higher requirements for biomedical materials. Novel biodegradable polymers with specific properties are in great demand. Biodegradable polymers can be classified as natural or synthetic polymers according to the source. Synthetic biodegradable polymers have found more versatile and diverse biomedical applications owing to their tailorable designs or modifications. This review presents a comprehensive introduction to various types of synthetic biodegradable polymers with reactive groups and bioactive groups, and further describes their structure, preparation procedures and properties. The focus is on advances in the past decade in functionalization and responsive strategies of biodegradable polymers and their biomedical applications. The possible future developments of the materials are also discussed.     

Ductile PLA modified with methacryloyloxyalkyl isocyanate improves mechanical properties

The majority of the biodegradable polymers in clinical use are composed of stiff materials that exhibit limited extendibility with unsuitably high Young’s modulus and low elongation at break values that make them non-optimal for various biomedical applications. Polylactide (PLA) is often used as a biomedical material because it is biodegradable, but the physical and mechanical properties of PLA need to be improved for biomedical applications. In order to improve the flexibility and strength of biodegradable PLA, various reaction conditions were studied. Urethane structure polymer materials were prepared; PLA was reacted with a small amount of methacryloyloxyethyl isocyanate (MOI) to obtain a ductile PLA with markedly improved mechanical properties. Elongation at break increased by 20 times when compared to neat PLA. Impact resistance (notched) improved 1.6 times. Thus, this modified PLA biodegradable polymer may have greater application as a biomedical material with increased mechanical properties.