Bionanomaterials and Their Recent Advancements in Tissue Engineering Applications

Advances in Drug Delivery

Microparticle delivery system is accepted as are reliable. Mean to delivery the drug to the target site with specificity,. The drug should be delivered to specific target site at a rate and concentration that provides optimum therapeutic efficacy and reducing the side effect to minimum. Microspheres are empty spherical particles, the particle size is less than 200 mm. Microspheres are free flowing powder consisting of natural and synthetic polymers. They have the potential controlled release drug. Polymers are the most important things of pharmaceutical drug delivery. There are many kind of polymers which varying the properties available those days for use in different pharmaceutical applications. Polymers use in the preparation of microspheres is the synthetic and natural polymers. Synthetic polymers are acrolein, poly anhydrides, methyl meth acrylate, lactides, and glycosides. Natural polymers are albumin, gelatin, collagen, agarose, chitosan, carragenene. Microspheres are the free flowing powders consist of protein and synthetic polymers having a particle size ranging from 1 ? 1000 micrometer. Microspheres are prepared by several techniques but the choice of method depends upon the drug. The polymers used and duration of action required. The evaluation parameters of microspheres are micromeritic properties particle size and shape, swelling index, tapped density, drug loading efficiency. In coming days by combining numerous other sceniorio, we will find the microspheres in novel drug delivery. Specifically in disease cell sorting diagnostics, gene and genetic materials, safe targeted and effective in vivo delivery and supplements a tiny interpretation of diseased organ and tissue in the body. Keywords: Microencapsulation, novel drug delivery, synthetic and natural polymers, duration of action.

19 - Chitin biopolymer in tissue engineering

Polymers can crosslink to produce intermingled materials with three-dimensional network structure known as interpenetrating polymeric network (IPN). They comprise elastic crosslinked polymeric chains. The chains of the hydrogels are either physically or chemically entangled together. Interpenetrating hydrogels can be tailored to provide enhanced materials. They can be classified according to methods of their synthesis as simultaneous or sequential IPNs and the structure to be homo or semi IPNs. The preparation factors play a role in controlling the properties of the produced IPNs. Moreover, the ambient conditions such as pH, temperature as well as the ionic strength may affect the performance of these hydrogels. The swelling capacity is an important feature that allows the prepared hydrogel to perform the required application. Some disadvantages may arise such as the low mechanical properties that are suggested to be overcome. IPNs can be used in various applications that serve the human requirements like drug delivery, tissue engineering, medical and packaging applications. Hydrogels present biocompatibility and nontoxicity when used in biomedical applications. Interpenetrating hydrogels can be prepared from natural or synthetic polymers. Polysaccharides as natural polymers can be used to produce efficient interpenetrating hydrogels. Polyacrylates, poly(ethylene glycol) and poly(vinyl alcohol) are designated as promising synthetic polymers capable of forming interpenetrating hydrogels.

Plant proteins show good potential for medical applications but offer considerable challenges in fabricating biomaterials. Despite substantial efforts, especially in the last decade, to develop polymeric biomaterials, there are no polymers that are ideally suited for tissue engineering, drug delivery and other medical applications. Therefore, the quest to find new sources for biomaterials continues. Natural proteins such as collagen and silk, carbohydrates such as chitosan and cellulose and synthetic biopolymers such as poly (lactic acid) have been extensively studied for potential medical applications. Biotechnology and nanotechnology have also been widely adopted to develop regenerated and recombinant polymers for medical applications. The advent of nanotechnology and its many advantages for medical applications have led to the development of nanofibers and nanoparticles from both the natural and synthetic polymers for tissue engineering, controlled release and other medical applications. However, both natural and synthetic polymers currently available have many limitations that restrict their use for medical applications. Biomaterials developed from natural polymers do not have the desired mechanical properties for medical applications. For instance, scaffolds developed from collagen have poor hydrolytic stability and efforts to crosslink and improve the properties have not been successful to provide cytocompatible biomaterials. Although silk has excellent mechanical properties and biocompatibility, silk has slow degradation rates and it is difficult to dissolve and process silk into various types of biomaterials. Biomaterials developed from most synthetic polymers have the biocompatibility and mechanical properties but their degradation into toxic substances in the body is a cause for concern. Similarly, metal and ceramic based biomaterials do not have the desired degradability and are difficult to process into different forms of biomaterials.

Synthetic polymers have been an integral part of modern society since the early 1960s. Besides their most well-known applications to the public, such as packaging, construction, textiles and electronics, synthetic polymers have also revolutionized the field of medicine. Starting with the first plastic syringe developed in 1955 to the complex polymeric materials used in the regeneration of tissues, their contributions have never been more prominent. Decades of research on polymeric materials, stem cells, and three-dimensional printing contributed to the rapid progress of tissue engineering and regenerative medicine that envisages the potential future of organ transplantations. This perspective discusses the role of synthetic polymers in tissue engineering, their design and properties in relation to each type of application. Additionally, selected recent achievements of tissue engineering using synthetic polymers are outlined to provide insight into how they will contribute to the advancement of the field in the near future. In this way, we aim to provide a guide that will help scientists with synthetic polymer design and selection for different tissue engineering applications.

In the present study, we have fabricated a ternary composite nanofibrous scaffold from PCL/gelatin/chitosan, by electrospinning technique, using a solvent system—chloroform/methanol for polycaprolactone (PCL) and acetic acid for gelatin and chitosan, for tissue engineering applications. Field emission scanning electron microscopy (FE-SEM) was used to investigate the fiber morphology of the scaffold and it was found that the fiber morphology was influenced by the concentrations of PCL, gelatin, and chitosan in polymer solution during electrospinning. X-ray diffraction, Fourier transform infrared, and thermogravimetric (TG) analysis results showed some interactions among the molecules of PCL, gelatin, and chitosan within the scaffold. In-vitro cell culture studies were done by seeding L929 mouse fibroblasts on fabricated composite scaffold, which confirmed the cell viability, high cell proliferation rate, and cell adhesion on composite scaffold as indicated by MTT assay, DNA quantification, and FE-SEM analysis of cell-scaffold construct. Thus, the ternary composite scaffold made from the combination of PCL (synthetic polymer), gelatin, and chitosan (natural polymer) may find potential application in tissue engineering.

Natural and synthetic polymeric hydrogel: A bioink for 3D bioprinting of tissue models

Biodegradable thermoresponsive polymers: Applications in drug delivery and tissue engineering

Injectable smart hydrogels, as types of stimuli-responsive materials, include covalently crosslinked polymeric hydrogels as well as supramolecular hydrogels formed due to self-assembly. Their physiochemical properties make them suitable for applications in tissue engineering. In addition to acting as carriers of cells, they can further mediate or regulate the process of cell growth and tissue regeneration. Until now, injectable smart hydrogels have been successfully utilized to repair and replace a wide range of tissues, including bone, cartilage, skin, myocardium, tendon, and so on.

A great variety of natural and synthetic polymer materials have been utilized in soft tissue engineering as extracellular matrix (ECM) materials. Natural polymers, such as collagen and fibrin hydrogels, have experienced especially broad adoption due to the high density of cell adhesion sites compared to their synthetic counterparts, ready availability, and ease of use. However, these and other hydrogels lack the structural and mechanical anisotropy that define the ECM in many tissues, such as skeletal and cardiac muscle, tendon, and cartilage. Herein, we present a facile, low-cost, and automated method of preparing collagen microfibers, organizing these fibers into precisely controlled mesh designs, and embedding these meshes in a bulk hydrogel, creating a composite biomaterial suitable for a wide variety of tissue engineering and regenerative medicine applications. With the assistance of custom software tools described herein, mesh patterns are designed by a digital graphical user interface and translated into protocols that are executed by a custom mesh collection and organization device. We demonstrate a high degree of precision and reproducibility in both fiber and mesh fabrication, evaluate single fiber mechanical properties, and provide evidence of collagen self-assembly in the microfibers under standard cell culture conditions. This work offers a powerful, flexible platform for the study of tissue engineering and cell material interactions, as well as the development of therapeutic biomaterials in the form of custom collagen microfiber patterns that will be accessible to all through the methods and techniques described here.Impact StatementCollagen microfiber meshes have immediate and broad applications in tissue engineering research and show high potential for later use in clinical therapeutics due to their compositional similarities to native extracellular matrix and tunable structural and mechanical characteristics. Physical and biological characterizations of these meshes demonstrate physiologically relevant mechanical properties, native-like collagen structure, and cytocompatibility. The methods presented herein not only describe a process through which custom collagen microfiber meshes can be fabricated but also provide the reader with detailed device plans and software tools to produce their own bespoke meshes through a precise, consistent, and automated process.

Animal polysaccharides belong to a class of biological macromolecules. They are natural biopolymers with numerous advantages for biomedical applications, such as biocompatibility, biodegradability, non-antigenicity and non-toxicity. Electrospinning is a versatile and facile technique which can produce continuous fibers with nanoscale from a wide range of natural and synthetic polymers. The review aims to provide an up-to-date overview of the preparation of animal polysaccharides nanofibers by electrospinning and their potential biomedical applications such as tissue engineering, wound healing, and drug delivery. Various animal polysaccharides including chitin and chitosan (CS), hyaluronic acid (HA), heparin and heparan sulfate (HS), and chondroitin sulfate (ChS), are discussed. The challenges and some useful strategies in electrospinning of animal polysaccharides also are summarized. In addition, future study of animal polysaccharides nanofibers by electrospinning is proposed.

8 - Graphene-based polymer nanocomposites in biomedical applications

The ability to artificially simulate the ‘mechanical’ niche, broadly termed as Extracellular Matrix (ECM), of the bone marrow determines success for stem cell growth, architectural organization and differentiation viz. tissue engineering. The advent of various natural and synthetic polymers has greatly influenced tissue engineering. The focus of the review is on various artificial niche simulations, ECM, scaffolds such as hydrogels, electrospun nano and micro fibers, bone-strengthening scaffolds and tissue infills. The utility of the ECMs in the treatment of various medical conditions including bone and cartilage tissues, nervous tissues, spinal cord and tendon tissues as well as wound healing, along with the ability of some ECMs in entrapment of elusive cell secretomes will be discussed. The future of tissue engineering has indeed got a new lease of life with polymer scaffolds and it is feasible that certain goals, thought of impossible so far, may become possible.

Smart hydrogels are special type of hydrogels that undergo solution-gelation transition in response to alterations in the environment. Solution-gel transformation is brought about through either physical or chemical cross-linking that occur between the hydrogel chains. Various stimulating factors have been identified to be responsible for the change in the physical state of the intelligent hydrogel. The most important triggering factors are the temperature, pH, ions, electrical signalling, magnetic field, glucose, light and others. Each of these stimulating factors can trigger the swelling of the hydrogel through unique mechanism. Many of these triggering factors are characteristics of the biological systems which make the smart polymers quite beneficial for different biomedical applications. Numerous natural and synthetic polymers have been distinguished to act as smart materials. These polymers impressed the scientists to use them in many biomedical and industrial applications such as drug delivery systems, gene therapy applications, tissue engineering and many other applications.