Tissue engineering has developed dramatically over the last 10 years which aims to restore, maintain, or improve tissue functions that are defective or have been lost by different pathological conditions, either by developing biological substitutes or by reconstructing tissues. Scaffolds plays a unique role in tissue regeneration and repair and have been used for tissue engineering such as bone, cartilage, ligament, skin, vascular tissues, neural tissues, and skeletal muscle and as vehicle for the controlled delivery of drugs, proteins, and DNA. In scaffold design and application, polymers have been widely used as biomaterials for the fabrication of medical device and tissue-engineering scaffolds. Synthetic polymers represent the largest group of biodegradable polymers, and they can be produced under controlled conditions
This essay is intended to achieve two tasks on this exciting research topic. Firstly, it summarizes the three most commonly used synthetic polymers in tissue engineering cum the other two synthetic polymers with different mechanical and physical properties. These include poly (glycolic acid) (PGA), poly (latic acid) (PLA), polyanhydrides, polycaprlactone (PCL) and Poly (Lactide-Co-Glycolide) (PLGA). Secondly, it illustrates four different methodologies or techniques adopted for polymeric scaffold fabrication. These include solvent casting and particulate leaching method, gas foaming method, thermal induced phase separation and rapid prototyping. Both advantages and limitations associated with each method are also illustrated and compared qualitatively.
Polyglycolide (figure 1) is a thermoplastic polymer which is the simplest aliphatic polyester which has high crystallinity between 46-50% and high tensile m...
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...the high tensile modulus which can be used in bone internal fixation and orthopaedic fixation devices. It is essential to note that PLA can be used in injectable form, cure the patient with immunodeficiency virus. The co-polymer PLGA has shorter degradation time compare with the monomer, it can apply in drug delivery vehicle, sutures anchors and orthopaedic implant. The modulus of PCL is near to zero, it cannot use in any mechanical support application. Meanwhile, due to long term zero order release, PCL can apply in contraceptive device. Lastly, polyanhydride can define as the safest polymer. The degradation products of polyanhydride are biocompatible and can be taken by human body without any side effect. It is essential to noted that the rate of degradation is based on following factors: copolymer ratio, crystallinity, molecular weight, porosity and structure.
There are two types of chemical cross-linkers; synthetic and naturally derived reagents. The most commonly employed cross-linking reagent for collagen-based biomaterials is glutaraldehyde (GA), a five carbon bifunctional aldehyde, bridging ɛ-amino group of lysyl residues present in the protein over a varying range of distances owing to its less expensive and higher efficiency properties [16]. The mechanical properties of glutaraldehyde-treated tissue is quite different from non-cross-linked, showing more stiffness and increased tensile strength. However, GA is associated
Prosthetic limbs have been in existence for thousands of years in various shapes and sizes and all have the same core purpose, which is to help improve the lives of people who have either been unfortunate or have lost limbs in accidents and/or wars. Over time, prosthetic limbs have evolved and changed due to changes in technology or an up-rise of different viable materials that humans have access to. The following report will asses the materials and benefits of such, in past and present prosthetic limbs whether they be hands, fingers or legs.
The future for the total artificial heart with respect to using polyurethanes comes in the form of thermoplastic polyurethane (TPU), also known as polyurethane elastomers that have molecular structures similar to that of human proteins. TPUs have slower protein absorption (protein absorption is the beginning of the blood clotting process) this makes TPUs ideal candidates in the manufacturing of the total artificial heart because it provides more adhesive strength and mimics certain elements within the body. Hence, biomedical polyurethanes can lead the way to eliminate some acute health challenges that the total artificial heart currently faces. By virtue of their range of properties, polyurethanes and their new applications will continue to play an important role in the future of the total artificial heart.
Solid Freeform Fabrication(SFF) has been possibly the most large scale fabrication technique among the different types of design and fabrication methods (Bose, et al., 2012). The main feature of SFF has three dimensional parts which are printed layer-by-layer depending on computer aided design (ask plagiarism). The fabrication of SFF on polymer, ceramic, metal and composite scaffolds has been widely accepted in bone tissue engineering applications (Bose, et al.,
... the usage of bioresorbable scaffold involves by selecting certain phenotype of cell and implants it on permeable substance before being implanted to the pulmonary position. The scaffold is presume to degenerate as the cells grow. The last approach involves constructing a mold for leaflets similar to the aortic shape using the collagen constructs (Vesely 2005).
Polymeric materials play a functional role in every aspect of daily life, from clothing to infrastructure. Polymers differ greatly from other materials, such as ceramics or metals, based upon the types of bonding. Metals bond metallically, creating a sea of electrons, and ceramics generally bond ionically, strongly tying electrons to lattice points. Polymers bond covalently in carbon chains, which (in general) make their properties more variable due to the possibilities of arrangement in bond length, angle, and molecular configuration. Polymers, on average, tend to be more lightweight, have a greater range of colors, lower thermal and electrical conductivity, less brittleness, more resistance to acids, bases, and moisture, and higher dielectric strength than their ceramic or metallic counterparts, but with great range. This variety of properties leads to a variety of classifications, and therefore differing processing methods based on the classification of polymer.
They are amorphous or solely moderately crystalline once injection shaped, but the degree of crystallinity will be abundant redoubled for fiber and film applications by orientation via mechanical stretching. The two most vital polyamides poly(hexamethylene adipamide) Nylon 6,6 and polycaprolactam Nylon 6. Both have wonderful mechanical properties together with high impact strength, high flexibility, high tensile strength, good resilience and low creep. They are straightforward to dye and exhibit wonderful resistance to wear due to a low constant of friction. Both amides have a high melting temperature (500 - 540 K) and glass transition temperature reports in excellent mechanical properties at elevated temperatures. For example, the heat rebound temperature of PA-6, 6 is usually between 180- 240°C that exceeds those of polycarbonate and polyester. They also have excellent resistance to fungi, oils, bases, etc. The main limitation is that the strong wet sensitivity water acts as a plasticizer and therefore the ensuring changes in mechanical properties. For example, the tensile strength of moist polyamide is 50% below that of dry polyamide. Another important polyamide is Nylon 6,12. It is less hydrophilic than Nylons 6,6 and 6 due to the larger range of chemical group of methylene within the compound backbone. For this reason, it has better dimensional
Today I finished observing all the scaffolds using the SEM Scanning Electron Microscopy (SEM). The end goal for the non-toxic (being tested today) scaffolds is to be use as a temporary bone until the bone repairs. Then the scaffold should degrade until the bone heals properly. Also, the scaffold has to be strong, so it doesn’t break or collapse in the body that was the purpose of the mechanical testing. We have to know every properties of the scaffolds to make the scaffolds are good to be put in the body .Today we will begin testing whether the scaffold is toxic for the cells because the human body is made up of cells. We don’t want to damage the human cells. We will first use animal cells and then we will move on to human cells if the scaffolds
A real-life example of its application in the human body is in wound repair. The main focus of tissue engineering in this application is in artificial skin to treat burns but it can also be used in various other dermal diseases. An example of this is the Advanced Tissue Sciences Dermagraft, which is a 3 dimensional human neonatal dermal fibroblast culture that has been grown on a biodegradable scaffold and has been cryopreserved (Nature Publishing Group., 2014). The main function of a scaffold is to direct cell behaviour such as migration, proliferation, differentiation and maintenance of phenotype (Amoabediny, Salehi-Nik, & Heli, 2011). The use of this Dermagraft is in the treatment of foot ulcers that have developed as a side effect of long – term diabetes. According to clinical trials, significant healing occurred with this material especially when the Dermagraft cells were alive and fully functional.
A wide choice of constituting polymers, both natural and synthetic, delivers diverse properties which can be engineered into the hydrogel matrices, such as cell adhesiveness low-fouling behavior, etc.[219] Hydrogel immobilization of biological materials is useful because pores within the gel are in the range of
What is a polymer? Polymers are substances containing a hefty amount of structural units joined by the same type of linkage. The minute you hear the word polymers you assume it is manufactured with massive chemical plants. Actually, polymers have been in nature from the start. All living things plants, animals, and people are made of polymers. However, what you do not know is they are different types of polymers the Synthetic ones which use harmful toxins to be synthesized, and are those which are Natural. They are numerous polymers that fall in the natural process and are utilized in both our society and our bodies, which are cellulose; starch, rubber, proteins and both are DNA and RNA, and many more
Polymers: A great variety of polymers are used as biomaterials in medicine. Their applications vary from facial prostheses to tracheal tubes, from dentures to hip and knee joints and from kidney and liver parts to heart components. Polymeric materials are also used for medical adhesives and sealants and are also used for coatings that perform a range of functions.
"Artificial" tissue is grown-up from the patient's personal cells. However, when the harm is so dangerous that it is unbearable to use the patient's own cells, artificial tissue cells are grown. The trouble is in discovery a scaffold that the cells can grow and organize on. The features of the support must be that it is biocompatible; cells can adhere to the support, mechanically durable and recyclable. One successful support is a copolymer of lactic acid and glycolic acid.
Polymers popularly coined as “plastics” have proved their importance in different areas like FMCG, pharma, automobiles, etc. Plastics are versatile materials with unique properties like high strength to weight ratio, good aesthetics; good Processability, balanced engineering properties and optimum cost led its entry into medical
The field of regenerative medicine encompasses numerous strategies, including the use of materials and de novo generated cells, as well as various combinations thereof, to take the place of missing tissue, effectively replacing it both structurally and functionally, or to contribute to tissue healing[29]