Selection Criteria And Surface Properties Of Polymeric Biomaterials

Criteria for selecting polymeric materials as biomaterials

Describe criteria for the selection of polymeric materials to be used as biomaterials. By giving suitable examples, explain the role of surface properties in biomaterials and how these properties can be evaluated.

 Biomaterials are used as a substitute material for biological applications. It is a synthetic material, which is used in manufacturing specialized pieces of equipment (Azab et al. 2006). These types of equipment are then replaced with a living organ or incorporated in a living tissue or cell system. The primary requirement for a suitable biomaterials is that it should be safe, economically affordable, and physiologically acceptable (Ramakrishna et al. 2001). Biomaterials are used in a broad range of clinical aspects like an artificial hip joint, bone plates, and screws, cardiac pacemaker, intra-ocular lens, mastectomy augmentation, chin augmentation, probes and catheters, artificial stapes, intra-medullary rod, etc. Material composed polymers are called polymeric compounds (Domb and Kumar, 2011). Polymers are composed of monomers that are the chemical units. Polymeric substances are highly used to manufacture the components mentioned. Along with low toxicity and reactive level, there are several factors like suitable surface properties are also maintained as a strong parameter (King and Lyman, 1975).

 Polymers are used widely in biotechnology and medical sector, surgical equipment, implants, drug delivery systems, as carriers of immobilized enzymes and cells (Domb and Kumar, 2011)..  Before considering a material as a biomaterial, it should be checked that whether the material's characteristics is matching with the parameters of an ideal biomaterial. Surface properties are one of the most important of these requirements as the surface properties can control a device’s performance (Domb and Kumar, 2011). Interfacial properties of both device and the material used are needed to be addressed from outside. It is also important to monitor and modify the intrinsic surface properties as the clinical functioning of the biomedical equipment (Schmalz , 2009). The central aspect for a suitable biomaterial is biocompatibility (the suggested material should not be carcinogenic, nonpyrogenic, nontoxic and should not give rise to any allergic reaction). Sterilizable (The material can be sterilized by autoclave, dry heating, ethyl oxide gas, radiation, etc.). Physical property (high strength, elasticity and durability) and  manufacturability (easy for machinability, molding, extruding and fiber forming) (Domb and Kumar, 2011)..

Newly developed technologies have implemented the use of different biomaterials in a clinical study. High-compliance elastic polymers, synthetic and natural absorbable materials provide the scope of designing new equipment in biomedical sectors (Domb and Kumar, 2011). The phenomenon of designing new materials helps the researchers to study various tissues of human and animal sources. The study can develop clinically useful equipment. Ceramics is also used as an inert and bioactive materials used in clinical situations (Maganti, 2011). The Carbon surfaces have a high degree of tissue compatibility in a variety of cases such as heart valves, dental implants, percutaneous accessing equipment, finger joints and bone plates. In recent years, composite biomaterials are also used in clinical studies. It is a well known fact that all natural tissues are composite (Ratner et al. 2012). Using this principle, scientists have developed equipment made up of composite biomaterials that possess flexibility and adaptation for blood contracting equipment. In recent studies. It is clear that spectroscopic techniques are used in the study of biomaterial surfaces and biomaterial-tissue interface study. These methods include the Fourier transform infrared spectroscopy (FITR) and electron spectroscopy for chemical analyzes (ESCA) are beneficial for both manufacturing and clinical follow-up (Maganti, 2011)..

Clinical problems that might be addressed

The surface property is one of the major aspects to be considered in the case of biomaterials. The surface property is determined through analysis of both chemical compositions and different conversion processes. Through these techniques effects of the particular biomaterial on the local tissues can be monitored on a cellular level by the biomaterial-tissue interface.The desired cellular response is therefore highly controlled for proper medical implant design. The main aspects of surface properties to be considered are nonspecific interaction, specific binding and surface topology (Ratner et al. 2012).

The physical, chemical, mechanical and electrical properties of a particular material should be evaluated carefully (Shi et al. 2006). These properties play a fundamental role in determining whether the material considered provided critical inputs to assess the interrelated biomechanical and biological analysis. In the case of clinical equipment, maximum yield strength, fatigue strength creep deformability, ductility and fracture possibility of the device should be considered. Elasticity, viscoelasticity of the material is also needed to be considered (Shi et al. 2006).

In the case of chemical properties, the toxicity of the material is required to be studied broadly. Toxicity of a substance can increase due to primary degradation of the studied material. The qualitative study of the material should be carried out in order to monitor the material's toxicity level in a biological environment (Shue, Yufeng and Mony, 2012).

RGD method can be applied to increase the cell adherence or the cell attachment of the biomaterials. RGD model is comprised of Arginine (R), Glycine (G) and Aspartic acid (D). Functionalized of materials using RGD immobilization techniques enhances the surface density, spatial arrangements, and integrin affinity. This method is mainly used in case of polymer modifications (Shue, Yufeng and Mony, 2012).

Plasma-surface modification is also used in biomedical engineering. Plasma sputtering and etching, plasma implantation, plasma deposition, plasma polymerization laser plasma deposition, plasma spraying are the techniques under this method that are broadly used. Through this process, surface properties of a biocompatibility of a material can be increased keeping the bulk properties unchanged (Shue, Yufeng and Mony, 2012).

Electron Spectroscopy for Chemical Analysis (ESCA) is broadly used for the characterization of biomaterials.Using the photoelectric effect phenomenon, X-rays are intensified upon the specimen material. The interaction between the X-rays and atoms of the specimen emits core level electron or inner shell. The energy in these electrons is measured and evaluated. These data will reflect and highlight key information about the particular material (Sun et al. 2012).

Importance of different properties

Secondary Ion Mass Spectroscopy (SIMS) In these methods a beam of primary ions are used and focused on the specimen. Secondary electrons that are emitted are then collected and analyzed. The mass of emitted ions is measured with this method (Sun et al. 2012).

Infrared Spectroscopy (IR) is also known as Fourier Transform Infrared (FTIR) Spectroscopy. This method is used for the characterization. The infra-red spectrum of the subject material is obtained through passing a beam of infrared light through the sample. The transmitted light is examined, and the data will show the amount of light absorbed by the specimen on each wavelength. An absorbance spectrum is made according to the data (Sun et al. 2012).

Contact Angle Method such as Wettability is also used for the characterization of a biomaterial.

Other methods such as Scanning Electron Microscopy (SEM), Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM) are used for the surface characterization of a biomaterial (Shi et al. 2006).

The development in biomaterial modification has been highly productive in the past few years. Newly developed techniques are used in clinical sectors that are helping many people across the globe. Currently development of artificial tissue, consisting macroscale and nanoscale features (Shue, Yufeng and Mony, 2012).. Chitosan is also developed as a biomaterial. Computerized additive and subtractive methods have recently used for the development of biomaterials. Now a day, atomic data obtained through computer tomography, MNR methods are also increasingly used. Recently, prostheses and biosensors are also developed using biomaterials to be implanted into organic systems. Electrospinning nano fibers are also developed in recent years from synthetic polymers. These nano fibers increase adhesion, proliferation, and differentiation of cells. These materials are used for intimating topographical architecture of human cells (Shue, Yufeng and Mony, 2012).

From, these data, it can be considered that developing biomaterials in recent years and the future has a huge prospect that will enrich the clinical and medical sector. Many applications of biomaterials are used in different cases such as cardiovascular diseases, lenses for eye treatment, bone plates, etc. Biomaterials are used as the substitute for natural organic organs, tissues, etc. There is no other way to regenerate the natural organs or tissues. So bio materials play a crucial and important role that cannot be substituted by any other means (Shi et al. 2006).

In conclusion, it can be considered that biomaterials play a crucial role in the artificial hip joint, bone plates, and screws, cardiac pacemaker, intra-ocular lens, mastectomy augmentation, chin augmentation, probes and catheters, artificial stapes, intra-medullary rod, etc. There are also some prospects such as nano fibers, artificial tissue, etc. Recently a GPS technology has been developed for the brain. There is also a huge future prospect as the equipment are needed to be enhanced and less cost efficient. Researchers are trying their level through scientific studies to develop more enhanced biomaterials. To produce such material, characterization of the materials is needed to be studied thoroughly. Existing characterization techniques are used as well as several new techniques are also used for a broader range of studies. These methods help to evaluate each character or properties more efficiently, which contributes to modify the substances more effectively.

References

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Schmalz, G., 2009. Determination of biocompatibility. In Biocompatibility of dental Materials (pp. 13-43). Springer Berlin Heidelberg.

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