Desktop version

Home arrow Health

  • Increase font
  • Decrease font


<<   CONTENTS   >>

POLYMER-BASED BIOMATERIALS

Transportation, building construction, electrical, and electronics, packaging, and aviation industries have attracted considerably with Polymer-based composites [7]. Polymers are used in biomedical applications [8] due to ease of processing, lightweight, flexibility, high strength to weight ratio, greater availability, and higher recyclability is their basic characteristics [9]. Even though metals and ceramics possess higher mechanical properties compared to polymers, polymers still are preferred due to its special characteristics. There can be further improvements by mixing with another polymer, addition of fibers, and nanoparticles [10]. Novel and smart materials are prepared out of polymer matrix with nanoparticle incorporation.

Polymers can be one of the highest among biomaterials which are extensively used in biomedical applications in large multitude. Polymers have appropriate physical, chemical, surface, and biomimetic properties, can be designed and prepared with various structures. Polymers are prepared with relative ease which leads to the versatility attributed by polymers.

Health care industiy has great technological advancements over the last two decades particularly in the field of biomaterials. This is considered as the latest revolution in the area of biomaterials. The survival and quality of life and have enhanced because of biomaterials-based technological developments. More efficient and sophisticated medical devices are available in the market today.

Significant changes happened in the lifestyle pattern. The aging population needs more medical attention. There exists a higher social pressure to reduce costs for health care also. There are several factors including increasing awareness among the public, knowing the efficiency and performance of biomaterials as medical devices, etc. Developments in nanotechnology and the delivery of bioactive agents for treating, repairing, and restoring the function of tissues are of great significance today.

Adhesives, coatings, foams, and packaging materials, textiles, high modulus fibers, composites, electronic devices, biomedical devices, optical devices, and high-tech ceramics are major applications of polymers [11]. Polymeric materials are used along with soil, provide mulch, and promote plant growth. Heart valve and blood vessels are made of Dacron, Teflon, and polyurethane (PU) like polymers are now made with biomaterials.

Polymers are attractive bio-materials, they are having excellent machin- ability, optically transparent used for detection, they are biocompatible with greater thermal and electrical properties, and with high-aspect-ratio for the microstructures. Polymers can be easily used for surface modification and functionalization. This is more applicable in the case of biopolymers including DNA, proteins, and natural polymers. Both synthetic and natural polymer materials are used in soft fabrication techniques.

Engineering plastics like polyetheretherketone is of excellent and notable properties compared to some of the special engineering plastics. There are remarkable advantages like it can take up heat, superior mechanical property, self-lubricating, corrosion-resistant, fire-resistant, irradiation resistant, higher insurability, hydrolytic resistant, and very easily processable. The applications include aerospace, automobile, electronic, electric, medical, and food industry.

Advanced researches are being conducted polymeric biomaterials from various disciplines of polymer chemistry, materials science, biomedical engineering, surface chemistry, biophysics, and biology. In the past few years, polymer-based biomaterial technologies are coming to the commercial applications at a very rapid pace. Polylactic acid (PLA) the most widely used synthetic polymer which introduced by Biscnoff and Walden in 1893 [7]. These are highly biocompatible, with controlled degradation rate and degrade into toxic-free components like CO, and water. They are used for biomedical applications, like natural polymers, polysaccharides or proteins, and synthetic polymers.

Other examples are poly(glycolic acid) (PGA), poly(hydroxyl butyrate) (PHB) and poly(e-caprolactone) (PCL) [8]. Plastics which are good for biomedical applications are polypropylene (PP), PU, and polyethylene (PE) and equally found usefiil. Some of the polymers are soluble in water. Polyvinyl alcohol (PVA), polyethylene glycol (PEG), polyvinyl acetate, polyacrylic acid (PAA), and guar gum have used for similar applications [12].

Recent developments in the field of biocompatible and biodegradable polymers for the applications in tissue engineering and drug delivery have renewed the quest for more efficient new generation polymers. Gomurash- villi et al. [2] have developed new biodegradable and tissue-resorbable co-poly(ester amides) (PEAs) using a versatile active polycondensation technique.

Amino acids, diols, and dicarboxylic acid components in the backbone have a wide range of mechanical properties and biodegradation rates. These PEAs can be used in drug delivery and tissue development. Chitosan-PEG superabsorbent gel prepared at ambient conditions by Chirachanchai et al. [3] may be veiy useful for bioactive agents as an injectable carrier. Metal containing polymeric complexes synthesized by Fraser et al. [7] used in biological activities for using as catalysts, act as materials to respond for stimuli centers and structural materials.

Cooper et al. [13] have developed polymers with high molecular weights. It also gives high tensile properties and melts processability similar to synthetic polymers. Hence can be used as similar as radiation sterilizable aromatic polyanhydride. Nicholas et al. [6] have developed a new route for the preparation of fluorescent bioconjugates by living radical polymerization using protein-derived macro initiators. These fluorescent bioconjugates can be easily traceable in biological environments, during biomedical assays. Cycloaddition reactions have been explored by Grayson et al. [14] to prepare macrocyclic poly(hydroxyl styrene). The presence of a phenolic hydroxyl group on each repeat unit in the cyclic polymer gives better scope for attachment of bioactive counterparts. The cyclization teclmique to have a wider application for preparing a wide range of functionalized macrocycles. Smith and coworkers [15] found poly(N-vinylpyrrolidinone) hydrogels functionalized with drug molecules as promising hydrogels for sustained release of drugs over several days.

Kumar et al. [16] have developed a green route to pegylated amphiphilic polymers with the use of immobilized enzyme, Candida Antarctica lipase B. The ability of these polymers to form the nano-micelles makes them suitable for application in drug delivery systems and in cancer diagnostics. Gong et al.

[17] developed a new highly innovative two-photon activated photodynamic therapy (PDT) which has three-fold level of application, (a) a photosensitizer: a porphyrin substituted on the meso positions by chromophores with large two-photon absorption and activated in the near infra-red region in the tissue transparency window and efficiently producing singlet oxygen as the cytotoxic agent; (b) which can target small molecule also target receptor sites on the tumor; and (c) a imaging agent near IR that can correctly give image of the tumor for treatment. Adronov et al. [14] synthesized carborane functionalized dendronized polymers and found them to be useful as potential boron neutron capture therapy (BNCT) agents. Nederberg and coworkers

[18] have developed a series of telechelic biodegradable ionomers based on polyftrimethylene carbonate) carrying zwitterionic, anionic, or cationic functional groups for protein drug delivery. Biodegradable ionomers was utilized for protein loading simply by letting the material swell in an aqueous protein solution. The process can be done either directly after loading or after a drying. Protein activity is maintained suggesting that these ionomers may favorably interact with guest proteins and denaturation is suppressed.

3.2.1 CHARACTERIZATION OF POLYMERIC BIOMATERIAL

For any polymer-based medical devices, an in-depth understanding of physical, chemical, biological, and engineering properties is highly relevant to get the performance. Efficient polymer-based medical devices and implants require the development of advanced instrumentation and characterization techniques, along with mathematical models to study the structure-property and functional performance relationships of various polymeric systems. Henderson et al. [19] give some of the concepts of NIST measurement technique can be used for tissue engineering which consists of high-throughput, combinatorial methods to produce test specimens of different material properties and advanced instrumentation procedures used for collecting data with high-resolution, non- invasive, multi-level imaging of cells and 3D visualization. Hassan et al. [20, 21] demonstrated the application of broadband dielectric spectroscopy can be used for the study of degradation polymeric materials.

Polymer characterization can use mass spectrometry (MS) which provides details of the development of ionization techniques like MALDI and ESI combined with the latest developments in mass analyzers such as reflection-TOF and FTICR. This has greatly enhanced the capabilities of MS to better understand the detailed composition of polymeric materials. These techniques are giving better mass resolution and accuracy along with hyphenated teclmiques, also give better details about the smallest components in polymeric biomaterials to be assessed, especially with regard to the composition of repeat and end groups. Maziarz and coworkers [22, 23] review the applications of MS in the characterization of polymeric biomaterials.

3.2.2 POLYMERIC INTERFACES

This is of veiy much important to have an in depth understanding of surface/interface characteristics of polymeric biomaterials and precise details of the interaction between their surface and biological entity. This is highly relevant for their successful and safe performance in various applications including biosensing, diagnostics, and medical devices. People are looking for the development of versatile, convenient, and more economical for providing resistant to the surface from fouling by proteins, cells, and microorganisms.

Glasgow et al. [24] review the biocompatibility of surfaces of various hydrophobic, hydrophilic, and heterogenic polymeric biomaterials related to their interactions with proteins and blood platelets. Nandivada et al. [25] give the review in the applications of reactive polymer surfaces created by chemical vapor deposition (CVD) polymerization can work as a strong substrate for biomimetic modifications. Wingkono and co-workers [26] report on the investigation of phase-separated microdomains in a PEG-PCL PU and their effect on osteoblast adhesion. Combinatorial libraries were employed to optimize microphase domain size and shape of PEG-poly(caprolactone) (PCL) PUs in which the effect of these surface structures on osteoblast adhesion was examined using the culmring teclmique of the cells directly on the libraries.

Tissue engineering that applies the principles of engineering and sciences is considered as an interdisciplinary field in the life development of biological substitutes that can be restored, or improve tissue functions. He et al. [27] reviews the materials requirements for tissue engineering application, and focus on polymer materials including both natural and synthetic polymers. It describes the most widely used and newly developed fabrication technologies for the construction of tissue-engineering scaffolds and surface modification or functionalization techniques of tissue engineering scaffolds. Komio et al. [28] developed a covalently crosslinked hydrogel material from a phospholipid polymer containing 2-methacryloyloxyethyl phosphorylcholine units and p-vinylphenylboronic acid (PMBV) in which PVA act as a cell container.

Hydrogels can be formed in pure water and also in saline water including cell culture medium. The viability of the cells in the entrapped in the hydrogel was not affected. Hydrogel based on the phospholipid polymer can be used as a cell container to preserve and transport the cells in tissue engineering applications. Cooper et al. [29] present the evaluation of bioabsorbable, aliphatic polyester blends comprising PLA and poly(ecaprolactone-co-p-dioxanone) (PCL: PDO) for application as a device for cranial fixation. Duran et al. [30] prepared poly(y-benzyl-Z,-glutamate) (PBLG) polypeptide nanotubes for optical biosensor applications using the synthesis of nanostructures within the pores of a nanoporous membrane as the technique.

 
<<   CONTENTS   >>

Related topics