Biocompatibility interactions

Determination of the exact mechanism leading to cellular internalisation of CNTs is considered very important in their development as components of biomedical devices and therapeutics intended for implantation or administration to patients. One of the most important parameters in all such studies is the type of nanotubes used, determined by the process by which they are made biocompatible. Interactions with cells have to be performed using biocompatible CNTs, achieved by either covalent or noncovalent surface functionalisation that results in water-dispersible CNTs. A variety of different functionalisation strategies for CNTs have been reported by different groups, therefore direct comparisons are often hampered by the inability to correlate experimental conditions. 

Silver F H and DoiUon Ch, Biocompatibility. Interactions of Biological and Implantable Materials, VCH-Wiley, New York, 1989. 

To be biocompatible is to interact with all tissues and organs of the body in a nontoxic manner, not destroying the cellular constituents of the body fluids with which the material interfaces. In some appHcations, interaction of an implant with the body is both desirable and necessary, as, for example, when a fibrous capsule forms and prevents implant movement (2). 

In this chapter an overview of both the opportunities and the problems presented by the biological system for the use of polymeric drug delivery systems will be presented. Since the area of biocompatibility of the delivery system is a well-known constraint also imposed by the biological system and is beyond the scope of this presentation, this (important) consideration will be ignored here. In order to examine how a delivery system interacts with the biological system to... 

Despite the evidence for the cytotoxicity of CNTs, there are an increasing number of published studies that support the potential development of CNT-based biomaterials for tissue regeneration (e.g., neuronal substrates [143] and orthopedic materials [154—156]), cancer treatment [157], and drug/vaccine delivery systems [158, 159]. Most of these applications will involve the implantation and/or administration of such materials into patients as for any therapeutic or diagnostic agent used, the toxic potential of the CNTs must be evaluated in relation to their potential benefits [160]. For this reason, detailed investigations of the interactions between CNTs/CNT-based implants and various cell types have been carried out [154, 155, 161]. A comprehensive description of such results, however, is beyond the scope of this chapter. Extensive reviews on the biocompatibility of implantable CNT composite materials [21, 143, 162] and of CNT drug-delivery systems [162] are available. 

The immobilisation of proteins into inorganic mesoporous host materials has attracted considerable attention due to the potential applications in biochemical, biomedical, industrial and bio-analytical fields [1] Biocompatible supports endowed with fluorescent tracers and adequately modified for specific interactions with cellular antigens are an amenable tool for image in living cells processes that are relevant to diseases. 

Similarly to the phospholipid polymers, the MPC polymers show excellent biocompatibility and blood compatibility [43—48]. These properties are based on the bioinert character of the MPC polymers, i.e., inhibition of specific interaction with biomolecules [49, 50]. Recently, the MPC polymers have been applied to various medical and pharmaceutical applications [44-47, 51-55]. The crosslinked MPC polymers provide good hydrogels and they have been used in the manufacture of soft contact lenses. We have applied the MPC polymer hydrogel as a cell-encapsulation matrix due to its excellent cytocompatibility. At the same time, to prepare a spontaneously forming reversible hydrogel, we focused on the reversible covalent bonding formed between phenylboronic acid and polyol in an aqueous system. 

The interaction in an interface of device/tissue is limited by two factors. There is the corrosive environment, such as biological fluid, which contains salts and proteins among other cellular structures in which the sensor device must survive [47, 48], Second, there is the encapsulation material which may induce a toxic reaction due to poor biocompatibility and hemocompatibility [49, 50], It is crucial to use a biomaterial that can overcome both limiting factors to maintain the lifetime of the sensor device and protect the body [51, 52],... 

CNTs offer an exciting possibility for developing ultrasensitive electrochemical biosensors because of their unique electrical properties and biocompatible nanostructures. Luong et al. have fabricated a glucose biosensor based on the immobilization of GOx on CNTs solubilized in 3-aminopropyltriethoxysilane (APTES). The as-prepared CNT-based biosensor using a carbon fiber has achieved a picoamperometric response current with the response time of less than 5 s and a detection limit of 5-10 pM [109], When Nation is used to solubilize CNTs and combine with platinum nanoparticles, it displays strong interactions with Pt nanoparticles to form a network that connects Pt nanoparticles to the electrode surface. The Pt-CNT nanohybrid-based glucose biosensor... 

This chapter will describe the potential of carbon nanotubes in biomedicine. It will illustrate the methodologies to render nanotubes biocompatible, the studies on their cell uptake, their application in vaccine delivery, their interaction with nucleic acids and their impact on health. 

Nanocarbon structures such as fullerenes, carbon nanotubes and graphene, are characterized by their weak interphase interaction with host matrices (polymer, ceramic, metals) when fabricating composites [99,100]. In addition to their characteristic high surface area and high chemical inertness, this fact turns these carbon nanostructures into materials that are very difficult to disperse in a given matrix. However, uniform dispersion and improved nanotube/matrix interactions are necessary to increase the mechanical, physical and chemical properties as well as biocompatibility of the composites [101,102]. 

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