Biocompatibility concepts

Over the years of evolution, Nature has developed enzymes which are able to catalyze a multitude of different transformations with amazing enhancements in rate [1]. Moreover, these enzyme proteins show a high specificity in most cases, allowing the enantioselective formation of chiral compounds. Therefore, it is not surprising that they have been used for decades as biocatalysts in the chemical synthesis in a flask. Besides their synthetic advantages, enzymes are also beneficial from an economical - and especially ecological - point of view, as they stand for renewable resources and biocompatible reaction conditions in most cases, which corresponds with the conception of Green Chemistry [2]. 

Although there are several definitions of biocompatibility, the concept named as biocompatibility is usually used to describe the ability of a material to perform a desired function without producing a negative effect on biological systems in specific... 

The demonstration of the potential of this stable and obviously excellently tolerated compound has inspired a great number of scientists to develop PFCLs as special tools for medical applications and to introduce therapies using the outstanding behaviours of PFCLs, like the well-known concepts of complete and partial liquid ventilation [4], oxygen support of the skin, wound treatment [5], artificial tears [6], and ocular endotamponade media [1], to name only a few. Until now, the mouse submersed in PFCLs is often used as an eye-catcher for the demonstration of the biocompatibility of PFCLs even in cases where the topic of the presentation is not reflected by this experiment. 

Biocompatibility (See Table 1), which is a phenomenological concept, is the essential property of biomaterials. For instance, the inner surface of an implanted vascular graft or blood pump (artificial heart) must be blood-compatible, while its outer surface must be tissue-compatible. In other words, the material surfaces must not exert any adverse elfects upon blood or tissue, or upon other biological elements at the interfaces. 

In this chapter and the one that follows, we will review the research concerning the uses of polyurethanes in biomedical applications. Such uses range from topical application of hydrophilic polyurethane pads to the implantation of scaffolds of reticulated foam as organ-assist devices. The range of applications is broad and each use requires that specific problems associated be addressed. This chapter begins with a discussion of biocompatibility — a broad concept ranging from the simple nonir-ritating characteristics required for topical applications to the complex type of compatibility (hemocompatibility) that allows use with whole blood. 

Water-based barrier dressings are attractive for application to injured tissue because of the biocompatibility between water and tissue. The concept of a water-based dressing initially consisted of latex-type particles of polymer suspended in an aqueous emulsion. The emulsion would be liquid applied to the tissue, water would evaporate and the particles would coalesce to form a continuous film. The rate of evaporation of water is slow compared to solvents as ethanol that was recognized to be a limitation to application time (time to place on the tissue and harden). The following description of miniemulsions (miniEP) involves a batch type... 

The response reaction of the host to a foreign material remaining in the body for an extended period of time is a concern. Thus, any polymeric material to be integrated into such a delicate system as the human body must be biocompatible. Biocompatibility is defined as the ability of a material to perform with an appropriate host response in a specific application [79]. The concept include all aspects of the interfacial reaction between a material and body tissues initial events at the interface, material changes over time, and the fate of its degradation products. To be considered bio compatible, a biodegradable polymer must meet a number of requirements, given in Table 2. 

Learmonth ID. Biocompatibility a biomechanical and biological concept in total hip replacement. Surgeon 2003 1 1-8. 

Channel walls are assumed to be biocompatible, but so is the carrier phase, which can be added with specific surfactants to avoid aggregation during separations so far, bovine serum albumin (BSA) " (and, recently, cholic acid) appeared to be more stable and at least as efficient. Such precautions must be associated with systematic recovery measurements—a multidimensional concept associated with the detector pattern, and a comparison of the cmde sample with every collected fraction. 

The concept of drug delivery devices is old, but new technologies are being applied. Surgical techniques and special injection devices are sometimes required for implantation. The materials used for these implants must be biocompatible. 

According to the critical log P concept, an organic solvent is considered biocompatible if it does not influence the activity of the ceUs of the MO used [10]. As a result, the Z value for the MO used in the presence of such a biocompatible diluent wiU be approximately equal to 100% [10]. Based on data in Fig. 8.2, Z is equal to 100% for a diluent with the log P value of 4.5. That means that any dUuent with a log P value higher than 4.5 will be biocompatible with the hypothetical MO used, and therefore log P value of... 

Terminal groups can be inserted on the surface of NPs with a procedure called functionalization , in order to increase their dispersability and their biocompatibility [181, 185], The creation of free carboxylic acid and amino acid moieties on the surface are the most commonly used functionalization procedure for enzyme immobilization and stabilization [181, 185], In the same concept, Jiang and his coworkers functionalized silica coated-NPs with imidazolium-based ionic liquids [179]. The immobilization of ionic liquid facilitates the reuse of these solvents, while it provides a microenvironment in which the enzyme exhibits high activity and stability. 

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