Biocompatible ionic liquid-based

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. 

Petkovic M, Ferguson JL, Nimal Gunaratne HQ, Ferreira R, Leitao MC, Seddon KS, Rebelo LPN, Pereira CS (2010) Novel biocompatible cholinium-based ionic liquids - toxicity and biodegradability. Green Chem 12 643-649... 

Amino acids (AA), as one of the most abundant biomaterials in nature, are known to be nontoxic, biodegradable, and biocompatible. They are excellent feedstocks for the synthesis of ILs, because of their reasonable cost and environment-friendly characteristics. In 2005, a group of amino acid ionic liquids (AAILs) was first synthesized by Fukumoto s group from 20 natural AA [85]. They prepared AAILs based on l-ethyl-3-methylimidazolium cation, [emim], by neutralization method. In this method, [emim]OH was prepared by anion exchange resin, followed by addition of [emim]OH to a slight excess of an equimolar AA aqueous solution to prepare salts and water as a by-product [86]. Further, they synthesized tetrabutylphosphonium-based AAILs ([TBP][AA]) by mixing AA with aqueous solution of tetrabutylphosphonium hydroxide ([TBP][OH]) [87]. Tao et al. [88] synthesized [AAE]N03 ILs ([AAE] stands for AA ester as cation and NO3 stands... 

Zaijun, L., Zhongyun, W., Xiulan, S. et al. (2010) A sensitive and highly stable electrochemical impedance immimosensor based on the formation of silica gel-ionic liquid biocompatible film on the glassy carbon electrode for the determination of aflatoxin B1 in bee pollen Talanta, 80,1632-1637. 

In this context, one good example of a biocompatible IL-based polymer gel was given by Sehgal and co-workers. (Vijayaraghavan et al., 2010) The authors have used choline salts, some of which can be described as ionic liquids, as crosslinking agents for collagen in order... 

Ionic liquids are often hygroscopic [371], and considerable amounts of water might "contaminate" the ionic liquid affecting its properties, especially the viscosity of the system [373-375]. Impurities in the ionic liquid (from its synthesis) might be a reason for its toxicity to the cells [376]. Biocompatibility tests using l-alkyl-3-methylpyridinium- or l-alkyl-3-methylimidazolium-based ionic liquids and baker s yeast have been performed [361], and their toxic effect for the cells was attributed to the amphiphilic nature of the cation [362,364,367,371,377-381]. Saccharomyces cerevi-siae tolerates [PFg] as a counterion better than [BFJ, which was more toxic to the cells [382]. Ionic liquids have also been used with inunobilized baker s yeast [364], and the toxicity of l-alkyl-3-methylimidazolium-based ionic liquids increased with the exposure time. 

Carboxymelhylated chitosan (CM-chitosan) has a similar molecular structure with amino acids and can be obtained by carboxymethylated reactions between chitosan and monochloroacetic acid [57]. Chitosan and CM-chitosan are attractive nontoxic, biocompatible, biodegradable, and film-forming biomaterials that can be used as biosensors and biocatalysis [58]. Despite a composite system based on chitosan and RTILs for electrochemistry applications presented by Lu et al. [59], to date, there are no other reports on the synthesis of ionic liquids composed of natural oligosaccharides. Furthermore, it will be helpful to improve the biocompatibility of ionic liquid by introducing CM-chitosan as an anion compound. Recently, RTIL based on l-ethyl-3-methylimidazolium hydroxide, [C2mim][OH], and CM-chitosan was prepared by a neutralization reaction (Fig. 7.7) [57]. 

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