Carbohydrates fluorescent derivatives

In long-wavelength UV light (2 = 365 nm) carbohydrates, e.g. glucose, fructose and lactose, yield pale blue fluorescent derivatives on a weakly fluorescent background. In situ quantitation can be performed at = 365 nm and 2fi = 546 nm (monochromatic filter M 546) [19]. Further differentiation can be achieved by spraying afterwards with p-anisidine-phosphoric acid reagent [8]. 

A typical application of the RI detector is in carbohydrate analysis. Carbohydrates do not adsorb in the UV, do not ionize and although fluorescent derivatives can be made, the procedure is tedious. Consequently, the RI detector can be ideal for detecting such materials and an example of such an application is shown in figure 18. 

In the determination of carbohydrates, sensitivity can often be increased by using fluorescence rather than absorbance for the final determination. With compounds that are not normally fluorescent, it becomes necessary to find fluorescent derivatives. Hirayama [160] concentrated the carbohydrates in coastal water samples, using electrodialysis and evaporation, and made fluorescent derivatives using anthrone and 5-hydroxyl-1-tetralone, determining pentoses separately from hexoses in the process. While this method does seem to have the extra sensitivity expected from fluorescent methods, the extra manipulations render it unsatisfactory for routine use. 

Fluorescent derivatives of carbohydrate-binding proteins have been used to detect cell-surface and intracellular glycoconjugates by microscopy and flow cytometry, to localize glycoproteins in gels and on protein blots, to precipitate glycoproteins in solution and to cause agglutination of specific cell types. 

Klaus et al. (1991) presented a TLC method for the simultaneous analysis of uric acid, creatine, creatinine, and uric acid together with glucose in the urine and serum of patients with diabetes and other carbohydrate anomalies. The method requires no special sample preparation, and separations are done on amino-modified HPTLC precoated plates. Detection of all substances is achieved by simply heating the plates to give stable fluorescent derivatives. 

First, the above-mentioned sensors have major drawbacks, as the detection and recognition event is a function of the nature and characteristics of the side chains, and the side chain functionalization of the CP requires advanced synthesis and extensive purification of numerous monomeric and polymeric derivatives. Second, this generation of sensors primarily employed optical absorption as the source for detection, resulting in lower sensitivity when compared with other sensing systems for biological processes. However, the use of fluorescence detection within these sensing systems could justify continued development. More recent examples include a fluorescent polythiophene derivative with carbohydrate functionalized side chains for the detection of different bacteria [15] and novel synthesis schemes for ligand-functionalization of polythiophenes [16]. 

Carbohydrate detection is important for applications such as glucose monitors these are arguably one of the most successful and relevant biosensors. An interesting fluorescence recovery-type saccharide sensor based on the reactivity of carbohydrates with boronic acids was reported in 2002 [36]. Specifically, modification of the cationic viologen-linked boronic acid derivative 40 to a zwitterionic species 41 upon covalent and reversible reaction of boronic acid with monosaccharides (Scheme 1) can cause the dissociation of the ion-pair in-... 

Qaqish, R.B., Amiji, M.M. (1999). Synthesis of a fluorescent chitosan derivative and its application for the study of chitosan-mucin interactions. Carbohydrate Polymers, 38, 99-107. 

Analytical Use of Fluorescence-Producing Reactions of Lipid- and Carbohydrate-Derived Carbonyl Groups with Amine End Groups of Polyamide Powder... 

During this period, Laurie also investigated the preparation of radiolabeled, iodo and bromo sugars via carbohydrate boranes (with J.-R. Neeser), fluorescent probe-sugar conjugates (with M. Yalpani), sugar ferrocene derivatives (with M. J. Adam), and extended his studies of the conformations of polycyclic sugar derivatives. 

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