The efficiency of current microcystin detection methods has been hampered by the low detection limits required in drinking water and that routine detection is restricted to a few of the congeners with high degree of undesired cross-reactivity. Here, we report the development of novel microcystin-targeting molecules and their application in microcystin detection. We have selected DNA aptamers from a diverse random library that exhibit high affinity and specificity to microcystin-LR, -YR, and -LA. We obtained aptamers that bind to all chosen congeners with high affinity with K(D) ranging from 28 to 60 nM. More importantly, we also obtained aptamers that are selective among the different congeners, with selectivity from 3-folds difference in binding affinity to total discrimination (K(D) of 50 nM versus nonspecific binding). Electrochemical aptasensors constructed with the selected aptamers were able to achieve sensitive and congener-specific microcystin detection with detection limit as low as 10 pM.

An on-line two-dimensional (2D) capillary electrophoresis (CE) system consisting of capillary isoelectric focusing (CIEF) and capillary gel electrophoresis (CGE) was introduced. To validate this 2D system, a dialysis interface was developed by mounting a hollow fiber on a methacrylate resin plate to hyphenate the two CE modes. The two dimensions of capillary shared a cathode fixated into a reservoir in the methacrylate plate; thus, with three electrodes and only one high-voltage source, a 2D CE framework was successfully established. A practical 2D CIEF-CGE experiment was carried out to deal with a target protein, hemoglobin (Hb). After the Hb variants with different isoelectric points (pIs) were focused in various bands in the first-dimension capillary, they were chemically mobilized one after another and fed to the seconddimension capillary for further separation in polyacrylamide gel. During this procedure, a single CIEF band was separated into several peaks due to different molecular weights. The resulting electrophoregram is quite different from that of either CIEF or CGE; therefore, more information about the studied Hb sample can be obtained.Two-dimensional polyacrylamide gel electrophoresis (2D PAGE) has been a standard technique for high-throughput separation and characterization of biological macromolecules, especially proteins. A main advantage of 2D PAGE is its ability to resolve and investigate the abundance of several thousand proteins in a single sample. 1 More than one sample can be dealt with in a single 2D PAGE run, but a total 2D PAGE process usually lasts for at least 1 day and all the manual operations are time-consuming and laborsome. Capillary electrophoresis (CE) is an easier and more rapid alternative to slab electrophoresis. CE was thoroughly reviewed 2-7 and now is a powerful tool for the separation of proteins and peptides. [8][9][10][11][12][13] Several kinds of CE mode are built based on different principles. Each single CE mode has its distinct capabilities and limitations. To take full advantage of the capabilities and to avoid the limitations of CE modes it is helpful to combine them one to another [14][15][16][17][18][19][20][21][22] or with separation methods based on other than electromigration principles. Much attention bas been paid to the hyphenation of CE with liquid chromatography (LC). [23][24][25][26][27][28][29][30][31] There has been a great deal of effort to interface CE with mass spectrometry (MS); nonetheless, MS was considered as a molecular weight detector rather than a separation tool. [32][33][34][35][36][37][38] * Corresponding author: (e-mail) ykzhang@dicp.ac.cn; (phone) +86-411-3693427; (fax) +86-411-3693427.(1) Lilley, K. S.; Razzaq, A.; Dupree, P. Curr. Opin. Chem. Biol. 2002, 6, 46-50. (2)

No abstract