Chemodosimeter-based fluorescent detection of l-cysteine after extracted by molecularly imprinted polymers

A chemodosimeter-based fluorescent detection method coupled with molecularly imprinted polymers (MIPs) extraction was developed for determination of l-cysteine (l-Cys) by combining molecular imprinting technique with fluorescent chemodosimeter. The MIPs prepared by precipitation polymerization with l-Cys as template, possessed high specific surface area of 145 m2/g and good thermal stability without decomposition lower than 300 °C, and were successfully applied as an adsorbent with excellent selectivity for l-Cys over other amino acids, and enantioselectivity was also demonstrated. A novel chemodosimeter, rhodamine B1, was synthesized for discriminating l-Cys from its structurally similar homocysteine and glutathione as well as various possibly co-existing biospecies in aqueous solutions with notable fluorescence enhancement when adding l-Cys. As l-Cys was added with increasing concentrations, an emission band peaked at 580 nm occurred and significantly increased in fluorescence intensity, by which the l-Cys could be sensed optically. High detectability up to 12.5 nM was obtained. An excellent linearity was found within the wide range of 0.05–50 μM (r=0.9996), and reasonable relative standard deviations ranging from 0.3% to 3.5% were attained. Such typical features as high selectivity, high sensitivity, easy operation and low cost enabled this MIPs-fluorometry to be potentially applicable for routine detection of trace l-Cys.