A simple and rapid method for detection of potassium ion (K+) based on a guanine chemiluminescence (CL) system is presented. In this system, one guanine-rich DNA molecule is used as the recognition element. K+ can cause the guanine-rich DNA to form a G-quadruplex conformation, resulting in remarkable quenching of the guanine CL intensity of guanine-rich DNA. The CL intensity of this CL system decreased with increasing K+ concentration, revealing a linear relationship in K+ concentration range from 3 x 10(-5) to 1 x 10(-3) M. A complete detection process can be accomplished in about 5 min. Other common cations (such as Na+, NH4 (+), Mg2+, Ca2+, Zn2+, and Pb2+) did not notably interfere with K+ detection. The mechanism of this strategy is also discussed. The sensing strategy is low cost and simple without the requirement of complex labeling of probe DNA. The scheme is applicable to the detection of other guanine-rich aptamer-binding chemicals or biomolecules.
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