A new ＂off-on＂ switch for sensitive and selective fluorescence detection of biothiols[glutathione（GSH）, cysteine（Cys） and homocysteine（Hcy）] was developed based on an anionic conjugated polyelectrolyte（CPE）, pyridyl-functionalized poly（phenylene ethynylene）（Pl）. The fluorescence of P1 can be significantly quenched by Ag＋ due to complexation-mediated interpolymer aggregation. Furthermore, biothiols can efficiently recover the fluorescence intensity of P1 as a result of the stronger binding between thiol group and Ag＋, which dissociates PI from the P1/Ag＋ complex and disrupts interpolymer aggregation. Under optimum conditions, a good linear relation- ship in a range of 100--4200 nmol/L is obtained for GSH with a detection limit of 80 nmol/L（S/N=3）. As a result of specific interaction between the thiol group and Ag＋, the proposed method shows a high selectivity for biothiols. In addition, the CPE-based fluorescence ＂off-on＂ switch has been used to quantitatively detect total biothiols in cell lysates.
XIAO YiLI ShaHUANG Hong-meiZHANG YeXUE Zun-zunTANG Xue-yanHE Xiao-xiaoWANG Ke-min
