A fluorescent conjugated polymer for trace detection of diamines and biogenic polyamines

The aggregation-based trace detection of diamines and biogenic polyamines has been developed utilizing a carboxylic acid-functionalized polyfluorene (PFCOOH-BT(5)) containing benzo[2,1,3] thiadiazole (BT). Upon addition of diamines or biogenic polyamines, the PFCOOH-BT(5) can be cross-linked via electrostatic interactions between the polymer carboxylic acid binding sites and the amino groups of the multiamines to form interpolymer aggregation, which leads to more efficient FRET from fluorene segments to BT units and thus a noticeable fluorescence color change from blue to orange. In contrast, addition of 1,3-propanediol does not lead to significant variations in the photoluminescence spectra of PFCOOH-BT(5). This unique fluorescence response from PFCOOH-BT(5) to diamines and biogenic polyamines can achieve a detection concentration as low as 2 mu M, indicating that PFCOOH-BT(5) can serve as a general and effective chemosensor to detect trace diamines and biogenic polyamines.