Utilization of host assisted aggregation-induced emission of ANS dye for ATP sensing

Photoemission efficiency of certain organic dyes gets augmented many fold when they are aggregated in solution. This AIE (Aggregation induced emission) property of dyes opens up new horizon in bio-imaging, fluorescence sensing of bio-analytes, molecular electronics, optoelectronics, chemical sensor etc. Herein, we report AIE enhancement of anionic ANS dye (8-anilinonaphthalene-1-sulfonic acid) aided by multi-cationic polymeric host, PAMA [poly(diallyl dimethyl ammonium) chloride] in aqueous solution. Anionic ANS loses its negative charge partially through charge neutralization at the vicinity of poly cationic PAMA host, leading to the reduction of like charge repulsion between the ANS molecules. This helps the dye molecules to stick together by π-π interaction, forming an aggregated assembly. Hence, there is a substantial reduction in torsional motion of the dye molecules, which is ultimately expressed as significant enhancement in its fluorescence intensity. The interaction of ANS dye with host polymer PAMA is primarily electrostatic in nature as indicated by ionic strength dependent study. This prompted the ANS-PAMA complex to be used as fluorescence probe to detect and quantify an important charged bio-analyte ATP (Adenosine triphosphate) in serum matrix at physiological pH 7.2, exhibiting the applicability of the studied system in the field of bio-sensing.