An AIEgen-protamine assembly/disassembly based fluorescence turn-on probe for sensing alkaline phosphatase

Alkaline phophatase (ALP) is indispensable for physiological functioning of living systems, and participates in the hydrolysis of monoester phosphate linkage from biological molecules, such as, nucleic acids, proteins etc. The abnormal concentration of ALP in human blood serum is an indicator of many diseases, therefore, ALP acts as a very useful biomarker for diagnosis of several diseases. In this contribution, we have exploited the unique phenomenon of aggregation induced emission (AIE) to design a rapid, easy, sensitive and highly selective fluorescence Turn-On probing system for monitoring ALP activity. The sensing units of the probing system are made up of an AIE active dye, di-anionic 1,2-Bis[4-(3-sulfonatopropoxyl)phenyl]-1,2-diphenylethene salt (BSPOTPE) and polycationic protamine sulphate (PrS) that electrostatically interact with each other to make a highly fluorescent BSPOTPE-PrS supra-molecular complex. Subsequently, the fluorescence of BSPOTPE-PrS complex is efficiently quenched by the introduction of sodium hexametaphospahte, (NaPO3)6. A rapid recovery in the fluorescence (turn-on) is obtained by adding ALP in the basic buffer conditions. The method registers LOD of 28.7 (+/- 3) mu U/mL of ALP in the linear concentration range of 0-36 mU/mL. The sensor exhibits remarkable specificity for ALP. The potential application of the sensing probe in real samples is demonstrated successfully in human serum samples.

Automated summary

The study introduced a fluorescence turn-on probing system for monitoring ALP activity by utilizing the unique phenomenon of aggregation induced emission (AIE), demonstrating rapid, easy, sensitive and highly selective detection. The sensor showed remarkable specificity for ALP and successfully displayed potential application in human serum samples.