A stepwise assembly strategy to enhance sensitivity in fluorogenic ALP assays

Area of Science:

• Analytical Chemistry
• Materials Science
• Biochemistry

Background:

• Highly fluorescent probes are crucial for sensitive and reliable fluorometry.
• Enhancing existing fluorescent probes is a meaningful alternative to synthesizing new ones.
• Alizarin Red S (ARS)/PyB(OH)2 (A/P) complexes show potential for fluorescence applications.

Purpose of the Study:

• To significantly enhance the brightness of Alizarin Red S (ARS)/PyB(OH)2 (A/P) complexes.
• To develop a novel, sensitive fluorescence turn-on method for Al3+ detection.
• To establish a highly sensitive sensing system for pyrophosphate (PPi) and alkaline phosphatase (ALP).

Main Methods:

• Coordination-induced assembly of ARS/PyB(OH)2 complexes with Al3+.
• Development of a fluorescence turn-on assay for Al3+ detection.
• Theoretical calculations (HOMO-LUMO gaps, configuration changes) to rationalize performance.
• Validation in complex biological matrices like fetal bovine serum.

Main Results:

• Unexpected and significant enhancement of brightness in A/P complexes upon Al3+ coordination.
• Development of a highly sensitive fluorescence turn-on method for Al3+ detection.
• Demonstration of a sensitive sensing system for PPi and ALP with an off-on readout.
• Successful detection of ALP in fetal bovine serum, validating practicality.

Conclusions:

• Al3+ coordination significantly enhances the brightness of A/P complexes, enabling sensitive fluorescence detection.
• A novel Al3+-based, off-on fluorescence assay for ALP was developed, outperforming existing methods.
• The strategy offers a versatile approach to enhance other fluorescent probes and has broad applicability.