Self-assembled small molecule based fluorescent detection of serum albumin proteins: Clinical detection and cell imaging

Abstract

We report perylenediimide-benzimidazolium based fluorescent ‘turn-on’ probe BIM-PDI for selective detection of human serum albumin (HSA) and bovine serum albumin (BSA) proteins. In HEPES buffer (0.1% DMSO), BIM-PDI self-assembles into aggregates and shows absorption maxima at 500nm and weak fluorescence centered at 577nm. The addition of HSA or BSA (1×10−9–5×10−8M) to the solution of BIM-PDI results in decrease in the emission intensity at 577nm. However, further increase in concentration of HSA/BSA results in appearance of new blue shifted emission band at 540nm. The minimum detection limit for HSA/BSA is 3.01×10−10M at 577nm and 4.2×10−8M at 540nm. On addition of BSA to the solution of BIM-PDI, the size of the aggregates decreased from 100 to 250nm to <10nm assigned to microencapsulation driven disassembly of BIM-PDI aggregates responsible for ‘turn-on’ response in fluorescence spectrum. Site-selective experiments using warfarin and diazepam drugs show that BIM-PDI preferably binds at site-I of HSA/BSA proteins. In clinical application of BIM-PDI, we estimated HSA content in blood serum and urine samples. BIM-PDI showed potential application in serum albumin protein tracking and imaging.