Application of a Novel Turn-on Fluorescent Material to the Detection of Aluminum Ion in Blood Serum

A novel turn-on fluorescent bioprobe, 1,2,3,4,5-penta(4-carboxypheny1)pyrrole sodium salt (PPPNa), with aggregation-enhanced emission characteristics was synthesized for the in situ quantitative detection of Al3+ in serum. It exhibited a high selectivity to Al3+ in both simulated serum and fetal calf serum with no interferences from other metal ions or serum components observed and no isolation required. A weak interaction between PPPNa and serum albumin was found, which caused no interference, but enhanced fluorescence response of PPPNa to Al3+ and improved detection sensitivity. The limit of detection was determined to be 1.50 mu mol/L Al3+ in phosphate-buffered saline solution containing 33 mu g/mL bovine serum albumin (BSA) and decreased to 0.98 mu mol/L as BSA concentration increased to 100 mu g/mL. The fluorescence turn-on mechanism of the PPPNa probe to detect AI' was proposed. A bidentate complex is formed between the carboxy group of PPPNa and Al3+, causing the photoluminescence (PL) emission enhancement by aggregation. BSA chains further strengthen the stacking compactness of the aggregates of PPPNa and Al3+ and consequently enhance the PL emission of PPPNa by further promoting the restriction of intramolecular rotation of the phenyl ring. Its application to the in situ Al3+ was successfully demonstrated with HeLa cells and NIH 3T3 cells. The low cytotoxicity and highly selective response of PPPNa to Al3+ endow its great potentials to in vivo detecting and imaging of Al' as well as an absorbent of Al3+.