A fluorescent and colorimetric dual-channel sensor based on acid phosphatase-triggered blocking of internal filtration effect.

A colorimetric and fluorescent dual-channel detection method for acid phosphatase (ACP) activity has been constructed, based on the internal filtering effect between oxidized 3,3',5,5'-tetramethylbenzidine (oxTMB) and rhodamine B (RB). Au3+, which in situ form gold nanoparticles (AuNPs), can oxidize colorless 3,3',5,5'-tetramethylbenzidine (TMB) to oxTMB (blue color). The fluorescence of RB can be quenched by oxTMB due to the spectral overlap of emission of RB and absorption of oxTMB. By means of the above process, ACP can be determined because ACP promotes the hydrolysis of 2-phospho-L-ascorbic acid trisodium salt (AAP) to generate ascorbic acid (AA), which can inhibit the internal filtering effect between RB and oxTMB. No material preparation was needed for the determination of ACP. The colorimetric and fluorimetric methods can quantify ACP in the range 0.06-5.0 mU/mL and 0.03-5.0 mU/mL, respectively. Furthermore, a smartphone-assisted sensing platform has been constructed for on-site monitoring of ACP in the range 0.75-50 mU/mL, and the detection limit is 0.3 mU/mL. The methods developed can measure ACP in human serum successfully.