An Enzyme-Induced Metallization-Based Electrochemical Signal Amplification Strategy for Ultrahigh Sensitive Alkaline Phosphatase Detection at Attomolar Concentrations

Abstract A highly sensitive enzyme-induced metallization-based electrochemical signal amplification strategy was developed based on the integration of the enzyme-induced metallization reaction, Au nanoparticles ( AuNPs )-induced silver deposition, chemically modified electrode and highly sensitive stripping voltammetry detection. The presence of alkaline phosphatase ( ALP ) catalyzed ascorbic acid 2-phosphate into ascorbic acid, which reduced Ag + to Ag 0 on the surface of the AuNPs/multi-walled carbon nanotubes/polyethyleneimine/glassy carbon electrode ( AuNPs/MWNTs/PEI/GCE ). As a result, the enzyme-generated product was accumulated on the surface of the AuNPs/MWNTs/PEI/GCE by means of silver deposition via this signal amplification strategy, which enhanced the detection signal dramatically. Amounts as low as 1 × 10 –8 U/mL (corresponding to 10 aM) ALP can be detected using this strategy, which is about 4−7 orders of magnitude more sensitive than with other reported methods for ALP determination. In addition, this strategy can be applied to ALP detection in real complex samples, which shows great potential in the early diagnosis of diseases.