Multi-enzyme layer-by-layer assembly for dual amplified ultrasensitive electronic detection of cancer biomarkers

摘要

The preparation and use of multi-enzyme layer-by-layer (LBL) assembled single wall carbon nanotube (SWCNT) composite labels for amplified ultrasensitive electrochemical detection of a cancer biomarker is described. The target protein, carcinoembryonic antigen (CEA), is sandwiched between an electrode surface-confined capture anti-CEA antibody and the secondary signal anti-CEA/enzyme-LBL/SWCNT bio-conjugate. The dual biocatalytic signal amplification for CEA monitoring is achieved through both the numerous enzymes loaded on the CNTs and redox-recycling of the enzymatic products in the presence of the secondary enzyme and the corresponding substrate. Our novel dramatic signal amplification strategy, with a detection limit of 0.04 pgmL~(-1), shows about 2-4 orders of magnitude improvement in sensitivity for CEA detection compared with other universal signal amplified assays, which makes our signal amplification approach hold great potential applications in detection of ultra-trace protein biomarkers.