Real-time monitoring of active caspase 3 during AFB1 induced apoptosis based on SERS-fluorescent dual mode signals

Aflatoxin B1 (AFB1) is the most toxic mycotoxin. Usually, the toxin activated apoptosis is considered mostly through intrinsic mitochondrial pathway while the caspase family as promoter and executor plays a crucial role. In this paper, a real-time and in situ detection of caspase 3 in living cells based on SERSfluorescence dual mode nanosensor was studied. Firstly, gold nanotriangles (AuNTs) modified with the caspase 3 specifically recognized polypeptide chain DEVD were synthesized as both SERS enhanced substrate and fluorescent quencher. Rhodamine B (Rb) as both Raman and fluorescent signal molecules was modified on the N end of DEVD chain. After active caspase 3 specifically cut off the recognition site in DEVD, partial peptide chain with Rb fell off from the surface of AuNTs. Thus, the Raman signal of Rb decreased while its fluorescent signal recovered. There was a good linear relationship between caspase 3 and both the SERS and fluorescence signals of Rb. The minimum detection limit was 0.001 nM. After cells were stimulated by AFB1, when Cyt C in the cytoplasm reached a certain level, caspase 3 was activated. This nanosensor was realized in certain living cells (HepG2, HeLa and A549). Based on monitoring the activation of specific apoptotic markers, the conduction of marker signals in real time can provide more detailed information for apoptosis. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study focused on real-time detection of caspase 3 in living cells using a dual-mode nanosensor based on SERS-fluorescence. The sensor showed good linear relationship between caspase 3 and both SERS and fluorescence signals, with a minimum detection limit of 0.001 nM. Activation of caspase 3 was observed in cells stimulated by AFB1, providing detailed information for apoptosis monitoring.