Quantitative evaluation of human carboxylesterase 1 by SERS-ELISA using a synergistic enhancement strategy based on gold nanoparticles and metal–organic framework

In this study, we synthesized gold nanoparticles (AuNPs) in situ on the surface of two-dimensional Cu-TCPP (meso-tetra(4-carboxyphenyl)porphine) metal– organic framework (MOF) nanosheets to produce AuNP@Cu-TCPP nanocomposites as surface-enhanced Raman scattering (SERS) substrates. The SERS signal was enhanced in two ways: aggregation of the AuNPs@Cu-TCPP near the SERS hotspot through the strong adsorption capacity of the MOF, and the synergistic effect between the charge-transfer enhancement of the Cu-TCPP MOF and the electromagnetic enhancement of plasmonic metal AuNPs. The SERS activity of AuNPs@Cu-TCPP was evaluated by the analysis of multiple model analytes; Rhodamine 6G (R6G) and benzidine were detected with detection limits below 10 –13 and 10 –12 mol·L –1 , respectively. We used AuNP@Cu-TCPP as a SERS substrate combined with an enzyme-linked immuno- sorbent assay (ELISA) to detect the tumor marker carboxylesterase 1 (hCE1) in human serum. The SERS signal of benzidine at 1609 cm −1 is linearly correlated with hCE1 in the concentration range of 0.1–120 ng·mL −1 . Owing to their high sensitivity and excellent SERS sensing capability, AuNPs@Cu-TCPP nanocomposites have potential applicability in the analysis of clinical samples.