Colorimetric-SERS dual-mode sensing of Pb(II) ions in traditional Chinese medicine samples based on carbon dots-capped gold nanoparticles as nanozyme

[Display omitted] •A novel colorimetric/SERS dual mode detection method for Pb (II) was proposed by using the peroxidase activity of CDs and Au NPs.•The dual-mode probe integrates the advantages of facile detection by colorimetric analysis and high-sensitive trace assay by SERS.•The dual-mode detection has the characteristic of fast, on-site, specificity, high sensitivity, and wide detection range for Pb (II) assay.•Realization of dual-mode detection of traditional Chinese medicine samples. Peroxidase (POD)-mimicking nanozymes have got great progress in the sensing field, but most nanozyme assaying systems are built with a single-signal output mode, which is vulnerable to the effect of different factors. Thus, establishment of a dual-signal output mode is necessary for acquiring dependable and durable performance. This work described an Fe doped noradrenaline-based carbon dots and Prussian blue (Fe,NA-CDs/PB) nanocomposite as a POD-like nanozyme and modified gold nanoparticles (AuNPs) for the colorimetric and surface-enhanced Raman scattering (SERS) dual-mode sensor of Pb(II) in traditional Chinese medicine samples. With 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 3,3′,5,5′-tetramethylbenzidine (TMB) as the substrates, it was found that the addition of Pb(II) inhibited the POD-like activity of Fe,NA-CDs/PB and AuNPs, so it was used for colorimetric and SERS dual-mode assays. The POD-like activity was shown to be a “ping-pong” catalytic mechanism, whereas the addition of Pb(II) produced noncompetitive inhibition with modulatory effects on Fe,NA-CDs/PB. The linear response range for colorimetric and SERS sensor detection of Pb(II) was 0.01–1.00 mg/L with the detection limit of 5 μg/L and 8 μg/L, respectively. This dual-mode detection system shows excellent selectivity. More importantly, the Pb(II) in traditional Chinese medicine samples have successfully assayed with good recovery from 90.4 to 108.9 %.