Triple bond-mediated ratiometric surface-enhanced Raman scattering nanoprobe for in vitro and ex vivo quantitative monitoring of mercury

Mercury poses a significant threat to both ecosystems and humans due to its high toxicity, non-biodegradability,   and persistent accumulation. The development of suitable tools for the quantitative and real-time detection of mercury in living organisms is extremely attractive. However, reliable quantitative analysis of mercury in living organisms using surface-enhanced Raman scattering (SERS) nanoprobe is still a challenge. Herein we reported the first triple bond-mediated ratiometric SERS nanoprobe for in vitro and ex vivo quantitative monitoring of mercury (Hg 2+ ). In the SERS nanoprobe, an internal standard (IS, 4-MBN)-embedded gold nanoflowers was first synthesized, and then the synthesized Raman reporter 4-MPA was bound to the surface as the recognition group for Hg 2+ . The SERS nanoprobe demonstrated a dose-dependent ratio change (I 2145 /I 2224 and I 2105 /I 2224 ) in the cellular Raman-silent region upon reacting with Hg 2+ , and the detection limit is as low as 5.6 nM (I 2145 /I 2224 ). Moreover, the nanoprobe was used to detect Hg 2+ in water samples, tea, and fish samples with high accuracy and recovery rate (91.31 %-107.9 %). Notably, the quantitative visualisation of Hg 2+ in living cells and mouse liver tissue was achieved based on Raman silent region ratio imaging without bio-interference. This study highlights the potential of the established bioorthogonal ratiometric SERS nanoprobe for in vitro and ex vivo quantitative monitoring of mercury. We anticipate that the novel SERS nanoprobe has great application potential in the study of Hg 2+ -related physiological and pathological events in the future.