Highly selective and sensitive surface enhanced Raman scattering nanosensors for detection of hydrogen peroxide in living cells.

Determination of hydrogen peroxide (H2O2) with high sensitivity and selectivity in living cells is a challenge for evaluating the diverse roles of H2O2 in the physiological and pathological processes. In this work, we present novel surface enhanced Raman scattering (SERS) nanosensors, 4-carboxyphenylboronic acid (4-CA) modified gold nanoparticles (Au NPs/4-CA), for sensing H2O2 in living cells. The nanosensors are based on that the H2O2-triggered oxidation reaction with the arylboronate on Au NPs would liberate the phenol, thus causing changes of the SERS spectra of the nanosensors. The results show the nanosensors feature higher selectivity for H2O2 over other reactive oxygen species, abundant competing cellular thiols and biologically relevant species, as well as excellent sensitivity with a low detection limit of 80 nM, which fulfills the requirements for detection of H2O2 in a biological system. In addition, the SERS nanosensors exhibit long term stability against time and pH, and high biocompatibility. More importantly, the presented nanosensors can be successfully used for monitoring changes of H2O2 levels within living biological samples upon oxidative stress, which opens up new opportunities to study its cellular biochemistry.