Surface-Enhanced Raman Scattering Bioimaging with an Ultrahigh Signal-to-Background Ratio under Ambient Light.

Surface-enhanced Raman scattering (SERS) nanoprobes have attracted particular interests in the field of bioimaging owing to their high sensitivity and specificity of the fingerprint spectrum. However, the limited signal-to-background ratio (SBR) in SERS imaging and the requirement to perform imaging in a dark environment have largely hindered its biomedical application. To circumvent this, we have developed a type of bio-orthogonal nanoprobes for SERS imaging with an ultrahigh SBR and ambient light anti-interference ability. The core-shell nanoprobes exhibit strongly enhanced Raman signals and depress the background from photoluminescence of metallic nanoparticles by off-resonance excitation and from the Raman scattering and auto-fluorescence of tissues by near-infrared laser excitation. Such nanoprobes have achieved an SBR of over 100 in SERS bioimaging, 5 times higher than the traditional on-resonant nanoprobes, and their bio-orthogonal signal in the Raman-silent region renders the anti-interference capability under ambient light. The development of these SERS probes opens up a new era for the future applications of Raman imaging in clinical medicine.