Reproducible, reusable, self-calibrating SERS substrate for single-molecule recognition
Surface Enhanced Raman Spectroscopy (SERS) is an ultra-sensitive, non-destructive spectroscopic technique that enables characterisation and identification of molecules for a wide variety of potential applications including environmental sensing, forensic analysis and medical diagnosis. It potentially replaces fluorescence techniques due to its photon yield, lack of bleaching and label-free molecular signatures.
Wide adoption of SERS-based techniques remains, however, limited by lack of reproducibility and reusability of the SERS substrates. Recently, scientists at Cambridge University developed a novel approach, based on cucurbiturils, that has the potential to dramatically improve the usability of SERS-based techniques.
By accurately controlling the gaps between aggregates of metal nanoparticles using cucurbilturils as rigid sub-nanometre ‘cages’, analyte molecules can be held in the intense electric field regions between the nanoparticles providing the possibility of reliable, highly sensitive, molecular recognition based on SERS. Not only does this technique open up the possibility of using SERS to identify single molecules that have no affinity for metal surfaces, it is also potentially self-calibrating due to the Raman-activity of the cucurbituril spacer molecules themselves and reusable due to the triggered release of analyte molecules from the cucurbilturil ‘cages’ by chemical, photo-initiation or thermal means.