A self-calibrated 2D nanoarchitecture for label-free SERS quantitation and distribution imaging of target

To achieve handy and reliable quantitative measurements of surface-enhanced Raman spectroscopy (SERS) for universal analysis, this work designs a self-calibrated 2D nanoarchitecture as a flexible sensor. This sensor consists of a self-assembled gold nanostars (AuNSs) monolayer sandwiched between two pieces of graphene, and can be easily attached on the surface of arbitrary samples. The inner AuNSs can offer a huge number of hot spots for strong Raman enhancement, and the existence of graphene further improves the stability and reproducibility of SERS signals for precise detection. By implanting Raman reporters as internal standard (IS) onto one side of the device and attaching the device with opposite side on sample surface, the distinct SERS signals from both IS and target can be quickly collected, which offers reliable quantification information of the target by IS calibration and has been demonstrated at the theoretical and experimental levels. Using carcinogenic dyestuff and agricultural fungicide as target models, this flexible nanoarchitecture realizes fast quantitative response to target in sample solution, and rapid in situ imaging of target distribution on solid surface. This sensor shows excellent reusability, good durability, and diversified structure collocation along with the simple operability, indicating great promise for fast on-site SERS detection in quantification and imaging applications.