The disclosure relates to metallic nanophotonic crescent structures, or “nanocrescent SERS probes,” that enhance detectable signals to facilitate molecular detections. More particularly, the nanocrescent SERS probes of the disclosure possess specialized geometries, including an edge surrounding the opening that is capable of enhancing local electromagnetic fields. Nanosystems utilizing such structures are particularly useful in the medical field for detecting rare molecular targets, biomolecular cellular imaging, and in molecular medicine.