BSA Conjugated Red Emissive Gold Nanocluster as a Fluorescent Nanoprobe for Super Resolution Microscopy.

Gold nanocluster (GNC), because of its interesting photoluminescence properties and the easy renal clearance from the body, has got tremendous biomedical applications. Unfortunately, it has never been explored for super resolution microscopy (SRM). Here, we present a protein conjugated red emissive GNC, for the super resolution radial fluctuation (SRRF) of lysosome in HeLa cells. The diameter of the lysosome obtained in SRRF is ~59 nm, which is very close to the original diameter of the smallest lysosome in HeLa cell. Protein conjugation to GNC helped for the specific labelling to lysosome. We hope that GNC will not only replace some of the common dyes used in SRM but due to their electron beam contrast could also be used as a multimodal probe for several other correlative bioimaging techniques.