One-step encapsulation of CsPbBr3 nanocrystals with customized polyethylene glycol for single-molecule localization microscopy imaging of cellular microstructures

All-inorganic perovskite nanocrystals have emerged as highly effective fluorophores for single molecule localization microscopy (SMLM) imaging due to their remarkable blinking behavior, high photoluminescence quantum yields, and facile synthesis methods. However, the development of all-inorganic perovskite nanocrystals with targeting imaging properties has been limited by their insufficient stability, which presents challenges for their application in the SMLM imaging of cellular microstructures. Herein, a straightforward approach is demonstrated by conjugating cesium lead bromide perovskite nanocrystals (CsPbBr 3 NCs) with streptavidin (SA) using ester-functionalized carboxyl polyethylene glycol (COOH-PEG-NHS) to achieve a core-shell composite of SA-modified CsPbBr 3 NCs (CsPbBr 3 @SA) as an immunofluorescence nanoprobe for SMLM imaging of cellular microstructures. The COOH-PEG-NHS served as a bridging agent that initially reacted with the amine groups of the SA and subsequently integrated with CsPbBr 3 NCs in a single-step process to minimize the impact of the biological modification process on the optical properties of the CsPbBr 3 @SA nanoprobe. The obtained CsPbBr 3 @SA exhibits a significant fluorescence characteristic along with the frequent blinking phenomena. Moreover, SMLM imaging of CsPbBr 3 @SA demonstrated a localization precision of approximately 3 nm and an elevenfold enhancement in spatial resolution. Furthermore, CsPbBr 3 @SA was utilized to label the nuclear lamina of the nuclear envelope via immunofluorescence technique. The improved spatial resolution suggests that CsPbBr 3 @SA is capable of facilitating SMLM imaging of the nuclear lamina. This innovative biological modification method presents significant potential for improving the biological application of all-inorganic perovskite nanocrystals in SMLM.