PyDNA-templated AgNPs coupled with poly (β‑cyclodextrin) enhanced fluorescence: A facile platform for signal amplification detection of biothiols in living cells and zebrafish.

Accurate and sensitive fluorescence imaging of biothiols is essential for understanding the mechanism underlying some physiological and pathological events, as well as the prevention and diagnosis of diseases. However, low signal transduction efficiency and poor biocompatibility of fluorescence tags associated with current sensors hinder their potential utilizations. Herein, a smart biothiols sensitive vivo imaging platform on the basis of amplifying nanoprobe has been designed. The as-prepared nanoprobe are composed of 5'-pyrene-labeled single-stranded DNA with C-rich (PyDNA), DNA-templated silver nanoparticles (AgNPs) and amplification carrier β-cyclodextrin-based polymer (βCDP). PyDNA was not only used as a signal tag, but also as a templated DNA for in situ growth of silver nanoparticles (PyDNA-AgNPs), resulting in fluorescence quenching of PyDNA through FRET. In the presence of GSH as a model biothiol, replace PyDNA off from the surface of AgNPs owing to the interact intensely between biothiol and AgNPs by forming S-Ag bonds, resulting in a fluorescence enhancement. Simultaneously, the released PyDNA was able to form a host-guest inclusion complex with βCDP to achieve signal amplification (10.1-fold enhancement). The obtained nanoprobe exhibits high sensitivity and selectivity to glutathione (GSH) with a detection limit as low as 71 nM. Using HeLa cells as a model, this nanoprobe not only realizes the highly sensitive amplifying detection and imaging of GSH in living cells, but also applies in vivo monitoring of exogenous GSH level in zebrafish. Further use of probes to reveal the overexpression of GSH with the high-contrast imaging in the tumor tissues from the lung disease model mice and clinical lung cancer patients was successfully demonstrated. It provides a facile tool for highly sensitive biothiols imaging and may pave a new avenue for the early and accurate diagnosis of tumors.