GdPO4-Based Nanoprobe for Bioimaging and Selective Recognition of Dipicolinic Acid and Cysteine by a Sensing Ensemble Approach

Multiple functions incorporated in one single-component nanoplatform pave the way for important biomedicine applications. Herein, a multifunctional terbium-doped gadolinium orthophosphate (GdPO4:Tb-EDTA) nanoplatform was prepared through a simple, ecofriendly, one-step hydrothermal method. Results showed that dipicolinic acid (DPA), the biomarker of bacterial spores, significantly increased the fluorescence intensity of this nanoplatform and conferred it with rapid response and excellent selectivity. Subsequently, the fluorescence of the ensemble GdPO4:Tb-EDTA-DPA can be remarkably quenched by Cu2+, which led to a rewritable nanosensor used in the detection of cysteine (Cys) with excellent sensitivity. In addition, GdPO4:Tb-EDTA can also be a potential T1-weighted magnetic resonance imaging (MRI) contrast agent, which indicated a satisfactory in vitro MRI with r1 relaxivity values of 13.9 mM–1 s–1 and in vivo MRI through intravenous administration on a rat model. Overall, the proposed assay may have great...