As a powerful signal amplification tool, the DNA walker has been widely applied to detect rare microRNA (miRNA) in vivo. Despite the significant advances, a nearinfrared (NIR) light controllable DNA walker for signal amplification powered by an endogenous initiator has not been realized, which is crucial for spatiotemporal imaging of miRNA in living cells with high sensitivity. Herein, we constructed a NIR-photoactivatable DNA walker system, which was powered by endogenous adenosine triphosphate (ATP) for in situ miRNA imaging with spatial and temporal resolution. The system was very stable with an extremely low fluorescent background for the bioimaging in living cells. We employed upconversion nanoparticles (UCNPs) as the carriers of the DNA probe and transducers of converting NIR to UV light. Coupled with the DNA walker fueled by intracellular ATP, a smart system based on the NIR light initiated DNA walker was successfully developed for precise spatiotemporal control in living cells. Triggered by NIR light, the DNA walker could autonomously and progressively travel along the track with the assistance of intracellular ATP. The system has been successfully applied for in situ miRNA imaging in different cell lines with highly spatial and temporal resolution. This strategy can expand NIR photocontrol the DNA walker for precise imaging in a biological system.

Epilepsy is a chronic neurodegenerative disease that has seriously threatened human health. Accumulating evidence reveals that the pathological progression of epilepsy is closely related to peroxynitrite (ONOO − ). Unfortunately, understanding the physiological roles of ONOO − in epilepsy is still challenging due to the lack of powerful imaging probes for the determination of the level of fluctuations of ONOO − in the epileptic brain. Herein, a near-infrared (NIR) two-photon (TP) fluorescent probe [dicyanomethylene-4H-pyran (DCM)−ONOO] is presented to trace ONOO − in living cells and in kainate (KA)-induced rat epilepsy models with satisfactory sensitivity and selectivity. The probe is composed of a NIR TP DCM fluorophore and a recognition moiety diphenylphosphinamide. The phosphoramide bond of the probe is interrupted after reacting with ONOO − for 10 min, and then, the released amino groups emit strong fluorescence due to the restoration of the intramolecular charge transfer process. The probe can effectively detect the changes of endogenous ONOO − with excellent temporal and spatial resolution in living cells and in rat epileptic brain. The imaging results demonstrate that the increasing level of ONOO − is closely associated with epilepsy and severe neuronal damage in the brain under KA stimulation. In addition, the low-dose resveratrol can effectively inhibit ONOO − overexpression and further relieve neuronal damage. With the assistance of TP fluorescence imaging in the epileptic brain tissue, we hypothesize that the abnormal levels of ONOO − may serve as a potential indicator for the diagnosis of epilepsy. The TP fluorescence imaging based on DCM−ONOO provides a great potential approach for understanding the epilepsy pathology and diagnosis.

The pathological progression of thyroid diseases poses a serious threat to human health. Because thyroid diseases are closely related to selenocysteine (Sec), it is necessary to investigate the relationship between Sec and thyroid diseases. Herein, we design and synthesize a ratiometric near-infrared fluorescent probe (Mito-Cy-Sec) to analyze the fluctuations and roles of Sec in cells and in mice thyroid diseases model. The probe is composed of a nearinfrared heptamethine cyanine fluorophore, an acrylamide as the response moiety, and a lipophilic triphenylphosphonium cation as the mitochondrial localization group. After reacting with Sec for 5 min, the probe Mito-Cy-Sec exhibits a distinct ratiometric fluorescence signal accompanied by a color change from green to blue. The applicability of Mito-Cy-Sec in mitochondrial localization is assessed via the super-resolution imaging. Mito-Cy-Sec has been successfully applied to detect the fluctuations of Sec concentration in human thyroid epithelial/cancer cell lines (Nthy-ori-3 cells/BHT101 cells) and mice thyroid disease (thyroiditis and thyroid cancer) models. Besides, both of our probes Mito-Cy-Sec and commercial ROSGreen H 2 O 2 are employed to examine the interrelationship between H 2 O 2 and Sec in cells and in mice models. The results demonstrate that the relevant-levels between H 2 O 2 and Sec are exactly negative correlation. The related-levels of Sec and H 2 O 2 may be identified as diagnostic indicators for the auxiliary diagnosis of thyroid diseases. We suppose that our probe Mito-Cy-Sec can be employed as a promising chemical tool for the diagnosis of thyroid diseases.

We introduce the synthesis strategy, photoluminescence features and biological applications of TMD QDs.

No abstract

We have established a near-infrared two-photon fluorescent probe for the detection of CE2 with high selectivity and sensitivity.

In this work, a novel phenomenon was discovered that the fluorescence intensity of silver sulfide quantum dots (AgS QDs) could be enhanced in the presence of rare earth ions through aggregation-induced emission (AIE). Based on the strong coordination between rare earth ions and F, a facile and label-free strategy was developed for the detection of F in living cells. AgS QDs were synthesized using 3-mercaptopropionic acid as sulfur source and stabilizer in aqueous solution. The near infrared (NIR) emitting QDs exhibited excellent photostalilty, high quantum yield and low toxic. Interestingly, the fluorescence intensity of QDs was obviously enhanced upon the addition of various rare earth ions, especially in the presence of Gd. The AIE mechanism was proved via the TEM, zeta potential and dynamic light scattering analysis. Moreover, the coordination between rare earth ions and F could lead to the quenching of fluorescence QDs due to the weakening the AIE. Based on these findings, we developed a highly sensitive and selective method for detection of F. The label-free NIR fluorescence probe was successfully used for F bioimaging in live cells.

A nanosized Tb-MOF with a boronic acid ligand can be used for the highly sensitive detection and scavenging of ROS in living cells.