No abstract

Graphene is an increasingly important nanomaterial that has shown great promise in the area of nanotechnology. In this study, fluorescein-functionalized graphene oxide (GO) is synthesized via a polyethylene glycol (PEG) bridge and its application in intracellular imaging is explored. GO is an oxide form of graphene that provides an ideal platform to prepare graphene-based functional nanomaterials via chemical modification. The PEG bridge was introduced to prevent GO-induced quenching of conjugated fluorescein. The fluorescein-PEG-GO conjugate thus prepared exhibits excellent pH-tunable fluorescent properties and, more significantly, can be efficiently taken up by cells and serve as a fluorescent nanoprobe for intracellular imaging.

We herein report the design of a dumbbell-shaped DNA probe that integrates target-binding, amplification and signaling within one multifunctional design. The dumbbell probe can initiate rolling circle amplification (D-RCA) in the presence of specific microRNA (miRNA) targets. This D-RCA-based miRNA strategy allows quantification of miRNA with very low quantity of RNA samples. The femtomolar sensitivity of D-RCA compares favorably with other existing technologies. More significantly, the dynamic range of D-RCA is extremely large, covering eight orders of magnitude. We also demonstrate miRNA quantification with this highly sensitive and inexpensive D-RCA strategy in clinical samples.