Multifunctional nanocomposites have the potential to integrate sensing, diagnostic, and therapeutic functions into a single nanostructure. Herein, we synthesize Fe 3 O 4 @polydopamine core-shell nanocomposites (Fe 3 O 4 @PDA NCs) through an in situ self-polymerization method. Dopamine, a melanin-like mimic of mussel adhesive proteins, can self-polymerize to form surface-adherent polydopamine (PDA) films onto a wide range of materials including Fe 3 O 4 nanoparticles used here. In such nanocomposites, PDA provides a number of advantages, such as near-infrared absorption, high fluorescence quenching efficiency, and a surface for further functionalization with biomolecules. We demonstrate the ability of the Fe 3 O 4 @PDA NCs to act as theranostic agents for intracellular mRNA detection and multimodal imaging-guided photothermal * Address correspondence to hhyang@fio.org.cn, gangliu.cmitm@xmu.edu.cn.. Conflict of Interest:The authors declare no competing financial interest. Supporting Information Available:Additional information as noted in the text. This material is available free of charge via the Internet at http://pubs.acs.org. Messenger RNA (mRNA), a single-stranded ribonucleic acid, is also the blueprint for the cellular production of proteins. Moreover, some mRNAs are disease-relevant and can be utilized as markers to determine the stage of the disease. 22 Recently, several methods such as microarray analysis 23 and real-time polymerase chain reaction (RT-PCR) 24 have been developed for mRNA detection. Although these methods are effective for detecting mRNA expression in bulk samples, they are incapable of identifying cell-to-cell mutations. Significantly, many important biological processes not only are related with bulk mRNA expression, but also rely highly on cell-to-cell variations in mRNA. 25 Thus, it is necessary to develop useful approaches for detecting mRNA in living cells. [26][27][28][29][30][31][32] In this work, we fabricated multifunctional Figure 1a). Furthermore, we demonstrated that PDA can adsorb dye-labeled singlestranded DNA (ssDNA) probe and effectively quench the fluorescence of the dye. In the presence of the target, the specific binding between the dye-labeled ssDNA probe and its Figure 1c). Our results suggest a high potential for the use of PDA in the construction of multifunctional nanocomposites for simultaneous diagnosis and therapy of cancer. HHS Public Access RESULTS AND DISCUSSIONFe 3 O 4 NPs were easily coated with a uniform PDA shell by dispersing them in an alkaline DA solution and mildly shaking at room temperature for 4 h. Transmission electron microscopy (TEM) revealed that approximately a 4 nm thick PDA shell was wrapped on the surface of the Fe 3 O 4 NPs after self-polymerization of the DA ( Figure 2a). The dynamic light scattering (DLS) data showed that the hydrodynamic diameter of the Fe 3 O 4 NPs was increased after the PDA coating (Supporting Information Figure S1), which is consistent with the TEM results. Moreover, the Fe 3 O 4 @PDA NCs exhibited excelle...

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Bright blue fluorescent glutathione-functionalized graphene quantum dots (GQDs@GSH) were prepared by a one-step pyrolysis method with a fluorescence quantum yield as high as 33.6%. Futhermore, the obtained GQDs@GSH can be used as a probe to estimate the ATP level in cell lysates and human blood serum.

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