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Abstract: To achieve the accurate diagnosis of tumor with the magnetic resonance imaging (MRI), nanomaterials‐based contrast agents are developed rapidly. Here, a tumor targeting nanoprobe of c(RGDyK) modified ultrasmall sized iron oxide is reported with high saturation magnetization and high T1‐weighted imaging capability, attributed to a large number of paramagnetic centers on the surface of nanoprobes and rapid water proton exchange rate (inner sphere model), as well as strong superparamagnetism (outer sphere model). These nanoprobes could actively target and gradually accumulate at the tumor site with a time‐dependent T1–T2 contrast enhancement imaging effect. In in vivo MRI experiments, the nanoprobes exhibit the best T1 contrast enhancement at 30 min after intravenous administration, followed by gradually vanishing and generating T2 contrast enhancement with increasing time at tumor site. This is likely due to time‐dependent nanoprobes aggregation in tumor, in good agreement with in vitro experiment where aggregated nanoprobes display larger r2/r1 value (19.1) than that of the dispersed nanoprobes (2.8). This dynamic property is completely different from other T1‐T2 dual‐modal nanoprobes which commonly exhibit the T1‐ and T2‐weighted enhancement effect at the same time. To sum up, these c(RGDyK) modified ultrasmall Fe3O4 nanoprobes have significant potential to improve the diagnostic accuracy and sensitivity in MRI. [ABSTRACT FROM AUTHOR]

Recently, surface-enhanced Raman scattering (SERS) nanoprobes (NPs) have shown promise in the field of cancer imaging due to their unparalleled signal specificity and high sensitivity. This study reports the development of a DNA aptamer targeted SERS NP. Recently, aptamers are being investigated as a viable alternative to more traditional antibody targeting due to their low immunogenicity and low cost of production. A strategy is developed to functionalize SERS NPs with DNA aptamers, which target Mucin1 (MUC1) in human breast cancer (BC). Thorough in vitro characterization studies demonstrate excellent serum stability and specific binding of the targeted NPs to MUC1. In order to test their in vivo targeting capability, MUC1-targeted SERS NPs are coinjected with nontargeted or blocked MUC1-targeted SERS NPs in BC xenograft mouse models. A two-tumor mouse model with differential expression of MUC1 (MDA-MB-468 and MDA-MB-453) is used to control for active versus passive targeting in the same animals. The results show that the targeted SERS NPs home to the tumors via active targeting of MUC1, with low levels of passive targeting. This strategy is expected to be an advantageous alternative to antibody-based targeting and useful for targeted imaging of tumor extent, progression, and therapeutic response. [ABSTRACT FROM AUTHOR]

Multimodal imaging, which combines complementary information of two or more imaging modalities, offers huge advantages. In this paper, the synthesis, characterization, and application of superparamagnetic nitrogen-doped carbon-iron oxide hybrid quantum dots (C-Fe3O4 QDs) is reported for triple-modal bioimaging through fluorescence/magnetic resonance/computed tomography (FL/MR/CT). Especially, C-Fe3O4 QDs are synthesized by using poly (γ-glutamic acid) as a precursor and stabilizer via a green and facile one-pot hydrothermal approach. The as-prepared C-Fe3O4 QDs exhibit excellent water dispersibility, wavelength-tunable FL property with high quantum yield of about 21.6%, good photostability, strong superparamagnetic property as well as favorable biocompatibility. Meanwhile, these C-Fe3O4 QDs also show a transverse relaxivity value ( r2) of 154.10 m m−1 s−1 for T2-weighted MR imaging mode and an observable X-ray attenuation effect for CT imaging mode. Moreover, the in vivo bioimaging of tumor-bearing nude mice by combining FL, MR, and CT images further demonstrates that the as-prepared C-Fe3O4 QDs can be readily and efficiently used in FL/MR/CT triple-modal tumor imaging. Hence, the new and facile one-pot synthesis strategy for preparing multifunctional C-Fe3O4 QDs nanoprobes provides a convenient way for achieving an effective and versatile agent for tumorous bioimaging/or diagnostics. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H2S) has been recognized as one of most important gaseous signaling molecules mediated by a variety of physiological and pathological processes. Yet, its functions remain largely elusive due to the lack of potent monitoring methods. Hereby this issue is addressed with a powerful new platform-dye-assembled upconversion nanoparticles (UCNPs). A series of chromophores with different absorption bands and fast responses towards H2S is combined with UCNPs and results in a library of H2S sensors with responsive emission signals ranging from the visible to the near-infrared (NIR) region. These nanoprobes demonstrate highly selective and rapid responses to H2S in vitro and in cells. Furthermore, H2S levels in blood can be detected using the developed nanoprobes. Hence the reported H2S sensing platform can serve as a powerful diagnostic tool to research H2S functions and to investigate H2S-related diseases. [ABSTRACT FROM AUTHOR]

Controlling synthesis of near-infrared emitting quantum rods (QRs) for in vivo imaging is a major challenge in the fabrication of multifunctional nanoprobes. Here, a reliable synthetic approach for CdTe xSe1- x/ZnS alloy nanocrystals to achieve highly bright (quantum yields up to 80%) with controllable rod-shape and near-infrared (650-870 nm) emission is developed. Aspect ratio and emission of QRs are correlated with composition, which can be easily tuned by changing Te and Se mole ratio. It illustrates that the content of Se plays an important role in maintaining the rod-shape, while Te has a significant impact on emitting of the nanorods. Besides exhibiting great stability over a broad range of pH (4-10) and ion strength (up to 2 mol L-1 NaCl solution), these hydrophilic QRs display good photo stability and storage stability. In particular, the specially absorbing of paramagnetic gadolinium ions on the QRs lead to a versatile method to engineer multimodal imaging nanoprobes, which are applied for in vivo lymph node dual-modal imaging (fluorescence and magnetic resonance imaging). These results suggest a promising strategy for engineering multifunctional imaging nanoprobes with the stable near-infrared QRs. [ABSTRACT FROM AUTHOR]

For the effective application of surface-enhanced Raman scattering (SERS) nanoprobes for in vivo targeting, the tissue transparency of the probe signals should be as high as it can be in order to increase detection sensitivity and signal reproducibility. Here, near-infrared (NIR)-sensitive SERS nanoprobes (NIR SERS dots) are demonstrated for in vivo multiplex detection. The NIR SERS dots consist of plasmonic Au/Ag hollow-shell (HS) assemblies on the surface of silica nanospheres and simple aromatic Raman labels. The diameter of the HS interior is adjusted from 3 to 11 nm by varying the amount of Au3+ added, which results in a red-shift of the plasmonic extinction of the Au/Ag nanoparticles toward the NIR (700-900 nm). The red-shifted plasmonic extinction of NIR SERS dots causes enhanced SERS signals in the NIR optical window where endogenous tissue absorption coefficients are more than two orders of magnitude lower than those for ultraviolet and visible light. The signals from NIR SERS dots are detectable from 8-mm deep in animal tissues. Three kinds of NIR SERS dots, which are injected into live animal tissues, produce strong SERS signals from deep tissues without spectral overlap, demonstrating their potential for in vivo multiplex detection of specific target molecules. [ABSTRACT FROM AUTHOR]

The table of contents for the August 12, 2013 issue of the journal "Advanced Functional Materials" is presented.

Activatable second near‐infrared window (NIR‐II; 1.0–1.7 µm) fluorescence probes that uncage deep‐tissue penetrating fluorescence by disease‐related biomarker stimuli hold great promise for detecting diseases with a poor understanding of the pathology at the molecular level with unprecedented resolution. However, currently, very few activatable NIR‐II fluorescence probes are reported mainly due to the lack of a simple yet general design strategy. Herein, a new and fairly generic design strategy using a bio‐erasable intermolecular donor–acceptor interaction to construct activatable NIR‐II fluorescence probes is reported. An organic semiconducting nanoprobe (SPNP) is constructed through blending a biomarker‐sensitive organic semiconducting non‐fullerene acceptor (3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐cyclopentane‐1,3‐dione‐[c]thiophen))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2',3'‐d']‐s‐indaceno[1,2‐b:5,6‐b'] dithiophene) (ITTC) (one of electric acceptors in organic solar cells) with a biomarker‐inert semiconducting polymer donor 5‐(4,8‐bis((2‐ethylhexyl)oxy)‐6‐methylbenzo[1,2‐b:4,5‐b']difuran‐2‐yl)‐10‐methylnaphtho[1,2‐c:5,6‐c']bis([1,2,5]thiadiazole) (PDF) in an amphiphilic‐polymer‐coated single nanoparticle to suppress NIR‐II fluorescence of the donor via a intermolecular donor–acceptor interaction. The acceptor ITTC is found to be specifically degraded by hypochlorite (an important biomarker) to erase its acceptor property, thus erasing the intermolecular donor–acceptor interaction and uncaging NIR‐II fluorescence. Consequently, SPNP exhibits a 17.5‐fold higher fluorescence brightness in the hypochlorite‐abnormal inflammation in vivo than in normal tissues. Our bio‐erasable intermolecular donor–acceptor interaction strategy provides simple yet general guidelines to design various biomarker‐activatable NIR‐II fluorescence probes. A generic design strategy for an activatable second near‐infrared window (NIR‐II; 1.0–1.7 µm) fluorescence probe is developed based on a bio‐erasable intermolecular donor–acceptor interaction. To exemplify the strategy, hypochlorite‐sensitive semiconducting acceptors are blended with hypochlorite‐inert semiconducting polymer donors to quench their NIR‐II fluorescence. In hypochlorite‐abnormal tissues, the acceptor can be degraded to erase its acceptor property for amplifying the NIR‐II fluorescence of the nanoprobe. [ABSTRACT FROM AUTHOR]