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    One-step synthesis of green emission carbon dots for selective and sensitive detection of nitrite ions and cellular imaging application
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    Abstract:
    In recent years, carbon dot (CD)-based fluorescent sensors for selective ions or small biomolecules have drawn great attention. In this work, highly fluorescent CDs (QY = 21%) were prepared from 2,3-diamino pyridine as the precursor through a facile solvothermal process. The CDs showed high stability and a green emission in aqueous, and the optimal emission wavelength of CDs is 508 nm under the excitation wavelength of 438 nm. Interestingly, a CDs-based nanoprobe was developed for a selective and sensitive fluorescence quenching response to NO2- in water, and the quenching mechanism was investigated in the work. Besides, the recovery rates of NO2- in the range of 98-103.5% were found to be acceptable, indicating that the proposed CDs could be act as potential candidates for determination of nitrite ions in real samples. Meanwhile, the nanoprobe was also successfully employed in a visualization biosensing platform for determination of NO2- in living cells due to its eminent biocompatibility.
    Keywords:
    Nanoprobe
    Biocompatibility
    Visualizing biological markers and delivering bioactive agents to living organisms are important to biological research. In recent decades, photoacoustic imaging (PAI) has been significantly improved in the area of molecular imaging, which provides high-resolution volume imaging with high optical absorption contrast. To demonstrate the ability of nanoprobes to target tumors using PAI, we synthesize convertible nanostructured agents with strong photothermal and photoacoustic properties and linked the nanoprobe with biotin to target tumors in small animal model. Interestingly, these nanoprobes allow partial to disassemble in the presence of targeted proteins that switchable photoactivity, thus the nanoprobes provides a fluorescent-cancer imaging with high signal-to-background ratios. The proposed nanoprobe produce a much stronger PA signal compared to the same concentration of methylene blue (MB), which is widely used in clinical study and contrast agent for PAI. The biotin conjugated nanoprobe has high selectivity for biotin receptor positive cancer cells such as A549 (human lung cancer). Then we subsequently examined the PA properties of the nanoprobe that are inherently suitable for in vivo PAI. After injecting of the nanoprobe via intravenous method, we observed the mice’s whole body by PA imaging and acquired the PA signal near the cancer. The PA signal increased linearly with time after injection and the fluorescence signal near the cancer was confirmed by fluorescence imaging. The ability to target a specific cancer of the nanoprobe was well verified by PA imaging. This study provides valuable perspective on the advancement of clinical translations and in the design of tumor-targeting phototheranostic agents that could act as new nanomedicines.
    Nanoprobe
    Molecular Imaging
    Fluorescence-lifetime imaging microscopy
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    Hydrogen peroxide is a biologically important reactive oxygen species (ROS) and plays crucial roles in living organisms. Herein, a FRET-based ratiometric fluorescent probe has been developed for detecting H2O2in vitro and in vivo. In this nanoprobe, carbon dots serve as the energy donor and carrier for the H2O2 recognition element. This nanoprobe exhibits fast-response, low toxicity, high sensitivity (with a detection limit of 0.5 μM) and selectivity towards H2O2 over other reactive oxygen or nitrogen species. The nanoprobe has been successfully applied in the detection of H2O2 in live cells and in zebrafish larvae. By incubating the nanoprobe with zebrafishes, the nanoprobe can be absorbed by the fishes within 1 h and accumulates mainly in the abdominal region. Due to its small size (∼4 nm), the nanoprobe is gradually excreted by zebrafishes without long-term accumulation. Moreover, as the first ratiometric chemoprobe that can detect H2O2in vivo, the nanoprobe has been found capable of detecting and locating endogenous H2O2 in zebrafishes as a result of drug-induced oxidative damage. The successful detection of H2O2 by the nanoprobe in vivo may support its eventual use in clinical applications.
    Nanoprobe
    Citations (46)
    Numerous researchers have committed to the development of combined therapy strategies for tumors, since their use in the treatment of tumors has more ideal therapeutic outcomes. In the study, we designed and prepared gold nanostars with CD147 modified on the surface and then efficiently loaded a photosensitive drug IR820 to construct a multifunctional nanoprobe. Due to the protection effect of gold, the nanoprobe has oxygen/heat energy generation capability and can also efficiently deliver the loaded drugs inside the tumor cells. Moreover, the nanoprobe has excellent photothermal/photodynamic therapeutic outcomes. The observation by photoacoustic real-time imaging validated the outstanding tumor-targeting characteristics of our nanoprobe. Finally, in the in vivo treatment experiment, the nanoprobe achieved ideal tumor-suppressive effects after the photothermal/photodynamic therapy. In summary, the findings of this experiment are useful in the development of new combined tumor therapy strategies based on nanomaterials.
    Nanoprobe
    Cancer Treatment
    Nanomaterials
    Abstract Background: Excellent imaging performance and good biocompatibility of contrast agents are considered as prerequisites for accurate tumor diagnosis and treatment. Results: Herein, a novel imaging nanoprobe with actively targeting performance based on ultrasmall paramagnetic iron oxide (USPIO) was constructed by a facile cation exchange strategy followed by conjugation with transferrin (Tf). The stable gadolinium (Gd 3+ ) chelation endows the nanoparticles (NPs) with a low value of r 2 /r 1 (1.28) and relatively high r 1 value of 3.2 mM -1 s -1 , enabling their use in T 1 -weighted positive MR imaging. Conclusion: This constructed transferrin modified gadolinium-iron chelate nanoprobe, named as TUG, shows high biocompatibility within a given dose range. More importantly, compared with clinically used Gd-based small molecule contrast agents, the obtained TUG can be more engulfed by breast cancer cells, showing much enhanced T 1 -weighted positive MR imaging in either subcutaneous or in situ tumor models of breast cancer. This novel nanoprobe holds enormous promise to be utilized as a targeting contrast agent with high efficacy for T 1 -weighted positive MR imaging.
    Nanoprobe
    Biocompatibility
    MRI contrast agent
    Iron oxide nanoparticles
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    Aim: To monitor cells in vivo or to detect the sentinel lymph node, we developed a PET/MRI silica nanoprobe with an enhanced near-infrared fluorescence signal. Methods: We developed enhanced near-infrared fluorescent (NIRF) magnetic silica nanoparticles, MNP-SiO2(NIR797), that encapsulate NIRF dye in the silica. We applied this probe to visualizing cells in the deep tissue of mice using NIRF imaging. After labeling with a radioisotope, 68Ga, on the surface of MNP-SiO2(NIR797), we injected it into the forepaw of mice to visualize the sentinel lymph node. Results: This encapsulated nanoprobe showed enhancement of fluorescent intensity and stability compared with the nanoprobe, which had the same dyes on the surface of the silica nanoparticles. We also obtained multimodal in vivo imaging of 68Ga-{MNP-SiO2(NIR797)} applied to sentinel lymph node detection of mice using PET/MRI/NIRF images. Conclusion: This multimodal nanoprobe with enhanced fluorescence may provide a useful tool for imaging diagnostics and cell tracking.
    Nanoprobe
    Fluorescence-lifetime imaging microscopy
    Molecular Imaging
    Citations (54)
    Cu2+ is closely related to the occurrence and development of Wilson's disease (WD), and quantitative detection of various copper indicators (especially liver Cu2 and urinary Cu2+) is the key step for the early diagnosis of WD in the clinic. However, the clinic Cu2+ detection approach was mainly based on testing the liver tissue through combined invasive liver biopsy and the ICP-MS method, which is painful for the patient and limited in determining WD status in real-time. Herein, we rationally designed a type of Cu2+-activated nanoprobe based on nanogapped gold nanoparticles (AuNNP) and poly(N-isopropylacrylamide) (PNIPAM) to simultaneously quantify the liver Cu2+ content and urinary Cu2+ in WD by photoacoustic (PA) imaging and ratiometric surface-enhanced Raman scattering (SERS), respectively. In the nanoprobe, one Raman molecule of 2-naphthylthiol (NAT) was placed in the nanogap of AuNNP. PNIPAM and the other Raman molecule mercaptobenzonitrile (MBN) were coated on the AuNNP surface, named AuNNP-NAT@MBN/PNIPAM. Cu2+ can efficiently coordinate with the chelator PNIPAM and lead to aggregation of the nanoprobe, resulting in the absorption red-shift and increased PA performance of the nanoprobe in the NIR-II window. Meanwhile, the SERS signal at 2223 cm–1 of MBN is amplified, while the SERS signal at 1378 cm–1 of NAT remains stable, generating a ratiometric SERS I2223/I1378 signal. Both NIR-II PA1250 nm and SERS I2223/I1378 signals of the nanoprobe show a linear relationship with the concentration of Cu2+. The nanoprobe was successfully applied for in vivo quantitative detection of liver Cu2+ of WD mice through NIR-II PA imaging and accurate quantification of urinary Cu2+ of WD patients by ratiometric SERS. We anticipate that the activatable nanoprobe might be applied for assisting an early, precise diagnosis of WD in the clinic in the future.
    Nanoprobe
    Citations (67)
    We report a new type of dual modal nanoprobe to combine optical and magnetic resonance bioimaging. A simple reverse microemulsion method and coating process was introduced to synthesize silica-coated Gd2(CO3)3:Tb nanoparticles, and the particles, with an average diameter of 16 nm, can be dispersed in water. As in vitro cell imaging of the nanoprobe shows, the nanoprobe accomplishes delivery to gastric SGC7901 cancer cells successfully in a short time, as well as NCI-H460 lung cancer cells. Furthermore, it presents no evidence of cell toxicity or adverse affect on kidney cell growth under high dose, which makes the nanoprobe's optical bioimaging modality available. The possibility of using the nanoprobe for magnetic resonance imaging is also demonstrated, and the nanoprobe displays a clear T1-weighted effect and could potentially serve as a bimodal T1-positive contrast agent. Therefore, the new nanoprobe formed from carbonate nanoprobe doped with rare earth ions provides the dual modality of optical and magnetic resonance imaging.
    Nanoprobe