ABSTRACT
Correction for 'pH-Responsive fluorescent graphene quantum dots for fluorescence-guided cancer surgery and diagnosis' by Zetan Fan et al., Nanoscale, 2017, 9, 4928-4933, https://doi.org/10.1039/C7NR00888K.
ABSTRACT
Telomerase (TE), a ribonucleoprotein reverse transcriptase, is enzymatically activated in most tumor cells and is responsible for promoting tumor progression and malignancy by enabling replicative immortality of cancer cells. TE has become an important hallmark for cancer diagnosis and a potential therapy target. Therefore, accurate inâ situ detection of TE activity, especially the simultaneous imaging of TE activity and its correlated biomolecules, is essential to medical diagnostics and therapeutics. DNA-based nanoprobes, with their effective cell penetration capability and programmability, are the most advantageous for detection of intracellular TE activity. This concept article introduces the recent strategies for inâ situ sensing and imaging of TE activity, with a focus on simultaneous detection of TE and related biomolecules, and provides challenges and perspectives for the development of new strategies for such correlated imaging.
Subject(s)
Neoplasms , Telomerase , Humans , Telomerase/metabolism , DNA , Neoplasms/diagnostic imaging , Neoplasms/pathology , DNA-Binding ProteinsABSTRACT
Design of biosensors capable of imaging ATP and glutathione (GSH) in mitochondria remains a challenge, despite their importance in elucidating their correlated pathophysiological events. Here, we report a new strategy that uses redox-activatable aptamer sensor design combined with nanoparticle-based targeting capability to achieve spatially controlled, AND-gated imaging of ATP and GSH in mitochondria. The DNA nanodevice was designed by the controlled assembly of the redox-responsive ATP aptamer probe on the nanoparticles and further decorated with mitochondria-targeting signals. We demonstrate that the system allows for mitochondria-specific, correlated imaging of ATP and GSH in living cells and in vivo. Furthermore, because the system can be lighted up only when meeting the "dual keys" (overexpressed ATP and GSH in mitochondria) simultaneously, the DNA nanodevice enables specific imaging of tumors in vivo with improved tumor-to-normal tissue ratio. This work illustrates the potential of the DNA nanodevices in the imaging of mitochondrial multivariate targets.
Subject(s)
DNA , Glutathione , Adenosine Triphosphate/metabolism , DNA/metabolism , Glutathione/metabolism , Mitochondria/metabolism , Oxidation-ReductionABSTRACT
The dynamic variation of the expression profile and spatial landscape of multiple enzymes are crucial factors influencing tumor progression and drug treatment. However, the comprehensive analysis of these events has been hampered by the limitations of existing imaging technologies. Here we report a cooperatively activatable, DNA-based fluorescent reporter programmed to detect the correlated activity of dual enzymes, telomerase (TE) and apurinic/apyrimidinic endonuclease 1 (APE1), both in vitro and in vivo. The conformational change of the DNA probe can be orthogonally triggered through TE-induced DNA elongation and APE1-mediated specific cleavage, producing a fluorescent signal for imaging the activity of the two enzymes in an AND-gated manner. Furthermore, we demonstrate the capability of the system for specific tumor imaging through "dual lock-and-key" strategy, and visualizing the correlated enzymatic activities during drug treatment of cancer.
Subject(s)
DNA-(Apurinic or Apyrimidinic Site) Lyase/analysis , DNA/chemistry , Fluorescent Dyes/chemistry , Cell Line , DNA-(Apurinic or Apyrimidinic Site) Lyase/metabolism , Humans , Optical ImagingABSTRACT
Cancer remains a major cause of morbidity and mortality around the world. Improved cancer treatment requires enhancement of cancer diagnosis and detection. To achieve this goal, here we report a novel imaging probe, pH-responsive fluorescent graphene quantum dots (pRF-GQDs). pRF-GQDs were prepared by electrolysis of graphite rods in sodium p-toluenesulfonate acetonitrile solution. The resulting pRF-GQDs, which have minimal toxicity, display a sharp fluorescence transition between green and blue at pH 6.8, a pH matching the acidic extracellular microenvironment in solid tumors. We found that this unique fluorescence switch property allows tumors to be distinguished from normal tissues. In addition to fluorescence, pRF-GQDs also exhibit upconversion photoluminescence (UCPL). We demonstrate that the combination of UCPL and fluorescence switch enables detection of solid tumors of different origin at an early developmental stage. Therefore, pRF-GQDs have great potential to be used as a universal probe for fluorescence-guided cancer surgery and cancer diagnosis.
Subject(s)
Fluorescent Dyes , Graphite , Neoplasms, Experimental/diagnostic imaging , Quantum Dots , A549 Cells , Animals , Female , HeLa Cells , Hep G2 Cells , Humans , Hydrogen-Ion Concentration , Mice , Mice, Inbred BALB C , Mice, Nude , Spectrometry, Fluorescence , Xenograft Model Antitumor AssaysABSTRACT
Cellular imaging after transplantation may provide important information to determine the efficacy of stem cell therapy. We have reported that graphene quantum dots (GQDs) are a type of robust biological labeling agent for stem cells that demonstrate little cytotoxicity. In this study, we examined the interactions of GQDs on human neural stem cells (hNSCs) with the aim to investigate the uptake and biocompatibility of GQDs. We examined the mechanism of GQD uptake by hNSCs and investigated the effects of GQDs on the proliferation, metabolic activity, and differentiation potential of hNSCs. This information is critical to assess the suitability of GQDs for stem cell tracking. Our results indicated that GQDs were taken up into hNSCs in a concentration- and time-dependent manner via the endocytosis mechanism. Furthermore, no significant change was found in the viability, proliferation, metabolic activity, and differentiation potential of hNSCs after treatment with GQDs. Thus, these data open a promising avenue for labeling stem cells with GQDs and also offer a potential opportunity to develop GQDs for biomedical applications.
Subject(s)
Biocompatible Materials/metabolism , Graphite/chemistry , Neural Stem Cells/metabolism , Quantum Dots/chemistry , Biocompatible Materials/chemistry , Biocompatible Materials/pharmacology , Cell Differentiation/drug effects , Cell Proliferation/drug effects , Cell Survival/drug effects , Cells, Cultured , Humans , Neural Stem Cells/cytology , Tubulin/metabolismABSTRACT
We report on a significant power conversion efficiency improvement of perovskite solar cells from 8.81% to 10.15% due to insertion of an ultrathin graphene quantum dots (GQDs) layer between perovskite and TiO2. A strong quenching of perovskite photoluminescence was observed at â¼760 nm upon the addition of the GQDs, which is pronouncedly correlated with the increase of the IPCE and the APCE of the respective cells. From the transient absorption measurements, the improved cell efficiency can be attributed to the much faster electron extraction with the presence of GQDs (90-106 ps) than without their presence (260-307 ps). This work highlights that GQDs can act as a superfast electron tunnel for optoelectronic devices.