Mitochondria-Directed Fluorescent Probe for the Detection of Hydrogen Peroxide near Mitochondrial DNA

It is important to detect hydrogen peroxide (H₂O₂) near mitochondrial DNA (mtDNA) because mtDNA is more prone to oxidative attack than nuclear DNA (nDNA). In this study, a mitochondria-targeted fluorescence probe, <b>pep3-NP1</b>, has been designed and synthesized. The probe contains a DNA-binding peptide, a H₂O₂ fluorescence reporter, and a positively charged red emissive styryl dye to facilitate accumulation in mitochondria. Due to groove binding of the peptide with DNA, the styryl dye of <b>pep3-NP1</b> intercalated into the bases of DNA, leading to an increase in red fluorescence intensity (centered at 646 nm) and quantum yield. In this case, <b>pep3-NP1</b> was a turn-on probe for labeling DNA. Subcellular locations of <b>pep3-NP1</b> and MitoTracker suggested that <b>pep3-NP1</b> mostly accumulated in the mitochondria of live cells. Namely, as an intracellular DNA marker, <b>pep3-NP1</b> bound to mtDNA. In the presence of H₂O₂, <b>pep3-NP1</b> emitted green fluorescence (centered at 555 nm). Thus, the ratio of green with red fluorescence of <b>pep3-NP1</b> was suitable to reflect the change of the H₂O₂ level near mtDNA in living cells. The detecting limit for H₂O₂ was estimated at 2.9 and 5.0 μM in vitro and in cultured cells, respectively. The development of <b>pep3-NP1</b> could help in studies to protect mtDNA from oxidative stress

A Highly Sensitive Ratiometric Fluorescent Probe for the Detection of Cytoplasmic and Nuclear Hydrogen Peroxide

As a marker for oxidative stress and a second messenger in signal transduction, hydrogen peroxide (H₂O₂) plays an important role in living systems. It is thus critical to monitor the changes in H₂O₂ in cells and tissues. Here, we developed a highly sensitive and versatile ratiometric H₂O₂ fluorescent probe (<b>NP1</b>) based on 1,8-naphthalimide and boric acid ester. In response to H₂O₂, the ratio of its fluorescent intensities at 555 and 403 nm changed 1020-fold within 200 min. The detecting limit of <b>NP1</b> toward H₂O₂ is estimated as 0.17 μM. It was capable of imaging endogenous H₂O₂ generated in live RAW 264.7 macrophages as a cellular inflammation response, and especially, it was able to detect H₂O₂ produced as a signaling molecule in A431 human epidermoid carcinoma cells through stimulation by epidermal growth factor. This probe contains an azide group and thus has the potential to be linked to various molecules via the click reaction. After binding to a Nuclear Localization Signal peptide, the peptide-based combination probe (<b>pep-NP1</b>) was successfully targeted to nuclei and was capable of ratiometrically detecting nuclear H₂O₂ in living cells. These results indicated that <b>NP1</b> was a highly sensitive ratiometric H₂O₂ dye with promising biological applications

Supplementary document for Saturable absorption properties and ultrafast photonics applications of HfS3 - 6821320.pdf

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Utilizing Intramolecular Photoinduced Electron Transfer to Enhance Photothermal Tumor Treatment of Aza-BODIPY-Based Near-Infrared Nanoparticles

Photothermal therapy (PTT) as a kind of noninvasive tumor treatment has attracted increasing research interest. However, the efficiency of existing PTT agents in the near-infrared (NIR) region is the major problem that has hindered further development of PTT. Herein, we present an effective strategy to construct the efficient photothermal agent by utilizing an intramolecular photoinduced electron transfer (PeT) mechanism, which is able to dramatically improve photothermal conversion efficiency in the NIR region. Specifically, an NIR dye (<b>A1</b>) constructed with dimethylamine moiety as the electron donor and the aza-BODIPY core as the electron acceptor is designed and synthesized, which can be used as a class of imaging-guided PTT agents via intramolecular PeT. After encapsulation with biodegradable polymer DSPE–mPEG₅₀₀₀, nanophotothermal agents with a small size exhibit excellent water solubility, photostability, and long-time retention in tumor. Importantly, such nanoparticles exhibit excellent photothermal conversion efficiency of ∼35.0%, and the PTT effect in vivo still remains very well even with a low dosage of 0.05 mg kg^–1 upon 808 nm NIR laser irradiation (0.5 W cm^–2). Therefore, this reasonable design via intramolecular PeT offers guidance to construct excellent photothermal agents and subsequently may provide a novel opportunity for future clinical cancer treatment

Luminescence Color Tuning by Regulating Electrostatic Interaction in Light-Emitting Devices and Two-Photon Excited Information Decryption

It is well-known that the variation of noncovalent interactions of luminophores, such as π–π interaction, metal-to-metal interaction, and hydrogen-bonding interaction, can regulate their emission colors. Electrostatic interaction is also an important noncovalent interaction. However, very few examples of luminescence color tuning induced by electrostatic interaction were reported. Herein, a series of Zn­(II)-bis­(terpyridine) complexes (<b>Zn-AcO</b>, <b>Zn-BF</b>_<b>4</b>, <b>Zn-ClO</b>_<b>4</b>, and <b>Zn-PF</b>_<b>6</b>) containing different anionic counterions were reported, which exhibit counterion-dependent emission colors from green-yellow to orange-red (549 to 622 nm) in CH₂Cl₂ solution. More importantly, it was found that the excited states of these Zn­(II) complexes can be regulated by changing the electrostatic interaction between Zn²⁺ and counterions. On the basis of this controllable excited state, white light emission has been achieved by a single molecule, and a white light-emitting device has been fabricated. Moreover, a novel type of data decryption system with <b>Zn-PF</b>_<b>6</b> as the optical recording medium has been developed by the two-photon excitation technique. Our results suggest that rationally controlled excited states of these Zn­(II) complexes by regulating electrostatic interaction have promising applications in various optoelectronic fields, such as light-emitting devices, information recording, security protection, and so on

Development of Upconversion Luminescent Probe for Ratiometric Sensing and Bioimaging of Hydrogen Sulfide

Merocyanines adsorbed into the mesopores of mSiO₂ shell of NaYF₄: 20% Yb, 2% Er, 0.2% Tm nanocrystals are demonstrated as ratiometric upconversion luminescence (UCL) probe for highly selective detection of HS^– in living cells through inhibition of energy transfer from the UCL of the nanocrystals to the absorbance of the merocyanines. The UCL probe has been used for ratiometric sensing of H₂S with high sensitivity and selectivity