Full-Range pH Stable Au-Clusters in Nanogel for Confinement-Enhanced Emission and Improved Sulfide Sensing in Living Cells

The sensitive and selective detection of hydrogen sulfide is of great importance due to its crucial role in pathological and physiological processes. Herein, we report a novel fluorescent platform, AuNCs@GC, for selective detection of hydrogen sulfide in living cells by impregnating the Au nanoclusters (AuNCs) into a biocompatible cationic polymer matrix, glycol-chitosan (GC) nanogel. The confinement effect significantly increased the emissive Au­(I) units, resulting in a 6-fold enhancement of quantum yield (from 6.38% to 36.42%). In addition, the prepared positively charged AuNCs@GC nanogel exhibits excellent selectivity and improved sensitivity to aqueous sulfides. Moreover, the as-fabricated AuNCs@GC showed very good biocompatibility and super fluorescence stability across the full pH range and good salt tolerance, which demonstrated excellent adaptability toward intracellular sulfide imaging

Embedding Nanocluster in MOF via Crystalline Ion-Triggered Growth Strategy for Improved Emission and Selective Sensing

Metal–organic frameworks (MOFs) containing metal nanoclusters (NCs) display great potentials, but the fabrication faces challenges because of the serious agglomeration of NCs during the MOF growth. We report a crystalline ion-triggered growth strategy for embedding AuNCs in ZIF-8. As control, when the encapsulation was triggered with other metal ions (e.g., Ca²⁺, Pb²⁺, Cd²⁺, Na⁺, Fe³⁺, Cu²⁺, and Ni²⁺), the AuNCs failed to be encapsulated. The quantum yields and lifetime of AuNCs were greatly enhanced after embedding in ZIF-8. The AuNCs@ZIF-8 were then successfully applied for the selective sensing of H₂S both in liquid and gas phases. This crystalline ion-triggered growth strategy was easily extended to other systems, such as AgNCs@ZIF-8 and AuNCs@ZIF-67, indicating the general adaptability of this design protocol

A General and Facile Strategy to Fabricate Multifunctional Nanoprobes for Simultaneous ¹⁹F Magnetic Resonance Imaging, Optical/Thermal Imaging, and Photothermal Therapy

¹⁹F magnetic resonance imaging (MRI), due to its high sensitivity and negligible background, is anticipated to be a powerful noninvasive, sensitive, and accurate molecular imaging technique. However, the major challenge of ¹⁹F MRI is to increase the number of ¹⁹F atoms while maintaining the solubility and molecular mobility of the probe. Here, we successfully developed a facile and general strategy to synthesize the multifunctional ¹⁹F MRI nanoprobes by encapsulating the hydrophobic inorganic nanoparticles (NPs) into a hybrid polymer micelle consisting of hydrolysates of 1<i>H</i>,1<i>H</i>,2<i>H</i>,2<i>H</i>-perfluorodecyltriethoxysilane (PDTES) and oleylamine-functionalized poly­(succinimide) (PSI_OAm). Due to their good water dispersibility, excellent molecular mobility resulting from the ultrathin coating, and high ¹⁹F atom numbers, these nanoprobes generate a separate sharp singlet of ¹⁹F nuclear magnetic resonance (NMR) signal (at −82.8 ppm) with half peak width of ∼28 Hz, which is highly applicable for ¹⁹F MRI. Significantly, by varying the inorganic core from metals (Au), oxides (Fe₃O₄), fluorides (NaYF₄:Yb³⁺/Er³⁺), and phosphates (YPO₄) to semiconductors (Cu₇S₄ and Ag₂S, ZnS:Mn²⁺) NPs, which renders the nanoprobes’ multifunctional properties such as photothermal ability (Au, Cu₇S₄), magnetism (Fe₃O₄), fluorescence (ZnS:Mn²⁺), near-infrared (NIR) fluorescence (Ag₂S), and upconversion (UC) luminescence. Meanwhile, the as-prepared nanoprobes possess relatively small sizes (about 50 nm), which is beneficial for long-time circulation. The proof-of-concept <i>in vitro</i> ¹⁹F NMR and photothermal ablation of ZnS:Mn²⁺@PDTES/PSI_OAm and Cu₇S₄@PDTES/PSI_OAm nanoprobes further suggest that these nanoprobes hold wide potentials for multifunctional applications in biomedical fields

Fluorescent Nanosensors via Photoinduced Polymerization of Hydrophobic Inorganic Quantum Dots for the Sensitive and Selective Detection of Nitroaromatics

We developed an efficient one-pot strategy for the preparation of hydrophilic amine-functionalized nanocomposites by using hydrophobic fluorescence quantum dots ZnS:Mn²⁺@allyl mercaptan (QDs@AM) as building blocks through novel light-induced in situ polymerization. The average size of as-prepared hydrophilic nanocomposites was ∼50 nm, which could be further tuned by varying the concentrations of the monomers. Importantly, these nanocomposites were further utilized for the facile, highly sensitive, and selective detection of nitroaromatics. The linear ranges for 2,4,6-trinitrotoluene (TNT) and 2,4,6-trinitrophenol (TNP) lie in 0.01–0.5 μg/mL and 0.05–8.0 μg/mL, respectively, barely interfered with by other nitroaromatics such as 2,4-dinitrotoluene (DNT) and nitrobenzene (NB). Moreover, the novel surface modification method developed here offered a general strategy for fabricating hydrophobic nanocomposites with hydrophilic properties and indicated various potential applications including sensing and imaging

Fluorine Grafted Cu₇S₄–Au Heterodimers for Multimodal Imaging Guided Photothermal Therapy with High Penetration Depth

We report the multifunctional nanocomposites (NCs) consisting of ¹⁹F-moieties grafted Cu₇S₄–Au nanoparticles (NPs) for negligible background ¹⁹F-magnetic resonance imaging (¹⁹F-MRI) and computed tomography (CT) imaging guided photothermal therapy. The localized surface plasmon resonance (LSPR) absorption can be reasonably tuned to the <i>in vivo</i> transparent window (800–900 nm) by coupling Au (<10 nm, LSPR ∼530 nm) with Cu₇S₄ (<15 nm, LSPR ∼1500 nm) into Cu₇S₄–Au heterodimers. The <i>in vivo</i> photothermal tests show that Cu₇S₄–Au show deeper light penetration with 808 nm irradiation, better photothermal efficacy, and less damage to normal tissues than Cu₇S₄ with 1500 nm irradiation. Moreover, compared to traditional ¹H-MRI, the ¹⁹F-MRI based on these NCs demonstrates much better sensitivity due to the negligible background. This work offers a promising strategy for multimodal imaging guided photothermal therapy of deep tissue with good efficacy

A Fluorescent Chemodosimeter for Live-Cell Monitoring of Aqueous Sulfides

Aqueous sulfides are emerging signaling agents implicated in various pathological and physiological processes. The development of sensitive and selective methods for the sensing of these sulfides is therefore very important. Herein, we report that the as-synthesized 1-oxo-1<i>H</i>-phenalene-2,3-dicarbonitrile (OPD) compound provides promising fluorescent properties and unique reactive properties toward aqueous sulfides. It was found that OPD showed high selectivity and sensitivity toward Na₂S over thiols and other inorganic sulfur compounds through a sulfide involved reaction which was confirmed by high-resolution mass spectroscopy (HRMS) and nuclear magnetic resonance (NMR) results. The fluorescence intensity increases linearly with sulfide concentration in the range of 1.0–30 μM with a limit of detection of 52 nM. This novel fluorescent probe was further exploited for the fluorescence imaging sensing of aqueous sulfide in HeLa cells

Highly Efficient Photothermal Semiconductor Nanocomposites for Photothermal Imaging of Latent Fingerprints

Optical imaging of latent fingerprints (LFPs) has been widely used in forensic science and for antiterrorist applications, but it suffers from interference from autofluorescence and the substrates background color. Cu₇S₄ nanoparticles (NPs), with excellent photothermal properties, were synthesized using a new strategy and then fabricated into amphiphilic nanocomposites (NCs) via polymerization of allyl mercaptan coated on Cu₇S₄ NPs to offer good affinities toward LFPs. Here, we develop a facile and versatile photothermal LFP imaging method based on the high photothermal conversion efficiency (52.92%, 808 nm) of Cu₇S₄ NCs, indicating its effectiveness for imaging LFPs left on different substrates (with various background colors), which will be extremely useful for crime scene investigations. Furthermore, by fabricating Cu₇S₄-CdSe@ZnS NCs, a fluorescent-photothermal dual-mode imaging strategy was used to detect trinitrotoluene (TNT) in LFPs while still maintaining a complete photothermal image of LFP