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AuxAg1-x Nanocomposites with 40-Fold Emission Enhancement Formed by the Electrostatic Assembly of Gold Nanoclusters and Silver Nanoclusters for Bioimaging and Bioanalysis
摘要： Noble metal nanoclusters (NCs) have been widely used in bioimaging and bioanalysis due to their unique molecular-like structures and good biocompatibility. Bright nanomaterials with high quantum yields are in need for widespread applications. Unfortunately, the weak photoluminescence (PL) of metal NCs hampers their biomedical applications, and thus it is urgent to develop effective routes to enhance their brightness, especially in aqueous solutions. In this work, we reported a facile strategy to prepare highly luminescent AuxAg1-x nanocomposites (x: molar ratio of Au) by electrostatic-induced assembly of non-luminescent glutathione (GSH) stabilized silver NCs (GSH-Ag NCs) and weak orange-emitting GSH stabilized gold NCs (GSH-Au NCs) in aqueous solutions. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), fluorescence spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), UV-vis absorption spectroscopy and dynamic light scattering (DLS) shed light on the mechanism of PL enhancement. It was found that the positively charged gold nanoclusters and the negatively charged silver nanoclusters formed aggregates by electrostatic force, leading to a 40-fold fluorescence intensity enhancement compared with GSH-Au NCs. This was a novel method to strengthen the fluorescence of nanoclusters with such large enhancement in aqueous solutions. With the molar ratio of Au and Ag changing from 80:1 to 2:3, the emission maximum of the AuxAg1-x nanocomposites could be tuned from 590 to 548 nm. The electrostatic force of the Au0.50Ag0.50 nanocomposites enabled them to respond to pH. The Au0.50Ag0.50 nanocomposites were fluorescent turn-on and turn-off at pH 2.6 and pH 7.5, respectively. In this respect, they can be used as a fluorescent switch and be further used as a general recyclable pH probe in the range of 2.6-7.5. This work will inspire even better strategies to further improve the brightness of noble metal NCs.
关键词： nanocomposites,fluorescent switch,electrostatic force,silver nanoclusters,fluorescence enhancement,gold nanoclusters
更新于2025-11-14 15:23:50
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Novel multi-responsive fluorescence switch for Hg2+ and UV/vis lights based on diarylethene-rhodamine derivative
摘要： A new multi-responsive fluorescent switch DTE-Pip-Rho 1O has been designed and synthesized in this study. For this molecule, the reactive site of spirolactam ring is far away from the diarylethene unit through the intramolecular piperazine. It exhibited high selectivity and sensitivity to Hg2+ in addition to obvious color change (colorless-pink) and fluorescence “off-on” (dark-orange) during this process. It is believed that the color change is due to Hg2+-assisted hydrolysis of rhodamine hydrazide. Therefore, the new molecule can be used as colorimetric and fluorescent chemosensor for Hg2+ with high selectivity. The detection limits of absorbance and fluorescence for Hg2+ were calculated to be 1.15 μM and 1.16 μM, respectively. The resulting DTE-Pip-Rho 1O-Hg2+ could also function as a reversible fluorescence photo-switch in response to UV/vis light owing to FRET mechanism. Moreover, it has been demonstrated that the photo-switchable system displayed excellent fatigue resistance and remarkable anti-photobleaching capability.
关键词： Multi-responsive,Fluorescent switch,Diarylethene,FRET mechanism,Sensor,Rhodamine
更新于2025-09-19 17:15:36
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Rhodamine-naphthalimide demonstrated a distinct aggregation-induced emission mechanism: elimination of dark-states <i>via</i> dimer interactions (EDDI)
摘要： Rhodamine B-naphthalimide (RhB-Naph) demonstrated a distinct aggregation-induced emission (AIE) mechanism, different from the restriction of intramolecular rotations or vibrations as in traditional AIE molecules. The monomers of RhB-Naph were non-emissive, due to the presence of a dark S1 state. Upon molecular aggregation, intermolecular interactions significantly altered the electronic properties of RhB-Naph, leading to the formation of a bright S1 state and endowing RhB-Naph with notable AIE properties. Besides, we demonstrated that RhB-Naph enabled the development of a solid-state three-color fluorescent switch upon multi-external stimuli.
关键词： fluorescent switch,dark state,dimer interactions,rhodamine-naphthalimide,aggregation-induced emission
更新于2025-09-19 17:15:36
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A graphene quantum dots-Pb2+ based fluorescent switch for selective and sensitive determination of D-penicillamine
摘要： Taking consideration of metal-induced fluorescence quenching and excellent coordination effect of D-penicillamine (D-PA), a graphene quantum dots (GQDs)-based fluorescent switch for D-PA detection was designed and established firstly with the help of lead ions. GQDs obtained from citric acids made them rich in carboxyl and hydroxyl groups, giving GQDs the ability to combine with lead ions. As anticipated, the fluorescence intensity was quenched by Pb2+ through electron transfer process. Further, the addition of D-PA effectively recovered the fluorescence due to the departure of Pb2+ from GQDs aroused by the strong coordination between D-PA and Pb2+. Thus, a fluorescent switch was activated for D-PA detection. The fluorescence recovery efficiencies were found to be proportional to the concentration of D-PA in the range of 0.6–50 μmol L-1 and the detection limit was 0.47 μmol L-1. The real sample detection was performed in human urea sample and satisfactory recoveries of 96.84%-102.13% were obtained. The GQDs-Pb2+ based fluorescent switch sensing method was firstly established with low detection limit and wide linear range, making it a supplement and improvement for D-PA detection.
关键词： lead ions,graphene quantum dots,D-penicillamine,fluorescent switch
更新于2025-09-12 10:27:22