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Facile Preparation of Highly Luminescent Nitrogen-Doped Carbonaceous Nanospheres and Potential Application in Intracellular Imaging of Quercetin
摘要： Highly luminescent nitrogen-doped carbonaceous nanospheres (LNCNs) were synthesized by a one-pot hydrothermal reaction of b-cyclodextrin (b-CD) and branched polyethylenimine (BPEI). Both the N-doping and amino-functionalisation of LNCNs were achieved simultaneously. The prepared LNCNs display excellent properties such as high physical and chemical stability, excitation wavelength-independent emission, and high photoluminescence quantum yields. Importantly, the LNCNs exhibit a quenching of photoluminescence in the presence of quercetin (Qc) based on the simple static quenching mechanism, making it possible to quantify concentrations from 0.5 to 80 mg mL(cid:1)1 with a detection limit of 0.21 mg mL(cid:1)1. Furthermore, the LNCNs probe was further used for imaging Qc in living cells.
关键词： quercetin,photoluminescence quenching,nitrogen-doped carbonaceous nanospheres,intracellular imaging
更新于2025-09-23 15:21:01
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Facile and highly effective synthesis of nitrogen-doped graphene quantum dots as a fluorescent sensing probe for Cu2+ detection
摘要： Nitrogen-doped graphene quantum dots (N-GQDs) with high blue fluorescence efficiency were synthesized by the hydrothermal method from p-Phenylenediamine and p-Coumaric acid. The N-GQDs possess several superiorities, most significantly in excellent solubility and superior photostability. Besides, the as-prepared N-GQDs exhibit a uniform size distribution with a diameter of about 3.8±0.5 nm. After dispersing the N-GQDs in water, the formed aqueous solution still presents a stable and homogeneous phase even after 2 months at room temperature. The N-GQD dispersion was further utilized as sensing probes for the selective detection of copper ions (Cu2+), which is realized by the photoluminescence (PL) quenching of N-GQDs after adding Cu2+. The detection limit for Cu2+ was found to be 57 nM L-1, with superior selectivity in the presence of other commonly interfering metal ions. The presented results in this study provide a facile and high-efficiency method for synthesizing N-GQDs, with ultra-high detectivity and selectivity for Cu2+ detection, offering numerous opportunities for the development of biosensing, bioimaging, environment monitoring, and others.
关键词： Nitrogen-doped graphene quantum dots,Hydrothermal method,Photoluminescence quenching,Cu2+ detection
更新于2025-09-19 17:13:59
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Ultrafast hole extraction from photoexcited colloidal CdSe quantum dots coupled to nitroxide free radicals
摘要： Organic free radicals related to the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical are known as photoluminescence-quenchers when coupled to group II-chalcogenide colloidal quantum dots (QDs), but the mechanism responsible for this phenomenon has so far remained unresolved. Using a combination of time-resolved photoluminescence and transient absorption spectroscopies, we demonstrate that photoexcited colloidal CdSe QDs coupled to 4-amino-TEMPO undergo highly efficient reductive quenching, that is, hole transfer from the valence band of the quantum dot to the organic paramagnetic species. Interestingly, the process is shown to occur on a subpicosecond time scale for bound 4AT; such a large rate constant for the extraction of holes from photoexcited CdSe QD by a molecular species is rare and underlines the potential that TEMPO derivatives can play in mediating efficient redox processes involving colloidal CdSe QDs.
关键词： TEMPO,photoluminescence quenching,ultrafast spectroscopy,colloidal quantum dots,hole transfer
更新于2025-09-12 10:27:22
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Attachment of a 1,8-Naphthalimide Moiety to a Conjugated Polythiophene Efficiently Improves the Sensing Abilities of Naphthalimide-Based Materials
摘要： A novel polythiophene-based conjugated polymer bearing 1,8-naphthalimide-based pendants is prepared by a two-step modification of regioregular poly[3-(6-bromohexyl)thiophene] involving a nucleophilic substitution reaction of the bromide end-groups with sodium azide followed by a robust, copper-catalyzed Huisgen click reaction with a novel 1,8-naphthalinmide derivative containing an active, N-substituted propyne group. Both the polymer and the highly luminescent-active synthesized dye are extensively studied in solution by UV–vis spectroscopy, photoluminescence, NMR, light-scattering and isothermal titration calorimetry. The materials prepared are considered potential chemosensors for different transition metals, such as Fe2+, Co2+, Ni2+, Cu2+, Zn2+, and Cd2+. Luminescence quenching shows that these materials have a higher sensitivity to Fe2+ than to the other metal ions tested. Moreover, the 1,8-naphthalimide-based conjugated polymer is more efficiently quenched by Fe2+ metal ions, at a significantly lower concentration and with a higher binding constant than its parent 1,8-naphthalimide derivative, thus indicating a high potential for sensor development.
关键词： Stern–Volmer constant,polythiophene,1,8-naphthalimide,photoluminescence quenching,conjugated polymers
更新于2025-09-10 09:29:36