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Dopamine-functionalized upconversion nanoparticles as fluorescent sensors for organophosphorus pesticide analysis
摘要： Organophosphorus pesticide (OP) residues in agricultural products, herbal medicines and environment have attracted increasing concerns because they cause high healthy risk. Herein, a tyrosinase-mediated photoinduced electron transfer system was constructed for OPs analysis by using dopamine-functionalized upconversion nanoparticles (UCNPs) as fluorescent (FL) sensors. Dopamine quinone was produced by tyrosinase-mediated oxidation of dopamine on the surface of UCNPs, which acted as electron accepter to quench the FL emission of UCNPs. The FL quenching was inhibited by OP since it inhibited the activity of tyrosinase. Chlorpyrifos was used as a model analyte to investigate the feasibility of the FL sensor for the analysis of OPs. Under the optimal conditions, chlorpyrifos can be analysed in a wide range of 1.0 ? 1000 ng mL?1, with a detection limit of 0.38 ng mL?1 (3σ). Some other groups pesticides, including organonitrogen pesticide, organochlorine pesticide and chloronicotinyl insecticide all showed negligible interference. The proposed sensor was successfully used to analyse chlorpyrifos spiked in Balloonflower and Angelica with acceptable recovery values of 95.4–120.0%, demonstrating its application potential for real samples. It exhibits some advantages like low cost, high sensitivity and free of autofluorescent interference and photobleaching.
关键词： Tyrosinase,Photoinduced electron transfer,Fluorescent sensor,Organophosphorus pesticide,Upconversion nanoparticles,Chlorpyrifos
更新于2025-11-14 17:15:25
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Phosphorimetric determination of 4-nitrophenol using mesoporous molecular imprinting polymers containing manganese(II)-doped ZnS quantum dots
摘要： Mesoporous molecularly imprinted polymers (MIPs) containing mangnanese-doped ZnS quantum dots (Mn-ZnS QDs) were prepared for specific recognition and detection of 4-nitrophenol (4-NP). The Mn-ZnS QDs display orange room-temperature phosphorescence with excitation/emission peaks at 295/590 nm and a decay time of 2.0 ms. In the presence of 4-NP, the orange phosphorescence is strongly reduced. Phosphorescence drops linearly in the 0.1–100 μM 4-NP concentration range, and the detection limit is 60 nM. The detection limit is far lower than the maximally allowed 4-NP concentrations in surface water and drinking water as specified by the U.S. Environmental Protection Agency. The intraday (n = 5) and interday (n = 6) spiked recovery rates were 96.0–104.5% and 97.9–107.9%, respectively, with relative standard deviations of 0.7–4.8% and 1.8–7.5% respectively. These MIPs integrated the characteristic features of phosphorimetry and molecular imprinting. Potential interference by competitive substances, background fluorescence or scattered light are widely reduced.
关键词： Room-temperature phosphorescence,Mesoporous molecularly imprinted polymers,Photoinduced electron-transfer,4-Nitrophenol,Decay time
更新于2025-11-14 17:04:02
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Determination of cholic acid in body fluids by β?cyclodextrin-modified N-doped carbon dot fluorescent probes
摘要： An easy, dependable, and sensitive cholic acid activity experiment was designed based on β?cyclodextrin-modi?ed carbon dot (β?CD-CD) nanoprobes with speci?c host–guest recognizing ability and photoelectron transfer capability. The β?CD-CD nanoprobes were characterized by infrared, ultraviolet-visible, and ?uorescence spectroscopy and transmission electron microscopy. The ?uorescence of the probes under optimized conditions linearly responded to cholic acid concentration from 0 to 650 μmol·L?1 with a detection limit of 25 nmol·L?1. The probes also performed well in detecting cholic acid in serum and urine samples with an average recovery rate of 97.1%–103.4%. Thus, this study provides a reliable, rapid, and easy method of cholic acid detection in body ?uids that can be potentially applied in medical studies.
关键词： Host–guest recognition,β?cyclodextrin,Cholic acid,Photoinduced electron transfer,Carbon dots
更新于2025-11-14 17:03:37
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Study of the photoresponse of a titanium anode coated with solution-processed fullerene-containing metal porphyrin/phthalocyanine films
摘要： The present paper deals with the recent studies on the preparation of porphyrin-based donor-acceptor complexes capable of photoinduced electron transfer for solution-processed organic solar cells. Here the synthesis and chemical structure of (octakis(3,5-di-tert-butylphenoxy)phthalocyaninato) cobalt(II) (1) and (2,3,7,8,12,18-hexamethyl,13,17-diethyl,5-(2-pyridyl)porphinato) manganese(III) chloride (2) are performed and self-assembly in toluene solution of 1 and 1′-N-methyl-2′-(pyridin-4-yl)pyrrolidino[3′,4′:1,2][60]fullerene (PyC60) were discussed in more details. The structure of the obtained dyad 1-PyC60 is con?rmed by means of chemical thermodynamics/kinetics, UV–vis, IR, 1H NMR spectroscopy. Photoelectrochemical studies of the phthalocyanine-fullerene dyad and its precursors were carried out by voltammetry and amperometry methods. A comparative analysis of the photoelectrochemical characteristics obtained in this paper and these for recent described cobalt(II)/manganese(III) porphyrin/phthalocyanine-fullerene dyads are introduced from which ideas for the future design of high performance organic solar cells will be developed.
关键词： donor-acceptor complexes,organic solar cells,phthalocyanine,photoinduced electron transfer,fullerene,porphyrin
更新于2025-11-14 15:14:40
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Fluorescent pH Probes based on PET Quenching of Long Fluorescence Lifetime Triangulenium Dyes Martin Rosenberg, Anne Kathrine R. Junker, Thomas Just S?rensen, and Bo W. Laursen*[a]
摘要： Azaoxatriangulenium dyes with long fluorescence lifetimes offer advantages in fluorescence lifetime imaging (FLIM), time-gated detection and polarization assays. However, the long excited state lifetimes are also expected to increase sensitivity to photoinduced electron transfer (PET) quenching, potentially increasing the on-off ratio of PET probes. We report the synthesis and investigation of the optical properties of azaoxatriangulenium salts substituted with phenol substituents for pH sensing. Two series of pH probes with the phenol hydroxy group placed in the ortho, meta, or para positions to azadioxatriangulenium (ADOTA) and diazaoxatriangulenium (DAOTA) chromophores are investigated. All the phenol substituted dyes possess pH responsive fluorescence signals in the biological relevant pH window (pH 6-9) due to efficient intramolecular PET from the phenolate form of the pendant arm. While the PET mechanism is partly suppressed in the phenol form the ADOTA derivatives, it is completely suppressed in the DAOTA derivatives. The long excited state lifetimes of the triangulenium dyes ensure efficient PET quenching leading to very high on-off ratios of the pH probes. The study clearly demonstrates effects of the position of the phenol/phenolate group relative to the chromophore on both PET quenching rates and pKa values.
关键词： PET probes,triangulenium,pH probes,photoinduced electron transfer,Fluorescent probes
更新于2025-10-22 19:40:53
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Photoinduced electron transfer kinetics of linked Ru-Co photocatalyst dyads
摘要： Two new supramolecular photocatalyst dyads based on the [Ru(2,2′-bipyridine)3]2+ photosensitizer linked to a macrocyclic Co(II)tetra(pyridyl) catalyst for proton reduction are reported. The dyads differ primarily in the bridging ligand which links the molecular modules; the first being a short and flexible linker, and the second a longer and electronically conjugated linker. Ultrafast transient optical spectroscopy was used to monitor the photoinduced kinetics of the dyads following visible excitation of the photosensitizer module. Direct comparison of transient spectra and kinetics indicates that there are indeed substantial differences between the ultrafast transient optical spectroscopy of the dyads, but there is no indication of oxidative quenching of the photosensitizer module by the catalyst module. These initial design and characterization studies of the linked Ru(II)—Co(II) dyads provide an important foundation for advanced designs of systems for efficient solar energy conversion by molecular architectures.
关键词： Ruthenium,Cobalt,Photoinduced electron transfer,Modular assembly,Photocatalyst dyads
更新于2025-09-23 15:22:29
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Synthesis and Properties of Novel Fluorescence Probe Based on 1,8-Naphthalimide for Detection of Hydrogen Sulfide
摘要： Two fluorescence-enhanced probes, 4-(2,4-dinitrophenoxy)-N-(2-hydroxyethyl)-1,8-naphthalimide(NTE-1) and 4-(2,4-dinitrophenoxy)-N-(4-(2,4-dinitrophenoxy)phenyl)-1,8-naphthalimide(NTE-2), have been designed and synthesized for detection of H2S. 4-Hydroxy-1,8-naphthalimide as fluorophore in combination with 2,4-dinitrophenyl ether as H2S response site constructed the fluorescence probes. The consequences showed that both NTE-1 and NTE-2 displayed large red-shift(excess 100 nm) in absorption spectra and more than 30-fold fluorescence enhancement in response to H2S. Moreover, the dual site probe, NTE-2, displayed wider linear range between fluorescence intensity and concentration of H2S(0—40 μmol/L) compared with single site probe, which can be applied to quantitative detection of high concentration of H2S. The photoinduced electron transfer(PET) response mechanism of probe was further studied by analyzing the distributions of molecular orbital. Importantly, the probes have potential practical applications in detection of H2S.
关键词： 2,4-Dinitrophenyl ether,Photoinduced electron transfer,Gaussian,Dual site
更新于2025-09-23 15:22:29
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Photoinduced electron transfer in non-covalent free-base octaethylporphyrin and 2-nitrofluorene donor-acceptor system: A combined experimental and quantum chemical study
摘要： Photosynthetic reaction center functions through non-covalent incorporation into a well-defined transmembrane proteins. In the context of exploring photoinduced electron transfer (PET) in non-covalent donor-acceptor systems, we have investigated electron transfer from free-base octaethylporphyrin (OEP) donor to 2-nitrofluorene (2NF) acceptor in acetonitrile (ACN), a polar solvent. Steady-state and time-resolved emission spectroscopic studies in conjunction with density functional theory (DFT) calculations were employed to explore the electron transfer process. Quenching of the fluorescence emission intensity as well as fluorescence lifetime of the OEP upon excitation at the Q band of OEP at 300 K, is attributed to the PET from OEP to 2NF. Our DFT [wB97XD functional and 6-31G (d,p) basis set] calculations also support the interaction between donor and acceptor and also reveals the co-facial π-π interaction energy of ?24.6 kcal/mol with intermolecular distance b4 ?. Our results are expected to shed light on PET in non-covalent donor acceptor systems.
关键词： Marcus theory,Photoinduced electron transfer,Octaethylporphyrin,Second-order bimolecular fluorescence quenching constant,2-Nitrofluorene,DFT study by wB97XD/6-31G(d,p),Time-resolved emission spectroscopy
更新于2025-09-23 15:22:29
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A Signal-On Fluorosensor Based on Quench-Release Principle for Sensitive Detection of Antibiotic Rapamycin
摘要： An antibiotic rapamycin is one of the most commonly used immunosuppressive drugs, and also implicated for its anti-cancer activity. Hence, the determination of its blood level after organ transplantation or tumor treatment is of great concern in medicine. Although there are several rapamycin detection methods, many of them have limited sensitivity, and/or need complicated procedures and long assay time. As a novel fluorescent biosensor for rapamycin, here we propose “Q’-body”, which works on the fluorescence quench-release principle inspired by the antibody-based quenchbody (Q-body) technology. We constructed rapamycin Q’-bodies by linking the two interacting domains FKBP12 and FRB, whose association is triggered by rapamycin. The fusion proteins were each incorporated position-specifically with one of fluorescence dyes ATTO520, tetramethylrhodamine, or ATTO590 using a cell-free translation system. As a result, rapid rapamycin dose-dependent fluorescence increase derived of Q’-bodies was observed, especially for those with ATTO520 with a lowest detection limit of 0.65 nM, which indicates its utility as a novel fluorescent biosensor for rapamycin.
关键词： rapamycin,fluorescent biosensor,fluorescence quenching,photoinduced electron transfer,antibiotics
更新于2025-09-23 15:22:29
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Light-Triggered Dual-Modality Drug Release of Self-Assembled Prodrug-Nanoparticles for Synergistic Photodynamic and Hypoxia-Activated Therapy
摘要： Photodynamic therapy (PDT) leads to tumor hypoxia which could be utilized for the activation of hypoxia-activated prodrugs (HAPs). However, conventional photosensitizer-loaded nanoformulations suffer from aggregation-caused quenching (ACQ) effect, which limits the efficiency of PDT and synergistic therapy. Herein, prodrug-nanoparticles (NPs) are prepared by the self-assembly of heterodimeric prodrugs composed of pyropheophorbide a (PPa), hypoxia-activated prodrug PR104A, and a thioether or thioketal linkage. In addition, a novel dual-modality drug release pattern is proposed on the basis of the structural states of prodrug-NPs. Under light irradiation, PR104A is released via photoinduced electron transfer (PET) due to the aggregating state of prodrugs. With the disassembly of prodrug-NPs, ACQ effect relieves, PPa produces singlet oxygen which further promotes the reactive oxygen species (ROS)-sensitive release of PR104A. Such prodrug-NPs turn the disadvantage of the ACQ effect to facilitate drug release, demonstrating high-efficiency synergy in combination with PDT and hypoxia-activated therapy.
关键词： aggregation-caused quenching,Photodynamic therapy,drug release,photoinduced electron transfer,hypoxia-activated prodrugs,reactive oxygen species
更新于2025-09-23 15:19:57