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Zwitterionic near-infrared fluorophore-conjugated epidermal growth factor for fast, real-time, and target-cell-specific cancer imaging
摘要： Epidermal growth factor receptor (EGFR) is overexpressed in many types of cancers, which is associated with metastatic potential and poor prognosis in cancer patients. Therefore, development of EGFR-targeted sensitive imaging probes has been a challenge in tumor targeting, image-guided cancer surgery, patient-selective anti-EGFR therapy, and efficient targeted therapies. Methods: We synthesized a zwitterionic near-infrared fluorophore (ATTO655)-conjugated epidermal growth factor (EGF) as a novel activatable molecular probe. Fluorescence OFF/ON property and EGFR-targeting specificity of EGF-ATTO655 as well as its utility in real-time near-infrared (NIR) fluorescence imaging of EGFR-positive cancers were evaluated using in vitro and in vivo studies. Results: When conjugated to EGF, the fluorescence of ATTO655 quenched efficiently by photo-induced electron transfer (PET) mechanism between the conjugated dyes and nearby amino acid quenchers (tryptophan/tyrosine residues), which was stably maintained at physiological pH and in the presence of serum for at least 17 h. The fluorescence of EGF-ATTO655 turned on by receptor-mediated endocytosis and subsequent disintegration of EGF in EGFR-positive A431 cancer cells, thereby enabling specific and real-time fluorescence imaging of EGFR-positive cancer cells. Consequently, EGFR-positive tumors could be clearly visualized 3 h post-injection with a significantly high tumor-to-background ratio (TBR = 6.37). Conclusion: This PET mechanism-based OFF/ON type of EGF probe showed great potential for rapid, real-time, and target-cell-specific imaging of EGFR-overexpressing cancers in vitro and in vivo.
关键词： photo-induced electron transfer,Epidermal growth factor,real-time cancer imaging,tumor-specific targeting
更新于2025-11-21 11:24:58
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AIE active fluorescent organic nanoaggregates for selective detection of phenolic-nitroaromatic explosives and cell imaging
摘要： Development of organic nanoparticles with high fluorescence, good biocompatibility along with strong resistance to photobleaching through simple synthetic routes is important for diverse applications such as sensing and bioimaging. Herein, we present the development of a pyrene excimer nanoaggregate which shows aggregation induced emission (AIE) effect in a solvent mixture of THF and water. The pyrene based fluorescent probe, dimethyl-5-(pyren-1-ylmethyleneamino)isophthalate (5-DP) was synthesized through a simple single step condensation reaction from inexpensive reagents. The photophysical studies of nanoaggregated system further corroborates the AIE active behavior of 5-DP probe at different water fractions (?w = 0% to 90%), where the hydrogen bonding interaction between imine and water molecules led to suppression of photoinduced electron transfer (PET) inducing significant enhancement in fluorescence. The highly photostable nanoaggregates were explored as a selective fluorescence “turn off” sensor for phenolic nitroaromatics and the chemo-selectivity was highly pronounced for 2,4,6-trinitrophenol (picric acid), that showed efficient quenching in aqueous as well as solid phase, with a detection limit of 10 nM in aqueous medium. The quenching efficiency of the nanoaggregates can be ascribed to a combination of factors including efficient fluorescence resonance energy transfer, inner filter effect and coulombic interaction between picric acid and the aggregated probe molecules. Further, random aggregation of the pyrene derivative could be controlled for the formation of fluorescent spherical nanoparticles using Pluoronics P-123 block copolymers as encapsulating agents. The resulting composite could be used as a neoteric cell imaging probe with significantly less cytotoxicity, thus showing their potential biological applications.
关键词： aggregation induced emission,electron transfer,explosive detection,cell imaging,Fluorescent organic nanoaggregates
更新于2025-11-21 11:03:13
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Construction of novel Z-scheme Ag/ZnFe2O4/Ag/BiTa1-xVxO4 system with enhanced electron transfer capacity for visible light photocatalytic degradation of sulfanilamide
摘要： A novel Z-scheme system, Ag/ZnFe2O4/Ag/BiTa1-xVxO4 with enhanced electron transfer capacity was constructed for degrading sulfanilamide (SAM) using solar light. The photocatalytic activity of Ag/ZnFe2O4/Ag/BiTa1-xVxO4 was investigated. The effects of the mass ratio (ZnFe2O4:BiTaO4), doped V dose, Ag wt.% content, and irradiation time on the catalytic performance were evaluated. The reasonable mechanism of Ag/ZnFe2O4/Ag/BiTa1-xVxO4 solar photocatalytic degradation was also presented. These results reveal Ag/ZnFe2O4/Ag/BiTa1-xVxO4 possesses enhanced photocatalytic performance. The loaded Ag as electron mediator increases the electron transfer rate. Particularly, the doped V and the Fe ions from ZnFe2O4 form a powerful electron driving force, which enhances the electron transfer capacity. Ag/ZnFe2O4/Ag/BiTa1-xVxO4 shows optimal photocatalytic performance at 2.0 wt.% Ag and 0.5% doped V dose (ZnFe2O4:BiTaO4=1.0:0.5). Also, Ag/ZnFe2O4/Ag/BiTa1-xVxO4 exhibits high stability and repeatability in photocatalytic degradation. Several active species (?OH, ?O2?, and h+) are produced in the Z-scheme photodegradation of SAM. These results on the enhanced photocatalytic activity of Ag/ZnFe2O4/Ag/BiTa1-xVxO4 are ascribed to synergistic photocatalytic effects of ZnFe2O4 and BiTa1-xVxO4 mediated through Ag and driven by doped V and Fe ions. Therefore, the Z-scheme Ag/ZnFe2O4/Ag/BiTa1-xVxO4 photocatalytic technology proves to be promising for the solar photocatalytic treatment of antibiotics under solar light.
关键词： visible light,Electron transfer capacity,Ag/ZnFe2O4/Ag/BiTa1-xVxO4,photocatalytic,sulfanilamide
更新于2025-11-21 10:59:37
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Tuning the luminescence of nitrogen-doped graphene quantum dots synthesized by pulsed laser ablation in liquid and their use as a selective photoluminescence on–off–on probe for ascorbic acid detection
摘要： In this work, nitrogen-doped graphene quantum dots (N-GQDs) were synthesized by pulsed laser ablation in liquid using Nd:YAG laser (532 nm). Graphite target was ablated in dimethylformamide, as solvent and nitrogen source, and the microstructure as well as optical properties of N-GQDs were studied. The N-GQDs structure consists of a graphitic core with oxygen and nitrogen functionalities and particle size about 3 nm, as demonstrated by X-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscopy. The as-prepared N-GQDs structure was modified by solvothermal treatment at 65, 90 and 120 °C reducing the oxygen functional groups, adding nitrogen and restoring the π-conjugated structure of N-GQD. The N-GQDs exhibit UV-Vis absorption spectrum with the characteristic π-π* and n – π* electronic transitions of the GQDs with a large amount of oxygen and nitrogen functionalities. These N-GQDs exhibited a visible light photoluminescence centered at 486 nm upon an excitation of 410 nm and the photoluminescence intensity enhanced up to 4.05% of quantum yield after solvothermal treatment. The N-GQDs dispersion was used for selective detection of ascorbic acid, through a signal-off and signal-on system. The results show the use of N-GQDs as a competent photoluminescence sensor for metal ions and ascorbic acid.
关键词： Fluorescence quenching,electron transfer,carbon nanoparticles
更新于2025-11-19 16:56:42
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Sensitized photochemical CO2 reduction by hetero-Pacman compounds linking a Re(I) tricarbonyl with a porphyrin unit
摘要： The hetero-Pacman architecture places two different metal coordination sites in close proximity, which can support efficient energy and/or electron transfer and allow for cooperative activation of small molecules. Herein, we present the synthesis of dyads consisting of a porphyrin unit as photosensitizer and a rhenium unit as catalytically active site, which are held together by the rigid xanthene backbone. Mononuclear [(NN)Re(CO)3(Cl)] complexes for CO2 reduction where NN represents a bidentate diimine ligand (e.g. bipyridine or phenanthroline) lack light absorption in the visible region, resulting in poor photocatalysis upon illumination with visible light. In order to improve their visible light absorption, we have focused on the incorporation of a strongly absorbing free base or zinc porphyrin unit. Resulting photocatalytic experiments showed a strong dependence of catalytic performance on both the type of photosensitizer and also the excitation wavelengths. Most notably, the intramolecular hetero-Pacman system containing a zinc porphyrin unit showed much better catalytic activity in the visible region (excitation wavelengths >450 nm) than the free base version, the corresponding mononuclear rhenium compound or an intermolecular system comprised of a 1:1 mixture of the mononuclear analogues.
关键词： photocatalysis,CO2 reduction,electron transfer,porphyrin,rhenium
更新于2025-11-19 16:56:35
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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