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1.
Luminescence ; 38(2): 127-135, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36581317

RESUMO

Carbon nanodots can function as photosensitizers that have the ability to generate reactive oxygen species such as singlet oxygen, hydroxy (OH) radicals, and superoxide ions. However, most of these can only be generated upon ultraviolet light excitation. Additionally, the mechanism of reactive oxygen species generation by carbon nanodots remains unclear. The development of carbon nanodots that can photosensitize under visible light irradiation is desirable for applications such as photodynamic therapy and pollutant decomposition under visible light. Here, we report novel carbon nanodot-based photosensitizers that generate reactive oxygen species under visible light; they were synthesized using a solvothermal method with two solvents (formamide and water) and amidol as the carbon source. Carbon nanodots from the solvothermal synthesis in formamide showed blue fluorescence, while those obtained in water showed green fluorescence. The photo-excited blue-fluorescent carbon nanodots produced OH radicals, superoxide ions, and singlet oxygen, and therefore could function as both type I and type II photosensitizers. In addition, photo-excited green-fluorescent carbon nanodots generated only singlet oxygen, therefore functioning as type II photosensitizers. It is proposed that the two photosensitizers have different origins of reactive oxygen species generation: the enrichment of graphitic N for blue-fluorescent carbon nanodots and molecular fluorophores for green-fluorescent carbon nanodots.


Assuntos
Fármacos Fotossensibilizantes , Oxigênio Singlete , Espécies Reativas de Oxigênio , Oxigênio Singlete/química , Fármacos Fotossensibilizantes/química , Superóxidos , Carbono/química , Luz , Formamidas , Água
2.
Angew Chem Int Ed Engl ; 62(52): e202316647, 2023 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-37968887

RESUMO

The development of ultra-long room-temperature phosphorescence (UL-RTP) in processable amorphous organic materials is highly desirable for applications in flexible displays, anti-counterfeiting, and bio-imaging. However, achieving efficient UL-RTP from amorphous materials remains a challenging task, especially with activation by visible light and a bright afterglow. Here we report a general and rational molecular-design strategy to enable efficient visible-light-excited UL-RTP by multi-esterification of a rigid large-plane phosphorescence core. Notably, multi-esterification minimizes the aggregation-induced quenching and accomplishes a 'four birds with one stone' possibility in the generation and radiation process of UL-RTP: i) shifting the excitation from ultraviolet light to blue-light through enhancing the transition dipole moment of low-lying singlet-states, ii) facilitating the intersystem crossing process through the incorporation of lone-pair electrons, iii) boosting the decay process of long-lived triplet excitons resulting from a significantly increased transition dipole moment, and iv) reducing the intrinsic triplet nonradiative decay by substitution of high-frequency vibrating hydrogen atoms. All these factors synergistically contribute to the most efficient and stable visible-light-stimulated UL-RTP (lifetime up to 2.01 s and efficiency up to 35.4 % upon excitation at 450 nm) in flexible films using multi-esterified coronene, which allows high-tech applications in single-component time-delayed white light-emitting diodes and information technology based on flashlight-activated afterglow encryption.

3.
Angew Chem Int Ed Engl ; 59(24): 9393-9397, 2020 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-32142188

RESUMO

Ambient afterglow luminescence from metal-free organic chromophores would provide a promising alternative to the well-explored inorganic phosphors. However, the realization of air-stable and solution-processable organic afterglow systems with long-lived triplet or singlet states remains a formidable challenge. In the present study, a delayed sensitization of the singlet state of organic dyes via phosphorescence energy transfer from organic phosphors is proposed as an alternative strategy to realize "afterglow fluorescence". This concept is demonstrated with a long-lived phosphor as the energy donor and commercially available fluorescent dyes as the energy acceptor. Triplet-to-singlet Förster-resonance energy-transfer (TS-FRET) between donor and acceptor chromophores, which are co-organized in an amorphous polymer matrix, results in tuneable yellow and red afterglow from the fluorescent acceptors. Moreover, these afterglow fluorescent hybrids are highly solution-processable and show excellent air-stability with good quantum yields.

4.
Mikrochim Acta ; 186(9): 663, 2019 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-31473835

RESUMO

The enzyme histone acetyltransferase (HAT) catalyzes the acetylation of a substrate peptide, and acetyl coenzyme A is converted to coenzyme A (CoA). A photoelectrochemical method is described for the determination of the HAT activity by using exfoliated MoS2 nanosheets, phos-tag-biotin, and ß-galactosidase (ß-Gal) based signal amplification. The MoS2 nanosheets are employed as the photoactive material, graphene nanosheets as electron transfer promoter, gold nanoparticles as recognition and capture reagent for CoA, and phos-tag-biotin as the reagent to link CoA and ß-Gal. The enzyme ß-Gal catalyzes the hydrolysis of substrate O-galactosyl-4-aminophenol to generate free 4-aminophenol which is a photoelectrochemical electron donor. The photocurrent increases with the activity of HAT. Under optimal conditions, the response is linear in the 0.3 to 100 nM activity range, and the detection limit is 0.14 nM (at S/N = 3). The assay was applied to HAT inhibitor screening, specifically for the inhibitors C646 and anacardic acid. The IC50 values are 0.28 and 39 µM, respectively. The method is deemed to be a promising tool for epigenetic research and HAT-targeted cancer drug discovery. Graphical abstract Histone acetyltransferase was detected using a sensitive photoelectrochemical method using MoS2 nanosheets as photoactive material.


Assuntos
Técnicas Biossensoriais , Dissulfetos/química , Técnicas Eletroquímicas , Inibidores Enzimáticos/análise , Histona Acetiltransferases/antagonistas & inibidores , Histona Acetiltransferases/análise , Molibdênio/química , Nanopartículas/química , Ácidos Anacárdicos/análise , Ácidos Anacárdicos/farmacologia , Benzoatos/análise , Benzoatos/farmacologia , Avaliação Pré-Clínica de Medicamentos , Inibidores Enzimáticos/farmacologia , Histona Acetiltransferases/metabolismo , Humanos , Nitrobenzenos , Tamanho da Partícula , Processos Fotoquímicos , Pirazóis/análise , Pirazóis/farmacologia , Pirazolonas , Propriedades de Superfície
5.
J Fluoresc ; 25(5): 1191-201, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26204811

RESUMO

Pyridine based fluorescence probe, DFPPIC and its functionalized Merrifield polymer has been synthesized, characterized and used as an arsenate selective fluorescence sensor. Arsenate induced fluorescence enhancement is attributed to inter-molecular H-bonding assisted CHEF process. The detection limit for arsenate is 0.001 µM, much below the WHO recommended tolerance level in drinking water. DFPPIC can detect intracellular arsenate in drinking water of Purbasthali, West Bengal, India efficiently. Graphical Abstract DFPPIC and its Merrifield conjugate polymer are used for selective determination and removal of arsenate from real drinking water samples of Purbasthali, a highly arsenic contaminated region of West Bengal, India. DFPPIC is very promising to imaging arsenate in living cells.


Assuntos
Arseniatos/análise , Arseniatos/isolamento & purificação , Corantes Fluorescentes/química , Imagem Molecular , Piridinas/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação , Arseniatos/química , Candida albicans/citologia , Sobrevivência Celular , Água Potável/química , Fatores de Tempo , Poluentes Químicos da Água/química
6.
Luminescence ; 30(7): 1071-6, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25691149

RESUMO

We used the synthesized dinaphthylmethane (Hdnm) ligand whose absorption extends to the visible-light wavelength, to prepare a family of ternary lanthanide complexes, named as [Ln(dnm)3 phen] (Ln = Sm, Nd, Yb, Er, Tm, Pr). The properties of these complexes were investigated by Fourier transform infrared (FT-IR) spectroscopy, diffuse reflectance (DR) spectroscopy, thermogravimetric analyses, and excitation and emission spectroscopy. Generally, excitation with visible light is much more advantageous than UV excitation. Importantly, upon excitation with visible light (401-460 nm), the complexes show characteristic visible (Sm(3+)) as well as near-infrared (Sm(3+), Nd(3+), Yb(3+), Er(3+), Tm(3+), Pr(3+)) luminescence of the corresponding lanthanide ions, attributed to the energy transfer from the ligands to the lanthanide ions, an antenna effect. Now, using these near-infrared luminescent lanthanide complexes, the luminescent spectral region from 800 to 1650 nm, can be covered completely, which is of particular interest for biomedical imaging applications, laser systems, and optical amplification applications.


Assuntos
Complexos de Coordenação/química , Cetonas/química , Elementos da Série dos Lantanídeos/química , Luz , Luminescência , Complexos de Coordenação/síntese química , Estrutura Molecular
7.
Front Chem ; 10: 1047960, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36569958

RESUMO

Visible-luminescent lanthanide (LnL) complexes with a highly planar tetradentate ligand were successfully developed for a visible-light solid-state excitation system. L was designed by using two 2-hydroxy-3-(2-pyridinyl)-benzaldehyde molecules bridged by ethylenediamine, which was then coordinated to a series of Ln ions (Ln = Nd, Sm, Eu, Gd, Tb, Dy, and Yb). From the measurement of single-crystal X-ray analysis of EuL, two phenolic O atoms and two imine N atoms in L were coordinated to the Eu ion, and each π-electronic system took coplanar with the edged-pyridine moiety through an intramolecular hydrogen bond. The enol group on the phenolic skeleton changed to the keto form, and the pyridine was protonated. Thus, intramolecular proton transfer occurred in L after the complexation. Other complexes take isostructure. The space group is P-1, and the c-axis shrinks with decreasing temperature without a phase transition in EuL. The yellow color caused by the planar structure of L can sensitize ff emission by visible light, and the luminescence color of each complex depends on central Ln ions. Furthermore, a phosphorescence band also appeared at rt with ff emission in LnL. Drastic temperature dependence of luminescence was clarified quantitatively.

8.
Natl Sci Rev ; 9(2): nwab085, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35223047

RESUMO

A set of red-light-excited, metal-free room-temperature phosphorescence (RTP) systems was constructed with brominated phenolsulfonephthaleine derivatives. The best metal-free RTP system has the reddest near-infrared (NIR) RTP emission (λp = 819 nm) with the highest phosphorescence quantum yield (ΦRTP = 3.0%) so far identified. The RTP emission can be switched ON-OFF by adding acid and alkali alternately. A logic operation with half-subtractor function and dual-channel response (visible light emission/NIR RTP emission) was also constructed based on these properties.

9.
Nanomaterials (Basel) ; 10(3)2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32143524

RESUMO

Carbon dots (CDs) with a room temperature phosphorescent (RTP) feature have attracted considerable interest in recent years due to their fundamental importance and promising applications. However, the reported matrix-free RTP CDs only show short-wavelength (green to yellow) emissions and have to be triggered by ultraviolet (UV) light (below 400 nm), limiting their applications in certain fields. Herein, visible-light-excited matrix-free RTP CDs (named AA-CDs) with a long-wavelength (orange) emission are reported for the first time. The AA-CDs can be facilely prepared via a microwave heating treatment of L-aspartic acid (AA) in the presence of ammonia and they emit unique orange RTP in the solid state with visible light (420 nm) excitation just being switched off. Through the studies of the carbonization process, the C=O and C=N containing moieties in the AA-CDs are confirmed to be responsible for the observed RTP emission. Finally, the applications of AA-CDs in information encryption and anti-counterfeiting were preliminarily demonstrated.

10.
Adv Mater ; 31(12): e1807887, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30721550

RESUMO

The development of organic materials displaying ultralong room-temperature phosphorescence (URTP) is a material design-rich research field with growing interest recently, as the luminescence characteristics have started to become interesting for applications. However, the development of systems performing under aerated conditions remains a formidable challenge. Furthermore, in the vast majority of molecular examples, the respective absorption bands of the compounds are in the near ultraviolet (UV) range, which makes UV excitation sources necessary. Herein, the synthesis and detailed analysis of new luminescent organic metal-free materials displaying, in addition to conventional fluorescence, phosphorescence with lifetimes up to 700 ms and tailored redshifted absorption bands, allowing for deep blue excitation, are reported. For the most promising targets, their application is demonstrated in the form of organic programmable tags that have been recently developed. These tags make use of reversible activation and deactivation of the URTP by toggling between the presence and absence of molecular oxygen. In this case, the activation can be achieved with visible light excitation, which greatly increases the use case scenarios by making UV sources obsolete.

11.
Biosens Bioelectron ; 132: 105-114, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30856426

RESUMO

An ultrasensitive Visible light-triggered photoelectrochemical (PEC) sensor was designed based on ideal photoactive lead sulfoiodide (Pb5S2I6) as low band gap crystal, which hydrothermally synthesized rapidly at low temperature (160 °C) in hydrochloride acid media followed by its incorporation into polydopamine as reactive photo-biointerface, through a facile in situ electropolymerization method, coated on nanoporous TiO2 grown by anodization on Ti foil. The structure of as-prepared samples and their photoelectrochemical properties were fully characterized. This unique photo-sensitive Pb5S2I6 catalyst-based PEC bioassay was constructed for the detection of low-abundant Cr(VI) ion in real samples. Applying central composite design, individual and mutual interaction effects were evaluated to obtain optimized solution pH, applied potential and radiant light wavelength as operational factors influencing the PEC efficiency for Cr(VI) detection. At optimal condition, the proposed sensor due to effective suppress in electron-hole recombinations showed a very low detection limit of 3.0 nM, over a broad linear concentration range of 0.01-80 µM in addition to high sensitivity versus 1.9 µA/µM Cr(VI). Proposed PEC sensor displayed high selectivity, reproducibility and stability as well as improved excitation conversion efficiency, which make it highly applicable using solar energy. The potential applicability of the designed sensor was evaluated in water, tomato juice and hair color.


Assuntos
Técnicas Biossensoriais/métodos , Cromo/análise , Indóis/química , Chumbo/química , Polímeros/química , Titânio/química , Poluentes Químicos da Água/análise , Cristalização , Técnicas Eletroquímicas/métodos , Sucos de Frutas e Vegetais/análise , Iodo/química , Luz , Limite de Detecção , Solanum lycopersicum/química , Nanoporos/ultraestrutura , Processos Fotoquímicos , Porosidade , Reprodutibilidade dos Testes , Enxofre/química , Águas Residuárias/análise
12.
Biosens Bioelectron ; 112: 193-201, 2018 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-29705617

RESUMO

In this work, a sensitive photoelectrochemical aptasensor was developed for kanamycin detection using an enhanced photocurrent response strategy, which is based on the surface plasmon resonance effect of gold nanoparticles deposited on a 3D TiO2-MoS2 flower-like heterostructure. A significant aspect of this development lies in the photoelectrochemical and morphological features of the unique ternary composite, which have contributed to the excellent performance of the sensor. To develop an aptasensor, mercapto-group modified aptamers were immobilised on the photoactive composite as a recognition unit for kanamycin. The TiO2-MoS2-AuNP composite was demonstrated to accelerate the electron transfer, increase the loading of aptamers and improve the visible light excitation of the sensor. Under optimal conditions, the aptasensor exhibited a dynamic range from 0.2 nM to 450 nM of kanamycin with a detection limit of 0.05 nM. Overall, we have successfully synergised both the electrical and the optical merits from individual components to form a ternary composite, which was then demonstrated as an effective scaffold for the development of PEC biosensors.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Canamicina/isolamento & purificação , Nanopartículas Metálicas/química , Ouro/química , Canamicina/química , Luz , Limite de Detecção , Molibdênio/química , Processos Fotoquímicos , Sulfetos/química , Titânio/química
13.
Adv Mater ; 29(35)2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28714219

RESUMO

Visible light is much more available and less harmful than ultraviolet light, but ultralong organic phosphorescence (UOP) with visible-light excitation remains a formidable challenge. Here, a concise chemical approach is provided to obtain bright UOP by tuning the molecular packing in the solid state under irradiation of available visible light, e.g., a cell phone flashlight under ambient conditions (room temperature and in air). The excitation spectra exhibit an obvious redshift via the incorporation of halogen atoms to tune intermolecular interactions. UOP is achieved through H-aggregation to stabilize the excited triplet state, with a high phosphorescence efficiency of 8.3% and a considerably long lifetime of 0.84 s. Within a brightness of 0.32 mcd m-2 that can be recognized by the naked eye, UOP can last for 104 s in total. Given these features, ultralong organic phosphorescent materials are used to successfully realize dual data encryption and decryption. Moreover, well-dispersed UOP nanoparticles are prepared by polymer-matrix encapsulation in an aqueous solution, and their applications in bioimaging are tentatively being studied. This result will pave the way toward expanding metal-free organic phosphorescent materials and their applications.

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