RESUMO
The photostability of fluorescent probes is critical in biological imaging, especially for long-term observational analyses. Here, we describe a simple and universal method to improve the photostability of semiconducting polymer dots (Pdots) and other fluorescent probes by using buffers. Using Pdots as a model system, we found that HEPES or MES buffer can improve the photostability of Pdots by a factor of 20. Through a systematic study, we show that Pdot photobleaching is dominated by photoinduced radicals which can be quenched by the piperazine or morpholine structures of these buffers, which act as radical scavengers. For conditions where choice of buffer is limited, we designed fluorescent polymers conjugated with radical scavengers to improve Pdot photostability. We then demonstrate a practical application in which HEPES buffer is used to improve the photostability of Pdots during cell imaging.
Assuntos
Corantes Fluorescentes/química , Imagem Óptica , Processos Fotoquímicos , Polímeros/química , Semicondutores , Soluções Tampão , Humanos , Concentração de Íons de Hidrogênio , Células MCF-7 , Microscopia Confocal , Estrutura Molecular , Células Tumorais CultivadasRESUMO
Simultaneous monitoring of biomarkers as well as single-cell analyses based on flow cytometry and mass cytometry are important for investigations of disease mechanisms, drug discovery, and signaling-network studies. Flow cytometry and mass cytometry are complementary to each other; however, probes that can satisfy all the requirements for these two advanced technologies are limited. In this study, we report a probe of lanthanide-coordinated semiconducting polymer dots (Pdots), which possess fluorescence and mass signals. We demonstrated the usage of this dual-functionality probe for both flow cytometry and mass cytometry in a mimetic cell mixture and human peripheral blood mononuclear cells as model systems. The probes not only offer high fluorescence signal for use in flow cytometry, but also show better performance in mass cytometry than the commercially available counterparts.
Assuntos
Citometria de Fluxo/métodos , Elementos da Série dos Lantanídeos/química , Polímeros/química , Semicondutores , Biomarcadores/sangue , Humanos , Células Jurkat , Leucócitos Mononucleares/metabolismo , Células MCF-7 , Microscopia Eletrônica de Transmissão , Sondas Moleculares/química , Espectrometria de FluorescênciaRESUMO
This article describes the design and development of squaraine-based semiconducting polymer dots (Pdots) that show large Stokes shifts and narrow-band emissions in the near-infrared (NIR) region. Fluorescent copolymers containing fluorene and squaraine units were synthesized and used as precursors for preparing the Pdots, where exciton diffusion and likely through-bond energy transfer led to highly bright and narrow-band NIR emissions. The resulting Pdots exhibit the emission full width at half-maximum of â¼36 nm, which is â¼2 times narrower than those of inorganic quantum dots in the same wavelength region (â¼66 nm for Qdot705). The squaraine-based Pdots show a high fluorescence quantum yield (QY) of 0.30 and a large Stokes shift of â¼340 nm. Single-particle analysis indicates that the average per-particle brightness of the Pdots is â¼6 times higher than that of Qdot705. We demonstrate bioconjugation of the squaraine Pdots and employ the Pdot bioconjugates in flow cytometry and cellular imaging applications. Our results suggest that the narrow bandwidth, high QY, and large Stokes shift are promising for multiplexed biological detections.
Assuntos
Ciclobutanos/química , Fluorescência , Neoplasias/patologia , Fenóis/química , Polímeros/química , Pontos Quânticos , Ciclobutanos/síntese química , Citometria de Fluxo , Humanos , Raios Infravermelhos , Células MCF-7 , Estrutura Molecular , Tamanho da Partícula , Fenóis/síntese química , Polímeros/síntese química , Semicondutores , Propriedades de SuperfícieRESUMO
This communication describes a new class of semiconducting polymer nanoparticle-quantum dot hybrid with high brightness, narrow emission, near-IR fluorescence, and excellent cellular targeting capability. Using this approach, we circumvented the current difficulty with obtaining narrow-band-emitting and near-IR-fluorescing semiconducting polymer nanoparticles while combining the advantages of both semiconducting polymer nanoparticles and quantum dots. We further demonstrated the use of this new class of hybrid nanomaterial for effective and specific cellular and subcellular labeling without any noticeable nonspecific binding. This hybrid nanomaterial is anticipated to find use in a variety of in vitro and in vivo biological applications.
Assuntos
Corantes Fluorescentes/análise , Nanopartículas/análise , Polímeros/química , Pontos Quânticos , Fluorescência , Corantes Fluorescentes/química , Células HeLa , Humanos , Microscopia Confocal , Nanopartículas/química , Nanopartículas/ultraestrutura , SemicondutoresRESUMO
Semiconducting polymer dots (Pdots) recently have emerged as a new class of ultrabright fluorescent probes with promising applications in biological detection and imaging. We developed photoswitchable Pdots by conjugating photochromic spiropyran molecules onto poly[9,9-dioctylfluorenyl-2,7-diyl)-co-1,4-benzo-{2,1'-3}-thiadiazole)] (PFBT). The modulation of fluorescence was achieved by ultraviolet irradiation, which converted spiropyran into its visible-absorbing merocyanine form. The merocyanine efficiently quenched the fluorescence of PFBT via Förster resonance energy transfer (FRET). We then reversed the quenching by subsequent irradiation with visible light to get back the fluorescence of PFBT. This FRET-based photomodulation of Pdot fluorescence could be repeated multiple times. We next conjugated biomolecules onto the surface of these photoswitchable Pdots and demonstrated their specific cellular and subcellular labeling to different types of cells without any noticeable nonspecific binding. We anticipate these photoswitchable and biocompatible Pdots will be useful in developing bioimaging techniques in the future.
Assuntos
Benzopiranos/química , Indóis/química , Luz , Nitrocompostos/química , Polímeros/química , Semicondutores , Fluorenos/química , Células HeLa , Humanos , Células MCF-7 , Imagem Molecular , Espectrometria de Fluorescência , Estreptavidina/químicaRESUMO
One-dimensional nanostructures containing heterojunctions by conjugated polymers, such as nanowires, are expected to greatly facilitate efficient charge transfer in bulk-heterojunction (BHJ) solar cells. Thus, a combined theoretical and experimental approach is pursued to explore spontaneous nanowire formation. A dissipative particle dynamics simulation is first performed to study the morphologies formed by rodlike polymers with various side-chain structures. The results surprisingly predict that conjugated polymers with branched side chains are well suited to form thermodynamically stable nanowires. Proof of this concept is provided via the design and synthesis of a branched polymer of regioregular poly(3-2-methylbutylthiophene) (P3MBT), which successfully demonstrates highly dense nanowire formation free from any stringent conditions and stratagies. In BHJ solar cells fabricated using a blend of P3MBT and [6,6]-phenyl-C71-butyric acid methyl ester (PC(71) BM), P3MBT polymers are self-organized into highly crystalline nanowires with a d(100) spacing of 13.30 Å. The hole mobility of the P3MBT:PC(71) BM (1:0.5 by weight) blend film reaches 3.83 × 10(-4) cm(2) V(-1) s(-1) , and the maximum incident photon-to-current efficiency reaches 68%. The results unambiguously prove the spontaneous formation of nanowires using solution-processable conjugated polymers with branched alkyl side chains in BHJ solar cells.
Assuntos
Nanofios/química , Energia Solar , Tiofenos/química , Absorção , Eletricidade , Microscopia de Força Atômica , Nanofios/ultraestrutura , Polímeros/química , Análise Espectral , Termodinâmica , Difração de Raios XRESUMO
The efficient selection and isolation of individual cells of interest from a mixed population is desired in many biomedical and clinical applications. Here we show the concept of using photoswitchable semiconducting polymer dots (Pdots) as an optical 'painting' tool, which enables the selection of certain adherent cells based on their fluorescence, and their spatial and morphological features, under a microscope. We first develop a Pdot that can switch between the bright (ON) and dark (OFF) states reversibly with a 150-fold contrast ratio on irradiation with ultraviolet or red light. With a focused 633-nm laser beam that acts as a 'paintbrush' and the photoswitchable Pdots as the 'paint', we select and 'paint' individual Pdot-labelled adherent cells by turning on their fluorescence, then proceed to sort and recover the optically marked cells (with 90% recovery and near 100% purity), followed by genetic analysis.
Assuntos
Fluorescência , Polímeros/química , Pontos Quânticos , Semicondutores , Humanos , Células MCF-7 , Microscopia Confocal , Microscopia de Fluorescência , Imagem Molecular/métodosRESUMO
This communication describes an approach for preparing monovalent semiconducting polymer dots (mPdots) with a size of 5 nm where each mPdot was composed of precisely a single active functional group.
Assuntos
Polímeros/química , Semicondutores , Química Click , Dióxido de Silício/química , Propriedades de SuperfícieRESUMO
A facile cross-linking strategy covalently links functional molecules to semiconducting polymer dots (Pdots) while simultaneously providing functional groups for biomolecular conjugation. In addition to greatly enhanced stability, the formed Pdots are small (<10 nm), which can be difficult to achieve with current methods but is highly desirable for most biological applications. These characteristics are significant for improving labeling efficiency and sensitivity in cellular assays that employ Pdots.
Assuntos
Maleatos/química , Maleatos/metabolismo , Imagem Molecular/métodos , Poliestirenos/química , Poliestirenos/metabolismo , Semicondutores , Aminas/química , Linhagem Celular Tumoral , Humanos , Coloração e RotulagemRESUMO
A record high PCE of up to 3.2% demonstrates that the efficiency of hybrid solar cells (HSCs) can be boosted by utilizing a unique mono-aniline end group of PSBTBT-NH(2) as a strong anchor to attach to CdTe nanocrystal surfaces and by simultaneously exploiting benzene-1,3-dithiol solvent-vapor annealing to improve the charge separation at the donor/acceptor interface, which leads to efficient charge transportation in the HSCs.