Exploring NIR Aza-BODIPY-Based Polarity Sensitive Probes with ON-and-OFF Fluorescence Switching in Pluronic Nanoparticles.

Because of their deep penetration capability in tissue, red or near infrared (NIR) fluorophores attract much attention in bio-optical imaging. Among these fluorophores, the ones that respond to the immediate microenvironment (i.e.

The Mechanisms and Biomedical Applications of an NIR BODIPY-Based Switchable Fluorescent Probe.

Highly environment-sensitive fluorophores have been desired for many biomedical applications. Because of the noninvasive operation, high sensitivity, and high specificity to the microenvironment change, they can be used as excellent probes for fluorescence sensing/imaging, cell tracking/imaging, molecular imaging for cancer, and so on (i.e.

A Dual-Modality System for Both Multi-Color Ultrasound-Switchable Fluorescence and Ultrasound Imaging.

Simultaneous imaging of multiple targets (SIMT) in opaque biological tissues is an important goal for molecular imaging in the future. Multi-color fluorescence imaging in deep tissues is a promising technology to reach this goal. In this work, we developed a dual-modality imaging system by combining our recently developed ultrasound-switchable fluorescence (USF) imaging technology with the conventional ultrasound (US) B-mode imaging.

Directly Attached Bisdonor-BF Chelated Azadipyrromethene-Fullerene Tetrads for Promoting Ground and Excited State Charge Transfer.

The efficiency and mechanism of electron- and energy-transfer events occurring in both natural and synthetic donor-acceptor systems depend on their distance, relative orientation, and the nature of the surrounding media. Fundamental knowledge gained from model studies is key to building efficient energy harvesting and optoelectronic devices. Faster charge separation and slower charge recombination in donor-acceptor systems is often sought out.

High-Resolution Ultrasound-Switchable Fluorescence Imaging in Centimeter-Deep Tissue Phantoms with High Signal-To-Noise Ratio and High Sensitivity via Novel Contrast Agents.

For many years, investigators have sought after high-resolution fluorescence imaging in centimeter-deep tissue because many interesting in vivo phenomena-such as the presence of immune system cells, tumor angiogenesis, and metastasis-may be located deep in tissue. Previously, we developed a new imaging technique to achieve high spatial resolution in sub-centimeter deep tissue phantoms named continuous-wave ultrasound-switchable fluorescence (CW-USF). The principle is to use a focused ultrasound wave to externally and locally switch on and off the fluorophore emission from a small volume (close to ultrasound focal volume).

Competitive electron transfer in a novel, broad-band capturing, subphthalocyanine-AzaBODIPY-C60 supramolecular triad.

A V-configured subphthalocyanine-azaBODIPY-C60 supramolecular triad has been newly synthesized, and sequential energy and electron transfer leading to the formation of charge separated states, useful properties relevant for solar energy harvesting and building optoelectronic devices, is reported.

Ultrafast Photoinduced Electron Transfer and Charge Stabilization in Donor-Acceptor Dyads Capable of Harvesting Near-Infrared Light.

To harvest energy from the near-infrared (near-IR) and infrared (IR) regions of the electromagnetic spectrum, which constitutes nearly 70 % of the solar radiation, there is a great demand for near-IR and IR light-absorbing sensitizers that are capable of undergoing ultrafast photoinduced electron transfer when connected to a suitable electron acceptor. Towards achieving this goal, in the present study, we report multistep syntheses of dyads derived from structurally modified BF2-chelated azadipyrromethene (ADP; to extend absorption and emission into the near-IR region) and fullerene as electron-donor and electron-acceptor entities, respectively. The newly synthesized dyads were fully characterized based on optical absorbance, fluorescence, geometry optimization, and electrochemical studies.

Multistep energy and electron transfer in a "V-configured" supramolecular BODIPY-azaBODIPY-fullerene triad: mimicry of photosynthetic antenna reaction-center events.

A new photosynthetic antenna-reaction-center model compound composed of covalently linked BF2 -chelated dipyrromethene (BODIPY), BF2 -chelated azadipyrromethene (azaBODIPY), and fullerene (C60 ), in a "V-configuration", has been newly synthesized and characterized by using a multistep synthetic procedure. Optical absorbance and steady-state fluorescence, computational, and electrochemical studies were systematically performed in nonpolar, toluene, and polar, benzonitrile, solvents to establish the molecular integrity of the triad and to construct an energy-level diagram revealing different photochemical events. The geometry obtained by B3LYP/6-31G* calculations revealed the anticipated V-configuration of the BODIPY-azaBODIPY-C60 triad.

Phenothiazine-azaBODIPY-fullerene supramolecules: syntheses, structural characterization, and photochemical studies.

Photoactive supramolecules composed of two entities of carbamoyl phenothiazines (PTZ) positioned at different locations of the BF2-chelated azadipyrromethene (azaBODIPY) periphery and fulleropyrrolidine (C60) have been newly designed and synthesized to probe excited state events. The X-ray structure of one of the precursor compounds, (PTZ)2-azaBODIPY, revealed spatially well separated PTZ entities without causing any steric hindrance. The supramolecules were fully characterized by spectral, computational, electrochemical and photochemical techniques.

Bis(subphthalocyanine)-azaBODIPY triad for ultrafast photochemical processes.

Multi-modular supramolecular systems capable of undergoing photoinduced energy and electron transfer are of paramount importance to design light-to-energy and light-to-fuel converting devices. Often, this has been achieved by linking two or more photo-active or redox-active entities with complementary spectral and photochemical properties. In the present study, we report a new triad made out of two entities of subphthalocyanine covalently linked to BF2-chelated azadipyrromethene ((SubPc)2-azaBODIPY).

Thieno-pyrrole-fused 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene-fullerene dyads: utilization of near-infrared sensitizers for ultrafast charge separation in donor-acceptor systems.

Donor-acceptor dyads featuring near-IR sensitizers derived from thieno-pyrrole-fused BODIPY (abbreviated as SBDPiR) and fullerene, C60 have been newly synthesized and characterized. Occurrence of ultrafast photoinduced electron transfer (PET) leading to the formation of charge-separated state in these dyads, capable of harvesting light energy from the near-IR region, is established from femtosecond transient absorption studies.

Piezomicrogravimetric and impedimetric oligonucleotide biosensors using conducting polymers of biotinylated bis(2,2'-bithien-5-yl)methane as recognition units.

A new conducting polymer of biotinylated bis(2,2'-bithien-5-yl)methane was prepared and applied as the recognition unit of two different biosensors for selective oligonucleotide determination using either electrochemical impedance spectroscopy (EIS) or piezoelectric microgravimetry (PM) for label-free analytical signal transduction. For preparation of this unit, first, a biotinylated bis(2,2'-bithien-5-yl)methane functional monomer was designed and synthesized. Then, this monomer was potentiodynamically polymerized to form films on the surface of a glassy carbon electrode (GCE) and a Au electrode of a quartz crystal resonator (QCR) for the EIS and PM transduction, respectively.

Excitation-wavelength-dependent, ultrafast photoinduced electron transfer in bisferrocene/BF2-chelated-azadipyrromethene/fullerene tetrads.

Donor-acceptor distance, orientation, and photoexcitation wavelength are key factors in governing the efficiency and mechanism of electron-transfer reactions both in natural and synthetic systems. Although distance and orientation effects have been successfully demonstrated in simple donor-acceptor dyads, revealing excitation-wavelength-dependent photochemical properties demands multimodular, photosynthetic-reaction-center model compounds. Here, we successfully demonstrate donor- acceptor excitation-wavelength-dependent, ultrafast charge separation and charge recombination in newly synthesized, novel tetrads featuring bisferrocene, BF2 -chelated azadipyrromethene, and fullerene entities.

A broad-band capturing and emitting molecular triad: synthesis and photochemistry.

A novel broad-band capturing and emitting supramolecular triad useful for solar energy harvesting and building optoelectronic devices is reported.