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Adenosine 5'-triphosphate (ATP), synthesized in mitochondria, is an energy molecule in all living things. ATP not only serves as an energy source for protein synthesis and muscle contraction, but also as an important indicator for various diseases, such as Parkinson's disease, cardiovascular disease, and others. Accordingly, detection and sensing of ATP, especially in mitochondria, are important. In this study, a unique ring-opening process of rhodamine was coupled to recognition of ATP via introduction of a thiourea moiety, which was further linked to a naphthalimide group. A strong fluorescent emission at ∼580 nm was accompanied by a color change from colorless to pink upon addition of ATP at pH 7.4. Fluorescent probe 1 successfully imaged mitochondrial ATP with a Pearson's coefficient of 0.8. In addition, green emission from the naphthalimide moiety at ∼530 nm was observed without any change upon addition of ATP. This emission can be considered equivalent to an internal standard to utilize probe 1 as a dual-channel probe for ATP. Furthermore, probe 1 showed negligible cytotoxicity based on MTT assays.

The development of activatable photosensitizers to allow for the reversible control of singlet oxygen (1O2) production for photodynamic therapy (PDT) faces great challenges. Fortunately, the flourishing field of supramolecular biotechnology provides more effective strategies for activatable PDT systems. Here, we developed a new reversible PDT on a switch that controls the 1O2 generation of self-assembled albumin nanotheranostics in vitro and in vivo. A new molecular design principle of aggregation-induced self-quenching photochromism and albumin on-photoswitching was demonstrated using a new asymmetric, synthetic diarylethene moiety DIA. The photosensitizer porphyrin and DIA were incorporated as building blocks in a glutaraldehyde-induced covalent albumin cross-linking nanoplatform, HSA-DIA-porphyrin nanoparticles (NPs). More importantly, the excellent photoswitching property of DIA enables the resultant nanoplatform to act as a facile, switchable strategy for photodynamic-immunotherapy.

Food fermentation, antibiotics, and pollutant degradation are closely related to bacteria. Bacteria play an irreplaceable role in life. However, some bacteria seriously threaten human health and cause large-scale infectious diseases. Therefore, there is a pressing need to develop strategies to accurately monitor bacteria. Technology based on molecular probes and fluorescence imaging is noninvasive, results in little damage, and has high specificity and sensitivity, so it has been widely applied in the detection of bacteria. In this review, we summarize the recent progress in bacterial detection using fluorescence. In particular, we generalize the mechanisms commonly used to design organic fluorescent probes for detecting and imaging bacteria. Moreover, a perspective regarding fluorescent probes for bacterial detection is discussed.

Summary Enzymes play a key role in many bioprocesses associated with diseases, and observation of enzyme dynamics in living bodies has become meaningful for understanding enzyme function. Thus, in situ real-time fluorescence imaging can prove to be a powerful tool for monitoring enzyme dynamics, enabling detailed understanding of changes in the activity and function of enzymes. This perspective summarizes the existing methods for in situ real-time fluorescence imaging of enzymes in vivo and discusses remaining challenges. This perspective is intended to encourage chemists and chemical engineers to develop additional methods for the in situ real-time monitoring of enzymes in complex biosystems.

Acetylcholinesterase (AChE) is an extremely critical hydrolase tightly associated with neurological diseases. Currently, developing specific substrates for imaging AChE activity still remains a great challenge due to the interference from butyrylcholinesterase (BChE) and carboxylesterase (CE). Herein, we propose an approach to designing specific substrates for AChE detection by combining dimethylcarbamate choline with a self-immolative scaffold. The representative P10 can effectively eliminate the interference from CE and BChE. The high specificity of P10 has been proved via imaging AChE activity in cells. Moreover, P10 can also be used to successfully map AChE activity in different regions of a normal mouse brain, which may provide important data for AChE evaluation in clinical studies. Such a rational and effective approach can also provide a solid basis for designing probes with different properties to study AChE in biosystems and another way to design specific substrates for other enzymes., In this work, a new approach was developed for designing the representative P10 with high selectivity and sensitivity for imaging AChE activity in the cells and normal mouse brain.

The recurrence of malignant tumors is mostly caused by incompleted surgical resection. Especially, it is difficult for surgeons to detect and accurately remove metastatic tumors by predominantly using visual examination and palpation owing to the lack of effective means to specifically distinguish the boundary range between normal and tumor tissues. Thus, the development of activated fluorescent probe with superior tumor-to-normal (T/N) tissue ratios is particularly urgent in clinics. In view of CD13/aminopeptidase N (APN) regarded as a cancer-specific biomarker, mediating with progression, invasion, and migration of malignant tumor, herein, we reported an APN-responsive fluorescent probe YH-APN and demonstrated its application to distinguish cancer cells. Through in situ spraying manner, fluorescent superior tumor-to-normal (T/N) tissue ratios (subcutaneous transplantation tumor, 13.86; hepatic metastasis, 4.42 and 6.25; splenic metastasis, 4.99) were achieved. More importantly, we have demonstrated the ability to image metastasis tumor tissue less than 1 mm in diameter, highlighting the potential for this probe to be used as a tool in surgical resection. This research may spur the use of enzyme-activatable fluorescent probes for the progress of tumor diagnosis and image-guided surgery (IGS).

Summary Cancer is one of the world’s most serious health challenges. Several problems and challenges still exist for cancer therapies especially because anti-cancer agents that are delivered to normal cells and tissues cause a number of severe side effects. In one general approach aimed at solving this problem, supramolecular systems, created by noncovalent interactions, have been designed and utilized for cancer-cell-targeted drug delivery. In addition, cancer-associated, turn-on supramolecular theranostic agents have received great attention in the biomedicine field because they can be selectively “switched on” in cancer cells. This attribute enables the avoidance of problems associated with cytotoxic effects on healthy cells and tissues. In this review, we summarize recent progress made in the design of turn-on supramolecular theranostic agents composed of host-guest nanosystems and their applications in biomedicine.

Traditional biochemical methods for enzyme detection are mainly based on antibody-based immunoassays, which lack the ability to monitor the spatiotemporal distribution and, in particular, the in situ activity of enzymes in live cells and in vivo. In this review, we comprehensively summarize recent progress that has been made in the development of small-molecule as well as material-based fluorogenic probes for sensitive detection of the activities of enzymes that are related to a number of human diseases. The principles utilized to design these probes as well as their applications are reviewed. Specific attention is given to fluorogenic probes that have been developed for analysis of the activities of enzymes including oxidases and reductases, those that act on biomacromolecules including DNAs, proteins/peptides/amino acids, carbohydrates and lipids, and those that are responsible for translational modifications. We envision that this review will serve as an ideal reference for practitioners as well as beginners in relevant research fields.

Two new cyanine-based fluorescent probes 1 and 2 have been developed. Probe 1 bears two cyanine units in a single molecule, and probe 2 contains a bis(trifluoromethyl)benzenethiol moiety. Both are non-fluorescent. The addition of intracellular glutathione (GSH) significantly enhanced the NIR fluorescence of the two probes. Both probes were used to image varying amounts of GSH in living cells. In tumor bearing mice, the in vivo fluorescence intensity of both probes was higher in tumors, where GSH is overexpressed, than in normal tissues. These results suggest that these new fluorogenic probes have potential for GSH-targeting diagnostic imaging.

A novel multifunctional aminophenylboronic acid connected to a diphenylketone gives both circular dichroism and fluorescence signals by in situ generation of a BODIPY-like chromophore in the presence of aminoalcohols. DFT calculations were used to understand the role of each functional group in the mechanism. This new sensor can distinguish different aminoalcohols and quantitatively indicate the concentration of the substrate, allowing for the convenient determination of the ee of racemic mixtures with a single probe.

Hypochlorous acid (HOCl) is an endogenously produced reactive oxygen species (ROS), which acts as a protector against microbes. However, its aberrant production is implicated in various oxidative-stress related pathophysiological processes, such as cardiovascular disorders, arthritis, and neurodegenerative diseases. Therefore, the direct, rapid, sensitive, and selective detection of endogenous HOCl in living systems is of essential importance for better understanding the HOCl-involved chemical biology. In the last two decades, sulfur-based fluorescent probes for HOCl have been widely designed and they usually show rapid reaction rate, high selectivity and excellent sensitivity. This review summarized the advances that have been made in the development of sulfur-based fluorescent probes for HOCl, and their reaction mechanisms were emphatically discussed. Lastly, the achievements, challenges, and perspectives in this field were outlooked.

Summary Glutathione is a major endogenous antioxidant in biological systems. As a result, highly selective fluorescent probes are significant components of studies aimed at gaining a better understanding of the role(s) glutathione plays in biological functions. In this study, we developed a dual-channel turn-on fluorescent probe for glutathione, comprising naphthalimide and cyanine, bridged by a thiol-reactive sulfonamide moiety. The probe selectively responds to glutathione and is not affected by cysteine and homocysteine. Important information has been gained about the chemical mechanism for operation of the probe, which responds to glutathione in visible and near-infrared channels synchronously and independently. Moreover, this probe exhibits the remarkable capability of targeting mitochondria and dual-channel tracking of intracellular glutathione in a spatiotemporal and synchronous manner. We believe that the strategy used to design the new dual-channel fluorescence-on probe will be applicable to the design of fluorescent probes that display specific responses in multiple channels.

Synaptic Zn2+ plays an important role in neurotransmission and a neuromodulator. The development of the imaging tools for monitoring spatiotemporal changes taking place in synaptic Zn2+ concentrations is necessary in order to understand the role of Zn2+ in the function of many aspects of the glutamate system. In this work, two-photon probes 1 and 2, bearing ifenprodil-like tails that have affinity for NMDA receptors of neuronal cells, were designed and prepared. The two-photon fluorescent probe 1, which bears (N-(6-acetylnaphthalen-2-yl)-N-methylglycine) as two-photon fluorophore, enables high resolution imaging of neuronal cells. The two-photon fluorescent probe 2, which contains the di-2-picolylamine (DPA) as a Zn2+-binding site, the naphthalimide unit as the two-photon fluorophore, and the ifenprodil-like tail as the NMDA receptor binding moiety, can be employed for selective detection of Zn2+ located near the NMDA receptor and for monitoring concentration changes of Zn2+ in live neurons and hippocampal tissues.

Intracellular pH values are some of the most important factors that govern biological processes and the acid-base homeostasis in cells, body fluids and organs sustains the normal operations of the body. Subcellular organelles including the acidic lysosomes and the alkalescent mitochondria undergo various processes such as intracellular digestion, ATP production and apoptosis. Due to their precise imaging capabilities, fluorescent probes have attracted great attention for the illustration of pH modulated processes. Furthermore, based on the unique acidic extracellular environment of acidic lysosomes, fluorescent probes can specifically be activated in cancer cells or tumors. In this review, recently reported lysosome and mitochondria specific pH imaging probes as well as pH-activatable cancer cell-targetable probes have been discussed.

A new quinone propionic acid locked TP fluorophore which can be used for human NAD(P)H:quinone oxidoreductase (hNQO1) detection was developed. The probe, TPQ, which displays high selectivity and anti-interference ability, was successfully applied to endogenous hNQO1 imaging and for the identification of different cancer cells.

Two new dinuclear iridium (Ir) complexes bridged by a conjugated aromatic tppz ligand, (bhq)2Ir(tppz)Ir(bhq)2 (1) and (ppy)2Ir(tppz)Ir(ppy)2 (2) (bhq = benzo(h)quinolone, ppy = phenyl-pyridine, tppz = tetrapyrido[3,2-a:2′,3′-c:3′′,2′′-h:2′′′,3′′′-j]phenazine), were prepared. The DNA binding properties of complexes 1 and 2 were studied using single-stranded DNA, double-stranded DNA, and G-quadruplex DNA. G-Quadruplex binding was characterized by higher emission enhancements than those observed with other control DNA strands. Photophysical properties of complexes 1 and 2 indicated that 1 displayed selective G-quadruplex binding affinity, but 2 did not. The emission properties of complexes 1 and 2 were also studied using liposomes in order to understand their possible interactions with lipid-rich organelles in live cells. The phosphorescence intensity of 1 and 2 was enhanced upon interaction with liposomes, but 2 showed greater enhancement. We also confirmed that 1 and 2 could be used as probes in live cells. Complexes 1 and 2 were intensely stained in HeLa cervical cancer cells. Excitation with a λ = 488 nm laser showed red emission localized in the cytosol of cells. Cellular studies showed that 1 and 2 were located inside HeLa cells, but neither complex passed through the nuclear membrane. However, complexes 1 and 2 possessed superior photostability, indicating their role as good luminescent agents for imaging and tracking the endoplasmic reticulum (ER) in live cells. Overall, complex 1 exhibited better selectivity for G-quadruplexes, liposomes, and ER staining.

Mitochondria play key roles in a variety of pathologies, such as Alzheimer's disease and cancer. Because of this, the development of mitochondria staining probes has attracted great attention. In the current study, we designed, prepared and explored the properties of the hemicyanine derivative, HCA-Mito, bearing an aniline moiety. The results show that this substance serves as a mitochondria staining probe. HCA-Mito, which is insensitive to pH and has a low cytotoxicity, shows a high coincidence with the mitochondria specific dyes, MitoTracker Red and MitoTracker Deep Red. More importantly, the fibrous network structure of mitochondria is clearly stained by using HCA-Mito.

Summary Selenium is an important trace element in living systems. Proteins incorporating selenium have a wide range of biological effects, ranging from anti-oxidant and anti-inflammatory effects to the production of active thyroid hormones. In the past decades, selenium has drawn enormous attention because of its important role in biology, which can be ascribed partly if not solely to its redox and hard and soft donor properties. With the use of chemical mimicry, a large number of selenium-related fluorescent probes have been developed for monitoring physiological and pathological processes. This review, which summarizes recent progress made in this area, comprises two major sections. In the first section, fluorescent probes for selenium-containing species, such as selenocysteine (Sec), hydrogen selenide, thioredoxin reductases (TrxRs), and selenite, are described. This is followed by a discussion of fluorescent probes that contain selenium and detect reactive oxygen, nitrogen, and sulfur species, as well as cations and anions.

A novel strategy for designing highly efficient and activatable photosensitizers that can effectively generate reactive oxygen species (ROS) under both normoxia and hypoxia is proposed. Replacing both oxygen atoms in conventional naphthalimides (RNI-O) with sulfur atoms led to dramatic changes in the photophysical properties. The remarkable fluorescence quenching (ΦPL ≈ 0) of the resulting thionaphthalimides (RNI-S) suggested that the intersystem crossing from the singlet excited state to the reactive triplet state was enhanced by the sulfur substitution. Surprisingly, the singlet oxygen quantum yield of RNI-S gradually increased with increasing electron-donating ability of the 4-R substituents (MANI-S, ΦΔ ≈ 1.00, in air-saturated acetonitrile). Theoretical studies revealed that small singlet-triplet energy gaps and large spin-orbit coupling could be responsible for the efficient population of the triplet state of RNI-S. In particular, the ROS generation ability of MANI-S was suppressed under physiological conditions due to their self-assembly and was significantly recovered in cancer cells. More importantly, cellular experiments showed that MANI-S still produced a considerable amount of ROS even under severely hypoxic conditions (1% O2) through a type-I mechanism.

ConspectusHypochlorous acid/hypochlorite (HOCl/OCl–), one of the most important reactive oxygen species (ROS), plays vital roles in various physiological and pathological processes. At normal conce...

Albumin is a promising candidate as a biomarker for potential disease diagnostics and has been extensively used as a drug delivery carrier for decades. In these two directions, many albumin-detecting probes and exogenous albumin-based nanocomposite delivery systems have been developed. However, there are only a few cases demonstrating the specific interactions of exogenous probes with albumin in vivo, and nanocomposite delivery systems usually suffer from tedious fabrication processes and potential toxicity of the complexes. Herein, we demonstrate a facile "one-for-all" switchable nanotheranostic (NanoPcS) for both albumin detection and cancer treatment. In particular, the in vivo specific binding between albumin and PcS, arising from the disassembly of injected NanoPcS, is confirmed using an inducible transgenic mouse system. Fluorescence imaging and antitumor tests on different tumor models suggest that NanoPcS has superior tumor-targeting ability and the potential for time-modulated, activatable photodynamic therapy.

Due to the simplicity and low detection limit, especially the bioimaging ability for cells, fluorescence probes serve as unique detection methods. With the aid of molecular recognition and specific organic reactions, research on fluorescent imaging probes has blossomed during the last decade. Especially, reaction based fluorescent probes have been proven to be highly selective for specific analytes. This review highlights our recent progress on fluorescent imaging probes for biologically important species, such as biothiols, reactive oxygen species, reactive nitrogen species, metal ions including Zn(2+), Hg(2+), Cu(2+) and Au(3+), and anions including cyanide and adenosine triphosphate (ATP).

In this study, the far-red-emitting fluorescence probe 1, containing a rhodamine derivative and a hydrazide reactive group, was developed for peroxynitrite detection and imaging. This probe, which is cell permeable and shows high sensitivity and selectivity in fluorometric detection of peroxynitrite over other ROS/RNS, was successfully utilized to detect exogenous and endogenous peroxynitrite in HeLa and RAW 264.7 cells, respectively. More importantly, 1 can also be used to detect endogenous peroxynitrite generated in Pseudomonas aeruginosa (PAO1)-infected mouse bone marrow-derived neutrophils. We anticipate that the new probe will serve as a powerful molecular imaging tool in investigations of the role(s) played by peroxynitrite in a variety of physiological and pathological contexts.

Switchable phototheranostic nanomaterials are of particular interest for specific biosensing, high-quality imaging, and targeted therapy in the field of precision nanomedicine. Here, we develop a "one-for-all" nanomaterial that self-assembles from flexible and versatile phthalocyanine building blocks. The nanostructured phthalocyanine assemblies (NanoPcTBs) display intrinsically unique photothermal and photoacoustic properties. Fluorescence and reactive oxygen species generation can be triggered depending on a targeted, protein-induced, partial disassembly mechanism, which creates opportunities for low-background fluorescence imaging and activatable photodynamic therapy. In vitro evaluations indicate that NanoPcTB has a high selectivity for biotin receptor-positive cancer cells (e.g., A549) compared to biotin receptor-negative cells (e.g., WI38-VA13) and permits a combined photodynamic and photothermal therapeutic effect. Following systemic administration, the NanoPcTBs accumulate in A549 tumors of xenograft-bearing mice, and laser irradiation clearly induces the inhibition of tumor growth.

The ability to monitor and quantify glutathione (GSH) in live cells is essential in order to gain a detailed understanding of GSH-related pathological events. However, owing to their irreversible response mechanisms, most existing fluorescent GSH probes are not suitable for this purpose. We have developed a ratiometric fluorescent probe (QG-1) for quantitatively monitoring cellular GSH. The probe responds specifically and reversibility to GSH with an ideal dissociation constant (Kd) of 2.59 mm and a fast response time (t1/2=5.82 s). We also demonstrate that QG-1 detection of GSH is feasible in a model protein system. QG-1 was found to have extremely low cytotoxicity and was applied to determine the GSH concentration in live HeLa cells (5.40±0.87 mm).

Glutathione (GSH) plays a crucial role in human pathologies. Near-infrared fluorescence-based sensors capable of detecting intracellular GSH in vivo would be useful tools to understand the mechanisms of diseases. In this work, two cyanine-based fluorescent probes, 1 and 2, containing sulfonamide groups were prepared. Evaluation of the fluorescence changes displayed by probe 1, which contains a 2,4-dinitrobenzenesulfonamide group, shows that it is cell-membrane-permeable and can selectively detect thiols such as GSH, cysteine (Cys), and homocysteine (Hcy) in living cells. The response of 1 to thiols can be reversed by treatment with N-methylmaleimide (NMM). Probe 2, which possesses a 5-(dimethylamino)naphthalenesulfonamide group, displays high selectivity for GSH over Cys and Hcy, and its response can be reversed using NMM. The potential biological utility of 2 was shown by its use in fluorescence imaging of GSH in living cells. Furthermore, probe 2 can determine changes in the intracellular levels of GSH modualated by H2O2. The properties of 2 enable its use in monitoring GSH in vivo in a mouse model. The results showed that intravenous injection of 2 into a mouse generates a dramatic image in which strong fluorescence is emitted from various tissues, including the liver, kidney, lung, and spleen. Importantly, 2 can be utilized to monitor the depletion of GSH in mouse tissue cells promoted by excessive administration of the painkiller acetaminophen. The combined results coming from this effort suggest that the new probe will serve as an efficient tool for detecting cellular GSH in animals.

A new ratiometric fluorescent probe for fluoride ions was developed which complexed fluoride by a tridentate receptor of boronic acid and imidazolium. In the current study, a tridentate receptor 1 with one ortho boronic acid and two imidazolium groups was designed. The boron center can co-operate with imidazolium to bind F-. The formation of B-F complex stabilizes the interaction between fluoride and imidazolium which induces a ratiometric fluorescence response. With the addition of F-, a strongly increased fluorescent emission centered at 370 nm appears at the expense of the fluorescent emission centered at 445 nm. (C) 2013 Elsevier Ltd. All rights reserved.

The development of multifunctional reagents for simultaneous specific near-infrared (NIR) imaging and phototherapy of tumors is of great significance. This work describes the design of a cathepsin B-activated fluorescent probe (CyA-P-CyB) and its applications as an NIR imaging probe for tumor cells and as a phototherapy reagent for tumors. In vitro experiments demonstrated that CyA-P-CyB was activated via the cleavage of a peptide linker by cathepsin B in tumor cells to produce fluorescence in the NIR region based on a FRET mechanism. MTT assays showed that the phototoxicity of CyA-P-CyB toward cells depended on the activity of cathepsin B, and the probe exhibited specific phototoxicity toward tumor cells. CyA-P-CyB was also successfully applied to the in vivo imaging and phototherapy of tumors. Histological analysis indicated that CyA-P-CyB had no cytotoxic effects on seven mouse tissues (lung, liver, heart, kidney, pancreas, spleen and brain) after the CyA-P-CyB treatment and laser irradiation.

Hypochlorite (OCl(-)) plays a key role in the immune system and is involved in various diseases. Accordingly, direct detection of endogenous OCl(-) at the subcellular level is important for understanding inflammation and cellular apoptosis. In the current study, a two-photon fluorescent off/on probe (PNIS) bearing imidazoline-2-thione as an OCl(-) recognition unit and triphenylphosphine (TPP) as a mitochondrial-targeting group was synthesized and examined for its ability to image mitochondrial OCl(-) in situ. This probe, based on the specific reaction between imidazoline-2-thione and OCl(-), displayed a selective fluorescent off/on response to OCl(-) with the various reactive oxygen species in a physiological medium. PNIS was successfully applied to image of endogenously produced mitochondrial OCl(-) in live RAW 264.7 cells via two-photon microscopy.

Reactive oxygen (ROS) and nitrogen (RNS) species cause oxidative and nitrosative stresses, respectively. These stresses are implicated not only in diverse physiological processes but also in various pathological processes, including cancer and neurodegenerative disorders. In addition, some ROS and RNS in the environment are pollutants that threaten human health. As a consequence of these effects, sensitive methods, which can be employed to selectively monitor ROS and RNS in live cells, tissues and organisms as well as in environmental samples, are needed so that their biological roles can be understood and their concentrations in environmental samples can be determined. In this review, fluorescent, luminescent and colorimetric ROS and RNS probes, which have been developed since 2011, are comprehensively discussed.

A new sensor for the fluorescent and colorimetric detection of CO(2) is described. The system utilizes fluoride to activate a tetrapropyl benzobisimidazolium salt and operates in the absence of an exogenous base. On the basis of spectroscopic and theoretical analyses, the mode of action of the present system is ascribed to the fluoride-induced formation of an N-heterocyclic carbene intermediate that reacts with CO(2) to form an imidazolium carboxylate.

State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009, ChinaReceived July 27, 2011, Accepted August 11, 2011Key Words : Polydiacetylenes, Sensor, Oleic acidOleic acid, a monounsaturated fatty acid, is the mostabundant fatty acid in human adipose tissue. As positivehealth effects, oleic acid may hinder the progression ofadrenoleukodystrophy (ALD), which is a fatal disease thataffects the brain and adrenal glands and attacks the myelinsheaths of the body, causing symptoms similar to those inmultiple sclerosis.

Peptide nucleic acids (PNA) are one of the most widely used synthetic DNA mimics where the four bases are attached to a N-(2-aminoethyl)glycine (aeg) backbone instead of the negative-charged phosphate backbone in DNA. We have developed a chimeric PNA (chiPNA), in which a chiral GNA-like γ(3)T monomer is incorporated into aegPNA backbone. The base pair opening kinetics of the aegPNA:DNA and chiPNA:DNA hybrid duplexes were studied by NMR hydrogen exchange experiments. This study revealed that the aegPNA:DNA hybrid is much more stable duplex and is less dynamic compared to DNA duplex, meaning that base pairs are opened and reclosed much more slowly. The site-specific incorporation of γ(3)T monomer in the aegPNA:DNA hybrid can destabilize a specific base pair and its neighbors, maintaining the thermal stabilities and dynamic properties of other base pairs. Our hydrogen exchange study firstly revealed the unique kinetic features of base pairs in the aegPNA:DNA and chiPNA:DNA hybrids, which will provide an insight into the development of methodology for specific DNA recognition using PNA fragments.

A new dual-polymer electro- chromic device (ECD) composed of polyAne-(2-ene)dioxy)- thiophene) (PBueDOT) and polyani- line (PANI) with a hydrophobic molten salt electrolyte has been developed. To build this system, an alkylenedioxy ring in the BueDOT backbone was expand- ed to include a strongly electron-donat- ing alkylenedioxy bridge, and the thick- ness and surface morphology of the corresponding PBueDOT film were controlled systematically. Not only the dual-electrochromic-polymer-electrode system, but also the expanded alkyle- nedioxy ring in the BueDOT back- bone, synergistically improved the elec- trochromic performance. From the col- oration efficiency (CE) value calcula- tions, we found that the CE was en- hanced up to 930 cm 2 C � 1 . Furthermore, these ECDs showed an extremely fast response time of less than 80 ms.

Various fluorescein derivatives were examined as fluorescent pH sensors. Fluorescein derivatives bearing benzylic amine moieties displayed opposite fluorescent changes compared to those of simple fluorescein derivatives upon pH changes. Photo-induced electron transfer (PET) mechanism controls the fluorescent changes of these derivatives. In this Letter, modulations of pKa values were successfully demonstrated through variations of substituent groups.

Tris(2-((ethylimino)methyl)pyren-1-ol)amine (1) was synthesized and introduced as the first tetrameric vanadate fluorescence sensor, the entire binding of which was successfully accomplished in two steps with distinct colorimetric changes and "off-on" fluorescent enhancement.

A new rhodamine-based derivative bearing a 1,8-naphthalimide group (1) was synthesized as a dual-mode Cu(2+)-selective sensor via the rhodamine ring-opening approach and ratiometric displacement. A colorimetric and "off-on" signal for Cu(2+) through rhodamine ring opening in 1 and ratiometric fluorescent signal output when Cu(2+) displaces the bound Zn(2+) in the 1-Zn(2+) complex can be observed.

Novel rhodamine B (RB) derivatives bearing mono and bis-boronic acid groups were investigated as Hg2+ selective fluorescent and colorimetric sensors. These derivatives are first examples of reversible fluorescent chemosensors for Hg2+ which utilized boronic acid groups as binding sites. Two new RB-boronic acid derivatives displayed selective ‘Off–On’-type fluorescent enhancements and distinct color changes with Hg2+. Selective fluorescent enhancement of two rhodamine derivatives was attributed to ring opening from the spirolactam (nonfluorescent) to ring-opened amide (fluorescent).

Absrtract A fluorescent probe based on selenolactone displays unique fluorescence enhancement and UV–vis spectral change for mercury/methylmercury species, which were attributed to deselenation reaction. The value of this system was successfully demonstrated by its use in detecting inorganic mercury/methylmercury species in cells and zebrafish.

A novel boron complex bearing a pyrene ligand (CPB) was synthesized and introduced as the first example of a binuclear boron complex in organic light-emitting diodes. In the solid state, CPB2 exhibited strong red emission. In the devices, red emission with Commission International de L'Eclairage (CIE) coordinates of (0.57, 0.42) was obtained by tuning the weight concentration of CPB2. CPB2 behaved as both an emitting and electron transporting material.

Two 4,5-disubstituted-1,8-naphthalimide derivatives 1 and 2 were synthesized as ratiometric fluorescent and colorimetric sensors for Cu2+, respectively. In 100% aqueous solutions of 1, the presence of Cu2+ induces a strong and increasing fluorescent emission centered at 478 nm at the expense of the fluorescent emission of 1 centered at 534 nm. Compound 2 senses Cu2+ by means of a colorimetric (primrose yellow to pink) method with a thorough quench in emission attributed to the deprotonation of the secondary amine conjugated to the naphthalimide fluorophore. 1-Cu2+ and 2-Cu2+ sense cyanide in ratiometric way via colorimetric and fluorescent changes.

It is still a significant challenge to develop a Zn(2+)-selective fluorescent sensor with the ability to exclude the interference of some heavy and transition metal (HTM) ions such as Fe(2+), Co(2+), Ni(2+), Cu(2+), Cd(2+), and Hg(2+). Herein, we report a novel amide-containing receptor for Zn(2+), combined with a naphthalimide fluorophore, termed ZTRS. The fluorescence, absorption detection, NMR, and IR studies indicated that ZTRS bound Zn(2+) in an imidic acid tautomeric form of the amide/di-2-picolylamine receptor in aqueous solution, while most other HTM ions were bound to the sensor in an amide tautomeric form. Due to this differential binding mode, ZTRS showed excellent selectivity for Zn(2+) over most competitive HTM ions with an enhanced fluorescence (22-fold) as well as a red-shift in emission from 483 to 514 nm. Interestingly, the ZTRS/Cd(2+) complex showed an enhanced (21-fold) blue-shift in emission from 483 to 446 nm. Therefore, ZTRS discriminated in vitro and in vivo Zn(2+) and Cd(2+) with green and blue fluorescence, respectively. Due to the stronger affinity, Zn(2+) could be ratiometrically detected in vitro and in vivo with a large emission wavelength shift from 446 to 514 nm via a Cd(2+) displacement approach. ZTRS was also successfully used to image intracellular Zn(2+) ions in the presence of iron ions. Finally, we applied ZTRS to detect zinc ions during the development of living zebrafish embryos.

A new rhodamine-based derivative bearing a pyrene group (PRC) was synthesized as a ratiometric and "off-on" chemosensor for Cu(2+). PRC displayed a selective and chelation enhanced ratiometric fluorescence change and colorimetric change with Cu(2+) among the metal ions examined.

A new 7-nitrobenz-2-oxa-1,3-diazole (NBD) based colorimetric and fluorescence chemosensor for Zn2+, an ion involved in many biological processes, was designed and synthesized. The NBD-probe 1 displays a red-to-yellow color change and an enhancement of fluorescent intensity in the presence of an aqueous solution of Zn2+ ions (pH 7.2). Internal charge transfer (ICT) and photoinduced electron transfer (PET) mechanisms are responsible for these changes. The practical use of this probe was demonstrated by its application to the biologically relevant detection of Zn2+ ions in pancreatic β-cells.

A new colorimetric anion sensor 1 was synthesized for the chiral recognition, which accommodates a combination of three different functional groups such as chromophore (azophenol dye), binding site (thiourea group), and chiral barrier (glucopyranosyl group). The colorimetric changes of host 1 with various α-amino carboxylates as well as chiral carboxylates such as naproxen were examined.

We introduce a cyanide selective microfluidic platform, in which fluorescent chemodosimeter 1 displayed a selective green fluorescence upon the addition of cyanide. Our system was examined in aqueous solution, and the ‘OFF–ON’ type emission change can be monitored over 500 nm. In addition, colorimetric change was also observed upon the addition of cyanide. The practical use of the probe was demonstrated by its application to the detection of cyanide in the living cells.

5-Substituted dipyrromethane analogues ( 8 ), ( 23 ) and ( 25 ) were synthesized by the reaction of 2-vinylpyrroles, 2-vinylthiophene or 2-vinylbenzenes with excess pyrrole in the presence of Lewis acids. Accordingly, tripyrromethane analogues could be obtained by starting with 2,5-divinyl thiophene or 2,6-divinylbenzenes. The reaction usually gave moderate yields and catalyst-dependent was seen in some cases. The reaction is compatible with other reported dipyrromethane syntheses and could be applied for the construction of unusual porphyrins.

Two new acridine derivatives bearing azacrown or azathiacrown ligand were synthesized as fluorescent chemosensors for Hg2+ and Cd2+ in aqueous solution. Compounds 1 and 2 displayed selective CHEF (chelation enhanced fluorescence) effects with Hg2+ or Cd2+ among the metal ions examined. The practical use of these probes was demonstrated by their applications to the detection of Hg2+ and Cd2+ ions in mammalian cells.