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.

Recent progress in the development of fluorescent, luminescent and colorimetric probes for detection of reactive oxygen and nitrogen species

In this review we will explore recent advances in the design and application of excited-state intramolecular proton-transfer (ESIPT) based fluorescent probes. Fluorescence based sensors and imaging agents (probes) are important in biology, physiology, pharmacology, and environmental science for the selective detection of biologically and/or environmentally important species. The development of ESIPT-based fluorescence probes is particularly attractive due to their unique properties, which include a large Stokes shift, environmental sensitivity and potential for ratiometric sensing.

/pdf/excited-state-intramolecular-proton-transfer-esipt-based-2q1srz3sm1.pdf

Excited-state intramolecular proton-transfer (ESIPT) based fluorescence sensors and imaging agents

The cyanine platforms including cyanine, hemicyanine, and squaraine are good candidates for developing chemosensors because of their excellent photophysical properties, outstanding biocompatibility, and low toxicity to living systems. A huge amount of research work involving chemosensors based on the cyanine platforms has emerged in recent years. This review focuses on the development from 2000 to 2015, in which cyanine, hemicyanine, and squaraine sensors will be separately summarized. In each section, a systematization according to the type of detection mechanism is established. The basic principles about the design of the chemosensors and their applications as bioimaging agents are clearly discussed. In addition, we emphasize the advances that have been made in improving the detection performance through incorporation of the chemosensors into nanoparticles.

Recent Development of Chemosensors Based on Cyanine Platforms

Despite its clinical promise, photodynamic therapy (PDT) suffers from a key drawback associated with its oxygen-dependent nature, which limits its effective use against hypoxic tumors. Moreover, both PDT-mediated oxygen consumption and microvascular damage further increase tumor hypoxia and, thus, impede therapeutic outcomes. In recent years, numerous investigations have focused on strategies for overcoming this drawback of PDT. These efforts, which are summarized in this review, have produced many innovative methods to avoid the limits of PDT associated with hypoxia.

Innovative Strategies for Hypoxic-Tumor Photodynamic Therapy

Coumarins are a very large family of compounds containing the unique 2H-chromen-2-one motif, as it is known according to IUPAC nomenclature. Coumarin derivatives are widely found in nature, especially in plants and are constituents of several essential oils. Up to now, thousands of coumarin derivatives have been isolated from nature or produced by chemists. More recently, the coumarin platform has been widely adopted in the design of small-molecule fluorescent chemosensors because of its excellent biocompatibility, strong and stable fluorescence emission, and good structural flexibility. This scaffold has found wide applications in the development of fluorescent chemosensors in the fields of molecular recognition, molecular imaging, bioorganic chemistry, analytical chemistry, materials chemistry, as well as in the biology and medical science communities. This review focuses on the important progress of coumarin-based small-molecule fluorescent chemosensors during the period of 2012-2018. This comprehensive and critical review may facilitate the development of more powerful fluorescent chemosensors for broad and exciting applications in the future.

Coumarin-Based Small-Molecule Fluorescent Chemosensors.

Owing to its spatiotemporal selectivity and noninvasive nature, photodynamic therapy (PDT) has become a clinically promising approach for the treatment of a wide range of cancers and other diseases. However, the full potential of PDT has not been achieved thus far as a consequence of the lack of optimal photosensitizers (PSs) and/or smart transport/activation strategies. These problems, which unfortunately lie at the core of the PDT paradigm, include the oxygen reliance limits, the effect of PDT on hypoxic tumors, limitations of light penetration, and undesired skin photosensitization induced by “always on” PSs. Recently, supramolecular approaches, which rely on the use of non-covalent interactions to construct biomedical active materials, have become suitable methods for developing innovative PSs. Non-covalent interactions enable supramolecular PSs to have sensitive and controllable photoactivities, important elements needed to maximize photodynamic effects and minimize side effects. In addition, versatile supramolecular PS-assemblies can be designed so that PDT occurs synergistically with other therapeutic modalities, e.g., photothermal therapy, leading to a potential improvement of therapeutic effectiveness. In this review, recent progress made in the development of supramolecular PSs for rejuvenating PDT will be presented. Importantly, this discussion also provides a view of future advances that will likely be made in this area and their potential clinical applications.

Supramolecular photosensitizers rejuvenate photodynamic therapy.

Xin Zhou,†,‡ Songyi Lee,† Zhaochao Xu,* and Juyoung Yoon*,† †Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 120-750, Republic of Korea ‡Research Center for Chemical Biology, Department of Chemistry, Yanbian University, Yanjii 133002, People’s Republic of China Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Shahekou, Dalian, Liaoning, People’s Republic of China

Recent Progress on the Development of Chemosensors for Gases.

Oxidative stress induced by reactive oxygen species (ROS) plays crucial roles in a wide range of physiological processes and is also implicated in various diseases, including cancer, chronic inflammatory diseases, and neurodegenerative disorders. Among the various ROS, hypochlorous acid (HOCl) plays as a powerful microbicidal agent in the innate immune system. The regulated production of microbicidal HOCl is required for the host to control the invading microbes. However, as a result of the highly reactive and diffusible nature of HOCl, its uncontrolled production may lead to an adverse effect on host physiology. Because of its biological importance, many efforts have been focused on developing selective fluorescent probes to image ROS. However, it is still challenging to design a fluorescent probe with exclusive selectivity toward a particular member of ROS. In the current work, we designed FBS as a new fluorescent HOCl probe which has high selectivity, sensitivity, and short response time in a broad ran...

A highly specific fluorescent probe for hypochlorous acid and its application in imaging microbe-induced HOCl production.

Pyrophosphate anions play key roles in various biological and chemical processes. During the last few years, many exciting results have emerged regarding the development of fluorescent and colorimetric sensors for this biologically important species. In this review, we will cover the fluorescent and colorimetric chemosensors developed for the detection of pyrophosphate (PPi) since 2010.

/pdf/fluorescent-and-colorimetric-chemosensors-for-pyrophosphate-4uaxgj9gfq.pdf

Fluorescent and colorimetric chemosensors for pyrophosphate

We developed a colorimetric and fluorescent turn-on carbon dioxide sensor that relies on a polydiacetylene, PDA-1, functionalized with amines and imidazolium groups. The pendant amines react with CO2 under basic conditions to form carbamoate anions, which partially neutralize the polymer’s positive charges, inducing a phase transition. PDA-1 allows for the selective sensing of CO2 with high sensitivity, down to atmospheric concentrations. Naked-eye detection of CO2 is accomplished either in water solutions of PDA-1 or in the solid state with electrospun coatings of PDA-1 nanofibers.

Songyi Lee

Papers

Supramolecular photosensitizers rejuvenate photodynamic therapy.

Recent Progress on the Development of Chemosensors for Gases.

A highly specific fluorescent probe for hypochlorous acid and its application in imaging microbe-induced HOCl production.

Fluorescent and colorimetric chemosensors for pyrophosphate

Polydiacetylene-based colorimetric and fluorescent chemosensor for the detection of carbon dioxide.