Juyoung Yoon

Fluorescent Chemosensors Based on Spiroring-Opening of Xanthenes and Related Derivatives

Fluorescent Chemosensors Based on Spiroring-Opening of Xanthenes and Related Derivatives Xiaoqiang Chen, Tuhin Pradhan, Fang Wang, Jong Seung Kim,* and Juyoung Yoon* Departments of Chemistry and Nano Science and of Bioinspired Science (WCU), Ewha Womans University, Seoul 120-750, Korea State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009, China Department of Chemistry, Korea University, Seoul 136-701, Korea

A new trend in rhodamine-based chemosensors: application of spirolactam ring-opening to sensing ions

This tutorial review focuses on the recent development of rhodamine derivatives, in which the spirolactam (non-fluorescent) to ring-opened amide (fluorescent) process was utilized.

Fluorescent and colorimetric probes for detection of thiols

Due to the biological importances of thiols, such as cysteine, homocysteine and glutathione, the development of optical probes for thiols has been an active research area in recent few years. This critical review focuses on the fluorescent or colorimetric sensors for thiols according to their unique mechanisms between sensors and thiols, including Michael addition, cyclization with aldehyde, cleavage of sulfonamide and sulfonate ester by thiols, cleavage of selenium-nitrogen bond by thiols, cleavage of disulfide by thiols, metal complexes-oxidation-reduction, metal complexes-displace coordination, nano-particles and others (110 references).

Imidazolium receptors for the recognition of anions

This tutorial review covers imidazolium receptors for anion recognition according to their topological and structural classification, and includes benzene tripodal, cyclophane and calix-imidazolium, fluorescent imidazolium, ferrocenyl imidazolium, cavitand and calixarene, and polymeric imidazolium systems.

Fluorescent and luminescent probes for detection of reactive oxygen and nitrogen species

Oxidative and nitrosative stress induced by ROS/RNS play crucial roles in a wide range of physiological processes and are also implicated in various diseases, including cancer and neurodegenerative disorders. Sensitive and selective methods for the detection of ROS/RNS based on fluorescent and luminescent probes are of great use in monitoring the in vivo production of these species and elucidating their biological functions. This critical review highlights recent advances that have been made in the development of fluorescent and luminescent probes employed to monitor various ROS/RNS (132 references).

Zn2+-Triggered Amide Tautomerization Produces a Highly Zn2+-Selective, Cell-Permeable, and Ratiometric Fluorescent Sensor

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.

Chemosensors for pyrophosphate.

The selective detection of the anion pyrophosphate (PPi) is a major research focus. PPi is a biologically important target because it is the product of ATP hydrolysis under cellular conditions, and because it is involved in DNA replication catalyzed by DNA polymerase, its detection is being investigated as a real-time DNA sequencing method. In addition, within the past decade, the ability to detect PPi has become important in cancer research. In general, the sensing of anions in aqueous solution requires a strong affinity for anions in water as well as the ability to convert anion recognition into a fluorescent or colorimetric signal. Among the variety of methods for detecting PPi, fluorescent chemosensors and colorimetric sensors for PPi have attracted considerable attention during the past 10 years. Compared with the recognition of metal ions, it is much more challenging to selectively recognize anions in an aqueous system due to the strong hydration effects of anions. Consequently, the design of PPi sensors requires the following: an understanding of the molecular recognition between PPi and the binding sites, the desired solubility in aqueous solutions, the communicating and signaling mechanism, and most importantly, selectivity for PPi over other anions such as AMP and ADP, and particularly phosphate and ATP. This Account classifies chemosensors for PPi according to topological and structural characteristics. Types of chemosensors investigated and reported in this study include those that contain metal ion complexes, metal complexes combined with excimers, those that function with a displacement approach, and those based on hydrogen-bonding interaction. Thus far, the utilization of a metal ion complex as a binding site for PPi has been the most successful strategy. The strong binding affinity between metal ions and PPi allows the detection of PPi in a 100% aqueous solution. We have demonstrated that carefully designed receptors can distinguish between PPi and ATP based on their different total anionic charge densities. We have also demonstrated that a PPi metal ion complex sensor has a bioanalytical application. This sensor can be used in a simple and quick, one-step, homogeneous phase detection method in order to confirm DNA amplification after polymerase chain reaction (PCR).

Recent progress in luminescent and colorimetric chemosensors for detection of thiols

In the past few decades, the development of optical probes for thiols has attracted great attention because of the biological importance of the thiol-containing molecules such as cysteine (Cys), homocysteine (Hcy), and glutathione (GSH). This tutorial review focuses on various thiol detection methods based on luminescent or colorimetric spectrophotometry published during the period 2010-2012. The discussion covers a diversity of sensing mechanisms such as Michael addition, cyclization with aldehydes, conjugate addition-cyclization, cleavage of sulfonamide and sulfonate esters, thiol-halogen nucleophilic substitution, disulfide exchange, native chemical ligation (NCL), metal complex-displace coordination, and nanomaterial-related and DNA-based chemosensors.

Fluorescence and Colorimetric Chemosensors for Fluoride-Ion Detection

Detection Ying Zhou,†,‡ Jun Feng Zhang, and Juyoung Yoon*,† †Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea ‡Key Laboratory of Medicinal Chemistry for Natural Resource, School of Chemical Science and Technology, Yunnan University, Kunming, 650091, P. R. China College of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650500, P. R. China

Unique sandwich stacking of pyrene-adenine-pyrene for selective and ratiometric fluorescent sensing of ATP at physiological pH.

A pincer-like benzene-bridged sensor 1 with a pyrene excimer as a signal source and imidazolium as a phosphate anion receptor was synthesized and investigated for ATP sensing. A unique switch of excimer vs monomer pyrene fluorescence of 1 is observed in the presence of ATP due to the charcteristic sandwich pi-pi stacking of pyrene-adenine-pyrene. On the other hand, four other bases of nucleoside triphosphates such as GTP, CTP, UTP, and TTP can interact only from the outside with the already stabilized stacked pyrene-pyrene dimer of 1, resulting in excimer fluorescence quenching. The fluorescent intensity ratio of monomer-to-excimer for 1 upon binding with ATP (I(375)/I(487)) is much larger than that upon binding with ADP and AMP. This difference is large enough to discriminate ATP from ADP and AMP. As one of the biological applications, sensor 1 is successfully applied to the ATP staining experiments. Sensor 1 is also applied to monitor the hydrolysis of ATP and ADP by apyrase. The results indicate that 1 is a useful fluorescent sensor for investigations of ATP-relevant biological processes.