Songyi Lee

Recent Progress on the Development of Chemosensors for Gases

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

Polydiacetylene-Based Colorimetric and Fluorescent Chemosensor for the Detection of Carbon Dioxide

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 polymers 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.

Selective homocysteine turn-on fluorescent probes and their bioimaging applications

The design and development of new pyrene-based fluorescent probes, P-Hcy-1 and P-Hcy-2, which display selective fluorescence enhancements in response to homocysteine (Hcy), are described. The distinctly different fluorescence responses of P-Hcy-1 and P-Hcy-2 to Hcy vs. Cys are explained by theoretical calculations. Finally, the results of cell experiments show that these probes can be used to selectively detect Hcy in mammalian cells.

Anion-activated, thermoreversible gelation system for the capture, release, and visual monitoring of CO2.

Carbon dioxide (CO2) is an important green house gas. This is providing an incentive to develop new strategies to detect and capture CO2. Achieving both functions within a single molecular system represents an unmet challenge in terms of molecular design and could translate into enhanced ease of use. Here, we report an anion-activated chemosensor system, NAP-chol 1, that permits dissolved CO2 to be detected in organic media via simple color changes or through ratiometric differences in fluorescence intensity. NAP-chol 1 also acts as a super gelator for DMSO. The resulting gel is transformed into a homogeneous solution upon exposure to fluoride anions. Bubbling with CO2 regenerates the gel. Subsequent flushing with N2 or heating serves to release the CO2 and reform the sol form. This series of transformations is reversible and can be followed by easy-to-discern color changes. Thus, NAP-chol 1 allows for the capture and release of CO2 gas while acting as a three mode sensing system. In particular, it permits CO2 to be detected through reversible sol-gel transitions, simple changes in color, or ratiometric monitoring of the differences in the fluorescence features.

Conjugated polydiacetylenes bearing quaternary ammonium groups as a dual colorimetric and fluorescent sensor for ATP

A PDA based sensor, derived from a quaternary ammonium substituted diacetylene monomer, displayed a selective colorimetric change and a large fluorescence enhancement in the presence of ATP at pH 7.0. The ratio between quaternary ammonium monomer and primary amine monomer and control of steric factors were critical points to induce color change. The ATP selective PDA-based chemosensor enabled easy detection of the presence of ATP in 100% aqueous solution by the naked eye.

A review: the trend of progress about pH probes in cell application in recent years

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.

An AIE and ESIPT based kinetically resolved fluorescent probe for biothiols

A new aggregation-induced emission and excited-state intramolecular proton transfer based fluorescent probe, containing a salicylaldazine moiety as a platform, displayed an excellent light-up ratio and a large Stokes shift for the detection of biothiols (cysteine, homocysteine, and glutathione). The salicylaldazine based fluorescent probe showed high selectivity, and sensitivity for biothiols. With the aid of different reactivities, a kinetically resolved method was successfully applied to distinguish different biothiols both in solution and cells.

Sensing and antibacterial activity of imidazolium-based conjugated polydiacetylenes

In the current study, we report the first example of polydiacetylenes (PDAs), where our PDA-based system acts as both a sensing probe and killer for bacteria. The contact of imidazolium and imidazole-derived PDA with various bacterial strains including MRSA (methicillin-resistant Staphylococcus aureus) and ESBL-EC (extended-spectrum β-lactamase-producing Escherichia coli) results in a distinct blue-to-red colorimetric change of the solution as well as a rapid disruption of the bacterial membrane, which is demonstrated by transmission electron microscopy and confocal microscopy. Zeta potential analysis supports that antibacterial activity of the PDA solution originates from an electrostatic interaction between the negatively charged bacterial cell surface and the positively charged polymers. These results suggest that the PDA has a great potential to carry out the dual roles of a probe and killer for bacteria.

Effective Strategy for Colorimetric and Fluorescence Sensing of Phosgene Based on Small Organic Dyes and Nanofiber Platforms

Three o-phenylendiamine (OPD) derivatives, containing 4-chloro-7-nitrobenzo[c][1,2,5]oxadiazole (NBD-OPD), rhodamine (RB-OPD), and 1,8-naphthalimide (NAP-OPD) moieties, were prepared and tested as phosgene chemosensors. Unlike previously described methods to sense this toxic agent, which rely on chemical processes that transform alcohols and amines to respective phosphate esters and phosphoramides, the new sensors operate through a benzimidazolone-forming reaction between their OPD groups and phosgene. These processes promote either naked eye visible color changes and/or fluorescence intensity enhancements in conjunction with detection limits that range from 0.7 to 2.8 ppb. NBD-OPD and RB-OPD-embedded polymer fibers, prepared using the electrospinning technique, display distinct color and fluorescence changes upon exposure to phosgene even in the solid state.

Polydiacetylenes Bearing Boronic Acid Groups as Colorimetric and Fluorescence Sensors for Cationic Surfactants

A new polydiacetylene oxyphenylboronic acid (PDA-OPBA-1) bearing group was synthesized and showed diverse colorimetric changes, such as yellow, orange, and red, upon the addition of cationic surfactants at pH 7.4. On the other hand, anionic surfactants and simple ammonium salts did not show any color change. Specifically, color changes to yellow for cetyl trimethylammonium chloride (CTAC), red for dodecyl trimethylammonium bromide (DTAB), orange for benzylcetyldimethylammonium chloride (BCDA), and dark orange for hexadecylpyridium bromide (HDPB) are observed, respectively. Different head groups and alkyl chain lengths of cationic surfactants can be intelligently distinguished via a unique penetration process.