Haishi Cao

Fluorescent Chemosensors for Carbohydrates: A Decade's Worth of Bright Spies for Saccharides in Review

This review provides a chronological survey of over fifty fluorescent chemosensors for carbohydrates from the period between 1992 to the present. The survey contains only those sensors that are synthetic or chemosensory, utilize boronic acids and display a fluorescence response in the form of intensity changes or shifts in wavelength. With each compound listed, a description of the saccharide probe is given with regard to concentration, excitation and emission wavelengths, pH and solvent mixture proportions. In addition, the selectivity of each chemosensor is provided as well as the trends in binding constants. Where possible, a description of the fluorescence signaling mechanism is given as well as commentary on the probes unique features within this class of sensors.

A new N-imidazolyl-1,8-naphthalimide based fluorescence sensor for fluoride detection

A chemosensor is reported with high sensitivity and selectivity for detection of fluoride anion. The recognition mechanism is attributed to a fluoride-triggered disruption of the hydrogen bond between imidazole and naphthalimide moieties, resulting in a noncoplanar geometry with low fluorescence.

Rational design of a rapid fluorescent approach for detection of inorganic fluoride in MeCN–H2O: a new fluorescence switch based on N-aryl-1,8-naphthalimide

A fluoride chemosensor (FCS-1) based on 1,8-naphthalimide bearing a trimethylsilyl ether has been designed and synthesized. FCS-1 displayed high selectivity and sensitivity to fluoride in inorganic forms (KF and NaF) with a short response time in MeCN–H2O media.

Enhanced photostability of ICG in close proximity to gold colloids

Photobleaching of fluorophores frequently limits their detectability or observation time. We examined Indocyanine green (ICG) which is widely used in medical testing and is highly unstable. We showed that spatial localization of ICG near metallic gold colloids resulted in increased photostability. This suggests the use of fluorophore-metal conjugates in situations adversely affected by photobleaching.

Reduction of Nitro Group on Derivative of 1,8-Napthalimide for Quantitative Detection of Hydrogen Sulfide

A fluorescence “turn-on” sensor (HSS) for detection of H2S was developed on the basis of NO2-NH2 reduction. HSS showed a high affinity and sensitivity to H2S over other reducing reagents, particularly for biothiols. Also, the short responding time and high linear dependence between fluorescence enhancement and H2S concentration had HSS behave as a rapid sensor for quantitatively detection of H2S in the biological level.

Investigation of a sensing approach based on a rapid reduction of azide to selectively measure bioavailability of H2S

A new reaction-based sensor (AHS) was synthesized for quantitative detection of H2S. AHS showed a high selectivity and sensitivity toward H2S over other thio-containing molecules, or reducing reagents with high abundance in living cells. In the presence of H2S, significant fluorescence enhancement (17-fold) was observed due to the reduction of the azide on AHS. The absorption (362 nm) and fluorescence emission (557 nm) of reduced AHS showed a highly linear correlation to H2S level, which were used to measure concentration of H2S in the range of 0–100 μM.