Mingming Hu

An ICT-based ratiometric probe for hydrazine and its application in live cells

Hydrazine is an important industrial chemical but also very toxic thus requiring rapid detection agents. A ratiometric fluorescence probe that enables rapid, low-limit and naked-eye detection is successfully designed and used for hydrazine determination in live cells.

A Fluorescent Ratiometric Chemodosimeter for Cu2+ Based on TBET and Its Application in Living Cells

Based on a through bond energy transfer (TBET) between Rhodamine and a naphthalimide fluorophore, a fluorescent ratiometric chemodosimeter RN1 was designed and prepared for single selective detection of Cu(2+) in aqueous solution and in living cells, as Cu(2+) acts as not only a selective recognizing guest but also a hydrolytic promoter.

The use of a near-infrared RNA fluorescent probe with a large Stokes shift for imaging living cells assisted by the macrocyclic molecule CB7

A near-infrared fluorescent dye Hsd was designed and synthesized, which absorbed as hemicyane and emitted as Cy7 and therefore produced a Stokes shift as large as 224 nm. Quantum chemistry calculation demonstrated that the large Stokes shift was produced by the combination of intramolecular charge transfer (ICT) and internal conversion. Significantly, Hsd showed selectively response to RNA in aqueous solution and fixed cells. Moreover, Hsd could be uptaken into the cells under the assistance of cucurbit[7]uril (CB7) and selectively stain RNA in living cells. The introducing of CB7 provides a platform to amplify the application of some cell-impermeant fluorescent stains through the supramolecular chemistry methods.

Optical Cu2+ probe bearing an 8-hydroxyquinoline subunit: High sensitivity and large fluorescence enhancement

A new fluorescent and colorimetric probe RCu1 with ultra-sensitivity (detection limit is 4.7 nM (3σ)) was developed. It is based on a rhodamine B derivative modified with a functionalized 8-hydroxyquinoline group as a copper-binding site which greatly increases the affinity for Cu(2+). Cu(2+) acts not only as a selective recognizing guest but also a hydrolytic promoter. RCu1 showed single-selectively sensing Cu(2+) over other cations and much larger fluorescence enhancement (as high as over 1000-fold) than those based on Cu(2+)-complexation. The detection mechanism was proved by TOF-MS, FT-IR, (1)H NMR and Gaussian calculations. Based on the outstanding recognition ability of RCu1 toward Cu(2+), an analytical procedure was developed for Cu(2+)-determination in natural water samples and soil sample.

Highly Sensitive and Fast‐Responsive Fluorescent Chemosensor for Palladium: Reversible Sensing and Visible Recovery

The well-known rhodamine spiro-lactam framework offers an ideal model for the development of fluorescence-enhanced chemosensors through simple and convenient syntheses. Herein, we report a new tridentate PNO receptor, which was introduced into a rhodamine spiro-lactam system to develop Pd(2+)-chemosensor RPd4, that displayed significantly improved sensing properties for palladium. Compound RPd4 shows a very fast response time (about 5 s), high sensitivity (5 nM), and excellent specificity for Pd(2+) ions over other PGE ions (Pt(2+), Rh(3+), and Ru(3+)). In addition, RPd4 displays quite different responses to different valence states of the Pd ions, that is, very fast response towards Pd(2+) ions but slow response towards Pd(0), which may provide us with a convenient method for the selective discrimination of Pd species in different valence states. According to proof-of-concept experiments, RPd4 has potential applications in Pd(2+)-analysis in drug compounds, water, soil, and leaf samples. Owing to its good reversibility, RPd4 can also be used as a sensor material for the selective detection and visual recovery of trace Pd(2+) ions in environmental samples.

Development of an oxidative dehydrogenation-based fluorescent probe for Cu2+ and its biological imaging in living cells

Based on a boron dipyrromethene (BODIPY) derivative containing an N, O and S tridentate ligand, a Cu(2+) fluorescent probe BTCu was developed. The detection mechanism was verified as Cu(2+)-promoted oxidative dehydrogenation of an amine moiety, leading to a formation of a fluorescent Cu(+)-Schiff base complex. Free BTCu exhibited a maximum absorption wavelength at 496 nm, and a very weak maximum emission at 511 nm. Upon addition of various metals ions, it showed large fluorescence enhancement toward Cu(2+) (417-fold in MeCN and 103-fold in MeCN/HEPES solution, respectively) with high selectivity. The detection limits are as low as 1.74×10(-8) M and 4.96×10(-8) M in the two different solutions, respectively. And BTCu could work in a wide pH range with an extraordinary low pK(a) of 1.21±0.06. Using fluorescence microscopy, the probe was shown to be capable of penetrating into living cells and imaging intracellular Cu(2+) changes.