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A novel multifunctional microsphere with a fluorescent CdTe quantum dots (QDs) shell and a magnetic core (Fe(3)O(4)) has been successfully developed and prepared by a combination of the hydrothermal method and layer-by-layer (LBL) self-assembly technique. The resulting fluorescent Fe(3)O(4)@C@CdTe core/shell microspheres are utilized as a chemosensor for ultrasensitive Cu(2+) ion detection. The fluorescence of the obtained chemosensor could be quenched effectively by Cu(2+) ions. The quenching mechanism was studied and the results showed the existence of both static and dynamic quenching processes. However, static quenching is the more prominent of the two. The modified Stern-Volmer equation showed a good linear response (R(2) = 0.9957) in the range 1-10 μM with a quenching constant (K(sv)) of 4.9 × 10(4) M(-1). Most importantly, magnetic measurements showed that the Fe(3)O(4)@C@CdTe core/shell microspheres were superparamagnetic and they could be separated and collected easily using a commercial magnet in 10 s. These results obtained not only provide a way to solve the embarrassments in practical sensing applications of QDs, but also enable the fabrication of other multifunctional nanostructure-based hybrid nanomaterials.

Fluorescent sensing TSRh6G-β-cyclodextrin fluorophore/adamantane-modified inclusion complex magnetic nanoparticles (TFIC MNPs) have been synthesized via the cooperation of a host-guest interaction and sol-gel grafting reaction. Powder X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and UV-visible absorption and emission spectroscopy have been employed to characterize the material. Fluorescence and UV-visible spectra have shown that the resultant multifunctional nanoparticle sensors exhibit selective 'turn-on' type fluorescent enhancements and a clear color change from light brown to pink with Hg(2+). Owing to a larger surface area and high permeability, TFIC MNPs exhibit remarkable selectivity and sensitivity for Hg(2+), and its detection limit measures up to the micromolar level in aqueous solution. Most importantly, magnetic measurements have shown that TFIC magnetic nanoparticles are superparamagnetic and they can be separated and collected easily using a commercial magnet. These results not only solve the limitations in practical sensing applications of nanosensors, but also enable the fabrication of other multifunctional nanostructure-based hybrid nanomaterials.

A novel surface modification strategy for an electrospun nanofibrous film was reported, allowing detection and removal of copper ions in the aqueous solution. This reusable dual fluorescent-colorimetric nanofibrous film can be utilized conveniently to achieve real-time naked-eye sensing in aqueous medium just like using a test paper.

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A novel naphthalimide-based fluorescent sensor bearing the N,N'-bis(salicylidene)diethylenetriamine receptor was developed, which exhibited dual signaling behaviors for Cd(2+) and Cu(2+), and was applicable to the environmental and biological milieus. Upon addition of Cd(2+), the fluorescence intensity enhanced in a linear fashion with the maximum fluorescence intensity increase of about 4-fold. Moreover, with the sensor 1 and 1-Cd(2+) complex, Cu(2+) was easily recognized by marked fluorescence quenching. The selectivity and sensitivity of the sensor 1 for Cd(2+) were satisfactory and achieving a detection limit at the nanomolar level. The living cell image experiments demonstrated the value of sensor 1 in fluorescent visualization of Cd(2+) ions in biological systems.

A novel rhodamine-based highly sensitive and selective colorimetric off-on fluorescent chemosensor for Hg(2+) ions is designed and prepared by using the well-known thiospirolactam rhodamine chromophore and furfural hydrazone as signal-reporting groups. The photophysical characterization and Hg(2+)-binding properties of sensor RS1 in neutral N, N-dimethylformamide (DMF) aqueous solution are also investigated. The signal change of the chemosensor is based on a specific metal ion induced reversible ring-opening mechanism of the rhodamine spirolactam. The response of the chemosensor for Hg(2+) ions is instantaneous and reversible. And it successfully exhibits a remarkably "turn on" response toward Hg(2+) over other metal ions (even those that exist in high concentration). Moreover, this sensor is applied for in vivo imaging in Rat Schwann cells to confirm that RS1 can be used as a fluorescent probe for monitoring Hg(2+) in living cells with satisfying results, which further demonstrates its value of practical applications in environmental and biological systems.

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