Sonochemical fabrication of 8-hydroxyquinoline aluminum (Alq3) nanoflowers with high electrogenerated chemiluminescence.

Well-defined Alq(3) nanoflowers were fabricated via a facile and fast sonochemical route. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the structure and shape of the as-prepared product. The results showed that the resulting Alq(3) was composed of nanobelts with thickness about 50 nm, average widths of 200 nm, and length up to 10 µm. The Alq(3) nanoflowers exhibited good electrogenerated chemiluminescence behavior.

Near infrared sensing based on fluorescence resonance energy transfer between Mn:CdTe quantum dots and Au nanorods.

A novel sensing system based on the near infrared (NIR) fluorescence resonance energy transfer (FRET) between Mn:CdTe quantum dots (Qdots) and Au nanorods (AuNRs) was established for the detection of human IgG. The NIR-emitting Qdots linked with goat anti-human IgG (Mn:CdTe-Ab1) and AuNRs linked with rabbit anti-human IgG (AuNRs-Ab2) acted as fluorescence donors and acceptors, respectively. FRET occurred by human IgG with the specific antigen-antibody interaction. And human IgG was detected based on the modulation in FRET efficiency. The calibration graph was linear over the range of 0.05-2.5 microM of human IgG under optimal conditions. The proposed sensing system can decrease the interference of biomolecules in NIR region and increase FRET efficiency in optimizing the spectral overlap of AuNRs with Mn:CdTe Qdots. This method has great potential for multiplex assay with different donor-acceptor pairs.

Versatile immunosensor using CdTe quantum dots as electrochemical and fluorescent labels.

A versatile immunosensor using CdTe quantum dots as electrochemical and fluorescent labels has been developed for sensitive protein detection. This sandwich-type sensor is fabricated on an indium tin oxide chip covered with a well-ordered gold nanoparticle monolayer. Gel imaging systems were successfully introduced to develop a novel high-efficient optical immunoassay, which could perform simultaneous detection for the samples with a series of different concentrations of a target analyte. The linear range of this assay was between 0.1 and 500 ng/mL, and the assay sensitivity could be further increased to 0.005 ng/mL with the linear range from 0.005 to 100 ng/mL by stripping voltammetric analysis. The immunosensor showed good precision, high sensitivity, acceptable stability, and reproducibility and could be used for the detection of real sample with consistent results in comparison with those obtained by the ELISA method.

Highly luminescent zinc(II)-bis(8-hydroxyquinoline) complex nanorods: sonochemical synthesis, characterizations, and protein sensing.

Highly luminescent zinc(II)-bis(8-hydroxyquinoline) (Znq(2)) complex nanorods have been synthesized via a sonochemical route from the microemulsion containing zinc acetate and 8-hydroxyquinoline. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that the products were rod-like morphology with a diameter of about 200-450 nm and a length of about 1-3 microm. A possible mechanism for the formation of Znq(2) nanorods is proposed that the ultrasound wave might urge the collision and fusion of initial Znq(2) nuclei to form nanorods. The photoluminescence (PL) and resonance light scattering (RLS) of the products were also investigated. The Znq(2) nanorods were found to be sensitive to several proteins, such as human serum albumin (HSA), bovine serum albumin (BSA), bovine hemoglobin (Hb), and egg albumin (EA), displaying an increase in intensities of both PL and RLS. The protein-concentration dependence of the PL and RLS intensities can be well described as a Langmuir-type binding isotherm. This is the first report on the enhancement of PL and RLS intensities of Znq(2) nanorods by proteins. On the basis of enhanced PL and RLS intensities, the protein could be detected at the nanogram per milliliter level. The experimental results clearly showed that the Znq(2) nanorods were good protein probes for easy and highly sensitive detection.

Sonochemical route for self-assembled V2O5 bundles with spindle-like morphology and their novel application in serum albumin sensing.

Novel self-assembled V2O5 bundles with highly ordered superstructures and spindle-like morphology were synthesized by a rapid high-yielding sonochemical method. The as-prepared samples were characterized by X-ray diffraction, a field-emission scanning electron microscope, and a transmission electron microscope. The spindle-like V2O5 bundles are composed of several tens of homogeneous nanowires with diameters of 30-50 nm and lengths of 3-7 microm. A sensitive resonance light scattering method for the detection of bovine serum albumin (BSA) based on the self-assembled V2O5 bundles was developed. The results of the polarized resonance light scattering demonstrated that the Cabannes factor for the V2O5 bundles-BSA aggregates was BSA concentration-dependent.

[Effect of cation surfactants on absorption spectra of silver nanoparticle in liquid phase].

Yellow Ag nanoparticles, with diameter of 20 nm, exhibit a resonance absorption peak at 400 nm. After adding some cation surfactants (CS), the absorbance at 400 nm becomes weak, (namely, there exists hypochromic effect), but the absorbance at wavelengths longer than 400 nm is enhanced and shows a red shift. When adding concentration of CS, the absorbance at wavelengths longer than 400 nm becomes weak again, the peak at 400 nm is enhanced (namely, there exists hyperchromic effect) and the absorption peaks show a blue shift. The results showed that this is caused by the strong hydrophobic force and electrostatic force between the CS and silver nanoparticls, which results in a change in the silver nanoparticle shape.

[Study on fluorescence quenching mechanism of HSA-PMA associated nanoparticle system].

In pH 7.40 Tris-HCl buffer solution, PMA is light yellow and has no absorption peak in the visible region. HSA has no color and no absorption peak in the visible region either. There is a fluorescence peak at 350 nm for HSA in pH 7.40 Tris-HCl buffer solution. HSA and PMA can combine into HSA-PMA association nanoparticles with a diameter about 80 nm by means of static gravitation. HSA has both hypochromic and color enhancement effects on PMA through our research. The fluorescence of Trp, Tyr and HSA can be quenched by PMA, but their quenching mechanisms are different. The fluorescence quenching of Trp and Tyr by PMA is due to molecule absorption in the range of emission wavelength, namely because of energy transfer often reported. The investigation results demonstrated that the formation of HSA-PMA associated nanoparticle and interface is the ultimate reason for fluorescence quenching, resonance scattering, and enhanced and hypochromic color.

[Absorption spectra study of the association nanoparticle system of berberine-[AuI4]- and its analytical application].

In 0.008 mol x L(-1) HCl medium, [AuCl4]- and I- combine to form [AuI4]-. [AuI4]- reacts with berberine (BB) to form (AuI4-BB) association molecule. The molecules aggregate automatically owing to strong hydrophobic and molecular forces. And (AuI4-BB)n association nanoparticles with orange-yellow color were observed. It exhibits a resonance scattering peak at 520 nm. The absorption peak for the nanoparticle system and the [AuI4]- is at 350 nm. However, the absorbance values for the nanoparticle system increased in the visible light region. Under the conditions chosen, the BB concentration in the range of 0.8 x 10(-6) mol x L(-1)-20 x 10(-6) mol x L(-1) is linear to the A(450 nm) value. The results show that the formation of (AuI4-BB)n nanoparticles produces the resonance scattering effect and the orange-yellow color.