SPR-based assay kit for rapid determination of Pb2.

A recyclable optical nanosensor was developed by immobilizing l-tyrosine functionalized silver nanoparticles (AgNPs) on the polyethylene terephthalate (PET) substrate for rapid determination of Pb2+ ions. At first, the l-tyrosine functionalized AgNPs were assessed in the solution phase; the response time was lower than 15 s, and a limit of detection lower than 9 nM was obtained in the dynamic range of 1-1000 nM. For fabrication of the optical assay kit, the design of experiment (DOE) was used to optimize the immobilization efficiency of the nanoparticles on PET films by studying AgNO3 concentration and pH as two crucial parameters. The assay kit in optimal conditions showed a sharp localized surface plasmon resonance band suitable for sensitive determination of Pb2+. The fabricated sensor showed promising results for rapid determination of lead ions with the limit of detection value as low as 1 nM (S/N = 3). The sensor reproduced the obtained results even after three consecutive runs, which proved the recyclability of the optical assay kit. The recoveries of the spiked concentration in real samples were in the range of 95%-103%, which confirmed the applicability of the sensor in practical applications.

Anti-HER2 VHH Targeted Magnetoliposome for Intelligent Magnetic Resonance Imaging of Breast Cancer Cells.

The combination of liposomes with magnetic nanoparticles, because of their strong effect on T2 relaxation can open new ways in the innovative cancer therapy and diagnosis. In order to design an intelligent contrast agent in MRI, we chose anti-HER2 nanobody the smallest fully functional antigen-binding fragments evolved from the variable domain, the VHH, of a camel heavy chain-only antibody. These targeted magnetoliposomes bind to the HER2 antigen which is highly expressed on breast and ovarian cancer cells so reducing the side effects as well as increasing image contrast and effectiveness. Cellular iron uptake analysis and in vitro MRI of HER2 positive cells incubated with targeted nanoparticles show specific cell targeting. In vitro MRI shows even at the lowest density (200 Cells/µl), dark spots corresponding to labeled cells which were still detectable. These results suggest that this new type of nanoparticles could be effective antigen-targeted contrast agents for molecular imaging.

Synthesizing and staining manganese oxide nanoparticles for cytotoxicity and cellular uptake investigation.

BACKGROUND: For decades, contrast agents have been used to reduce longitudinal (T1) or transverse (T2) relaxation times. High toxicity of gadolinium-based contrast agents leads researchers to new T1 contrast agents. Manganese oxide (MnO) nanoparticle (NP) with the lower peril and good enough signal change ability has been offered as a new possibility for magnetic resonance imaging (MRI). METHODS: The synthesized NPs were investigated for physicochemical and biological properties by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscope, dynamic light scattering (DLS), inductively coupled plasma, enzyme-linked immunosorbent assay, and 3T magnetic resonance imaging. RESULTS: Due to physical contact importance of T1 contrast agents with tissues' protons, extremely thin layer of the surfactant, less than 2nm, was coated on NPs for aqueous stabilizing. The hydrophilic gentisic acid with low Dalton, around 154, did that role truly. Moreover, decreasing NP size to 5nm which increases available surface for the proton relaxation is another important parameter to reach an appropriate longitudinal relaxation rate. The NPs didn't reveal any side effects on the cells, and cellular uptake was considerable. CONCLUSIONS: The synthesized NPs represented a promising result in comparison to clinical gadolinium chelates, due to higher r1 relaxivity and lower toxicity. GENERAL SIGNIFICANCE: In addition to considerable signal change and cellular uptake, Prussian blue was tried on MnO NPs for the initial time, which can be observed within cells by pale blue color.

On the effect of cooling rate during melt spinning of FINEMET ribbons.

The effect of quenching wheel speed on the structure and Curie temperature of Fe73.5Si13.5B9Nb3Cu1 alloy has been investigated using X-ray diffraction, differential scanning calorimetry, transition electron microscopy and a SQUID magnetometer. Ribbons were melt-spun at different wheel speeds and then were annealed to nucleate nano crystals embedded in the amorphous matrix. The results indicated that the thickness of the ribbons was inversely proportional to the wheel speed following the power law of the type t∝V(s)(-1.231). DSC and XRD results showed that at higher wheel speeds the greater potential energy triggers the formation of Fe (Si) crystallites and thus, increases the crystallinity. TEM observations confirmed the presence of an α-Fe (Si) phase with ∼11 nm crystallite size in the amorphous matrix of annealed ribbons. Special emphasis was placed on the effect of the quenching wheel speed on the Curie temperature during the measurements. To this end, the magnetization variations versus temperature were studied before and after annealing. It was found that increasing the wheel speed results in the reduction of the Curie temperature in as-spun ribbons. Moreover, the Curie temperature of the intergranular amorphous region in the annealed ribbons was at least 80 °C higher than that of corresponding amorphous phase in as-spun ribbons due to exchange interaction penetration of the adjacent Fe (Si) crystallites and relaxation processes.

Long-term investigation on the phase stability, magnetic behavior, toxicity, and MRI characteristics of superparamagnetic Fe/Fe-oxide core/shell nanoparticles.

To efficiently enhance the contrast obtaining from magnetic resonance imaging (MRI), pharmaceutical grade colloidal dispersions of PEG coated iron-based nanoparticles were prepared and compared to conventional pure iron oxide contrast agent. In this study, we synthesized ~14 nm iron nanoparticles via NaBH(4) reduction of iron(III) chloride in an aqueous medium. The resulting nanoparticles were further oxidized by two different methods via (CH(3))(3)NO oxygen transferring agent and exposure to oxygen flow. XRD and electron microscopy analyses confirmed the formation of a second layer on the surface of α-Fe core. As magnetic measurements and Mössbauer spectra of 4-months post prepared nanoparticles showed, 2.3±0.5 nm amorphous oxide shell produced in oxygen flow could not protect the inner metallic iron from oxidation and resulting sample suffered from drastic change in its characteristics. However, (CH(3))(3)NO yielded nanoparticles with 3.6±0.4 and 4.5±0.7 nm crystalline oxide shells that retained their key properties even in long-term examinations. In addition, no significant difference was detected in cytotoxicity results of MTT assay test up to 4-months for core/shell nanoparticles, in comparison with pure iron oxide sample, and all fall below 50% viability in the iron concentration of 400 µg. In vitro MR signal reduction and corresponding relaxometry parameters, especially r(2)/r(1)>2, assure that all nanoparticles can be administrated for negative contrast enhancement. Accumulation of core/shell nanoparticles in axillary and brachial lymph nodes of examined rats and minimum contrast enhancement of 20% regarding to pure iron oxide implies the efficiency of these materials as potential contrast agent.