19 research outputs found
A novel ratiometric fluorescent approach for the modulation of the dynamic range of lateral flow immunoassays
The majority of lateral flow assays (LFAs) use single-color optical labels to provide a qualitative naked-eye detection, however this detection method displays two important limitations. First, the use of a single-color label makes the LFA prone to results misinterpretation. Second, it does not allow the precise modulation of the sensitivity and dynamic range of the test. To overcome these limitations, a ratiometric approach is developed. In particular, using anti-HIgG functionalized red-fluorescent quantum dots on the conjugate pad (as target dependent labels) and blue-fluorescent nanoparticles fixed on the test line (as target independent reporters), it is possible to generate a wide color palette (blue, purple, pink, red) on the test line. It is believed that this strategy will facilitate the development of LFAs by easily adjusting their analytical properties to the needs required by the specific application
Synthesis, Optical Characterization, and Size Distribution Determination by Curve Resolution Methods of Water-Soluble CdSe Quantum Dots
Stability, size and optical properties of colloidal silver nanoparticles prepared by electrical arc discharge in water
We have fabricated and characterised colloidal silver
nanoparticles by the electrical arc discharge method in DI water. Size and
optical properties of the silver nanoparticles were studied versus different
arc currents. Optical absorption indicates a plasmonic peak at 392 nm for
10 A which increases to 398 nm for 20 A arc current. This reveals that by
raising the arc current the size of the nanoparticles increases. Optical
absorption of silver nanoparticles after 3 weeks shows precipitation of them
in a water medium. The effect of different surfactant and stabilizer
concentrations such as cethyl trimethylammonium bromide (CTAB), polyvinyl
pyrrolidone (PVP), sodium citrate, sodium dodecyl sulfate (SDS), sodium
di-2-ethylsulfosuccinate (AOT) and carboxymethyl cellulose (CMC) on the
stability of silver nanoparticles was investigated. The colloidal silver
nanoparticles with 100 μM concentration were stable for more than
3 months at 50 μM CTAB and 6 months at 10 μM sodium citrate
concentration, respectively. SEM images of the sample prepared at 50 μM
CTAB concentration reveal uniform and fine nanoparticles. The mean size from
TEM images is about 14 nm. TEM images of the sample prepared at 10 μM
sodium citrate concentration show a shell of citrate that covers the silver
nanoparticles