Measurement of mouse urinary type IV collagen using time-resolved fluoroimmunoassay

Indole-3-acetic acid biosensor based on G-rich DNA labeled AuNPs as chemiluminescence probe coupling the DNA signal amplification

A highly sensitive chemiluminescence (CL) method for detection of phytohormone indole-3-acetic acid (IAA) was developed by using G-rich DNA labeled gold nanoparticles (AuNPs) as CL probe coupling the DNA signal amplification technology. The IAA antibody was immobilized on carboxyl terminated magnetic beads (MBs). In the presence of IAA, antibody labeled AuNPs were captured by antibody functionalized MBs. The DNA on AuNPs is released by a ligand exchange process induced by the addition of DTT. The released DNA is then acted as the linker and hybridized with the capture DNA on MBs and probe DNA on AuNPs CL probe. The CL signal is obtained via the instantaneous derivatization reaction between a specific CL reagent, 3,4,5-trimethoxyl-phenylglyoxal (TMPG), and the G-rich DNA on AuNPs CL probe. IAA can be detected in the concentration range from 0.02 ng/mL to 30 ng/mL, and the limit of detection is 0.01 ng/mL.

Lanthanide complex-based fluorescence label for time-resolved fluorescence bioassay

Different from organic fluorescence dyes, fluorescent lanthanide complexes have the fluorescence properties of long fluorescence lifetime, large Stokes shift and sharp emission profile, which makes them favorable be used as the fluorescent labeling reagents for microsecond time-resolved fluorescence bioassay. Lanthanide complex-based fluorescence labels have been successfully used for highly sensitive time-resolved fluorescence immunoassay, DNA hybridization assay, cell activity assay, and bio-imaging microscopy assay. Since the technique allows easy distinction of the specific fluorescence signal of the long-lived label from short-lived background noises associated with biological samples, scattering lights (Tyndall, Rayleigh and Raman scatterings) and the optical components (cuvettes, filters and lenses), the sensitivity of fluorescence bioassay has been remarkably improved. This paper summarized the recent developments of lanthanide complex-based fluorescence labels and their applications in time-resolved fluorescence bioassays mainly based on the authors' researches and relative publications.