A new immunochemistry platform for a guideline-compliant cardiac troponin T assay at the point of care: proof of principle.

Background: A multitude of troponin assays for the point-of-care (POC) have been developed showing a lack of analytical sensitivity and precision. We present a new platform solution for the high-sensitivity detection of cardiac troponin T (cTnT) in a 30 μL whole blood sample with a turnaround time of 11 min.

Methods: The immunoassay was completely run in a ready-to-use plastic disposable, a centrifugal microfluidic disc with fully integrated reagents.

Long-range fluorescence quenching by gold nanoparticles in a sandwich immunoassay for cardiac troponin T.

We report the first homogeneous sandwich immunoassay with gold nanoparticles (AuNPs) as fluorescence quenchers. The sandwich assay is designed for the detection of the protein cardiac troponin T (cTnT) by its simultaneous interaction with two different antibodies, one attached to AuNPs and the other labeled with fluorescent dyes. We demonstrate the working principle of the assay and using time-resolved fluorescence spectroscopy, we determine the quenching efficiency of the gold nanoparticles.

Competitive homogeneous digoxigenin immunoassay based on fluorescence quenching by gold nanoparticles.

We report on a competitive, homogeneous immunoassay for the detection of the hapten digoxigenin. The assay is based on competitive fluorescence quenching by gold nanoparticles. Digoxigenin is indirectly labeled with the fluorophore Cy3B through bovine serum albumin and used as a marker.

Streptavidin reduces oxygen quenching of biotinylated ruthenium(II) and palladium(II) complexes.

Transition metal complexes such as biotinylated ruthenium(II) tris(bipyridyl) and palladium(II) porphyrin show an increase in luminescence intensity and lifetime upon binding to streptavidin in aqueous solution. Here we show that this increase of luminescence lifetime and intensity are caused by the shielding of the transition metal complexes from dissolved oxygen through streptavidin rather than by hydrophobicity effects as recently claimed.

Shaping emission spectra of fluorescent molecules with single plasmonic nanoresonators.

We show that plasmonic nanoresonators composed of two gold nanoparticles change not only the intensity but also the spectral shape of the emission of fluorescent molecules. The plasmonic resonance frequency can be tuned by varying the distance between the nanoparticles, which allows us to selectively favor transitions of a fluorescent molecule to a specific vibrational ground state. Experimental data from correlated scattering and fluorescence microscopy agree well with calculations in the framework of generalized Mie theory.