Using fluorescence correlation spectroscopy (FCS) for IFN-g detection: a preliminary study.

Nowadays, enzyme-linked immunosorbent assay (ELISA) based detection of Mycobacterium tuberculosis (M. tuberculosis) antigen triggered interferon-gamma (IFN-g) secretion by blood T cells displays an improved diagnostic value for M. tuberculosis infection. Applications of fluorescence correlation spectroscopy (FCS) have been explored in various subfields of medicine and molecular biology, including detection of a certain biomarker in liquid instead of ELISA. Here, we present a preliminary study of detecting IFN-g using FCS-based technique.

In vitro detection of adrenocorticotropic hormone levels by fluorescence correlation spectroscopy immunoassay for mathematical modeling of glucocorticoid-mediated feedback mechanisms.

Performing quantitative, highly sensitive measurements at a single molecule level is often necessary to address specific issues related to complex molecular and biochemical systems. For that purpose, we present a technique exploiting both the flexibility of immunoassays as well as the low operating costs and high throughput rates of the fluorescence correlation spectroscopy (FCS) method. That way we have established a quantitative measurement technique providing accurate and flexibly time resolved data of single molecules. Nanomolar changes in adrenocorticotropic hormone (ACTH) levels have been detected in a short time-frame that are caused by fast feedback actions in AtT-20 anterior pituitary glands in vitro. Especially with respect to clinical diagnostic or mathematical modeling this improved FCS setup may be of high relevance in order to accurately quantify the amounts of peptide hormones-such as ACTH-as well as signaling molecules, transcription factors, etc., being involved in intra- and extracellular reaction networks.