Biochemical Analyses

Biochemical Laboratory

The Biochemical Laboratory of the Department of Biological and Clinical Psychology provides a range of analytical methods for assessing biomarkers in blood, saliva, urine, and cell culture supernatants.

Salivary Cortisol – DELFIA
More than 30 years ago, the development of a highly specific method for analyzing cortisol in saliva (Dressendörfer et al., 1992) laid the foundation for numerous studies on hypothalamic-pituitary-adrenal (HPA) axis reactivity. Cortisol, the end product of the HPA axis, is commonly measured in psychobiological research. Since only the unbound fraction of cortisol is biologically active, salivary cortisol provides a reliable, non-invasive index of free cortisol levels, showing high correlations with serum concentrations (r ≈ .90).
We determine salivary cortisol concentrations using the highly sensitive DELFIA (Dissociation-Enhanced Lanthanide Fluorescent Immunoassay). This fluorescence-based immunoassay employs lanthanide chelates as markers, offering low background noise, high sensitivity, and a broad dynamic range.

Salivary Alpha-Amylase
Alpha-amylase is an enzyme found in saliva and other body fluids that breaks down starch and glycogen into simple sugars. It is produced mainly by the salivary glands and the pancreas. In psychophysiological research, salivary alpha-amylase serves as an indirect marker of sympathetic activation and acute stress responses.
Activity is quantified using a colorimetric assay with 2-Chloro-4-Nitrophenyl-αD-maltotrioside (CNP-G3) as the substrate. The color change resulting from enzymatic cleavage is measured photometrically and reflects alpha-amylase activity.

Salivary Sex Steroids
Steroid hormones such as estradiol, progesterone, and testosterone can also be measured in saliva, providing a non-invasive index of endocrine function. Correlations with plasma levels are moderate to high, depending on the hormone and assay used (r ≈ 0.5–0.9).
Hormone quantification is performed using commercial ELISA kits (e.g., Demeditec, Salimetrics, IBL) based on competitive binding principles. The resulting colorimetric reaction is photometrically analyzed, and hormone concentrations are calculated by interpolation from standard curves.

Together, these methods enable precise and non-invasive assessment of key psychobiological markers involved in stress, endocrine regulation, and emotion-related physiological processes.