Focal molography (“molography” in short) is a biophysical method for robust and sensitive detection of biomolecular interactions in a label-free manner. The new method enables biomolecular interaction analysis in complex biological samples without the use of additional fluorescent labels. Molography widens the analytic scope of biomolecular interaction analysis techniques in a broad range of applications, e.g. label-free trace analysis of a targeted molecule (called biomarker) in complex samples, such as blood sera, bioreactor fluid or cell culture media. Contrary to refractometric methods for label-free biomolecular interaction analysis, such as surface plasmon resonance (SPR) and reflectometric interference spectroscopy (RIfS), molography allows quantification of molecular interactions in living cells in real time.