The thesis aimed to develop and characterize a novel detection approach, which we termed aptaPCR exploiting nucleic acid aptamers as combined recognition and reporter biocomponents for the ultrasensitive detection of analytes. Nucleic acid aptamers are synthetic ligands selected from vast combinatorial libraries through a process referred to as SELEX – Systematic Evolution of Ligand By Exponential Enrichment. As compared to other natural and synthetic receptor, aptamers possess unique chemical and biochemical characteristics, such as: a well known chemistry, remarkable stability, an ability to be selected against virtually any target even in non-physiological conditions