The development of efficient drug carriers is a major challenge in the field of drug delivery. Most existing delivery systems do not deliver their cargo efficiently or are rapidly inactivated by the immune system leading to unwanted side effects or no effect at all. Shedding microvesicles are cell-derived membrane vesicles constituting the body's own intercellular “shuttle service”. Due to their physiological constitution and stability in biological liquids these carriers hold great promise in fundamentally improving efficient drug delivery. The goal of this project is to assess the potential of shedding microvesicles as drug delivery vehicles by means of an innovative and broadly applicable assay for the detection of enzymes in living cells. Measurement of intracellular enzyme activity is crucial for the elucidation of molecular disease mechanisms and the development of efficient treatment strategies. The versatile enzyme assay is based on a novel nanoneedle system which allows parallel detection of intracellular enzyme activity. Nanoneedles are functionalized with different enzyme-specific, short fluorophore-labelled peptides. Once introduced into living cells, peptides will be cleaved intracellular releasing the fluorophore leading to a specific emission pattern depending on which intracellular enzymes are active. The assay constitutes a simple but broadly applicable technique for the measurement of any intracellular enzyme activity and can be adapted to monitor other cellular processes. In this regard, I propose to study shedding microvesicles and to develop them as unique drug loaded “Trojan horses” using the versatile enzyme nano assay. These microvesicles have not been explored in-depth for drug delivery purposes. Thus, this project will pave the way towards a better understanding of successful drug delivery. It will enable a plethora of new treatment strategies which will be highly beneficial for patients and will strengthen scientific excellence in Europe.