Biomembranes are frequently in contact with other substrates, often mediated by a polymeric interface such as the glycocalyx. A number of challenges which this form of surface tethering involve also matter for biomedical membrane applications, in particular drug delivery. In this talk I will propose a novel design for drug delivery carriers, namely nanoparticles to which an enveloping membrane is tethered via a mediating polymer brush. Simple ideas, such as geometry, scaling, and membrane or polymer theory, permit one to significantly reduce the in principle large parameter space for such a design. Coarse-grained simulations of complete tethered nanoparticle complexes can verify these predictions, but also provide new insights into phenomena that are difficult to treat in an analytical way, such as cooperative deformations, polymer polydispersity, or actual dynamical pathways for the creation of such constructs in the laboratory. The lessons learned from this biomedical inspired system might ultimately also help to better understand the much more complex case of biomembranes anchored to other substrates via polymer cushions.