Abstract: The emerging nanotechnology in biomedicine has sparked new hope for the treatment and diagnosis of various important human diseases. However, development of functional nanomaterials and nanodevices can be encumbered by unanticipated material properties and biological events, which can negatively impact their effectiveness when introduced into complex, physiologically relevant systems. In this talk I will report on the preparation of a polymeric nanoparticle enclosed in the plasma membrane of natural human cells (e.g., RBCs, platelets, cancer cells, etc). The resulting cell membrane-coated nanoparticles are demonstrated to possess many surface functions of natural cells via studies of interactions with plasma proteins, cells, tissues, and microorganisms. Such multifaceted cell-mimicking properties can be attributed to the preservation of biomembrane on nanoparticle surfaces, which facilitates the display of intricate biochemistry that is difficult to replicate using conventional functionalization approaches. As the platform is entirely biocompatible and biodegradable, it can be applied toward a myriad of biomedical applications, including drug delivery, detoxification and vaccination, where the vast implications of cell surface properties may benefit a variety of disease treatments.