Max-Planck-Institute of Colloids and Interfaces, 14424 Potsdam, Germany
The endocytosis of nanoparticles by biomembranes is essential for many processes such as biomedical imaging, drug delivery, nanotoxicity, and viral infection. In all cases, the cellular uptake of the nanoparticles starts with the adhesion of the nanoparticles to the membranes, followed by the complete engulfment of these particles. The key parameters for these endocytic processes are particle size and adhesive strength of the particle-membrane interactions as well as bending rigidity and spontaneous curvature of the membranes. [1, 2] In fact, these parameters determine four different regimes for the engulfment of a single nanoparticle.  When a vesicle interacts with many nanoparticles, it can exhibit a variety of engulfment patterns consisting of up to three different engulfment regimes. [3, 4] Under certain conditions, the nanoparticles may assemble into membrane nanotubes.  Partially engulfed particles ex- perience curvature-induced forces that push the particles towards minima of the membrane curvature.  Completely engulfed particles involve a narrow membrane neck that connects the particle-bound membrane with the mother membrane. The formation of these necks is gov- erned by local stability conditions. [2, 6] Our theory provides a quantitative explanation for the nonmonotonic dependence of particle uptake on particle size as observed for clathrin-dependent endocytosis of gold nanoparticles. 
 R. Lipowsky and H. G. Döbereiner. Vesicles in contact with nanoparticles and colloids. Europhys. Lett., 43:219–225, 1998.
 J. Agudo-Canalejo and R. Lipowsky. Critical Particle Sizes for the Engulfment of Nanopar- ticles by Membranes and Vesicles with Bilayer Asymmetry. ACS Nano, 9:3704–3720, 2015.
 J.Agudo Canalejo and R.Lipowsky. Adhesive Nanoparticles as Local Probes of Membrane Curvature. Nano Letters, 15:7168–7173, 2015.
 J. Agudo-Canalejo and R. Lipowsky. Uniform and janus-like nanoparticles in contact with vesicles: energy landscapes and curvature-induced forces. Soft Matter, page DOI: 10.1039/c6sm02796b, 2017.
 A. H. Bahrami, R. Lipowsky, and T. R. Weikl. Tubulation and Aggregation of Spherical Nanoparticles Adsorbed on Vesicles. Phys. Rev. Lett., 109:188102, 2012.
 J. Agudo-Canalejo and R. Lipowsky. Stabilization of membrane necks by adhesive parti- cles, substrate surfaces, and constriction forces. Soft Matter, 12:8155–8166, 2016.
Summary of academic career
Prof. Reinhard Lipowsky received his doctoral degree in physics from the University of Munich in 1982. He subsequently worked as a research associate at Cornell University and at the Re- search Center Jülich, and became a Professor of Theoretical Physics at the University of Munich in 1989. From 1990 until 1993 he was department head at the Research Center Jülich and pro- fessor at the University of Cologne. In 1993, he became a scientific member of the Max Planck Society and established the new department of “Theory and Biosystems” at the Max Planck Insitute of Colloids and Interfaces. The department currently hosts 11 research groups with 57 researchers. Prof. Lipowsky is a member of the Berlin-Brandenburg Academy of Sciences, has a honorary professorship at the University of Potsdam and at the Humboldt-University Berlin, and is the speaker of the International Max Planck Research School (IMPRS) on "Multiscale Biosystems".