We are pleased to present this joint special issue of Macromolecular Bioscience and Advanced Materials Interfaces titled “Biointerfaces and Biopolymers”. In the last decades there has been an explosion in material science with revolutionary concepts that merge the state-of-the-art in chemistry, physics, and biology, with nanoscience and technology. Concurrently, basic research in biological materials has started to shed light in nature's design rules, which allows unprecedented functionality by the self-assembly of molecules across several levels of hierarchy, scales and time domains. These advances are synergistically being translated to a number of biomaterials, implants, medical devices, biosensors or drug carriers which are having a huge impact in society. A contemporary example of this, are vaccines consisting of RNA encapsulated in lipid nanoparticles that protect us against SARS-CoV-2. Arguably, the success of these technologies demands a seamless integration by programming and controlling what happens at the interface between the non-biological material and the biological environment. Following the scientific advances of especially the last two decades, the current trend is to deliver increasingly cleverly designed complexity at the molecular and supramolecular level and to steer lifeless matter towards tuned and often optimized interactions with biological materials. A cornerstone for this goal – and we expect this to be a further trend in the decade to come – is to display a high degree of selectivity, which means to be invisible to unwanted interactions while allowing or preferably even enhancing the specific ones. This issue encompasses work on antifouling, antimicrobial coatings, efforts to understand the way they interact with biological media, including nucleic acid, proteins, bacteria, marine organisms and blood as well as applications such as biolubrication, adhesion, biosensing, tissue engineering, drug and gene delivery. The breadth of the research is immediately clear by the number of different material classes studied, including polymer nanocoatings, sharklet-inspired microstructures, inorganic materials, cell membrane mimics as well as by the applications addressed. The articles summarize some of the most important and urgent challenges of the field and also pose some central questions which should be pursued. We thank all who contributed their articles for this issue as well as the Macromolecular Bioscience and Advanced Materials Interfaces' editorial offices, and hope and trust this issue will spark new ideas and contribute to further advances in the field.