The immunoinhibitory receptor PD-1 and its ligand PD-L1 exhibit a flat, undruggable interaction interface formed by rich β-strands, which creates challenges for the development of artificial antagonists with which to block this interface. Peptide self-assemblies (PSAs) are thought to undergo a hierarchical bottom-up process based on the formation of secondary structures such as β-sheets, which results in increased rigidity and control over the display angle of the binding motif. Zhang et al. aimed to target the PD-1–PD-L1 interface by preparing a series of cross-β PSAs with different β-sheet tilted angles of NQ30, a peptide identified as targeting PD-L1. NQ30 alterations with hydrophobic residues or hydrophilic residues generated NQ0 or NQ40, respectively. NQ0 formed nanobelts, whereas NQ40 formed nanotubes, which suggests that the thickness of PSAs varies as a result of the different degrees of tilting. Structure–activity relationship analysis indicated that NQ40 can transform into nanofibers that can recognize, respond to and block the flat surface pharmacophore on PD-L1 at molecular, cellular and in vivo levels. This innovative strategy for constructing β-sheets with tilted angles will enable the controllable design of tailored peptide assembly structures for specific applications.