•A stepwise molecular design of peptide to functionalize the large-diameter SWCNT.•Two kinds of functional peptides were designed for the armchair (24, 24) SWCNT.•The residues with aromatic rings and long alkylene chains were found to be most effective in the adsorption of peptide on the SWCNT surface.•The predominant driving force of protein/peptide onto the SWCNT surface was VDW interaction.•The adsorption manner of the protein/peptide was affected by the flexibility of size chains.Single-walled carbon nanotube (SWCNT) is one of the most popular low-dimensional carbon materials in material science, nanomedicine, and nanoscale electronics. Yet the application of the SWCNTs was hindered by the self-aggregation. To purify and disperse the SWCNTs, non-covalent wrapping is one of the effective options to overcome such defects. In this work, two kinds of short peptides were designed to facilitate the modification of large-diameter SWCNT. The design of the peptide was carried out in a stepwise manner. The effective residues of helix-rich and sheet-rich proteins on SWCNT were studied at the first step, and then a coarse model peptide composed of the key adsorption residues above was built to investigate the adsorption dynamics on SWCNT. In the end, the residues include long alkyl side chain and that include aromatic rings were found to play key roles on the adsorption of protein/peptide on hydrophobic SWCNT. And two peptides rich in the long alkyl chain and aromatic rings were constructed respectively. The predominant adsorption capabilities of the two kinds of peptides were discerned by the adsorption details.

Insulin-like growth factor-binding proteins (IGFBPs) control bioactivity and distribution of insulin-like growth factors (IGFs) through high-affinity complex of IGFBP and IGF. To get more insight into the binding interaction of IGF system, the site-directed mutagenesis and force-driving desorption methods were employed to study the interaction mechanism of IGFBP4 and IGF-I by molecular dynamics (MD) simulation. In IGF-I, residues Gly7 to Asp12 were found to be the hot spots and they mainly anchored on the N-domain of IGFBP4. The contact area, the shape and size of protein, the surroundings of the binding site, the hydrophobic and electrostatic interaction between the two proteins worked as a complex network to regulate the protein-protein interaction. It was also found that the unfolding of the helix was not inevitable in the mutant, and it could be regulated by careful selection of the substituted amino acid.