Peptide-Mediated Synthesis of Zeolitic Imidazolate Framework-8 with Controllable Morphology and Size.

Peptides with a sequence of Nap-I-GPLGLAG-R-NH ( = 2, 4, and 6, shorted as IR, IR, and IR) were used as capping agents for the synthesis of zeolitic imidazolate framework-8 (ZIF-8) in water. Peptide addition can significantly inhibit the growth of ZIF-8 crystals. The shape and size of ZIF-8 crystals was related closely to the number of isoleucine (Ile, I) residues as well as concentration of the peptide. The shape of ZIF-8 crystals changes from rhomboid dodecahedron to truncated rhombic dodecahedron to cube with the decreasing number of isoleucine residues from six to two. At a peptide concentration of 1.0 mM, the morphology of ZIF-8 crystals was cubic, truncated rhombic dodecahedron, and typical rhombic dodecahedron in the cases of IR, IR, and IR, respectively. Also, the particle size can be regulated from ca. 1.7 μm to <100 nm by controlling the peptide concentration from 0 to 2.0 mM. This work develops a simple and green method for the synthesis of ZIF-8 crystals with controllable shape and size in water, which shows high potential for biomedical and biological applications.