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Rational Design of Multilayer Collagen Nanosheets with Compositional and Structural Control
- Jiang, Tao, Vail, Owen A., Jiang, Zhigang, Zuo, Xiaobing, Conticello, Vincent P.
- Journal of the American Chemical Society 2015 v.137 no.24 pp. 7793-7802
- calcium, collagen, electrostatic interactions, image analysis, microscopy, nanoparticles, nanosheets, peptides, zeta potential
- Two collagen-mimetic peptides, CP⁺ and CP–, are reported in which the sequences comprise a multiblock architecture having positively charged N-terminal (Pro-Arg-Gly)₃ and negatively charged C-terminal (Glu-Hyp-Gly)₃ triad extensions, respectively. CP⁺ rapidly self-associates into positively charged nanosheets based on a monolayer structure. In contrast, CP– self-assembles to form negatively charged monolayer nanosheets at a much slower rate, which can be accelerated in the presence of calcium(II) ion. A 2:1 mixture of unassociated CP– peptide with preformed CP⁺ nanosheets generates structurally defined triple-layer nanosheets in which two CP– monolayers have formed on the identical surfaces of the CP⁺ nanosheet template. Experimental data from electrostatic force microscopy (EFM) image analysis, zeta potential measurements, and charged nanoparticle binding assays support a negative surface charge state for the triple-layer nanosheets, which is the reverse of the positive surface charge state observed for the CP⁺ monolayer nanosheets. The electrostatic complementarity between the CP⁺ and CP– triple helical cohesive ends at the layer interfaces promotes a (CP–/CP⁺/CP–) compositional gradient along the z-direction of the nanosheet. This structurally informed approach represents an attractive strategy for the fabrication of two-dimensional nanostructures with compositional control.