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  3. Ligand Presentation Inside Protein Crystal Nanopores: Tunable Interfacial Adhesion Noncovalently Modulates Cell Attachment

Ligand Presentation Inside Protein Crystal Nanopores: Tunable Interfacial Adhesion Noncovalently Modulates Cell Attachment

  • Mater Today Nano. 2023 Dec:24:100432. doi: 10.1016/j.mtnano.2023.100432.
Dafu Wang 1 2,  Mohammadhasan Hedayati 1,  Julius D Stuart 3,  Liszt Y C Madruga 1,  Ketul C Popat 1,  Christopher D Snow 1 2 3 4,  Matt J Kipper 1 2 4
Affiliations

Affiliations

  • 1 Department of Chemical and Biological Engineering, Colorado State University, 1370Campus Delivery, Fort Collins, CO 80523, U.S.A.
  • 2 School of Advanced Materials Discovery, Colorado State University, 1617 Campus Delivery, Fort Collins, CO 80523, U.S.A.
  • 3 Department of Chemistry, Colorado State University, 1872 Campus Delivery, FortCollins, CO 80523, U.S.A.
  • 4 School of Biomedical Engineering, Colorado State University, 1301 Campus Delivery, Fort Collins, CO 80523, U.S.A.
PMID: 38370345 DOI: 10.1016/j.mtnano.2023.100432
Abstract

Protein crystals with sufficiently large solvent pores can non-covalently adsorb Polymers in the pores. In principle, if these Polymers contain cell adhesion ligands, the polymer-laden crystals could present ligands to cells with tunable adhesion strength. Moreover, porous protein crystals can store an internal ligand reservoir, so that the surface can be replenished. In this study, we demonstrate that poly(ethylene glycol) terminated with a cyclic cell adhesion ligand peptide (PEG-RGD) can be loaded into porous protein crystals by diffusion. Through atomic force microscopy (AFM), force-distance correlations of the mechanical interactions between activated AFM tips and protein crystals were precisely measured. The activation of AFM tips allows the tips to interact with PEG-RGD that was pre-loaded in the protein crystal nanopores, mimicking how a cell might attach to and pull on the ligand through Integrin receptors. The AFM experiments also simultaneously reveal the detailed morphology of the buffer-immersed nanoporous protein crystal surface. We also show that porous protein crystals (without and with loaded PEG-RGD) serve as suitable substrates for attachment and spreading of adipose-derived stem cells. This strategy can be used to design surfaces that non-covalently present multiple different ligands to cells with tunable adhesive strength for each ligand, and with an internal reservoir to replenish the precisely defined crystalline surface.

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