title: Forced unfolding of single-chain polymeric nanoparticles.
abstract: Atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS) is applied to single-chain polymeric nanoparticles (SCPNs) to acquire information about the internal folding structure of SCPNs and inherent kinetic parameters of supramolecular self-assembling motifs embedded into the SCPNs. The SCPNs used here are polyacrylate-based polymers carrying 2-ureido-4-[1H]-pyrimidinone (UPy) or benzene-1,3,5-tricarboxamide (BTA) pendants that induce an intramolecular chain collapse into nanoparticles consisting of one polymer chain only via internal supramolecular cross-linking. The SCPN is stretched by an AFM cantilever to unfold mechanically, which allows measuring of force-extension profiles of the SCPNs. Consecutive peaks observed in the force profiles are attributed to rupture events of self-assembled UPy/BTA units in the SCPNs. The force profiles have been analyzed statistically for a series of polymers with different UPy/BTA incorporation densities. The results provide insights into the internal conformation of SCPNs, where the folding structure can be changed with the incorporation density of UPy/BTA. In addition, dynamic loading rate analysis allows the determination of kinetic parameters of BTA self-assembly, which has not been accessible by any other method. This study offers a rational tool for understanding the folding structure, kinetics, and pathway of two series of SCPNs.
authors.affiliation: †Institute for Complex Molecular Systems and Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.|‡Department of Chemistry, University of California, 1102 Natural Sciences 2, Irvine, California 92697, United States.
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Hosono
authors.affiliation: ‡Department of Chemistry, University of California, 1102 Natural Sciences 2, Irvine, California 92697, United States.
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Kushner
authors.affiliation: ‡Department of Chemistry, University of California, 1102 Natural Sciences 2, Irvine, California 92697, United States.
authors.forename: Jaeyoon
authors.initials: J
authors.lastname: Chung
authors.affiliation: †Institute for Complex Molecular Systems and Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: Anja R A
authors.initials: AR
authors.lastname: Palmans
authors.affiliation: ‡Department of Chemistry, University of California, 1102 Natural Sciences 2, Irvine, California 92697, United States.
authors.forename: Zhibin
authors.initials: Z
authors.lastname: Guan
authors.affiliation: †Institute for Complex Molecular Systems and Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: E W
authors.initials: EW
authors.lastname: Meijer
mesh_terms: D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*
chemical_list: D011108:Polymers