title: Novel polymer linkers for single molecule AFM force spectroscopy.
abstract: Flexible polymer linkers play an important role in various imaging and probing techniques that require surface immobilization, including atomic force microscopy (AFM). In AFM force spectroscopy, polymer linkers are necessary for the covalent attachment of molecules of interest to the AFM tip and the surface. The polymer linkers tether the molecules and provide their proper orientation in probing experiments. Additionally, the linkers separate specific interactions from nonspecific short-range adhesion and serve as a reference point for the quantitative analysis of single molecule probing events. In this report, we present our results on the synthesis and testing of a novel polymer linker and the identification of a number of potential applications for its use in AFM force spectroscopy experiments. The synthesis of the linker is based on the well-developed phosphoramidate (PA) chemistry that allows the routine synthesis of linkers with predetermined lengths and PA composition. These linkers are homogeneous in length and can be terminated with various functional groups. PA linkers with different functional groups were synthesized and tested in experimental systems utilizing different immobilization chemistries. We probed interactions between complementary DNA oligonucleotides; DNA and protein complexes formed by the site-specific binding protein SfiI; and interactions between amyloid peptide (Aβ42). The results of the AFM force spectroscopy experiments validated the feasibility of the proposed approach for the linker design and synthesis. Furthermore, the properties of the tether (length, functional groups) can be adjusted to meet the specific requirements for different force spectroscopy experiments and system characteristics, suggesting that it could be used for a large number of various applications.
authors.affiliation: Department of Pharmaceutical Sciences, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE 68198, USA.
authors.forename: Zenghan
authors.initials: Z
authors.lastname: Tong
authors.forename: Andrey
authors.initials: A
authors.lastname: Mikheikin
authors.forename: Alexey
authors.initials: A
authors.lastname: Krasnoslobodtsev
authors.forename: Zhengjian
authors.initials: Z
authors.lastname: Lv
authors.forename: Yuri L
authors.initials: YL
authors.lastname: Lyubchenko
mesh_terms: D000577:Amides / Q000737:chemistry; D000588:Amines / Q000737:chemistry; D016229:Amyloid beta-Peptides / Q000737:chemistry; D004247:DNA / Q000737:chemistry; D015252:Deoxyribonucleases, Type II Site-Specific / Q000737:chemistry; D055595:Mechanical Phenomena; D018625:Microscopy, Atomic Force / Q000379:methods*; D010446:Peptide Fragments / Q000737:chemistry; D010756:Phosphoric Acids / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry*; D011485:Protein Binding; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000577:Amides; D000588:Amines; D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; D010756:Phosphoric Acids; D013438:Sulfhydryl Compounds; C075222:amyloid beta-protein (1-42); D011092:Polyethylene Glycols; D004247:DNA; C011067:phosphoramidic acid; C041749:endodeoxyribonuclease SfiI; D015252:Deoxyribonucleases, Type II Site-Specific