Feeling Inter‐ or Intramolecular Interactions with the Polymer Chain as Probe: Recent Progress in SMFS Studies on Macromolecular Interactions

Abstract

Single-molecule force spectroscopy (SMFS) opens new avenues for elucidating the structures and functions of large coiled molecules such as synthetic and biopolymers at the single-molecule level. In addition, some of the features in the force-extension curves (i.e. force spectra) are closely related to primary/secondary structures of the molecules being stretched. For example, the long force plateau in the DNA stretching curve is related to the double-helix structure. These features can be regarded as the force fingerprints of individual macromolecules. These force fingerprints can therefore be used as indicators/criteria of single-molecule manipulation during the measurement of some unknown intra- or intermolecular interactions. By comparing the force spectra of a single polymer chain before and after interaction with other molecules, the mode/strength of such molecular interactions can be derived. This Review focuses on recent advances in AFM-based SMFS studies on molecular interactions in both synthetic and biopolymer systems using a single macromolecular chain as probe, including interactions between nucleic acids and proteins, mechanochemistry of covalent bonds, conformation-regulated enzymatic reactions, adsorption and desorption of biopolymers on a flat surface or from the nanopore of a carbon nanotube, and polymer interactions in the condensed state.

Dependance of Poly(acrylic acid) Interfacial Adhesion on the Nanostructure of Electrodeposited ZnO Films

“…Finally, the as-obtained values are, in any case, lower than those belonging to the covalent regime. For instance, Si–C, C–C, or Au–S bonds would be in the range of 1.7–2.3, 2.0–13, and 1.5–2.2 nN, respectively. ,− …”

Pressure sensitive adhesives based on interpolymer complexes

“…Among others, the freely jointed chain (FJC) model [280,305], the wormlike chain (WLC) model [306,307], and the freely rotating chain (FRC) model and their modified forms [165,308,309] have often been used in the recent literature. In the past 20 years the many advances in singlemolecule experimental methods have provided a good opportunity to test these models [270,281,309,310]. To date, the stretching behavior of many kinds of polymers, including neutral polymers and polyelectrolytes, has been investigated at the single-chain level [281,304].…”

Single-Molecule Force Spectroscopy Study on the Mechanism of RNA Disassembly in Tobacco Mosaic Virus

“…According to the brilliant work by Vanzi et al (67), we know that Escherichia coli 70S ribosomes can hold the messenger RNA even at an external force of 100 pN. In addition, the translocation energy during ribosomal protein synthesis is~7.3 kcal/mol  4.2 ¼ 30.66 kJ/mol z 12.4 kT per amino acid (35), which is not very far from the one estimated by our AFM experiment (3  0.7 nm  60 pN z 30 kT). The difference may be ascribed to the different environment inside the plant cell.…”