Single polymer chains as specific transducers of molecular recognition in scanning probe microscopy.
A new approach for the specific detection and mapping of single molecule recognition is presented, based on the nonlinear elastic behavior of a single polymer chain. The process of molecular recognition between a ligand and a receptor is inherently accompanied by a decrease in the translational and rotational degrees of freedom of the two molecules. We show that a polymeric tether linked to the ligand can effectively transduce the configurational constraint imposed by molecular recognition into a measurable force, which is dominated by the entropic elasticity of the polymer. This force is specifically characterized by a strong nonlinearity when the extension of the polymer approaches its contour length. Thus, a polymer chain tethering the ligand to an oscillating cantilevered tip gives rise to a highly anharmonic motion upon ligand-receptor binding. Higher-harmonics atomic force microscopy allows us to detect this phenomenon in real time as a specific signature for the probing and mapping of single-molecule recognition.
Gabai
Rachel
R
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel.
Segev
Lior
L
Joselevich
Ernesto
E
D019277:Entropy; D008024:Ligands; D018625:Microscopy, Atomic Force / Q000379:methods*; D015335:Molecular Probes / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D014159:Transducers
D008024:Ligands; D015335:Molecular Probes; D011108:Polymers