Polymer-Based Accurate Positioning: An Exact Worm-like-ChainStudy

摘要

Precise positioning of molecular objects from one location toanother is important for nanomanipulation and is also involved in molecularmotors. Here, we study single-polymer-based positioning on the basis of theexact solution to the realistic three-dimensional worm-like-chain (WLC) model.The results suggest the possibility of a surprisingly accurate flyfishing-likepositioning in which tilting one end of a flexible short polymer enablespositioning of the other diffusing end to a distant location within an error of ～1nm. This offers a new mechanism for designing molecular positioning devices.The flyfishing effect (and reverse process) likely plays a role in biologicalmolecular motors and may be used to improve speed of artificial counterparts.To facilitate these applications, a new force?extension formula is obtained fromthe exact WLC solution. This formula has an improved accuracy over the widelyused Marko?Siggia formula for stretched polymers and is valid for compressedpolymers too. The new formula is useful in analysis of single-moleculestretching experiments and in estimating intramolecular forces of molecular motors, especially those involving both stretchedand compressed polymer components.