Bioconjugated Core–Shell Microparticles for High-Force Optical Trapping

Juan Carlos Cordova, Dana N. Reinemann, Daniel J. Laky, William R. Hesse, Sophie K. Tushak, Zane L. Weltman, Kelsea B. Best, Rizia Bardhan, Matthew J. Lang

Due to their high spatial resolution and precise application of force, optical traps are widely used to study the mechanics of biomolecules and biopolymers at the single-molecule level. Recently, core–shell particles with optical properties that enhance their trapping ability represent promising candidates for high-force experiments. To fully harness their properties, methods for functionalizing these particles with biocompatible handles are required. Here, a straightforward synthesis is provided for producing functional titania core–shell microparticles with proteins and nucleic acids by adding a silane–thiol chemical group to the shell surface. These particles display higher trap stiffness compared to conventional plastic beads featured in optical tweezers experiments. These core–shell microparticles are also utilized in biophysical assays such as amyloid fiber pulling and actin rupturing to demonstrate their high-force applications. It is anticipated that the functionalized core–shells can be used to probe the mechanics of stable proteins structures that are inaccessible using current trapping techniques.

DOI