Single-Molecule Studies of Confined Branched Polymers

Densely branched polymers such as lubricin and mucin play a crucial role in controlling biolubrication behavior. Biolubrication occurs at interfaces, which can be modeled as confined environments. Understanding the behavior of branched polymers at the single-molecule level is critical to understanding their behavior at the ensemble level. In this study, we investigate topologically complex polymers placed in confined environments by observing changes in the diffusivity of branched polymers in 1D slit-like confinement. We demonstrate the synthesis of branched DNA polymers by enzymatic replication of linear precursors and biochemical coupling of DNA branches onto DNA backbones. We fabricate nanofluidic devices with high-aspect-ratio nanochannels using wet etch lithography on borosilicate glass substrates. We observe the single-molecule behavior of branched polymers inside nanochannels using 2-color fluorescence optical microscopy with different fluorophores coupled to the polymer backbone and branches to distinguish sub-molecular mechanisms. Understanding of molecular- scale contributions to biolubrication will enable the design of novel materials to treat lubrication-deficient diseases.