Abstract
Nanophotonic tweezers represent emerging platforms with significant potential for parallel manipulation and measurements of single biological molecules on-chip. However, trapping force generation represents a substantial obstacle for their broader utility. Here, we present a resonator nanophotonic standing-wave array trap (resonator-nSWAT) that demonstrates significant force enhancement. This platform integrates a critically-coupled resonator design to the nSWAT and incorporates a novel trap reset scheme. The nSWAT can now perform standard single-molecule experiments, including stretching DNA molecules to measure their force-extension relations, unzipping DNA molecules, and disrupting and mapping protein-DNA interactions. These experiments have realized trapping forces on the order of 20 pN while demonstrating base-pair resolution with measurements performed on multiple molecules in parallel. Thus, the resonator-nSWAT platform now meets the benchmarks of a table-top precision optical trapping instrument in terms of force generation and resolution. This represents the first demonstration of a nanophotonic platform for such single-molecule experiments.
Highlights
Nanophotonic tweezers represent emerging platforms with significant potential for parallel manipulation and measurements of single biological molecules on-chip
The light is split via a 50/50 beam splitter into two paths, which are directed to two separate nanophotonic standing-wave array trap (nSWAT) that work in conjunction in an experiment
The single-molecule sample is sent into the nSWAT flow chamber (“method similar to what has been described32 (Methods)”) through a gravity flow cell system (Supplementary Method 6)
Summary
Nanophotonic tweezers represent emerging platforms with significant potential for parallel manipulation and measurements of single biological molecules on-chip. Using near-field evanescent waves at the surface of an on-chip structure, these new trapping platforms can be mass-produced, are efficient at trapping particles at high throughput, are more compact than traditional optical tweezers, and are inherently robust against noise They open new opportunities for the manipulation and measurement of individual biological molecules on-chip[16,17]. This type of experiment is essential in optical trapping instruments This performance expectation has presented substantial challenges for previous nanophotonic structures[22,23,24,25,26,27,28,29,30,31], a promising platform is the recent development of the nanophotonic standing-wave array trap (nSWAT)[32] (Fig. 1a; Supplementary Movie 1) that is capable of precision position control and flexible relocation of a trap array. The nSWAT creates an array of traps by recycling the same light without proportionally increasing the light power
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