Accessible high-performance double nanohole tweezers

Abstract

Nanohole optical tweezers have been used by several groups to trap and analyze proteins. In this work, we demonstrate that it is possible to create high-performance double nanohole (DNH) substrates for trapping proteins without the need for any top-down approaches (such as electron microscopy or focused-ion beam milling). Using polarization analysis, we identify DNHs as well as determine their orientation and then use them for trapping. We are also able to identify other hole configurations, such as single, trimers and other clusters. We explore changing the substrate from glass to polyvinyl chloride to enhance trapping ability, showing 7 times lower minimum trapping power, which we believe is due to reduced surface repulsion. Finally, we present tape exfoliation as a means to expose DNHs without damaging sonication or chemical methods. Overall, these approaches make high quality optical trapping using DNH structures accessible to a broad scientific community.

Future Prospects for Biomolecular Trapping with Nanostructured Metals

“…Unlike biolayer interferometry, the aperture optical tweezer does not require surface tethers/binding, and it operates at the single molecule level. Fabrication complexity and cost has also been a challenge for nanotechnologies; however, colloidal-based techniques offer a facile way of creating high-quality DNHs for optical tweezing of proteins and other biomolecules. , Field-induced breakdown may allow for colocating the DNH with a nanopore, which would greatly simplify this dual method that has already shown remarkable application to immunotherapy targets. , Therefore, it is my perspective that recent advances have improved the prospects of this technique becoming a widely used technology.…”

“…The double-nanohole structure can be fabricated by inexpensive colloidal methods and identified and oriented without the need for electron microscopy or ion beam milling . This makes the approach accessible to anyone that has a common laser tweezer setup and the facilities to evaporate thin metal films.…”

“…The double-nanohole structure can be fabricated by inexpensive colloidal methods 49 and identified and oriented without the need for electron microscopy or ion beam milling. 50 This makes the approach accessible to anyone that has a common laser tweezer setup and the facilities to evaporate thin metal films. Therefore, aperture-based optical tweezers for single protein analysis have become a tool broadly accessible to researchers without any specialized facilities or advanced nanofabrication.…”

Fringe Dielectrophoresis Nanoaperture Optical Trapping with Order of Magnitude Speed-Up for Unmodified Proteins

“…36,37 Nanohole film samples were prepared in gold on glass as in a past work. 37 The dimensions were 20 nm for the cusp size and 330 nm for the diameter. A typical electron micrograph of the sample is shown in the Supporting Information Figure 1.…”

“…Figure a shows a schematic of the optical tweezer system containing a gold film with double nanoholes, fabricated as described previously. , Nanohole film samples were prepared in gold on glass as in a past work . The dimensions were 20 nm for the cusp size and 330 nm for the diameter.…”