Abstract
Confinement of single molecules within nanoscale environments is crucial in a range of fields, including biomedicine, genomics, and biophysics. Here, we present a method that can concentrate, confine, and linearly stretch DNA molecules within a single optical field of view using dielectrophoretic (DEP) force. The method can convert an open surface into one confining DNA molecules without a requirement for bonding, hydrodynamic or mechanical components. We use a transverse DEP field between a top coverslip and a bottom substrate, both of which are coated with a transparent conductive material. Both layers are attached using double-sided tape, defining the chamber. The nanofeatures lie at the “floor” and do not require any bonding. With the application of an alternating (AC) electric field (2 Vp-p) between the top and bottom electrodes, a DEP field gradient is established and used to concentrate, confine and linearly extend DNA in nanogrooves as small as 100-nm in width. We also demonstrate reversible loading/unloading of DNA molecules into nanogrooves and nanopits by switching frequency (between 10 kHz to 100 kHz). The technology presented in this paper provides a new method for single-molecule trapping and analysis.
Highlights
DNA linearization plays an important role in achieving scientific insights into polymer physics and shows great potential in DNA sequencing and mapping[1]
Dielectrophoresis (DEP) is a phenomenon that occurs with a non-uniform electric field, in which an electrically neutral particle feels a force due to the interaction between the electric field and the particle’s induced dipole moment
Switching between positive and negative DEP can be achieved by adjusting the frequency of the electric field
Summary
DNA linearization plays an important role in achieving scientific insights into polymer physics and shows great potential in DNA sequencing and mapping[1]. In the micro-nano fluidic approach, the abrupt increase in dimension from the macro- to the nano-scale is associated with sharp increase in free energy and a large free energy barrier, preventing molecules from entering the nanoconfined region Overcoming this barrier requires high hydrodynamic pressure at the micro-nano interface, which can potentially lead to DNA fragmentation. Due to the radius of curvature of the curved surface, the confinement varies from the convex surface to the centre of the confinement area, creating only a localized degree of confinement Another approach, mechanical collapse of triangular elastomeric nanochannels for stretching DNA offers a robust method for confinement that avoids creating a large confinement gradient[30]. The nanochannel approach allows for continuous measurement while keeping the DNA constantly in the field of view for extended periods
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